Just a simple poll:
Is the ISF Recommended Luminance of 12 foot-lamberts Bright Enough for Your Tastes?

nope nowhere close.

I dont even wake up unless its over 20... and prefer 30+

I like this because of a couple things
1. you can actually see the image
2. I have a very big theater room. Like volume of audio if you put xx decibels that sound good in a small room into a big room you likely will yawn. You have to push the volume up to engross the soundstage. Same with light. 12 ftlamberts in a small room may be fine. My theater room is 1200+ square feet with 14' ceilings. The light has to be brighter to not feel wimpy.

For those who need a bit of science to study before voting:
http://en.wikipedia.org/wiki/Foot-lambert

Most people have no clue what footlamberts they are at. Unless you have a light meter and regularly measure. Your guesses will likely be no where near the truth.

Even knowing your manufacturers lumen specs and what screen you have is a pretty poor indicator.

This is a high-end forum so there are exceptions. However if you don't know then use a typical movie theater (which is approximately 16fl) as a relative guide.

No. 20fl is becoming the de facto standard if not minimum.

This figure is also gathering ground for future digital cinema standards. 20fl has been positively White Papered by the SMPTE, Barco and Christie.

The ISF are also working within the industry to achieve this as a minimum for digital cinema.

There is utterly no substitute for a 24fl image on a very large screen, listened to in excess of reference SPL.

Just a simple poll:
Is the ISF Recommended Luminance of 12 foot-lamberts Bright Enough for Your Tastes?

No. I do feel with a extremely high contrast projector and a very well controlled room light it is adequate however.

I certainly prefer over twenty no doubt.

Edit: The president of the ISF has recommended 20fL as the starting value for screening rooms.

Art

Someone one this forum put it very well a year or two ago. Let me paraphrase them from memory:

"For years the goal has been to duplicate the look of film in a movie theater, but as technology has rapidly improved I don't see why we should be limiting ourselves to mimicking the film-look and movie theater light levels. Our goal for the future should be to try to mimic the look of real life through our eyes."

This is a high-end forum so there are exceptions. However if you don't know then use a typical movie theater (which is approximately 16fl) as a relative guide.

16fl is the guideline without film. Screening brightness is obviously less

I personally care more about the black floor than I do brightness. 8)

Another thing worth mentioning is that visual acuity is far less in low light than bright. Some people may be losing detail.

I voted for 12 but ideal for me might be like 15. At 20 or above it is painful to my eyes and I would have to wear dark glasses or turn on the lights.

I have friends that like 35 and I can't even watch a movie in their home theater.

Ideally, I like it a little brighter than 12, but not much more. 30 is too much, it gives me a headache in a dark room after a while, besides being annoying. And I'm not one to watch FP with the lights on, that's what the flat panel is for.

I think a lot of the answer to this also has to do with the room you're viewing in. Depending on how much light control you have 12fL might not be enough anyways. My room is 100% light controlled and pretty much a black hole. If I get up above about 15fL I would start getting headaches, especially with content that has a lot of light transitions. Plasmas put out a lot of light but it's also good to use a bias light with them because of this very same reason.

When most source material was SD, going brighter than 12fl would often show up image artifacts such as mpg compression and I would find that distracting. In fact I felt 12 was the upper limit for SD and preferred somewhat less (7 to 9fL not unlike commercial theaters though I can watch at lower levels in a fully light controlled room provided the pj has a reasonable amount of contrast). It also made the image more cinematic and less like video (IIRC 12fL with film in the gate was derived to reduce gate flicker so is probably a legacy of the technology limitation rather than anything else). If I set up my pj for around 12fL with a new lamp, I may see some image noise But I know that it will be subdued as the lamp ages, so that tends to be brightest I really want it.

With HD of course image artifacts are (hopefully) much less so going brighter will not necessarily be at the detriment of image quality. Digital Theater should hopefully not have any source problems but if the black level suffers I don't necessarily see that as a good thing.

I've seen the 20fL figured mentioned quite a bit from the likes of Joe Kane, but what's the driving force behind 20fL as the new standard? Is it just because the eye naturally likes a brighter image or something else?

Gary

12~16 ftl is perfect for me and I can see all the detail. Pushing it more might impress my guests but I feel with such torch mode I won't be able to see the details in low apl in quick tranisition.

Is the ISF Recommended Luminance of 12 foot-lamberts Bright Enough for Your Tastes?
It depends...If the ANSI CR is high, then 12 to 16 ftLs is optimal, but if the ANSI CR is low then the picture needs to be brighter to make up for the lack of intrascene contrast in medium to bright scenes. Once you get to 20 ftLs the MPEG artifacts (on film, not digital animation) become too obvious to ignore any longer.

One other thing to note: Every bit of contrast helps percieved brightness levels. An image might be bordering on dim looking if your screen is against a light colored wall. Even with the lights out your eyes will tend to percieve the wall (especially in darker scenes). But if you completely mask that same image in black (e.g. velvet masking) it will appear brighter, in contrast to the background.

I've experimented with masking projected images, and have masked my plasma for years and this has been a consistent result.

To a certain extent isnt it true that the more black your blacks are the greater chance that very low end detail will be lost, or at least glossed over unless you pause the image and look really hard? 8)

I can have my PJ as bright as up to 24 foot lamberts in my HT .. where black is essentially grey and I can see every nuance on the rocks in 300. I would much rather see black than grey, just to the point that that slightest nuance is (possibly) lost (unless you look really hard at a paused shot.)

This is really just a matter of preference. Even millerwill, who uses his RS1 with a HP, and prefers his image hovering around 20 foot lmberts wasnt convinced that all (or most all) of the detail is not lost with such black blacks, will attest that in the tests that we ran the detail was present in iris 1 just as it was in iris 3 in the very dark Casino Royale shots that we examined.

He actually was surprised at how good the image looked, although he admittedly preferred the brighter image.

A lot depends on the contrast figure your PJ will give with the high fl figure. Sacrificing contrast for lumens is a lost cause, and vice versa.

Seeing an image with 24fl at high contrast numbers without using high gain and with large ANSI numbers is very engaging.

This is where digital cinema and HT are heading and genuinely belong.

I dont doubt that it is, CM. I just really prefer a black black.

I can see the difference with an ND2 filter. At the same contrast, just with different brightness settings.

When I had my HD1, I was preferring the image with an ND4 .. with the same contrast numbers, but with grey blacks without it. I was essentially preferring the blacks at 5 foot lamberts over the same CR at 20 foot lamberts, or even 10.

This is where digital cinema and HT are heading and genuinely belong.


I try to never say never, but you know what they say about opinions.

Lets take a look at some recent projector releases:

Sony VW200
Marantz 11S2
JVC RS2

All are arguably dimmer than their predecessors, and even the Sharp 20k is about as dim as any of those. I think it could probably be argued that there is a push by some to want to raise the so called standard to 20 foot lamberts but there still is also a push by many to advance the best picture quality possible, over brightness.

The RS2 is arguably 30% dimmer than the RS1. The 11S2 20% dimmer than the 15S1.

Dan Miller advised in another thread that Marantz looked at alternative lamp options for the 15S1 and 11S2, presumably VIDI and OSRAM, and elected to not sacrifice picture quality for "output."

I've seen the 20fL figured mentioned quite a bit from the likes of Joe Kane, but what's the driving force behind 20fL as the new standard?


Maybe it was back in 2002 when I said 12 ft lamberts was BS...and thus started preaching the values of high gain screens.

Dan Miller advised in another thread that Marantz looked at alternative lamp options for the 15S1 and 11S2, presumably VIDI and OSRAM, and elected to not sacrifice picture quality for "output."
:)

Lets take a look at some recent projector releases:

Sony VW200
Marantz 11S2
JVC RS2

All are arguably dimmer than their predecessors, and even the Sharp 20k is about as dim as any of those. I think it could probably be argued that there is a push by some to want to raise the so called standard to 20 foot lamberts but there still is also a push by many to advance the best picture quality possible, over brightness.

The RS2 is arguably 30% dimmer than the RS1. The 11S2 20% dimmer than the 15S1.

Dan Miller advised in another thread that Marantz looked at alternative lamp options for the 15S1 and 11S2, presumably VIDI and OSRAM, and elected to not sacrifice picture quality for "output."

Makes me glad I bought a projector with two bulbs and a power iris. I have picture quality and brightness!!!:)

How about an analysis of the posts vs. the voting?

26 posts total sample

Posts
-----
35% - were neutral
26% - were brighter biased (vs. 80% of votes)
4% - were dimmer biased (vs. 4% of votes)
30% - stay at 12fl biased (vs. 15% of votes)

Posts Ratio to Voting Ratio
-------------------------
Those who preferred a brighter picture were under represented by a 3:1 ratio
Those who preferred 12fl were over represented by a 2:1 ratio

Greetings,

A couple of thoughts. First, the SMPTE standard, I believe has been in place for a long time. However, movie theaters aren't as dark as they once were, as most of you who still take in a movie at a theater from time to time. Safety laws seem to prevent today's theaters from the virtual pitch blackness that was common 20-30 years ago.

Room conditions come into play. Dark walls/ceiling/floors seem to make a dimmer projector look brighter, than those with lighter surroundings.

While I have in particular found projectors with better black levels to be easier to view at lower ft-lamberts, than those will less impressive black levels, myself, I find 16+ ft-lamberts to, overall, be more to my taste. 20, sounds very nice, but few projectors can do it in their best modes, on screens much larger than 100".

As to the tendency of some newer projectors to be dimmer than their predecessors, I think most of that is chasing better black levels, which is still more highly prized than brightness among home theater enthusiasts. I suspect, in that regard, manufacturers are catering to market demands for black levels, as their highest priority.

Maybe it was back in 2002 when I said 12 ft lamberts was BS...and thus started preaching the values of high gain screens.

Yea, that was it.:rolleyes::D

Art

How about an analysis of the posts vs. the voting?

26 posts total sample

Posts
-----
35% - were neutral
26% - were brighter biased (vs. 80% of votes)
4% - were dimmer biased (vs. 4% of votes)
30% - stay at 12fl biased (vs. 15% of votes)

Posts Ratio to Voting Ratio
-------------------------
Those who preferred a brighter picture were under represented by a 3:1 ratio
Those who preferred 12fl were over represented by a 2:1 ratio

This poll would be suspect since I'd be willing to bet that there are many here who have never seen over 20fL on a large screen in a good room with decent source material.

Art

This poll would be suspect since I'd be willing to bet that there are many here who have never seen over 20fL on a large screen in a good room with decent source material.

Art

That is so true. I dont know about you, I suspect you are in a similar position, but every guest Ive had who was into HT was an instant convert when the saw the combination done properly.

I guess I'm surprised by the poll numbers as well. I didn't figure there were that many people who had spectra meters laying around. I didn't answer because I have no idea what the ftl is on my screen. I could go by PJC's numbers but I have a feeling that is a shot in the dark. My only reference is my TW700 at 19 ft back on a 96" 1.0 gain screen (low lamp mode) was just about perfect. That's what makes me nervous about stepping up to a 130" 2.35 at the same throw on these new 1080p machines.

Greetings,

A but few projectors can do it in their best modes, on screens much larger than 100".

As to the tendency of some newer projectors to be dimmer than their predecessors, I think most of that is chasing better black levels, which is still more highly prized than brightness among home theater enthusiasts. I suspect, in that regard, manufacturers are catering to market demands for black levels, as their highest priority.

Very few can do it on even a 6ft screen without using high gain. Even then most that produce the lumens are at such low contrast they are unwatchable. Some are so bad that they need irises to obtain even a decent CR but then the lumens cant even light 6ft without high gain, and thats new.

I tested 2 machines recently that after some lamp hours could only light up screens of 56" and 58" wide to 20fl. They were not cheap machines, one was LC based and one was DLP. I was very very surprised.

I think many companies rely on HP screens to obtain average performance. I dont think they are chasing the market, rather just taking the technically easier route by hiding poor performance with an iris to the overall detriment od the machine.

Here are the voting results from the $<3,000 forum:

Yes - 12fl is optimal 6 28.57%
No - I like my picture brighter than 12fl 15 71.43%
No - I like my picture dimmer than 12fl 0 0.0%

I measured my RS1 when I first got it and calculated 20.5fl on my 119" screen. That's if my screen is truly 2.0 gain (Draper M2500) I felt 20fL was a tad bright for my eyes but OK to live with. Setting the bulb to high was over 24fl and that was way too bright for my eyes. My viewing angle is about 30 degree. I sit 16 feet back from a 104 inch wide 16x9 screen. Now that I have 80 hours on the bulb the brightness has dropped a little and I find it pretty good. My last projector was only 12fL and I really liked it at 12fL. My eyes didn't feel strained nor did they need to adjust to a bright scene. 20fL or lower is what I like in my theater room.

By the way every ones pupil doesn't open as much as the next guy after dark adaptation. When we are young the eye's pupil can open up as much as 7mm or more but in some people it never opens more than 5mm or even less. This could be why some people like it brighter than others. One of my hobbies is Astronomy so I have read into this in the past. I own a few telescopes up to an 11 inch so optics is an interest.

Ron

Here are the voting results from the $<3,000 forum:

Yes - 12fl is optimal 6 28.57%
No - I like my picture brighter than 12fl 15 71.43%
No - I like my picture dimmer than 12fl 0 0.0%

As was said earlier, many probably have no idea what fL they're really getting, and I wouldn't be surprised if most had less than 12fL but thought they had much more.

I remember not long ago I calibrated an H79 and noticed that the time between continuous readings just a couple of feet from the pj was quite long from a 100 IRE field. I usually get that kind of delay at lower IREs so I did a quick measure at the screen with my light meter and found he was getting around 3fL (can't remember if that included the screen gain or not). He was quite happy with the image (total light control) and to be honest it looked fine to me too. The screen was over 9ft wide IIRC.

Gary

I think this poll is a lot like asking ,all other things being equal would you like your girl with an A cup size or C cup size.:D

art

No kidding.. 12fl, sounds great on paper, but how many people have actually measured what they are really getting?

We have some people on here just by virtue of the size and gain of the screen they use, the projector they are using, are way way below this and reporting it as fine.

I think this poll is a lot like asking ,all other things being equal would you like your girl with an A cup size or C cup size.:D

art

Depends, are we talking now or 10 years down the road. :D

To each his own but I prefer a dimmer picture. In a properly dark room, you don't need that many lumens on the screen. The irises in your eyes shut down and I get plenty of "blackout" when the scene rapidly transitions from bright to dark or vice versa.

I run my RS1 with an ND4 filter (on a High Power Screen). I was plenty happy with the brightness on my old Sharp 12k, a projector that many consider to be dim.

I tried the RS1 without any ND filter and it just gave me a headache because it was way too bright.

To each his own but I prefer a dimmer picture. In a properly dark room, you don't need that many lumens on the screen. The irises in your eyes shut down and I get plenty of "blackout" when the scene rapidly transitions from bright to dark or vice versa.

I run my RS1 with an ND4 filter (on a High Power Screen). I was plenty happy with the brightness on my old Sharp 12k, a projector that many consider to be dim.

I tried the RS1 without any ND filter and it just gave me a headache because it was way too bright.

Law..........Just curious, why run an HP screen and the use an NDF. Is there something Im missing, legacy screen perhaps.

Law..........Just curious, why run an HP screen and the use an NDF. Is there something Im missing, legacy screen perhaps.


You got it.

Plus, I'm like Tryg. I love the HP screen and I have no plans to change it.

Also, it comes in handy on those occasions when I have friends over to watch a game. I take off the ND filter, turn on the lights, and bingo, I have a giant Plasma on my wall.

I would never watch movies like that, but it comes in handy.

You got it.

Plus, I'm like Tryg. I love the HP screen and I have no plans to change it.

Also, it comes in handy on those occasions when I have friends over to watch a game. I take off the ND filter, turn on the lights, and bingo, I have a giant Plasma on my wall.

I would never watch movies like that, but it comes in handy.

Thanks.

I think this poll is a lot like asking ,all other things being equal would you like your girl with an A cup size or C cup size.

art


Way I see it, its C or DD. 8) A DD would be nice to play with every once in a while, like a sporting event, but the C would be the keeper for me. 8) Some guys though, like em bigger.8)

To each his own but I prefer a dimmer picture. In a properly dark room, you don't need that many lumens on the screen. The irises in your eyes shut down and I get plenty of "blackout" when the scene rapidly transitions from bright to dark or vice versa.

I run my RS1 with an ND4 filter (on a High Power Screen). I was plenty happy with the brightness on my old Sharp 12k, a projector that many consider to be dim.

I tried the RS1 without any ND filter and it just gave me a headache because it was way too bright.

Not to mention those blacks probably look like crap relative to them with the ND4.

I preferred my HD1 with an ND4, too, and my screen was just a 10' wide Carada BW .. not even a HP.

I preferred my HD1 with an ND4, too, and my screen was just a 10' wide Carada BW .. not even a HP.

What are you viewing at? 3 or 4fl

What are you viewing at? 3 or 4fl

If Cat's local Dept. of Human Services knew that he actually has his kids watch with him; they would probably what to take his kids based on acute/severe lumen starvation syndrome.

Im guessing its around there with the ND2 filter on, with my .8 gain screen factored in .. at iris 1. Without the ND filter and at iris 3, I should be at about 5x that amount on my HCG screen .. which I use for sports.

I was shocked initially when I realized that the HD1/ND4 image was around 5 foot lamberts.

I prefer the Marantz on the HCG screen image over it with the BW's image, and prefer the ND2 filter on top of the HCG screen in iris 1 most of the time. Ill try it without the ND2 filter often, and I usually put the ND filter back on right away. Same with iris settings, always back to iris 1.

If Cat's local Dept. of Human Services knew that he actually has his kids watch with him; they would probably what to take his kids based on acute/severe lumen starvation syndrome.

When they watch one of their animated ones, I usually jack it up to iris 3 for them (2+x brighter.)

I bet if one of them counselors went in there to check it out their panties would be wet when they left. 8) If millerwill visits this thread he can comment about what he thought about the 3+ foot lamberts picture. I believe he thought it looked very suprisingly good, actually (he was shocked it was 3+ fl) ..but he does prefer his image brighter coming from an RS1/highpower.

Im guessing its around there with the ND2 filter on, with my .8 gain screen factored in .. at iris 1. Without the ND filter and at iris 3, I should be at about 5x that amount on my HCG screen .. which I use for sports.

I was shocked initially when I realized that the HD1/ND4 image was around 5 foot lamberts.

I prefer the Marantz on the HCG screen image over it with the BW's image, and prefer the ND2 filter on top of the HCG screen in iris 1 most of the time. Ill try it without the ND2 filter often, and I usually put the ND filter back on right away. Same with iris settings, always back to iris 1.

At least i know what to get you for Christmas.............

http://en.wikipedia.org/wiki/Night_vision_goggles

8)

I found when you first put on an ND filter it looks dim but watch it a for a while and your eyes open up and adjust to it. I can measure my setup and when it gets down to 9fL or lower it does start to look dim. It takes a half hour for that feeling of dim to go away and then it looks good. Tell you the truth I haven't tried it with my RS1 yet. With 20fL setup my eyes don't have to adjust when I go get a drink and return to the movie.

I have a 6' ladder that I keep tucked away behind my cabinet in the media room and every once in a while I give in to some peer pressure and take away the ND filter. It is noticeably dimmer at first but the blacks are noticeably MUCH more black and to me the blacks become noticeably much more grey.

I will climb on up with my white carada gloves and do A/Bs on all sorts of material. Except for sports and animated features I prefer the image with the ND2 instantly .. I dont need a 30 minute warmup. 8) I wish that the ND-less image could satisfy me enough, but it doesnt. I try to go without it for any length of period, I notice the greys all the time.

When I had the HD1, before the ND4, I always felt that the blacks were lacking. Something was missing. I dont feel that way about the brightness, now. Not if it means I dont get the blackness.

In my setup I measured 110 lux at 100IRE at my 119" 16x9 screen projecting from 23 feet and my black level was below .01 lux on my meter at the screen. My meter stops reading at .01 lux. The long throw setup gives me very good contrast ratio. Standing at the screen the black level throws so little light I can't see my meter at all. I had to hit hold and turn the lights up to see it. I can't even see my hands in front of me. Thats without an ND filter. So I really haven't felt I needed the ND filter. I have to try it though. I have an ND2 and ND4 I can experiment with.

I dont think youll be disappointed, Ronomy. I know there is a lot of skepticsm, but in one of the old RS1/ND filter threads there were a few who tried it and most everyone (of those who tried it) preferred an ND2 or ND4 for movie watching, anyways.

The increase(decrease) in blacks is certainly very noticeable and is much more obvious than the decrease in brightness.

Oh I'll try it for sure! I did put the ND2 filter on once for a moment but it got dim. I never gave my eyes a chance to adjust and I know they will because my old projector was dim and the blacks were very high yet an ND filter help the blacks so much it was better to watch it dim. I went from an old Sony VW10HT to the RS1. It was a massive leap in contrast ratio. Talk about WOW! Not planning on turning on the projector tonight but I'll post back after I give it a go.

Ron

Let us know. Believe me, Id love to be able to say that I prefer to watch my movies at a manly 20 fl .. but for whatever reason I keep reverting back to preferring black levels, black levels - even at a very embarassing to admit, and unmanly, 3-4 fl. 8)

Let us know. Believe me, Id love to be able to say that I prefer to watch my movies at a manly 20 fl .. but for whatever reason I keep reverting back to preferring black levels, black levels - even at a very embarassing to admit, and unmanly, 3-4 fl. 8)

Well I watched Bourne Ultimatum this weekend and although it looked very good I thought a few times that when it got bright it was too bright and then my eyes had to adjust to the dark scenes just to see them. I know a dimmer picture will not do that to my eyes. In fact I'll try this with that film since I just watched it.

Thats a good choice, too. If you want to throw in some others, 300 and Casino Royale are a tour de force for blacks. Two of my personal favorites. 8)

Keep in mind that for me its not a matter of the image being too bright without the ND filter, its a matter of the blacks not being black enough. Look at those as you put the filter in front of and away from your lens. Quick A/Bs of several scenes.

Sometimes the movie should be 'too bright' because that is what is going on in the scene. Some really want their blacks black because that is realistic but do not seem to feel that the brights should have the same realism.

The brights, specially when relative to the blacks come accross as very bright to me. This really might be a matter of preferences and psychology but its harder for me, personally, to believe the blacks than the brights.

When I am at a movie theater I definitely notice blacks being grey and I dont really notice the image not being bright enough .. if that makes sense.

I am not sure how 4 ft-L can come across as bright :) but I definitely understand the compromise. After all black level is easier to tell if it is correct because, well, its supposed to be black. Bright is relative--bright probably wouldn't look so bright in your theater compared to a 100 watt bulb (well maybe even 25 watt :)).

Unfortunately with most of today's pjs we can't have both so we get the black level to an acceptable level and live with whatever brightness level we have. I am not sure if I have ever seen 20+ ft-L with excellent black level but I have seen crt double stacks and I would imagine they must be close (?) and they looked amazing...

When they watch one of their animated ones, I usually jack it up to iris 3 for them (2+x brighter.)

I bet if one of them counselors went in there to check it out their panties would be wet when they left. 8) If millerwill visits this thread he can comment about what he thought about the 3+ foot lamberts picture. I believe he thought it looked very suprisingly good, actually (he was shocked it was 3+ fl) ..but he does prefer his image brighter coming from an RS1/highpower.

Cat

You might be right assuming the counselors are not RBE sensitive or biased towards LCOS or LCD technology.

When I am at a movie theater I definitely notice blacks being grey and I dont really notice the image not being bright enough .. if that makes sense.

Thats the truth! The blacks I get from my RS1 are way better than what I see at the Theater. You must be an old CRT guy to like the dark images so much. I am not sure if 4-5fL will look any good to me but I used to watch between 9-12 and enjoyed the picture. Will an ND2 lower the blacks enough to make me want to keep the ND filter on? I'll let you know.

300 would be a good one...watched that again last week too.

Ron

Wow, I personally can't image watching an image that dim and it has nothing to do with manliness. I "threw up" my BO cloth tonight and put on my ND2 filter just to get refeel of what Catdaddy is referring to but even after doing this yet once again this levels are not satifying. At least for me eye biasing turns grey into black in all but the darkest scenes and for me in all but the darkest scenes the brighter whites seem to do more for darkening blacks through than darker blacks do for the perception of brighter whites. A couple years ago I spent much time perusing studies of the "highest luminance rule" which appeared to conclud that when viewing black and white images, with your head in a box, that lowering overall brightness levels while maintaining the same CR actually boosts percieved contrast ratio. Putting this into practice, however, while viewing colored video I find this not to be absolute. For me anyway in my room there's a definite threshold where whites just don't have the proper feel effect on my eyes and therefore possibly don't look correct and this, for me coincidentally, is at around 12 fL's. Daytime scenes feel and look most correct between 16-25 fL's for me (yes it's been measured), and at these levels eye-biasing also seems to give blacks there dues in all but the lowest APL scenes.

Catdaddy, I hope my post comes off as intended, as in, not derogatory to your preferences but instead a "to each system his own" type rant. Generally I only post after having a few and sometimes this clouds my better judgment.:D

I certainly see yours and the other's point. Idid not take offense to, or find your post offensive.

Ive always preferred the blacks, even with my Sharp 10k and Sharp 12k (which were my first experiences with projectors ..not CRTs, Ronomy.) Even though I liked the punch of high brightness, it was never enough for me to give up the blacks of high contrast, regardless of the relatively dimmer image.

I do like the brighter images/scenes lit up well without the ND2 but surely a lower APL scene will come along soon enough where I find the lack of black unsatisfying. Inversely, I do not find myself griping at,or finding lacking, the higher APL images with the ND2 on.

As with most of us, Im sure, I have only received praises on the PQ at the dimmest settings on my PJ. Initially most people like the brighter image, but after I point out the difference in blacks most do tend to prefer the perceptively better contrasting "black" look of the dimmer one.

I watch football on Sundays for something like 12 straight hours with breaks for necessities only. I have a variety of projectors available. Repeatedly I prefer watching my CRT which blazes the screen at about 7 ft lamberts compared to a wide variety of expensive digitals which can out as much as 60 ft lamberts on the screen. Normal digital blasting gives me 20 to 30 ft lamberts. Way way too bright. Tiring on the eyes for long viewing periods. And the blacks. While I can enjoy the picture and my eyes don't say the blacks are gray because of course the dynamic range makes the blacks appear much blacker than they are, switching to the CRT is like looking at an enturely different picture. Much more realistic and natural. Dimming the digitals down with iris on, low lamp modes, ND filters yada yada to get the foot lamberts down to 12 or 13 gives to my eyes a much better, more accurate, and pleasing image.

Cheapest I found was $6999 for 2000 ansi lumens. OUCH!

Does anyone know at what level the eye's color response begins to degrade and is replaced by black and white?
Does our visual acuity change at these low brightness levels?
Someone mentioned that as we age our eyes need more light. That is definitely true for people I know over age 50.

Let us know. Believe me, Id love to be able to say that I prefer to watch my movies at a manly 20 fl .. but for whatever reason I keep reverting back to preferring black levels, black levels - even at a very embarassing to admit, and unmanly, 3-4 fl. 8)

I couldn't wait and tried this late last night. ND2 still looked good but I didn't find the blacks to get much better. ND4 was way to dark for me. The blacks are so good already that visually even with a completely dark black picture the ND filters affect was minimal on the screen. Its hard to see the screen already without the ND filter. My room is like a bat cave too. All I noticed was the picture got dimmer buy a lot at the top end. I think the brighter images in dark scenes also close my pupil more and blacks look blacker with the brighter picture. This is completely different from the benefit I got with my old Sony VW10HT.

I think 15 to 20fL on the screen is a good target for this projector. Blacks look great! IMO

Ron

In my setup I measured 110 lux at 100IRE at my 119" 16x9 screen projecting from 23 feet and my black level was below .01 lux on my meter at the screen. My meter stops reading at .01 lux. The long throw setup gives me very good contrast ratio. Standing at the screen the black level throws so little light I can't see my meter at all. I had to hit hold and turn the lights up to see it. I can't even see my hands in front of me. Thats without an ND filter. So I really haven't felt I needed the ND filter. I have to try it though. I have an ND2 and ND4 I can experiment with.

Hi Ron,

For a more accurate measure of your on/off CR, place the light meter a couple of feet away from the pj lens rather than at the screen. Having it at the screen will put the black level beyond the meters sensitivity. With it at the screen if you measured the CR over a period of time you may think that CR reduces as the lamp dims with age :) (don't laugh - some people actually measure on/off CR like that and think that's the case!).

Gary

Thanks Gary! I do plan to do that at some point. I did try it but the numbers were way off. I need to make sure light spill from the projector doesn't screw up the measurement. My black room tends to absorb any spill when I am at the screen. I have a black blanket I'll use to get better results. Mark sure I am only measuring the image and not any stray light.

Ron

I haven't owned a projector or measured the FLs I like to watch (yet). But I can say that
I have been watching my plasma in pitch dark, masked and surrounded by black material, for a couple years and have been comfortable with it. A lot of folks talk about the need for bias lighting and I tried various iterations of bias lighting. But I found that illuminating the background behind the image worked against the immersion factor of the image being surrounded by darkness, so I much preferred it without bias lighting.

It's one of the things I love about projection: watching in the dark, with the image perfectly surrounded by darkness for that suck-you-into-the-image experience.

I plan on going with the JVC RS2 projector and Carada brilliant white screen (1.4 gain) - going for a little gain to off-set the fact the RS2 is a bit dimmer than the RS1 I was originally planing on.

It's one of the things I love about projection: watching in the dark, with the image perfectly surrounded by darkness for that suck-you-into-the-image experience.



So true and all the more impressive at higher fL IMO.

Art

Hi Ron,

Measuring directly and close to the pj removes all other errors from creeping in and gives you just the pj contrast. You need to get a good measure of black while not overloading the meter for white. Try to get as high a black reading as possible. You may then find you have a higher cr figure since before the black level was lower than the meter could read.

You can use the black blanket to mask the screen if you want to take ANSI contrast measures there since that will absorb a lot of the light so you have less bouncing around the room and back onto the screen. It can take a lot of the room out of the equation.

Gary

I haven't owned a projector or measured the FLs I like to watch (yet). But I can say that I have been watching my plasma in pitch dark, masked and surrounded by black material, for a couple years and have been comfortable with it. A lot of folks talk about the need for bias lighting and I tried various iterations of bias lighting. But I found that illuminating the background behind the image worked against the immersion factor of the image being surrounded by darkness, so I much preferred it without bias lighting.

I think what can happen is the eye will adjust for an overall dark image (more black in the field of view) so the iris will open up to let more light in, but with a small tv being around 36fL the small area of bright light can be painful on the eye. Bias lighting causes the iris to shut down and allow a more comfortable level of light in. You have to be careful how much bias lighting is used otherwise the iris may close down too much and not let enough light in from the dark areas of the image so in effect cruch shadow detail into black. Blacks can look much blacker though. Maybe your plasma is filling enough of your field of view to the same effect as your screen so allows the iris to shut down enough for comfortable viewing.

I can see the need for it with a tv, but not with a front projector (though I know some people do use it for that).

Gary

Gary I would think the light meters would read better towards the low end of the scale. I bet the sensor would begin to compress at higher levels and then comparing high and low levels would be off. I would think it is better to keep the meter on one range when comparing levels. Changing ranges just throws another unkown into the equation.

I know a guy who works at a cal house. I may have him check my meter...just for shits and giggles! :)

Hey Ronomy, the blacks on the RS1 are nice and dark for sure .. just not dark enough for me .. the RS2, however.. 8)

i voted 20FTL or more
some data:
if considering a 3meters hdtv no gain screen (and not perforated fabric which can eat up to 25% britghness). area is 45.9sq ft
12FTL requires 45.9x12= 550.9 lumens
pjs that match this are for instance: HD1 HD100 D80E 380E etc
20FTL requires 45.9x20=918 lumens
C3XE does it
30FTL requires 45.9x30=1377 lumens
C3XE does it too
(that's tv plasma brigthness i'd say)
if 4meter scope screen considered it's 68.4sq feet area
12FTL requires 68.4x12=820.8lumens
20FTL requires 68.4x20=1368lumens


all these at fresh lamps and black room of course and non perforated (-10%) or seamed screens (-20%). and no gain considered.
with a mperforated gain 1.5screen:
12FTL 10ft wide hdtv=45.9x12/1.5 +10% for screen holes loss= 403.92 lumens required
12FTL 13.3ft wide scope=68.4x12/1.5 +10%= 601.92
i use this screen (scope 13.3ft, 1.4gain) and the HD1/D80E/W5000 fit it. i don't know in 500hrs though...
20FTL would require 673lumens (10FT hdtv screen 1.5 mperforated) and 1003lumens (13.3 scope 1.5 mperforated screen)
ALL THESE DATA VALID FOR.... BLACK ROOMS of course....
bottom line: screen gain and black rooms needed.

Hey Ronomy, the blacks on the RS1 are nice and dark for sure .. just not dark enough for me .. the RS2, however.. 8)

Greetings, Catdaddy! It sounds to me that the RS2 may be the 'king of blacks', and thus the answer to the feature most important to you. GregR's review is truly impressive; if I didn't have the RS1 already, then it sounds like what I would go for. It seems that it will be increasingly hard to justify $20K or so for a SIM2, or whatever, compared to the JVC's RSn's.

As it is for me, I think I will stay with the RS1 for another year (at least) and see what the RS3 is like; I would most like to see it have an internal CMS to allow one to choose various color standards, e.g., the expanded ones present on the RS1/2, the SMPTE C, or the Rec 709 (?) etc.

Hey Dr Bill!

Looks like Ill be having that RS2 in here very soon to compare. Im very excited to get it in and you know Ill report on it as soon as I have it set up. 8)

Hi Ron,


Gary I would think the light meters would read better towards the low end of the scale. I bet the sensor would begin to compress at higher levels and then comparing high and low levels would be off. I would think it is better to keep the meter on one range when comparing levels. Changing ranges just throws another unknown into the equation.

I know a guy who works at a cal house. I may have him check my meter...just for shits and giggles! :)

I think you misunderstood me about moving the meter for lumens readings at the screen and readings for on/off contrast at the projector to get a better black level reading.

If you place the meter too close to the pj and overload it for the white reading you can get the same error you're getting for having the meter too far away to get a good reading for the black level. In both instances you need readings that are away from the extremes of the meters range. I.e black readings at 0.01 lux or white readings that are 20000 lux. Both are at or beyond (you won't know which) the meters range so will give inaccurate results.

Make sure the readings are well within the extremes and you should get more accurate results; 0.15 lux is a far better reading than 0.01 for example (3 significant digits is better still), since the meter may fluctuate between 0.14 and 0.16 before it settles but when that's happening you know you're getting a reading that hasn't bottomed out in the meter. At 0.01 it may really be 0.002 but it's outside the range and the meter is just 'rounding up'.

As for moving the meter - you don't for taking on/off readings or as you quite rightly say you have added an unknown into the equation, so you take white and black in the same location. It doesn't matter where you take the reading for a lumen calculation provided it's at 100IRE and you know the screen area at that location. Measuring at the screen (facing the pj) for lumens is convenient since you know the screen size and can easily calculate the area. You could simply project onto a white board a couple of feet in front of the pj and do all your calcs there (screen area is considerably smaller of course but the lux reading is much higher). It's up to you.

Gary

I prefer to be in the mid-20s, myself.

15 FL seems pretty good to me. I haven't had chance to experiment.

I prefer to be in the mid-20s, myself.

I'm in your camp.

Hey Ronomy, the blacks on the RS1 are nice and dark for sure .. just not dark enough for me .. the RS2, however.. 8)

I understand you are sensitive to blacks. I just didn't see the black level drop much with a black screen up and the ND filter added. It dropped but it was so slight that it was insignificant to my eyes. I found by eye the picture to have less contrast/pop with the ND filter on. In other words I find the black looks black either way to my eyes and the ND filter just makes the peak whites drop too much. The picture still looked watchable and that is good. I should be able to get a lot of hours out of the bulb. I also have high bulb setting to boost it more when I get down to 10-12 fL. I am probably around 10fL with the filter on.

I am completely satisfied with the RS1. To me it would have to be 100,000:1 contrast ratio for me to upgrade in order to drop blacks enough for it to be worth the upgrade. Even then I don't see the need. I guess I am just not that picky. The price difference between the RS1 ans RS2 just doesn't seem worth it to me just for the contrast increase. Maybe my long throw setup has something to do with why the blacks look so good. Long throw has better contrast ratio...closer to 19,000:1. I also can't see bright corners on my projector so a black screen is... looks black.

Ron

What did Greg end up with with lumens from the RS2 ?

Art

Well, now that I finally measured my screen I figured I'd chime in, I'm not sure how to answer. I measured under 9ftL at my screen last night and it was satisfyingly bright. If I bump the lamp to high power, I can get to almost 12ftL, but the difference is insignificant IMO.

So to answer the question, is 12ftL optimal? I don't know, but IMO, for me it is sufficient.

I believe you made a mistake with your calculation:


i voted 20FTL or more
some data:
if considering a 3meters hdtv no gain screen (and not perforated fabric which can eat up to 25% britghness). area is 45.9sq ft

3meters = ca. 9.8425 ft
9.842 5 * 9 / 16 = ca. 5.5364 ft height

So the area would be about 54.5 sq ft.


12FTL requires 45.9x12= 550.9 lumens
pjs that match this are for instance: HD1 HD100 D80E 380E etc
20FTL requires 45.9x20=918 lumens
C3XE does it
30FTL requires 45.9x30=1377 lumens
C3XE does it too
(that's tv plasma brigthness i'd say)
if 4meter scope screen considered it's 68.4sq feet area
12FTL requires 68.4x12=820.8lumens
20FTL requires 68.4x20=1368lumens

All these calculations should have 54.5 instead of 45.9, e.g.
12ftl requires 54.5 x 12 = 654 lumens
20ftl requires 54.5 x 20 = 1090 lumens
30ft requires 54.5 x 30 = 1635 lumens

What did Greg end up with with lumens from the RS2 ?

Art

From his usual throw distance (1.77 SW) he got 603 lumens and 25200:1 CR in high lamp mode, and 502 lumens in Normal (low) lamp.

At min throw distance, and High lamp, he reported 661 lumens and 19200:1 CR, and at max throw this became 473 lumens with 30900:1 CR.

I got a surprise when I worked this out (as I don't have a light meter), so I had to vote for less than 12fL:eek: Unless my calculations are way off: 105" x 59" 16:9 screen = 43sq/ft, using Cine4home's review of my AE2000 at minimum zoom (near enough in my setup) using 'Cinema 1' mode and Econ mode for the lamp was measured as 340 lumens. My screen is a 1.8 gain, but I use an ND2 filter:

340 lumens/43sq/ft = 7.9fL, multiply by screen gain of 1.8 = 14.2fL this gives me my 'unfiltered' screen brightness. The ND2 filter cuts 50% so 14.2/2 = 7.1fL. Maybe I'm a closet CRT owner.:D I find it too bright if I take off the ND2 filter which would give me 14.2fL (with a new bulb). I tried my ND4 filter but found it too dim although the blacks looked perfect...that would be 3.55fL (14.2/4) if I worked that out correctly.

As I mask off the top section of my 16:9 screen to give me 105" wide scope screen, does this make any difference to the readings? I use the zoom method so my PJ is projecting at 43sq/ft, it's just that only the middle 2.35:1 section is actually lighting up the screen due to the black bars.:confused: In other words the black bars are projecting onto the dark brown wall above and below the screen.

From his usual throw distance (1.77 SW) he got 603 lumens and 25200:1 CR in high lamp mode, and 502 lumens in Normal (low) lamp.

At min throw distance, and High lamp, he reported 661 lumens and 19200:1 CR, and at max throw this became 473 lumens with 30900:1 CR.

Thanks !

Art

Maybe I haven't read this thread closely enough but I find it all very confusing. What is the "preferred, expected, commonly accepted method" for finding fL off the screen?

1. Displayed image (full field 100IRE?)

2. Distance of meter from screen

I read somewhere that the 16fL "average for typical movie theater" is for projecting with no film in the projector. Since there is no equivalent for video projectors, what's the right test screen to use?

The spec for Digital Theater is 12fL +-1fL.

Use a 100IRE test image as you surmised and with the projector calibrated (or at least with the black and white levels set using a test disk) take a reading at the screen with the meter facing the projector. Multiply the lux reading by the screen area in meters and that will give you the pj lumens. Divide the lumens by the screen area in square feet and that will give you the fL for a unity gain screen. If the screen has gain, multiply by the gain.

HTH

Gary

Bias lighting causes the iris to shut down and allow a more comfortable level of light in. You have to be careful how much bias lighting is used otherwise the iris may close down too much and not let enough light in from the dark areas of the image so in effect cruch shadow detail into black.
Gary,

In fact, a bias light is utilized to prevent the iris from shutting down in dark scenes. The problem is akin to what happens with oncoming car headlights at night. The iris shuts to prevent the bright lights from blinding you, then has to open to adjust to the darkness after the car has passed. When this happens continually, viewing fatigue sets in.

The SMPTE spec calls for a production environment calls for 10% of the peak white output of the monitor be used for bias lighting.


Ken Whitcomb

Thanks Ken,

I'll have a re-read. :)

Gary

Use a 100IRE test image as you surmised and with the projector calibrated (or at least with the black and white levels set using a test disk) take a reading at the screen with the meter facing the projector. Multiply the lux reading by the screen area in meters and that will give you the pj lumens. Divide the lumens by the screen area in square feet and that will give you the fL for a unity gain screen. If the screen has gain, multiply by the gain.

HTHIt does Gary, it helps a lot! Thanks!!! Heck, I'd have taken my reading off the screen, not pointed at the pj... :o

If you or anyone knows how screen gain is determined/measured I'd like to learn that too...

It does Gary, it helps a lot! Thanks!!! Heck, I'd have taken my reading off the screen, not pointed at the pj... :o

If you or anyone knows how screen gain is determined/measured I'd like to learn that too...

I think it's very hard to measure screen gain. Usually people just take the value quoted for the screen (in order to calculate ftL = (lumens/screen area)*gain = fc*gain).

I agree with Milerwell regarding taking screen gain measurements, and you may need an illuminance meter rather than a luminace meter to do it. Some screens have been measured and if you can find that info that will make your calculation more accurate. For example, Projector Central compared some screens to a unity gain white board and found that the Stewart Studiotec 130 material had a gain of 1.3 and the Draper M1300 material was 1.25. The rest of the tested screens are on their website somewhere (needs a little searching).

You could of course just do the calculation for unity gain and for the advertised gain and that will give you a probable min and max figure.

Gary

Here is a simple real-world formula to calculate the maximum diagonal screen size given the brightness of the projector using the current SMPTE recommendations of 12fl brightness.

maximum diagonal screen size (in inches) for 12fl with a measured new bulb =
sqrt(14* projector new bulb lumen output * screen gain)


maximum diagonal screen size in inches) for 12fl with an measured aged bulb =
sqrt(28* projector aged bulb lumen output * screen gain)


Examples:
JVC RS2 :
Greyhawk with 0.9 gain
sqrt(14 new bulb factor * 473 WSR measured lumens * 0.9 screen gain) = 77 inches maximum diagonal screen size

JVC RS2 :
Studiotek with 1.3 gain
sqrt(14 new bulb factor* 473 WSR measured lumens * 1.3 screen gain) = 93 inches maximum diagonal screen size

Note: Is this why Greg Rodgers uses a small 87" screen even with 1.3 gain?

JVC RS2:
Di-Lite High Power with 2.5 gain
sqrt(14 new bulb factor* 473 WSR measured lumens * 2.5 screen gain) = 128 inches maximum diagonal screen size

JVC RS1:
Di-Lite High Power with 2.5 gain
sqrt(14 new bulb factor* 595 WSR measured lumens * 2.5 screen gain) = 144 inches maximum diagonal screen size


Notes:
1) The maximum screen size should be even smaller for those like their picture brighter than 12fl. And from this poll most people apparently do!
2) As a general rule the eye needs more light over the age of 50
3) Smaller screens increase contrast which is why my image is "only" 110 inches. Quality over quantity.
4) I took the time to brush up a bit on my Algebra skills. I don't know why I've never seen this simple equation before. I hope its correct! :)

I don't see very many folks in that screen size range at all.

Art

I think too much is made about having to stick to certain "ideals". Just like the audiophile who won't admit to themselves they would prefer a non-linear frequency response, I think many of us would rather go larger at the expense of some brightness.

Sure, I may prefer a brighter screen to a dimmer one at a given size, but if the choice was small and bright, over large and not so bright, I'm going for the real estate!

1) My setup: sharp 12k, 104" x 44" 2.35:1 HP manual pull down screen. 200hrs on bulb. Projector on the back wall, 5 ft off the ground.

2) For movies only, no lights allowed (no tuner even connected to the projector.) I even hate the LED on the back of my sub-woofer as it lights up the wall a bit. Not a bat cave, as the wife won't allow dark paint on the cathedral ceiling, but lots of dark curtains.

For TV, pioneer 50" plasma.

3) I'm over 50.

4) My opinion before trying to measured carefully: Seems very much like the movies (brightness) to me. (been awhile, last movie at the theater for me was south park).
But plenty bright enough. Black levels could be darker, but that too seems pretty good. In Nemo, when the angler fish lights up the screen from the previously fairly dark sceen, it "hurt my eyes".


Now for the measurements:

5) I have a gossen ultra-pro light meter that can read light levels directly off the screen in cd/m^2, so no guessing about what the effective gain of you screen is.

I also bought a monaco ez color sensor and software, to calibrate my computer monitor several years back. The sensor in this can be used by the freeware HCFR to calibrate/measure your TV/projector's color accuracy.

6) I used the Monoco software to measure my LCD display's output at full white: 109 cd/m^2 (32 FL). I used my Gossen to measure the same patch of white: 94 cd/m^2 (27 FL). The 2 independant sensors agree within 16%, pretty good.

7) I used the Gossen to measure my Pioneer 50 " plasma (100% white in a window): 140 cd/m^2 (41 FL)

8) Finally I measured my Sharp 12K at: 25 cd/m^2 or 7.3 FL, and this was at brightest possible viewing position, directly in line with the projector. Off axis it is much lower.

I get no complaints about brightness, and I don't think it needs to be brighter (for movies). Sports would be a different thing.

So for me: < 12 FL is perfectly acceptable.

Your posts raise the possibility that many viewers are not reaching 12fl at peak brightness. This would account for at least some of the reason why 75% of members want a brighter screen. Maybe if they really had 12fl that would be enough. Which follows why you seldom hear a complaint from the high-gain screen owners.
Hopefully its evident that low (and especially negative) gain screens appear to have little or no place in the modern home theater.

Time to go gather the information of some popular projectors reviews and post the maximum screen size/gain to achieve 12 fl long term.

Epson Cinema 1080 UB Brightness Calculations

From the Projector Central review the Cinema 1080 UB is a very bright projector. However the lens telephoto setting reduces light by a substantial 45%. Then picture mode greatly affects the brightness. Finally the review does not take into account the 50% reduction in brightness due to bulb aging. Screen sizes are all over the map so choose carefully.

Cinema Night Mode
--------------------
Epson 1080 UB, telephoto, 1.0 screen gain
sqrt(14*260*1.0) = 60 inches maximum diagonal screen size

Epson 1080 UB, telephoto, 2.5 screen gain
sqrt(14*260*2.5) = 95 inches maximum diagonal screen size

Epson 1080 UB, midpoint zoom, 1.0 screen gain
sqrt(14*365*1.0) = 71 inches maximum diagonal screen size

Epson 1080 UB, midpoint zoom, 2.5 screen gain
sqrt(14*365*2.5) = 113 inches maximum diagonal screen size

Epson 1080 UB, wideangle, 1.0 screen gain
sqrt(14*470*1.0) = 81 inches maximum diagonal screen size

Epson 1080 UB, wideangle, 2.6 screen gain
sqrt(14*470*2.5) = 128 inches maximum diagonal screen size


Cinema Day Mode
-------------------
Epson 1080 UB, telephoto, 1.0 screen gain
sqrt(14*440*1.0) = 78 inches maximum diagonal screen size

Epson 1080 UB, telephoto, 2.5 screen gain
sqrt(14*440*2.5) = 124 inches maximum diagonal screen size

Epson 1080 UB, midpoint zoom, 1.0 screen gain
sqrt(14*620*1.0) = 93 inches maximum diagonal screen size

Epson 1080 UB, midpoint zoom, 2.5 screen gain
sqrt(14*620*2.5) = 147 inches maximum diagonal screen size

Epson 1080 UB, wideangle, 1.0 screen gain
sqrt(14*800*1.0) = 105 inches maximum diagonal screen size

Epson 1080 UB, wideangle, 2.6 screen gain
sqrt(14*800*2.5) = 167 inches maximum diagonal screen size

1) The Epson brightness levels vary hugely. Avoid simultaneous telephoto and Cinema Night mode regardless of the screen size or gain
2) Carefully set-up with a high gain screen, this is the projector to buy for huge high-quality images
3) Determine the picture quality of the Cinema Day Mode and Night mode before purchasing

Sony VPL-VW60 Screen Calculations for 12fl Brightness

From the Projector Central review the Sony VPL-VW60 is a dim projector. The lens telephoto setting reduces light by 33%. The review does not take into account the 50% reduction in brightness due to bulb aging. We do here

Sony VPL-VW60 , telephoto, 1.0 screen gain
sqrt(14*235*1.0) = 57 inches maximum diagonal screen size

Sony VPL-VW60, telephoto, 2.5 screen gain
sqrt(14*235*2.5) = 91 inches maximum diagonal screen size

Sony VPL-VW60, wideangle, 1.0 screen gain
sqrt(14*350*1.0) = 70 inches maximum diagonal screen size

Sony VPL-VW60, wideangle, 2.6 screen gain
sqrt(14*350*2.5) = 110 inches maximum diagonal screen size


1) Calculations reveal that to meet SMPTE standards of 12fl, mate this projector with a 2.5 gain screen

Marantz VP-11S1 - Screen Calculations for 12fl Brightness

From the Wide Screen Review the Marantz VP-11S1 is a dim projector in the economy mode with iris aperture set to high-contrast (F6.0). These settings provide the best picture quality. The review does not take into account the 50% reduction in brightness due to bulb aging. We do here

Marantz VP-11S1, Economy lamp, high-contrast (F6.0), 1.0 screen gain
sqrt(14*330*1.0) = 67 inches maximum diagonal screen size

Marantz VP-11S1, Economy lamp, high-contrast (F6.0), 2.5 screen gain
sqrt(14*330*2.5) = 107 inches maximum diagonal screen size

Marantz VP-11S1, Normal lamp, high-contrast (F6.0), 1.0 screen gain
sqrt(14*416*1.0) = 76 inches maximum diagonal screen size

Marantz VP-11S1, Normal lamp, high-contrast (F6.0), 2.5 screen gain
sqrt(14*416*2.5) = 120 inches maximum diagonal screen size


1) Calculations reveal that to meet SMPTE standards of 12fl and reasonable screen size, mate this projector with a 2.5 gain screen
2) Investigate the pros and cons of the Normal lamp setting before purchase as the numbers indicate it use being essential to meet SMPTE digital cinema standards

Panasonic PT-AE2000U - Screen Calculations for 12fl Brightness

From the Projector Central Review the Panasonic PT-AE2000U is a dim projector in its best PQ Cinema 1 mode. The Normal mode with blue reduced comes close. The review does not take into account the 50% reduction in brightness due to bulb aging. We do here

Panasonic PT-AE2000U, Cinema 1, 1.0 screen gain
sqrt(14*330*1.0) = 67 inches maximum diagonal screen size

Panasonic PT-AE2000U, Cinema 1, 2.5 screen gain
sqrt(14*330*2.5) = 107 inches maximum diagonal screen size

Panasonic PT-AE2000U, Normal mode with blue reduced, 1.0 screen gain
sqrt(14*600*1.0) = 92 inches maximum diagonal screen size

Panasonic PT-AE2000U, Normal mode with blue reduced, 2.5 screen gain
sqrt(14*600*2.5) = 144 inches maximum diagonal screen size


1) Calculations reveal that to meet SMPTE standards of 12fl and larger screen size, mate this projector with a 2.5 gain screen
2) Investigate the pros and cons of the reduced color quality in the Normal setting before purchase as the numbers indicate this mode being the most practical. Are there better choices?

Sony VPL-VW200 SXRD Video Projector - Screen Calculations for 12fl Brightness

Tom Norton is the rare reviewer who discusses bulb aging:
"But if there's one thing likely to disappoint some potential VPL-VW200 users, it's the projector's maximum brightness. I could never get more than a bit over 19fL out of it. I never felt that it looked too dim, but I was using it on a relatively small (78-inch wide) 1.3-gain screen. And with around 60 hours on the projection lamp as I finish this report, lamp wear over time could reduce that peak output by 30% or more. If you want to fill a very large screen with a lot of light, this projector might not be your best choice."

Tom review supplies no lumen figure directly but we can easily derive it:
Diagonal = 78/0.8723 = 89 inches

336 * L = 19* 89*89
L= 448 lumens --> finally subtract the 1.3 gain screen 448/1.3 = 344 lumens

Sony VPL-VW200 SXRD, 1.0 screen gain
sqrt(14*344*1.0) = 69 inches maximum diagonal screen size

Sony VPL-VW200 SXRD, 2.5 screen gain
sqrt(14*344*2.5) = 110 inches maximum diagonal screen size

http://www.guidetohometheater.com/videoprojectors/1207sonyvw200/index2.html

Here is a simple real-world formula to calculate the maximum diagonal screen size given the brightness of the projector using the current SMPTE recommendations of 12fl brightness.

maximum diagonal screen size (in inches) for 12fl with a measured new bulb =
sqrt(14* projector lumen output * screen gain)


maximum diagonal screen size in inches) for 12fl with an measured aged bulb =
sqrt(28* projector lumen output * screen gain)

Looking at the formula - why would a measured aged bulb allow a *larger* maximum screen size than a new one?
I believe something is wrong here.

Example:
Fresh bulb sqrt(14*1000*1) = 118.32"
Aged bulb sqrt(28*1000*1) = 167.33"

Is this wishful thinking? ;)

Hopefully its evident that low (and especially negative) gain screens appear to have little or no place in the modern home theater.


I will not disagree with your point regarding that there is a place for high gain screens but they sure aren't for everyone or every installation. To say that low gain screens have no place I disagree with. Joe Kane made the comment that I agree with. It is time to stop attempting to compensate for projector problems with the screen.

In my room the ideal is a low gain AT screen and I wanted a pretty good size screen for immersion. This required a higher light output projector.

Art

Looking at the formula - why would a measured aged bulb allow a *larger* maximum screen size than a new one?
I believe something is wrong here.

I think what that means is you assume the lumens are from an aged bulb, ie the "size with aged lamp" really means not taking into account dimming over time. If you take into account dimming (ie use lumens from a "new" lamp), then your screen size will be smaller.

Example:
Fresh bulb sqrt(14*1000*1) = 118.32"
Aged bulb sqrt(28*1000*1) = 167.33"

Is this wishful thinking? ;)

That's basically correct, if you had a PJ that put out 1000 lumens on an aged lamp, you could go pretty big.

Now getting a PJ that puts out 1000 lumens with an "aged" lamp is probably wishful thinking. ;)

That's basically correct, if you had a PJ that put out 1000 lumens on an aged lamp, you could go pretty big.

Now getting a PJ that puts out 1000 lumens with an "aged" lamp is probably wishful thinking. ;)


Yes ,one needs to think about a projector with almost double that with a new lamp.

Art

Looking at the formula - why would a measured aged bulb allow a *larger* maximum screen size than a new one?
I believe something is wrong here.

Example:
Fresh bulb sqrt(14*1000*1) = 118.32"
Aged bulb sqrt(28*1000*1) = 167.33"

Is this wishful thinking? ;)
I understand the confusion as I get confused like this too.
A fresh new bulb measures 1000 lumens. The same bulb "aged" loses approximately 50% of its brightness and would measure approximately 500 lumens:
Fresh bulb sqrt(14*1000*1) = 118.32"
Aged bulb sqrt(28*500*1) = 118.33"

From the original posted equations:
maximum diagonal screen size (in inches) for 12fl with a measured new bulb =
sqrt(14* projector new bulb lumen output * screen gain)

maximum diagonal screen size in inches) for 12fl with an measured aged bulb =
sqrt(28* projector aged bulb lumen output * screen gain)

The whole point here is to take the mystery and confusion out of selecting a screen and projector to fit your room and viewing preferences based upon SMPTE standards. Many members complain of their picture being to dim but seldom too bright - as this poll indicates. These equation(s) should clear it up the confusion. Its all science (with the right equation).

Screen size can change dramatically because its dependent upon the square of the projectors output and the screen gain.
How about if we add "new bulb " and "aged bulb" into the equation to be even more explicit? Thank you for the peer review :cool:

The whole point here is to take the mystery and confusion out of selecting a screen and projector to fit your room and viewing preferences based upon SMPTE standards. Many members complain of their picture being to dim but seldom too bright - as this poll indicates. These equation(s) should clear it up the confusion. Its all science (with the right equation).


Reincarnate, I appreciate the effort you've made here, but it's much simpler (for me) to simpler remember that ftL = gain*lumens/screen area (ft^2), and then everyone can go from there. [E.g., in my case I'm always wanting to quickly estimate the ftL produced by various pj's for my 126" HiPower screen, gain = 2.8, area = 47.1 ft^2; this ftL = 6*(lumens/100), so I only need to remember the number 6!]

I will not disagree with your point regarding that there is a place for high gain screens but they sure aren't for everyone or every installation. To say that low gain screens have no place I disagree with. Joe Kane made the comment that I agree with. It is time to stop attempting to compensate for projector problems with the screen.

In my room the ideal is a low gain AT screen and I wanted a pretty good size screen for immersion. This required a higher light output projector.

Art
I will not disagree with either you or Mr. Kane either. There are many different philosophies here. I did calculate the maximum screen size for a no-gain (1.0) screen as a reference. I also cut some slack by only provided an equation for the SMPTE standard of 12fl.
Are Mr. Kane, SMPTE and ISF now recommending 20fl? If so, is it time to start buying large 65" high-output flat panels? :rolleyes:

The simple provided equation allows even laymen with a PDA to tell how bright their new system will be before committing to a purchase. The advice here has been quite inconsistent. The results show that staying with a no-gain screen makes the lower output projectors none too practical. Sixty or seventy inches are just not immersive enough for the thrill which front projector technology is capable. We need an image which takes up over 30 degrees of our eyes field of view. Now even the reviewers are using 1.3 gains screens but still under 90". This is just too small to keep the technology competitive.

The most efficient screen would only send light to our eyes location. In other words over 99% of the light today is wasted and actually degrades the PQ as it bounces off of surrounding surfaces and then makes it to our eyes as interference. High gain screens are more efficient because they are directional for the viewer and sometimes also the source. Think green. :D

My concern now is reviewers will quite publishing lumen output, as for every action there is a reaction. (Some already did it for contrast measurements). :(

The most efficient screen would only send light to our eyes location. In other words over 99% of the light today is wasted and actually degrades the PQ as it bounces off of surrounding surfaces and then makes it to our eyes as interference. High gains screens are more efficient because they are directional for the viewer and sometimes also the source.




If this were all there were to consider, I'd not have anything but a high gain but angular reflective high gain screens all hot spot and have poor off axis performance. The better retro-reflective high gain screens require the the projector to be low in the room ,have a very narrow viewing cone and have no AT options.

Art

Sony VPL-VW60 Screen Calculations for 12fl Brightness

From the Projector Central review the Sony VPL-VW60 is a dim projector. The lens telephoto setting reduces light by 33%. The review does not take into account the 50% reduction in brightness due to bulb aging. We do here

Sony VPL-VW60 , telephoto, 1.0 screen gain
sqrt(14*235*1.0) = 57 inches maximum diagonal screen size

Sony VPL-VW60, telephoto, 2.5 screen gain
sqrt(14*235*2.5) = 91 inches maximum diagonal screen size

Sony VPL-VW60, wideangle, 1.0 screen gain
sqrt(14*350*1.0) = 70 inches maximum diagonal screen size

Sony VPL-VW60, wideangle, 2.6 screen gain
sqrt(14*350*2.5) = 110 inches maximum diagonal screen size


1) Calculations reveal that to meet SMPTE standards of 12fl, mate this projector with a 2.5 gain screen


Yeah, something just doesn't sit right with me with these numbers, and I realize the math is correct (I worked it out myself last night). But really I don't see a whole lot of value working backward to find screen size, I look at it the opposite way, I've got a room and know how big I want the screen to be. I think it's much more useful to take the screen size and figure out how many lumens/gain you need.

Unfortunately the numbers aren't quite as friendly that way:
Lumens = 0.0356 * Diag^2 / gain
Or, to approximate:
Lumens = Diag^2 / gain / 30

For example I've got a 110x46" screen, ~36sqft. It's reportedly 1.16x gain. So 36*12/1.16 = 370Lumens.

Going by Jason's measurements, the VW60 can do that at short throw.

And then of course, don't overestimate the difference 3 ftL can make. I mentioned it above, but between high and low lamp on my IN76, the difference is 3ftL or 30%. However if I had to quantify the qualitative difference between the two, I'd say high lamp looks 5%, or at most maybe 10% brighter. It's really not significant IMO.

and the 11S2 is BRIGHTER than the 11S1.

so what you say does not make any sense.


Lets take a look at some recent projector releases:

Sony VW200
Marantz 11S2
JVC RS2

All are arguably dimmer than their predecessors, and even the Sharp 20k is about as dim as any of those. I think it could probably be argued that there is a push by some to want to raise the so called standard to 20 foot lamberts but there still is also a push by many to advance the best picture quality possible, over brightness.

The RS2 is arguably 30% dimmer than the RS1. The 11S2 20% dimmer than the 15S1.

Dan Miller advised in another thread that Marantz looked at alternative lamp options for the 15S1 and 11S2, presumably VIDI and OSRAM, and elected to not sacrifice picture quality for "output."

"The size of the pupil is an important factor affecting visual acuity. Large pupils allows more light to stimulate the retina and reduces diffraction but resolution will be affected by aberrations of the eye. On the other hand, a small pupil will reduce optical aberrations but resolution will be diffraction limited. Therefore, a mid-size pupil of about 3 mm to 5 mm would be optimal, as this is a compromise between the diffraction and aberration limits (Atchison et al, 1979; Smith and Atchison, 1997)."

Do we we need to measure the diameter of our pupils?
Problem is the pupils diameter varies with the brightness of the movie's content :confused:

and the 11S2 is BRIGHTER than the 11S1.

so what you say does not make any sense.




The 11S2 is brighter than the 15S1? Not according to Marantz (their specs), and also Dan Miller of Marantz who posts on these forums.

THX Best Viewing Distance Calculation for 1920*1080 Screens

best viewing distance(ft) = diagonal screen size(inches) /10

70" diagonal screen size... = 7ft best viewing distance
80" diagonal screen size... = 8ft
90" diagonal screen size... = 9ft
100" diagonal screen size = 10ft
110" diagonal screen size = 11ft
120" diagonal screen size = 12ft
130" diagonal screen size = 13ft
140" diagonal screen size = 14ft
150" diagonal screen size = 15ft
160" diagonal screen size = 16ft

As we see by examining the data, just take the diagonal screen size (in inches) and divide by 10 to get the THX optimal viewing distance in feet. Anyone can do it :cool:

I personally think this might be the closest you want to be seated at. But it is a good match for the maximum screen sizes already calculated for each projector. The two extremes tend to cancel each other out.

I understand the confusion as I get confused like this too.
A fresh new bulb measures 1000 lumens. The same bulb "aged" loses approximately 50% of its brightness and would measure approximately 500 lumens:
Fresh bulb sqrt(14*1000*1) = 118.32"
Aged bulb sqrt(28*500*1) = 118.33"

From the original posted equations:
maximum diagonal screen size (in inches) for 12fl with a measured new bulb =
sqrt(14* projector new bulb lumen output * screen gain)

maximum diagonal screen size in inches) for 12fl with an measured aged bulb =
sqrt(28* projector aged bulb lumen output * screen gain)

The whole point here is to take the mystery and confusion out of selecting a screen and projector to fit your room and viewing preferences based upon SMPTE standards. Many members complain of their picture being to dim but seldom too bright - as this poll indicates. These equation(s) should clear it up the confusion. Its all science (with the right equation).

Screen size can change dramatically because its dependent upon the square of the projectors output and the screen gain.
How about if we add "new bulb " and "aged bulb" into the equation to be even more explicit? Thank you for the peer review :cool:
Ah, I thought you intended something different with the "aged bulb" equation.
I find it very confusing, as you usually start with a new bulb, and the known ANSI lumen measurements of various projectors are done with (almost) new bulbs. I certainly overlooked the "measured aged bulb" statement. But what sense does it make to calculate the possible diagonal with a new bulb from an the lumen output of an aged bulb? The drop in lumen through bulb aging isn't easy to predict, I have seen different drop in lumen on the same projector in the same time period with two different bulbs. I believe calculating with aged bulbs can be nothing more than an estimate.

How about this:

maximum diagonal screen size (in inches) for 12fl with a measured new bulb =
sqrt(14* projector new bulb lumen output * screen gain)

But beware, if you want to achieve 12fl with an aged bulb, consider this estimation:

maximum diagonal screen size in inches) for 12fl with an measured new bulb =
sqrt(7* projector aged bulb lumen output * screen gain)

Example:
Brand new bulb:
sqrt(14*1000*1)=118.32"

Same projector can light up this after 600 hours (estimation):
sqrt(7*1000*1)=83.66"

Sharp XV-Z20000 DLP Projector- Screen Calculations for 12fl Brightness & Best Viewing Distance

Home Theater Review measurements: “After calibration and using a full-field 100-IRE white (9.117 foot-lamberts) and a full-field 0-IRE black (0.001 ft-L), the contrast ratio was 9,117:1. Using a 16-box checkerboard pattern (ANSI contrast), the contrast ratio was 606:1. The best contrast ratio/PQ was achieved with the iris set to High Contrast and the lamp at Eco + Quiet.”
The review does not take into account the 50% reduction in brightness due to bulb aging. We do here
Screen: 87-inch-wide, 1.0-gain
Diagonal = 87/0.8723 = 100 inches diagonal
336 * L = 9.12* 100*100
L= 271 lumens

Sharp XV-Z20000 DLP Projector, High Contrast, lamp at Eco + Quiet, 1.0 screen gain
sqrt(14*271*1.0) = 62 inches maximum diagonal screen size, 6.2 ft best viewing distance

Sharp XV-Z20000 DLP Projector, High Contrast, lamp at Eco + Quiet, 2.5 screen gain
sqrt(14*271*2.5) = 97 inches maximum diagonal screen size, 9.7 ft best viewing distance

http://www.hometheatermag.com/frontprojectors/1006sharpz20000/index2.html

Optoma HD80 Screen Calculations for 12fl Brightness & 1920*1080 Best Viewing Distance

Adrienne Maxwell of Home Theater Magazine 3/2008
The review does not take into account the 50% reduction in brightness due to bulb aging. We do here

Normal Lamp Mode
------------------
Screen: 87-inch-wide, 1.0-gain
Diagonal = 87/0.8723 = 100 inches diagonal
336 * L = 6.764fl* 100*100
L= 201 lumens

Optoma HD80, Normal Lamp, Image AI on, IRIS 16, 1.0 screen gain
sqrt(14*201*1.0) = 53 inches maximum diagonal screen size, 5.3ft best THX viewing distance

Optoma HD80, Normal Lamp, Image AI on , IRIS 16, 2.5 screen gain
sqrt(14*201*2.5) = 84 inches maximum diagonal screen size, 8.4ft best THX viewing distance


Bright Lamp Mode
-----------------
336 * L = 16.26fl* 100*100
L= 483 lumens

Optoma HD80, Bright Lamp, IRIS 0, 1.0 screen gain
sqrt(14*483*1.0) = 82 inches maximum diagonal screen size, 8.2ft best THX viewing distance

Optoma HD80, Bright Lamp, IRIS 0, 2.5 screen gain
sqrt(14*483*2.5) = 130 inches maximum diagonal screen size, 13.0ft best THX viewing distance

1) Reviewer noted HD picture lacked “pop” in Normal lamp mode
2) Very loud fan noise in bright lamp mode
3) Image AI is best turned off as its operation is visible

do you need reading glasses? I know that I do but have been holding off.

anyways.... I did NOT say 15S1.... I said the 11S2 is brighter then the 11S1.

The 11S2 is brighter than the 15S1? Not according to Marantz (their specs), and also Dan Miller of Marantz who posts on these forums.

Sorry, Cape .. misread your post.

Sony VPL-VW50 Screen Calculations for 12fl Brightness & 1920*1080 Best Viewing Distance

Measurements are from WSR magazine issue 115. The calculations are being provided because the new Sony VPL-VW40 is supposed be similar to this model.
We are taking the long route here with four screen sizes per lamp setting, as these are the boundaries from which the auto iris adjusts itself, depending upon the particular frames signals content. In other words the Auto iris varies from best contrast to best brightness while also introducing compression at the top. Take you pick of one or the other, but never the two simultaneously.

The review does not take into account the 50% reduction in brightness due to bulb aging for selecting a screen size. We do here

Best Contrast, Worst Brightness (Auto Iris mode = off)
-------------------------------------
Sony VPL-VW50, low lamp, minimum lens aperture, 1.0 screen gain
sqrt(14*234*1.0) = 57 inches maximum diagonal screen size, 5.7ft best THX viewing distance

Sony VPL-VW50, low lamp, minimum lens aperture, 2.5 screen gain
sqrt(14*234*2.5) = 90 inches maximum diagonal screen size, 9.0ft best THX viewing distance

Sony VPL-VW50, high lamp, minimum lens aperture, 1.0 screen gain
sqrt(14*361*1.0) = 71 inches maximum diagonal screen size, 7.1ft best THX viewing distance

Sony VPL-VW50, high lamp, minimum lens aperture, 2.5 screen gain
sqrt(14*361*2.5) = 112 inches maximum diagonal screen size, 11.2ft best THX viewing distance

Worst Contrast, Best Brightness (Auto Iris mode = off)
--------------------------------------
Sony VPL-VW50, low lamp, maximum lens aperture, 1.0 screen gain
sqrt(14*432*1.0) = 78 inches maximum diagonal screen size, 7.8ft best THX viewing distance

Sony VPL-VW50, low lamp, maximum lens aperture, 2.5 screen gain
sqrt(14*432*2.5) = 123 inches maximum diagonal screen size , 12.3ft best THX viewing distance

Sony VPL-VW50, high lamp, maximum lens aperture, 1.0 screen gain
sqrt(14*652*1.0) = 96 inches maximum diagonal screen size, 9.6ft best THX viewing distance

Sony VPL-VW50, high lamp, maximum lens aperture, 2.5 screen gain
sqrt(14*652*2.5) = 151 inches maximum diagonal screen size, 15.1ft best THX viewing distance

Notes
1) reviewers state the picture quality is superior with the auto iris engaged
2) auto/dynamic iris mode makes exact screen selection painful as the size falls somewhere between the highest contrast or highest brightness sizes. As a rule, higher contrast equates to better picture quality. Each owner must select some screen size. Or as an alternative, choose a projector which does not require a dynamic iris to achieve optimal picture quality
3) For best picture quality use no vertical or horizontal lens shift with any projector

Sanyo PLV-Z2000Screen Calculations for 12fl Brightness & 1920*1080 Best Viewing Distance

Adrienne Maxwell of Home Theater Magazine 3/2008
The review does not take into account the 50% reduction in brightness due to bulb aging. We do here

Screen: 87-inch-wide, 1.0-gain
Diagonal = 87/0.8723 = 100 inches diagonal
336 * L = 11.0fl* 100*100
L= 327 lumens

Best picture quality (best contrast, highest brightness and black level) with lamp = A1 mode, iris = fast

Sanyo PLV-Z2000, best picture quality settings, 1.0 screen gain
sqrt(14*327*1.0) = 68 inches maximum diagonal screen size, 6.8ft best THX viewing distance

Sanyo PLV-Z2000, best picture quality settings, 2.5 screen gain
sqrt(14*327*2.5) = 107 inches maximum diagonal screen size, 10.7ft best THX viewing distance


1) Only use with high gain screen
2) black level a bit flat
3) oversaturated primary colors
4) audible fan noise
5) needs professional calibration
6) ok value with $600 rebate

Has anyone considered that Xenon Bulbs do not deteriorate like UHP bulbs.

One of the Head Sony Engineers for the Vw Series projectors had made it very clear the Xenon Bulbs remain almost exact their whole life.

Where are you people getting this degradation factors from ?

Check out my New BMW Car, it has Xenon's, same concept.. Look at my partners year old BMW, same output.. They dont look any less bright..

Craig

Keep in mind that all movies are timed and approved by the DP at anywhere from 12fl to 16fl per SMPTE specs. So watch it at any light level you wish but if you want to see the film exactly as the DP intended, then you need to use 12-16fl just as they did.

These ideas of 24fl to 48fl are ridiculous if the movie was timed at 12fl. Now if you have high ambient light such as a living room, that's different. But then you aren't getting the true theater expereince either.

Has anyone considered that Xenon Bulbs do not deteriorate like UHP bulbs.

Craig

The opposite was found to be true with the Xenon lamp in the Sony Ruby IIRC. The lamp output degraded sharply then settled (lost 30% of it's lumen output after 200 hours IIRC). I seem to remember someone on this forum actually recorded the lumen output so a graph could be drawn.

Not sure why that's the case with projector lamps and not with car lamps, but seeing as you need to see a reduction of 82% of light to perceive a 50% drop, it's quite likely a car light does degrade but isn't as perceivable as you'd think.

Gary

Sony SRX-R-110 - 4k Projector- Screen Calculations for 12fl Brightness & Best Viewing Distance

The manufacture specifications do not take into account the 50% reduction in brightness due to bulb aging. We do here

Sony SRX-R-110 - 4k (4096 x 2160p) 3-chip SXRD Cine Alta 10,000 ANSI Lumen, 1.0 screen gain
sqrt(14*10,000*1.0) = 374 inches maximum diagonal screen size, 37.4 ft best viewing distance

Sony SRX-R-110 - 4k (4096 x 2160p) 3-chip SXRD Cine Alta 10,000 ANSI Lumen, 2.5 screen gain
sqrt(14*10,000*2.5) = 592 inches maximum diagonal screen size, 59.2 ft best viewing distance

The Kipnis studio standard screen is 247 inches diagonal so this ISF certified design is well above 12fl. Here we see by how much:
Kipnis studio standard foot-lamberts = 10,000/18*10.125 = 54.86fl new bulb, 27.5 aged bulb

Notes:
1) Perfect for them jet-set parties! Who's your sugar daddy?
2) Who needs an LCD flat panel in the kitchen anymore? :cool:
3) No HDMI - too many service calls
4) Econo-bulb setting optional

http://www.abelcine.com/store/pdfs/SXRD_specs.pdf

http://kipnis-studios.com/The_Kipnis_Studio_Standard/Equipment.html

Wow at first I was a little surprised at the results of this poll, but it has now shed some light (heh heh) on the general views of the posters here.

To me, in a light controlled room, 12fl is WAY more than enough brightness.

It's also been my experience that, generally speaking, as you gain brightness you sacrafice image quality; people will refute that and I've seen plenty of posts in this thread that say "I have both!" but then again I would venture to guess that it's the minority out there who really understand and appreciate a high-quality image.

High contrast, deep blacks and good shadow detail are not negotiable for what makes a "high quality image" and, at the moment, it's rare (if not impossible) to have 20fl AND the best possible image.

People will say "I have all those things" but I would bet a month's salary that if an ISF tech came to your house, he would most likely laugh at your contrast and "deep blacks."

Why do you think the #1 response to an ISF callibration is "wow that picture looks too dark to me now?" Because most people haven't experienced a truly high-end image and, if they have, haven't given themselves the time to appreciate it (they usually make it brighter as soon as the tech leaves).

Of course, most people think the steaks at Black Angus are REALLY good.

To be fair, to each his own, and if someone with a 30fl light cannon likes to watch football with the lights on and thinks he has the most amazing image ever, more power to him.

But I think you'd be hard pressed to find very many examples where the brightest image is also the best image.

Has anyone considered that Xenon Bulbs do not deteriorate like UHP bulbs.

One of the Head Sony Engineers for the Vw Series projectors had made it very clear the Xenon Bulbs remain almost exact their whole life.

Where are you people getting this degradation factors from ?


Craig

Experiences of very reputable xenon lamp based front projector owners.Xenon degrades rapidly in light output initially then levels ,a few hundred hours can eat 40% from the new lamp number.

Art

Not mauch data yet from the new Sony VPL-vw200 owners butnoone is reporting niticeable fallof yet.i have war few enough hours to offer anything anecdotal on bulb life in my machine and probably will never have enough hours on it because I have so many other machines to play with. This week its an RS2. And then there is my CRT which i am always referencing again.

Fenix T1 Portable Light Projector- Screen Calculations for 12fl Brightness & Best Viewing Distance

This unit uses an LED source so the brightness should fall off at a much slower rate than traditional bulbs. What you see initially will be what you get for long term. The stability and light quality is unmatched.

L= 225 lumens

Fenix T1 Light Projector, 1.0 screen gain
sqrt(28*225*1.0) = 79 inches maximum diagonal screen size, 7.9 ft best viewing distance

Fenix T1 Light Projector, 2.5 screen gain
sqrt(28*225*2.5) = 125 inches maximum diagonal screen size, 12.5 ft best viewing distance

1) unit is silent in operation
2) reviewer noted central hot-spotting
3) manufacture claims of 200 meters throw distance needs to be verified
4) standard lens assembly is spherical, anamorphic stretch lens needs to be designed

http://www.fenixtactical.com/fenix-t1.html ;)

No offense, reincarnate, but shouldn't your posts offering details on getting 12fl with any given projector have it's own thread called something like "how to get 12fl on any given projector?" I'm sure a lot of people would find specs like that useful and they probably don't realize it's in here.

In addition, I'd like to see this thread stay focused on discussion of people's feelings about brightness, which seems to be getting lost in a flurry of technical posts.

No offense, reincarnate, but shouldn't your posts offering details on getting 12fl with any given projector have it's own thread called something like "how to get 12fl on any given projector?" I'm sure a lot of people would find specs like that useful and they probably don't realize it's in here.

In addition, I'd like to see this thread stay focused on discussion of people's feelings about brightness, which seems to be getting lost in a flurry of technical posts.
I agree and will do something like: in the first post provide a link to each manufactures projectors:
...
Epson
JVC
Marantz
Panasonic
Sanyo
Sony
...
This will be the reference section which will grow in time as more projectors are added. Then everyone else can post their divergent views. I just need the will and time. But I will do it because I can't stand the never-ending confusion otherwise. Suggestions are welcome. Thanks :)

Hopefully its evident that low (and especially negative) gain screens appear to have little or no place in the modern home theater.

I've been reading more of this thread in detail and I find this remark utterly ludicrous.

First of all, it's understood that high gain screens (above about 1.3) degrade video quality and cause hotspotting, so really it's HIGH gain screens that have no place in a home theater if you care about picture quality.

Most people are looking for a good balance between brightness and quality, so perhaps a 1.5 gain screen is the acceptable compromise - but all of the "recommendations" being posted to get 12fl out of these projectors are suggesting closer to 2.0 or higher! And/or you're generally suggesting screens under 80", when the average screen seems to be about 100."

That may be what it takes to get 12fl, but I think it's highly unlikely that many people (if any) are going to go with a 2.4 gain or 72" screen.

All this does is prove that very few people are experiencing 12fl and that most people who are satisfied with their home theater are watching an image that's dimmer than they think. So, the idea that home theaters "must" have 12fl to be taken seriously is a bogus concept.

What's interesting about this thread is the people who think brighter is better have just said "yeah I need high brightness or bust, more than 12fl for me!" and the people who care most about black level and image quality have actually taken measurements and discovered that their perfectly acceptable image was much lower than they assumed.

If anything, this thread has shown that approximately 7 footlamberts is the averge amount of brightness people are getting in a dark room with a videophile image and it's very, very acceptable.

People should NOT have drilled into them that less than 12fl is unacceptable - that's total BS and the lessons of this thread have been that 7fl is the "sweet spot," with 5fl being the (more or less) acceptable minimum; those concerned with image quality and good black level would most likely find 12 too bright, but 12fl gives you the wiggle room you need to experiment with ND filters.

First of all, it's understood that high gain screens (above about 1.3) degrade video quality and cause hotspotting, so really it's HIGH gain screens that have no place in a home theater if you care about picture quality.

I agree that high gain screens (> 1.3) don't work in all setups, but for those for which they do this statement is just not true (as are most such categorical pronouncements in HT).

I agree that high gain screens (> 1.3) don't work in all setups, but for those for which they do this statement is just not true (as are most such categorical pronouncements in HT).

Can you tell me in what setups a 2.0 gain screen will work? And by "work" I mean will not degrade image quality?

I think the vast majority of folks around here would agree that 2.0 is really pushing it. I agree that blanket statements don't work, but I would also argue that "low gain screens have no place in a home theater" is a far more outlandish suggestion than "high gain screens hurt image quality."

Mojo_LA,
Everyone is entitled to their opinion. You are obviously part of this polls 5.49% vocal minority.

If you have a factual brightness argument to make, then why not take it to the Society of Motion Picture and Television Engineers (SMPTE)? Or the Imaging Science Foundation (ISF)? I'd like to see anyone prove their studies and standards "total BS".
Thank you for sharing your viewing preferences :)

Can you tell me in what setups a 2.0 gain screen will work? And by "work" I mean will not degrade image quality?

I think the vast majority of folks around here would agree that 2.0 is really pushing it. I agree that blanket statements don't work, but I would also argue that "low gain screens have no place in a home theater" is a far more outlandish suggestion than "high gain screens hurt image quality."

There is another 'vast high gain conspiracy' that would disagree. E.g., if you can set your pj up not far from eye level--as had been discussed extremely thoroughly in many threads on the forum--then the retro-reflective Dalite HiPower has essentially no drawbacks: it does not hot spot, show any screen surface structure, provides a highly uniform illumination of the entire screen, and by concentrating the light back toward the pj (and thus the viewer) it also reduces the effects of reflected light from room surfaces.

Again, as has been widely discussed, the only limitation is that your room setup allow you to locate the pj in this way. It then is IDENTICAL to having a brighter pj on a lower gain screen: as other have said better than I, "ftL's is ftL's, it doesn't matter how you generate them".

What I'm saying is "total BS" is the idea that you NEED 12fl to have a great home theater image and that bending over backwards to achieve it would be folly, especially when it can potentially hurt your image quality.

This thread is telling people (and possibly nubies) that you have to have 12fl and anything less is sub-standard.

Sure, maybe 12fl is ideal, but if you can find me ONE tech from ISF who recommends doing whatever it takes to acheive 12fl and "to hell with all the rest" I'll never post again.

It is not simply my "viewing preference" to suggest that a 2.4 gain screen is going to significantly affect image quality; it may be someone's preference to enjoy that bright image (as long as he's sitting dead center) over accuracy, but to insinuate that it should be "12fl or bust" is misleading.

I don't think very many people here would be happy with their image of they followed the specs being posted here to achieve 12fl (a small, high gain screen); take the poll THEN and you'll see that 5% number go way up.

Besides, as has been mentioned, how many of those 136 people who think they need a brighter image actually MEASURED their current brightness? As the "vocal minority" have shown, most of us have an image much dimmer than we think and that 12fl is far brighter than people realize.

Sure, maybe 12fl is ideal, but if you can find me ONE tech from ISF who recommends doing whatever it takes to acheive 12fl and "to hell with all the rest" I'll never post again.

My understanding is that the president of ISF (don't remember his name) had recently taken the position that 20 ftL is the new ideal. Maybe others who know this better than I can chime in.

And I certainly have measured the brightness of my screen and have always been between 18 and 28 ftL.

And Mojo, I'm not trying to convince you that are 'wrong' for preferring < 12 ftL, only saying that there plenty of persons who like it otherwise. Nothing wrong with this, either way, it's whatever one finds most pleasing for their specific situation and viewing habits.

This thread is telling people (and possibly nubies) that you have to have 12fl and anything less is sub-standard.

Exactly. By definition anything less than the industry standard is sub-standard. These "nubies" may love their initial bright PQ (as documented here) but over time they tend to loose enthusiasm as the picture dims by half. So why not develop scheme up-front to counteract for the bulb dimming?

The goal is to provide the scientific measurements and calculations to the front projector enthusiast to assemble a system which will give long-term satisfaction based upon the motion picture standards.

The end result will be much less confusion too, as we begin to talk from the same sheet of paper.

Sony VPL-VW40 Screen Calculations for 12fl Brightness & 1920*1080 Best Viewing Distance

Measurements are from Projector Central review. We report screen size for Cinema mode, which is the default and the preferred mode for watching high definition movies.
The review does discuss the various maximum screen size vs power mode and lens zoom setting.
The review does not take into account the 50% reduction in brightness due to bulb aging for selecting a screen size. We do here

Measurements:
Cinema mode, low lamp, wide angle = 261 lumens
Cinema mode, low lamp, telephoto = 176 lumens
Cinema mode, hi lamp, wide angle = 373 lumens
Cinema mode, hi lamp, telephoto = 252 lumens

Screen Gain = 1.0
-----------------
Sony VPL-VW40 Cinema mode, low lamp, telephoto
sqrt(14*176*1.0) = 49.6 inches maximum diagonal screen size, 5.0ft best THX viewing distance

Sony VPL-VW40 Cinema mode, low lamp, wide angle
sqrt(14*261*1.0) = 60.4 inches maximum diagonal screen size, 6.4ft best THX viewing distance

Sony VPL-VW40 Cinema mode, hi lamp, telephoto
sqrt(14*252*1.0) = 59.3inches maximum diagonal screen size, 5.9 ft best THX viewing distance

Sony VPL-VW40 Cinema mode, high lamp, wide angle
sqrt(14*373*1.0) = 72.3 inches maximum diagonal screen size, 7.2 ft best THX viewing distance


Screen Gain = 2.5
-----------------
Sony VPL-VW40 Cinema mode, low lamp, telephoto
sqrt(14*176*2.5) = 78.5 inches maximum diagonal screen size, 7.8 ft best THX viewing distance

Sony VPL-VW40 Cinema mode, low lamp, wide angle
sqrt(14*261*2.5) = 95.6 inches maximum diagonal screen size, 9.6ft best THX viewing distance

Sony VPL-VW40 Cinema mode, hi lamp, telephoto
sqrt(14*252*2.5) = 93.9 inches maximum diagonal screen size, 9.4ft best THX viewing distance

Sony VPL-VW40 Cinema mode, high lamp, wide angle
sqrt(14*373*2.5) = 114 inches maximum diagonal screen size, 11.4ft best THX viewing distance


1) The usual strategy is to us the projectors low lamp power setting initially, then as the bulb ages (and dims) switch to the high power setting
2) wide angle lens setting and high gain screen are recommended

When a projector is very bright, like it has high capability for contrast, it looks very unnatural to me. When I'm watching a film, I've often turned down the contrast on my CRT rear projection set, even though the TV can produce higher contrast without blooming. I don't consider film at the theaters to be very bright, but it looks very natural to me, and that is probably what I refer to most, so in general my contrast is probably on the low side.

Dan

My understanding is that the president of ISF (don't remember his name) had recently taken the position that 20 ftL is the new ideal. Maybe others who know this better than I can chime in.

And I certainly have measured the brightness of my screen and have always been between 18 and 28 ftL.

And Mojo, I'm not trying to convince you that are 'wrong' for preferring < 12 ftL, only saying that there plenty of persons who like it otherwise. Nothing wrong with this, either way, it's whatever one finds most pleasing for their specific situation and viewing habits.

The 20fL is recommended for HD source material, and not SD material which is now a 1939 standard, so technology has moved on and I suspect that Joel Silver is trying to do the same given that we now have brighter projectors and considerably higher quality source material. As I mentioned in an earlier post, the 12fL was chosen in part to hide the 24fps and 48fps flicker that film projectors produce, but with higher frequencies now available to us in digital projectors that limitation is no longer present.

SD source material doesn't fall under his same guidelines. Since many of us still have a lot of SD source material I'd stick to 12fL or less for the reasons given earlier.

Gary

If you have a factual brightness argument to make, then why not take it to the Society of Motion Picture and Television Engineers (SMPTE)? Or the Imaging Science Foundation (ISF)? I'd like to see anyone prove their studies and standards "total BS".Man you have some nerve lecturing anyone on the subject matter of SMPTE standard specifications! When I answered your question (link below), you literally bit the hand that just fed you:)
http://www.avsforum.com/avs-vb/showthread.php?t=995363
SMTPE video standard white = 30 fl. I could find no reference to 30fl for video sources using Google. Can you point me in the right direction? Thanks!My response:

http://www.filmlight.ltd.uk/services_support/library
The Datasheets and White Papers section of our website provides access to FilmLight's publicly available documentation. Standard Colour Spaces:

SMTPE video standard white = 30 Foot-Lamberts = 100 Candelas/sq.m

SMTPE cinema standard white = 16 Foot-Lamberts = 55 Candelas/sq.m

I personally think that there is change afoot for several reasons not the least of which is technologies that make the old 12fL standards less relevant.

I watched between 9fL and 12fL on my two CRT stacks for eight years and felt that it was a tremendous picture.Now ,however, some of the reasons for the illumination standards, like flicker visibility , are becoming less important.

From the experience of my CRTs to now the biggest difference I see in watching over 20fL is greater visibilty of image detail (good and bad) and the perception that high APL material, like daylight street scenes, etc., actually are perceived more like daylight than they were with my 11fL average days..

I've see films at commercial theaters where there was lots of CGI that I knew that I could not make out detail enough to make it seem three dimensional at all. The greater fL I have at home now allows one to clearly see all detail that is in the image.

I'm not saying that this is right or wrong but for me personally it is a better overall experience.

Art

The goal is to provide the scientific measurements and calculations to the front projector enthusiast to assemble a system which will give long-term satisfaction based upon the motion picture standards.

The end result will be much less confusion too, as we begin to talk from the same sheet of paper.
I don´t mean any disrespect saying this but I´m not sure if the data posted here is fair to all projectors as a comparison. Data is from so many different test environments and measuring equipment (different measuring method also?) that as a comparison it does not strike me as valid even though the individual measurements can be. I admit that I haven´t read the whole thread so it could be that this has already been discussed, but how broadly can we compare projectors based on these measurements from different reviewers.

I know that I can´t find lumen measurements from all of these projectors from any one reviewer with the same set of equipment and same room. Thats why I am interested in the nicely put together information in this thread and would like to know more about the validity part. :)

There is another 'vast high gain conspiracy' that would disagree. E.g., if you can set your pj up not far from eye level--as had been discussed extremely thoroughly in many threads on the forum--then the retro-reflective Dalite HiPower has essentially no drawbacks: it does not hot spot, show any screen surface structure, provides a highly uniform illumination of the entire screen, and by concentrating the light back toward the pj (and thus the viewer) it also reduces the effects of reflected light from room surfaces.

.


I think you need to add one thing that you omitted,viewing cone and it's a narrow one with HP. There is one ideal setup for the HP screen and I've seen it implemented with great results and that is with the projector right at head level behind two seats projecting between.

Art

I think you need to add one thing that you omitted,viewing cone and it's a narrow one with HP. There is one ideal setup for the HP screen and I've seen it implemented with great results and that is with the projector right at head level behind two seats projecting between.

Art

Your "one ideal" hp setup is only ideal if you need the full 2.8 gain of the screen. If one requires less than full gain the ideal setup would place the PJ lower or higher from this full gain head level location. Or are you referring to attributes other than gain which dictate the ideal setup being a head level?

Your "one ideal" hp setup is only ideal if you need the full 2.8 gain of the screen. If one requires less than full gain the ideal setup would place the PJ lower or higher from this full gain head level location. Or are you referring to attributes other than gain which dictate the ideal setup being a head level?

Gain and the primary selling point of the HP. In my room, only three seats of thirteen would be in positive gain with the HP setting the projector where my HT5000 is now.

Art

I think you need to add one thing that you omitted,viewing cone and it's a narrow one with HP. There is one ideal setup for the HP screen and I've seen it implemented with great results and that is with the projector right at head level behind two seats projecting between.Art

Absolutely right, Art; I forgot to add the viewing cone requirement in my synopsis re the HP screen. For best results viewers should be not outside the L and R sides of the screen.

Incidentally, your description of the 'ideal setup' is precisely mine: a RS1 on a 4 ft stand, between and just behind my wife's and my 2 recliners. Having this setup is probably why I'm such a fan of the HP.

Gain and the primary selling point of the HP. In my room, only three seats of thirteen would be in positive gain with the HP setting the projector where my HT5000 is now.

Art

Ok that makes sense, I thought your comment "there is one ideal setup for the HP screen" was a general one and not specific to your system.

Absolutely right, Art; I forgot to add the viewing cone requirement in my synopsis re the HP screen. For best results viewers should be not outside the L and R sides of the screen.

Incidentally, your description of the 'ideal setup' is precisely mine: a RS1 on a 4 ft stand, between and just behind my wife's and my 2 recliners. Having this setup is probably why I'm such a fan of the HP.


No doubt it is a hell of a screen ! Glad to hear you are enjoying your set up.:)

Art

I personally think that there is change afoot for several reasons not the least of which is technologies that make the old 12fL standards less relevant.

I watched between 9fL and 12fL on my two CRT stacks for eight years and felt that it was a tremendous picture.Now ,however, some of the reasons for the illumination standards, like flicker visibility , are becoming less important.

From the experience of my CRTs to now the biggest difference I see in watching over 20fL is greater visibilty of image detail (good and bad) and the perception that high APL material, like daylight street scenes, etc., actually are perceived more like daylight than they were with my 11fL average days..

I've see films at commercial theaters where there was lots of CGI that I knew that I could not make out detail enough to make it seem three dimensional at all. The greater fL I have at home now allows one to clearly see all detail that is in the image.

I'm not saying that this is right or wrong but for me personally it is a better overall experience.

Art
Excellent points and glad to see you adapting, as too many people become set in their ways. :)
I really like the terms realism and daylight. At low brightness levels, the eye looses its color ability too.

I don´t mean any disrespect saying this but I´m not sure if the data posted here is fair to all projectors as a comparison. Data is from so many different test environments and measuring equipment (different measuring method also?) that as a comparison it does not strike me as valid even though the individual measurements can be. I admit that I haven´t read the whole thread so it could be that this has already been discussed, but how broadly can we compare projectors based on these measurements from different reviewers.

I know that I can´t find lumen measurements from all of these projectors from any one reviewer with the same set of equipment and same room. Thats why I am interested in the nicely put together information in this thread and would like to know more about the validity part. :)
Peak brightness is relatively easy and basic measurement. Contrast would be much harder to validate especially between reviewers as the lower light levels are difficult to measure and prone to environment and instrumentation error.

As an validity exercise, compare the screen calculations between the Sony 40, 50, 60 and 200 projectors. Trends and consistencies do become apparent.:)

Excellent points and glad to see you adapting, as too many people become set in their ways. :)
I really like the terms realism and daylight. At low brightness levels, the eye looses its color ability too.

Not to speak of how the eye dims with age (b-day # 67 coming up in a couple of weeks!).

BenQ W5000 Screen Calculations for 12fl Brightness & 1920*1080 Best Viewing Distance

Measurements are from Projector Central February 2008. The Brilliant Color mode affects brightness and apparently the gamma. We calculate from the peak whites.

Brilliant Color On
----------------
BenQ W5000, maximum aperture, 1.0 screen gain
sqrt(14*600*1.0) = 92 inches maximum diagonal screen size, 9.2ft best THX viewing distance

BenQ W5000, maximum aperture, 2.5 screen gain
sqrt(14*600*2.5) = 145 inches maximum diagonal screen size, 14.5 ft best THX viewing distance

BenQ W5000, minimum aperture, 1.0 screen gain (best contrast)
sqrt(14*350*1.0) = 70 inches maximum diagonal screen size, 7.0ft best THX viewing distance

BenQ W5000, minimum aperture, 2.5 screen gain (best contrast)
sqrt(14*350*2.5) = 111 inches maximum diagonal screen size, 11.1ft best THX viewing distance

Brilliant Color Off
----------------
BenQ W5000, maximum aperture, 1.0 screen gain
sqrt(14*600*1.0*0.68) = 76 inches maximum diagonal screen size, 7.6ft best THX viewing distance

BenQ W5000, maximum aperture, 2.5 screen gain
sqrt(14*600*2.5*0.68) = 119 inches maximum diagonal screen size, 11.9 ft best THX viewing distance

BenQ W5000, minimum aperture, 1.0 screen gain (best contrast)
sqrt(14*350*1.0*0.68) = 58 inches maximum diagonal screen size, 5.8ft best THX viewing distance

BenQ W5000, minimum aperture, 2.5 screen gain (best contrast)
sqrt(14*350*2.5*0.68) = 91 inches maximum diagonal screen size, 9.1ft best THX viewing distance


1) Reviewer notes excellent sharpness, high static contrast and a three-dimensional image
2) The projector is bright in the Brilliant Color mode at the expense of digital noise and artifacts. (Do dimmer projectors have less subjective noise levels? Is dither still a DLP limitation at higher brightness levels?)

Peak brightness is relatively easy and basic measurement. Contrast would be much harder to validate especially between reviewers as the lower light levels are difficult to measure and prone to environment and instrumentation error.

As an validity exercise, compare the screen calculations between the Sony 40, 50, 60 and 200 projectors. Trends and consistencies do become apparent.:)
Thank you for this answer and the idea to look for consistencies between similar projectors.

Marantz VP-15S1 - Screen Calculations for 12fl Brightness & Best Viewing Distance

Shane Buettner and Tom Norton wrote up an impressive review of this Marantz in December 2007.
There are many combinations of settings which affect brightness. We use what these expert reviewers found best.
The review does not take into account the ~50% reduction in brightness due to bulb aging. We do here

Best Compromise between Contrast and Brightness
------------------------------------------------
Gamma: Standard, Contrast: +15, Brightness: -13
Lamp: Normal, Iris: 2, Color temperature: 3
White Balance (after calibration)
Red gain: 12, Red bias: -3, Green bias: -1, Blue bias: -1, Others: 0

11.03 foot-Lamberts peak white measured
The review supplies no lumen figure directly but we can easily derive it:
Screen diagonal = 78/0.8723 = 89 inches
336 * L = 11* 89*89
L= 259 lumens --> finally subtract the 1.3 gain screen 259/1.3 = 199 lumens

Marantz VP-15S1, 1.0 screen gain
sqrt(14*199*1.0) = 53 inches maximum diagonal screen size, 5.3ft best THX viewing distance

Marantz VP-15S1, 2.5 screen gain
sqrt(14*199*2.5) = 84 inches maximum diagonal screen size, 8.4ft best THX viewing distance

Best Black Level and Contrast
----------------------------
“Closing the iris down to 1, with the Contrast on zero and in Normal lamp mode produced a contrast ratio of 2463:1, with an impressive black level of 0.003 but a not so good impressive peak white level of 7.39fL.”
336 * L = 7.4* 89*89
L= 174 lumens --> finally subtract the 1.3 gain screen 174/1.3 = 134 lumens

Marantz VP-15S1, 1.0 screen gain
sqrt(14*134*1.0) = 43 inches maximum diagonal screen size, 4.3ft best THX viewing distance

Marantz VP-15S1, 2.5 screen gain
sqrt(14*134*2.5) = 68 inches maximum diagonal screen size, 6.8ft best THX viewing distance

1) Reviewer noted superb resolution, terrific blacks and natural color
2) The Marantz color space indicates significant oversaturation in both red and green with no built in color management system
3) the projector is much quieter in Economy than in Normal

http://www.guidetohometheater.com/videoprojectors/1207mar15s1/index6.html

Why the inconsistencies? First you give us screen size recommendations for the W5000 at max lumens IRIS wide open and new bulb, then you give us VP-15S1 screen size recommendations when bulb is at half life and at IRIS 2 instead of wide open at 3.....Why?

A 53" screen for front projection? Is your point to say this projector is useless for front projection or is your point to say we don't need 12 foot-lamberts?

Not trying to flame, just want to understand the point of these two posts?

Marantz VP-15S1 - Screen Calculations for 12fl Brightness & Best Viewing Distance

Shane Buettner and Tom Norton wrote up an impressive review of this Marantz in December 2007.
There are many combinations of settings which affect brightness. We use what these expert reviewers found best.
The review does not take into account the ~50% reduction in brightness due to bulb aging. We do here

Best Compromise between Contrast and Brightness
------------------------------------------------
Gamma: Standard, Contrast: +15, Brightness: -13
Lamp: Normal, Iris: 2, Color temperature: 3
White Balance (after calibration)
Red gain: 12, Red bias: -3, Green bias: -1, Blue bias: -1, Others: 0

11.03 foot-Lamberts peak white measured
The review supplies no lumen figure directly but we can easily derive it:
Screen diagonal = 78/0.8723 = 89 inches
336 * L = 11* 89*89
L= 259 lumens --> finally subtract the 1.3 gain screen 259/1.3 = 199 lumens

Marantz VP-15S1, 1.0 screen gain
sqrt(14*199*1.0) = 53 inches maximum diagonal screen size, 5.3ft best THX viewing distance

Marantz VP-15S1, 2.5 screen gain
sqrt(14*199*2.5) = 84 inches maximum diagonal screen size, 8.4ft best THX viewing distance

Best Black Level and Contrast
----------------------------
“Closing the iris down to 1, with the Contrast on zero and in Normal lamp mode produced a contrast ratio of 2463:1, with an impressive black level of 0.003 but a not so good impressive peak white level of 7.39fL.”
336 * L = 7.4* 89*89
L= 174 lumens --> finally subtract the 1.3 gain screen 174/1.3 = 134 lumens

Marantz VP-15S1, 1.0 screen gain
sqrt(14*134*1.0) = 43 inches maximum diagonal screen size, 4.3ft best THX viewing distance

Marantz VP-15S1, 2.5 screen gain
sqrt(14*134*2.5) = 68 inches maximum diagonal screen size, 6.8ft best THX viewing distance

1) Reviewer noted superb resolution, terrific blacks and natural color
2) The Marantz color space indicates significant oversaturation in both red and green with no built in color management system
3) the projector is much quieter in Economy than in Normal

http://www.guidetohometheater.com/videoprojectors/1207mar15s1/index6.html

Ok, as a newbie reading this, what I'm REALLY getting out of this is

a) The PJ I'm considering *VW40 can't light up my 118" 1.4g screen up to "Standard" no matter what I try

and

b) I should of stuck with a TV because pretty much nothing can do over 110" to acceptable standards short of a flashlight.

If we are talking 70" screens.... why do we even have PJ's?
:(

Ok, as a newbie reading this, what I'm REALLY getting out of this is

a) The PJ I'm considering *VW40 can't light up my 118" 1.4g screen up to "Standard" no matter what I try

and

b) I should of stuck with a TV because pretty much nothing can do over 110" to acceptable standards short of a flashlight.

If we are talking 70" screens.... why do we even have PJ's?
:(

While there's nothing wrong with what reincarnate has posted, I don't like looking at things that way, I think it's backwards to look at a projector and see how big you can go, I think it's far better to look at the screen size you want, determine how much light you need, and then use that to help filter your projector choices.

For example you want to light a 118" (I'm going to be lazy and assume width) 1.4 gain screen, lets also assume standard 12 ftL. Figuring out the light requirements is quite easy:

Lumens = Screen Area * brightness / Gain

Therefore

(118 * 66/144) or 54 sqft * 12 ftL / 1.4 = 462 Lumens

462 Lumens will give you 12 ftL on that screen, now it's probably good to realize that lamps dim over time (rather quickly for the first couple hundred hours) so you probably want some sort of a "buffer" so you don't end up with a really dim image quickly. A 100% buffer would mean you start out twice as bright but shouldn't drop below 12ftL for the life of the bulb. You could also probably go with a 50% buffer, that would keep you above 12 ftL for part of the life and hopefully you wouldn't drop too far below it.

So, the next step is to look at projectors, let's take Jason's handy review thread of several new "high end" projectors:
http://www.avsforum.com/avs-vb/showthread.php?t=934831&highlight=in82

The IN82 is really quite versatile, it can throw anywhere from 230 all the way to 1100 Lumens depending on lamp and iris settings. Obviously this PJ could light that screen with plenty of "safety buffer".

The VW60 is less versatile regarding light output, perhaps more "normal"? It wil do between 280 and 570 Lumens. So the VW60 could light your screen in high lamp at short throw when new, but there's really no buffer there for lamp dimming.

The Marantz 15S1 will do between 270 and 840 depending on configuration, it could light your screen with a decent buffer.

The Sim2 D80E does between 608 and 760 Lumens so again, it could light your screen as well.

The JVC RS1 is known as being one of the brighter PJs:
http://www.avsforum.com/avs-vb/showthread.php?t=812816&highlight=rs1
Jason measured between 380 and 630 Lumens from it, so it could light your screen with a little buffer, perhaps not a lot.

The BenQ W5000 has been measured a couple places, looks to do 400-500 Lumens with the manual iris mostly closed, and any anywhere up to 1200+ depending on settings.

Bottom line is, there are projectors out there that will light up "reasonable" sized screens, you just need to look around and keep an open mind. The other thing to realize is the brightness you want plays a big role, if you're happy with 6ftL, your options are wide open, if you want 24, you're in mega-$$ territory. Also a screen with gain can change the whole picture as well.

For me, I think 9 ftL is probably a good minimum to shoot for, ie figure 9ftL + 100% buffer, so shoot for 18ftL out of the box and you'll get a nice bright picture and long use of the lamp.

stanger89: I would only add to your excellent post that screen gain--i.e., the choice of screen--is also an imp variable that can be brought into play to obtain the necessary ftL for the screen size you want.

But I agree with you very much: decide first what screen size you want, and then research the pj and screen that will get you your desired brightness (ftL) on it.

Ok, as a newbie reading this, what I'm REALLY getting out of this is
a) The PJ I'm considering *VW40 can't light up my 118" 1.4g screen up to "Standard" no matter what I try and
b) I should of stuck with a TV because pretty much nothing can do over 110" to acceptable standards short of a flashlight.
If we are talking 70" screens.... why do we even have PJ's?
:(
You are looking at near worst case here, but it is a reality which every projector owner will experience as the bulb ages. Careful reading of projector reviews reveals that they typically use small 90" diagonal 1.3 gains screens. Now you know why! The evidence has always been there, but here its presented like a splash of cold water in the face.
With careful design/system selection you can easily achieve 120" screens @ SMPTE 12fl, best picture quality settings, even when using the lamps low power setting.
Is it better to be have the knowledge up-front or literally be left in the dark?

While there's nothing wrong with what reincarnate has posted, I don't like looking at things that way
The measurements are generally taken from what the reviewer determined to be the best picture quality. The posts do repeatedly emphasis this fact.

Claiming high lumens is a rather meaningless when the picture quality is greatly degraded. Dynamic mode is not for the normal serious movie watching. Neither is skewing the color balance or gamma. So why attempt to mix the two together? Do we want to confuse the newbies in using a mode they will seldom, if ever use? Remember there are several bright $1K projectors...

Perhaps it would would be enlightening to discuss why there are technological brightness limitations with typical sized screens in a separate thread?

Again, its easy to have it all today: best picture quality, high SMPTE specified brightness with a large screen.
Hopefully LED light sources will make this discussion irrelevant in a year or two.

Thank you for the input as I will STRONGLY emphasize picture quality over quantity in the new reference thread.

Thank you for the input as I will STRONGLY emphasize picture quality over quantity in the new reference thread.

No, you misread my post, the only thing I disagree with is the order of your information. You start with a projector and then calculate how big you can go. I think that's the wrong way to go, you shouldn't pick a projector and try and make it work. Doing so will end up sacrificing quality because we will undoubtedly try and squeeze as much size as possible out of it.

IMO, the better way to go is to figure out what size screen you want, and then from there figure out how many Lumens you need and what projectors can do that for you.

We're using the same math, same standards I just think it's more useful, and will result in a more satisfying experience to start with the screen size and work backward to the projector, than to start with the projector and then realize how small the screen has to be.

For example, I've been looking at projectors and I'd almost decided to get a VW60, it's a great machine at a great price. But I've already got a screen that's the size I like (well, I'd go bigger if I had the room) and it's got a fixed gain. So I ran the numbers to figure out how many Lumens I need for my screen, turns out to be about 370. So I look at reviews and find that the VW60 can only just do that on a new lamp (and only in high lamp mode).

So had I picked a projector and then tried to make it work, I'd have had a VW60 and then been in the position where I needed to get a new (smaller) screen, or been settling for a image that's dimmer than what I have now after only a few hundred hours.

But instead I figured out how many Lumens I need to achive 12 ftL (with that buffer for lamp dimming) up front, so I know to look for a PJ that has the capability for 500-600+ lumens in some calibrated configuration.

Like I said there's nothing technically wrong with your information, and I agree with you on the targets for picture quality (12 ftL), I just think it's better for people to work the problem starting with the screen rather than the projector. After all we watch movies on the screen, not the projector ;)

Sony VPL-VW60 Screen Calculations for 12fl Brightness

From the Projector Central review the Sony VPL-VW60 is a dim projector. The lens telephoto setting reduces light by 33%. The review does not take into account the 50% reduction in brightness due to bulb aging. We do here

Sony VPL-VW60 , telephoto, 1.0 screen gain
sqrt(14*235*1.0) = 57 inches maximum diagonal screen size

Sony VPL-VW60, telephoto, 2.5 screen gain
sqrt(14*235*2.5) = 91 inches maximum diagonal screen size

Sony VPL-VW60, wideangle, 1.0 screen gain
sqrt(14*350*1.0) = 70 inches maximum diagonal screen size

Sony VPL-VW60, wideangle, 2.6 screen gain
sqrt(14*350*2.5) = 110 inches maximum diagonal screen size


1) Calculations reveal that to meet SMPTE standards of 12fl, mate this projector with a 2.5 gain screen

reincarnate, thanks for the analysis here - I think you're doing an important task in helping newbies (like me) to level-set expectations about projectors.

I am in the midst of researching a not too distant purchase of either a 60" Pio Kuro pdp or a front pj, either the VW60 or the RS1x. The primary, in fact only, draw of the pjs (for me) is screen size. I am primarily a cinephile and desire a cinematic experience at home, which I'm not convinced 60 inches will give me. But naturally, I began to wonder if the other trade-offs were worth it in light of the guides you've posted.

However, it seems to me your guide exaggerates the effect of bulb dimming due to aging. Most manufacturers list the various life spans of their bulbs as the time it takes for the bulb to reach 50% of it's original luminance. It therefore seems to me you're writing your guide to screen sizes based on bulb brightness just prior to the bulb being replaced.

Wouldn't it make more sense to average the initial luminance against the final luminance of the bulb prior to replacement? Substituting a number like 33% for your 50% yields a substantial increase in screen size. My calculations (always a risky proposition) suggest that for the VW60, the telephoto mode with a 1x gain screen would grow from 57 to 66 inches, while the wide-angle mode with a 2.5x gain would grow from 110 to 128 inches.

You guys want to hear something really scary, the following is from the SMPTE standard for drive-ins.

When maximum compromise must be made... the luminance at the center of the screen, measured from any car position, shall in no case be less than 4.5 fL (15 cd/m^2)

Alan,
We still have a drive in here. More for the fun of having the family out on lawn chairs ,eating, playing etc but no doubt, it is really really dim.

Art

You guys want to hear something really scary, the following is from the SMPTE standard for drive-ins.

Not that scary considering there isn't a standard from what I can tell about what to project onto. I've seen many drive ins with painted white corrugated metal white roofing for the screen.

Alan,
We still have a drive in here. More for the fun of having the family out on lawn chairs ,eating, playing etc but no doubt, it is really really dim.

Art

I agree with Art, the whole point on going to a movie at a drive-in "theater" was never just about the movie. Back in the stoneage of our teenage years it was a social event, excuse to take your girl out, show off our car, sneak in your friends in the trunk, etc. If you think the video was bad, how about the audio? :D By the way, if you were caught measuring foot lamberts you would definitely be forever classified a major nerd. ;)

Alan,
We still have a drive in here. More for the fun of having the family out on lawn chairs ,eating, playing etc but no doubt, it is really really dim.

Art

I always loved drive in theaters and bemoaned their loss - virtually all had disappeared where I live in Toronto. I live downtown so any vestiges of a drive in are waaaaay on the outskirts of the city. Especially when my son was reaching Drive-In age I thought wistfully how I'd like to take him to the drive in. I have so many great memories from my childhood of drive-in movies.

Then...one of the world's biggest drive-ins opens up 5 minutes from my house near the harbour front! Whoo-hoo!

Ever since my sons and I have been having a ball attending movies at the Drive in during summer, with all the classic stuff going on: families that bring lawnchairs, teenagers in vans, mini-golf and a hot dog before the movie.

One happy pappy.

And, yes...it's a pretty dim picture, but sometimes surprises me how good it is all things considered.

reincarnate, thanks for the analysis here - I think you're doing an important task in helping newbies (like me) to level-set expectations about projectors.

I am in the midst of researching a not too distant purchase of either a 60" Pio Kuro pdp or a front pj, either the VW60 or the RS1x. The primary, in fact only, draw of the pjs (for me) is screen size. I am primarily a cinephile and desire a cinematic experience at home, which I'm not convinced 60 inches will give me. But naturally, I began to wonder if the other trade-offs were worth it in light of the guides you've posted.

However, it seems to me your guide exaggerates the effect of bulb dimming due to aging. Most manufacturers list the various life spans of their bulbs as the time it takes for the bulb to reach 50% of it's original luminance. It therefore seems to me you're writing your guide to screen sizes based on bulb brightness just prior to the bulb being replaced.

Wouldn't it make more sense to average the initial luminance against the final luminance of the bulb prior to replacement? Substituting a number like 33% for your 50% yields a substantial increase in screen size. My calculations (always a risky proposition) suggest that for the VW60, the telephoto mode with a 1x gain screen would grow from 57 to 66 inches, while the wide-angle mode with a 2.5x gain would grow from 110 to 128 inches.
In the initial calculations it was explained to use 28 (rather than 14) to calculate the maximum screen size for a new bulb.
An aging bulb is like a many a love affair, lots of fun and excitement initially but after awhile you wonder what ever happened.
Well at least for projectors, you now know.

Pointing out that 28 should be used instead of 14 for new bulb screen sizes only restates my criticism: you are still defining the maximum screen size for a given projector to obtain 12fl by 50% of it's original luminance. Thus, you are defining your "real world" screen sizes to luminance levels based upon the end of life bulb brightness. An age factor of "21" would better represent the average viewing conditions over the life of the bulb, wouldn't it?

Also, at least with respect to the VW60, the figures you cite are for low power settings. High power settings result in calibrated lumens (according to projectorcentral.com) of 525 and 350 for wide angle and telephoto respectively. This naturally reduces bulb life, and I understand your choice of low power as it reflects the most common approach to bulb management (I assume). Still, its worth including the high power numbers along with your originals with the averaged bulb age factor:

Sony VPL-VW60 , telephoto, 1.0 screen gain - Low Power
sqrt(21*235*1.0) = 70 inches maximum diagonal screen size

Sony VPL-VW60, Low Power wideangle or High Power tele, 1.0 screen gain
sqrt(21*350*1.0) = 86 inches maximum diagonal screen size

Sony VPL-VW60, wideangle, 1.0 screen gain - High Power
sqrt(21*525*1.0) = 105 inches maximum diagonal screen size

So, averaging the bulb age rather than selecting it's end of life brightness results in a significant increase in screen size overall while maintaining 12fl. But this raises another important point. What are the ageing patterns of the various manufacturers' bulbs? As has already been pointed out, there may be variance within a single manufacturer's run. A study showing the average decline in brightness for a given bulb type would be very useful to the consumer. That way, one could weigh the risk that Sony's bulbs would maintain 75% of maximum luminance for 75% of it's given lifespan (remembering that lifespan is defined as the time in hours until the bulb reaches 50% of it's original luminance, as opposed to an off brand bulb which might maintain only 65% for 50%.

Those are just completely arbitrary examples, obviously. But they show that we need luminance curves to properly evaluate the screen size to bulb replacement relationship.

Pointing out that 28 should be used instead of 14 for new bulb screen sizes only restates my criticism: you are still defining the maximum screen size for a given projector to obtain 12fl by 50% of it's original luminance.
This is incorrect. 28 is twice 14 and thus uses the full new bulbs measured output in the maximum screen calculation.
Bulbs generally degrade quite rapidly in the first several hundred hours of use (an inverse exponential), then decay much less rapidly, even though they are rated by the manufacture for 2000-3000 hours. Engineers design for the typical reasonable worst case and that is 50% here. Feel free to use 60% or even 70%, if you feel lucky today.

The other points are well taken. Maybe there is a link to some ageing curves? Then there is also the costly issue of premature bulb failure. AVS does have some threads started by disgruntled owners.
All this is why my next projector will be LED powered, as putting up with these bulbs is a hassle.

This is incorrect. 28 is twice 14 and thus uses the full new bulbs measured output in the maximum screen calculation.
Bulbs generally degrade quite rapidly in the first several hundred hours of use (an inverse exponential), then decay much less rapidly, even though they are rated by the manufacture for 2000-3000 hours. Engineers design for the typical reasonable worst case and that is 50% here. Feel free to use 60% or even 70%, if you feel lucky today.

I was wondering why you're so resistant to the fact that 14 is 50% of 28 until I noticed that all but 2 of the figures you've provided use only the 14 number. The 2 which use 28 (and thus the "new" bulb luminance) are for a LED lighted projector.

The other points are well taken. Maybe there is a link to some ageing curves? Then there is also the costly issue of premature bulb failure. AVS does have some threads started by disgruntled owners.
All this is why my next projector will be LED powered, as putting up with these bulbs is a hassle.

I'd certainly be interested in a discussion of LED vs. UHP bulbs in upcoming projectors (I'm assuming here by your comments in favor of them that such projectors are upcoming). I've looked briefly for studies or analyses of luminance decay in UHP bulbs but have so far been unable to find any. I'd be interested to know what the decay curve is for LED systems and what the expected replacement costs will be.

Nevertheless, all of the numbers you've provided in this thread for UHP bulbs are designed in such a way that they only describe the luminance to screen size ratio for the bulb at the end of it's lifecycle.


Manufacturers state the lifecycle of their bulbs based on the time it takes the bulb to reach 50% of it's original luminance (often 3000 hours in the low power settings).
You state that "28" in your calculations represents a bulb at the beginning of it's lifecycle.
You use "14" in your calculations to represent bulb ageing.
14 is 50% of 28.


Therefore, you have exaggerated the effects of ageing on the luminance to screen size ratio by only representing the UHP bulbs at the end of their lifecycles. You have compounded this by only listing the low power luminance for UHP bulbs (without actually stating this fact), which further reduces screen size at 12fl.

The effect of this is to minimize the maximum screen size for a given projector while maintaining 12fl, using UHP bulbs.

Absent any studies you might provide showing that the average UHP bulb has a very flat decay curve with rapid initial drop off (ie, to 55% within the first 500 hours and from there to 50% by 3000 hours), your readers are likely to conclude that your numbers are mistaken.

Newbie alert --> In the post above, I pointed out what I consider to be a mistake in estimating bulb ageing at 50% of it's original luminance in unnecessarily personal terms. While I stand by my criticism, it isn't reincarnate who has suggested the 50% number. I'm not sure who has, as it is relatively common to estimate this way. What I don't understand is why.

My concern about using the 50% number is simply this: why would someone choose the screen size for their expensive new projector based on it's absolute weakest bulb output? This puts one in the position of essentially throwing away screen size for the majority of the bulb's life in order to ensure that either the 12fl minimum is met or that one obtains the longest bulb life possible - but not both.

Wouldn't it make more sense to calculate ageing at a number like 65%, realizing that as the bulb passed that point in it's lifecycle that either the screen luminance would begin to fall somewhat below 12fl or that the projector's power level could be increased (switching to high power to lengthen the time the bulb can maintain 12fl), or that the bulb should be replaced.

Doing so significatly increases the estimated screen sizes the various UHP projectors can drive.

65%, 50% it doesn't matter. The difference in observable light output here is probably indistinguishable. what you are trying to do is just have a realistic predictor so that you have a general idea of what you should expect to happen over time

Lupin3: I respectfully replied to your original post. You figured out that I did not reply again because you went too personal (in attacking the messenger). Your writings contain several mis-statements as to what was posted earlier in the thread.
It is always suspicious when a new member (or at least a new log-on identity) has some considerable knowledge yet twists easily understood concepts seemingly to cast doubt. That is why it is important to establish a reputation here as it allows for trust and credibility to be established.
I do understand why you might be upset from being told the truth of the situation, which is why politicians will spin if they think it’s in their own interest. They want to stay in business.

Would you be mad if I told you that 95% of the food sold today is bad for you as it leads to many medical issues such as being overweight and diabetes? Would you also be mad if I told you Wall Street/Fed is unfairly ripping off the hard working people's savings and forcing us to pay huge sums in interest?

Perhaps its better to live with rose colored sunglasses and just be happy? So why not just go mate a 150" 0.9 gain screen with a $15K light-challenged projector? To hell with the SMPTE motion picture standards. Other experts here have done exactly just that. Completely unrelated but you can pick up hardly used projector bargains in the AVS classified section. Some with only a few hundred hours use. Go figure! :)

I understand your point, reincarnate! I also understand why you mention the low hours projectors for sale in the AVS classifieds, and that its not "completely unrelated" to your position.

I am in the position of trying to evaluate whether or not I should buy a Kuro plasma or a projector. Since it's not a one to one comparison, its a difficult evaluation to make. When I initially saw your figures, I immediately began to doubt that the smaller screen size than I expected warranted the overall loss of picture quality on a projector compared to the Kuro. You made a very forceful argument that nearly turned me off to projectors.

But as I looked closer I realized things might not be quite as dire as your figures suggested. Partly this was due to your figures, and the contributions of Tryg and others: I realize now that for this generation of low lumen powered lamps, high gain screens are important to obtain the overall cinematic impact projectors promise.

I guess I was insistent on having my question answered because I felt there was something misleading in your study's design, but Tryg's comment above gets to the point. You are trying to help level newbies' expectations as to what performance to expect, and you may as well have answered my question with "well, why not?" (Indeed, any mis-statements on my part were due entirely to ignorance. In fact I confess to not knowing what those mis-statement are!)

So while I respectfully disagree with you on certain aspects of your study, I do appreciate that you've posted it in the first place.

The following UHP projector lamp truths are only revealed by the SIMS manufacture because its from a patent application:

"The choice of the illumination system is particularly important with reference to the performance and reliability of a videoprojector:
Arc lamps are normally used, which release a high light intensity, though they have a few non irrelevant drawbacks. First of all, the average life of a lamp is rather short, requiring frequent interventions of the Service Assistance and a consequent financial cost for the user. Moreover, the lamp produces considerable heat inside the videoprojector (usually over 100 W), so an adequate cooling system is needed to avoid jeopardizing the product reliability. Other drawbacks caused by the lamps are the crystallization phenomena impairing the light flow quality, and the so-called arc-jump, which may cause flickering of the image. Finally, as known, in the videoprojectors using one device alone (especially DMD), the primary colors are obtained filtering the light emitted by the lamp with the color wheel, which is often a source of annoying noise caused by the motor actuating the wheel, and above all reduces the system brightness"**.

** Now you know why single chip DLP projectors are usually dim. :D Notice too, they omit the bulbs reduced brighntess as the bulb ages in the just first few hundred hours.

Typically manufactures will only frankly discuss a limitation after they have found a solution:
"In order to obviate to the above drawbacks, a light source consisting of one or more LED (Light Emitting Diode) diodes matrixes has been proposed; this solution removes all the above drawbacks ; in particular, the average life of the LED diodes estimated in about 100.000 hours, is considerably longer than the life of a lamp. Moreover, the light radiation of the LED diodes has a wider color triangle than that obtained through a standard arc lamp with associated color wheel; therefore, when using one device alone, the chromatic result is better, i. e. several color tones can be reproduced."

Thank you SIMS :)
This is why I will only purchase an LED based projector.

http://v3.espacenet.com/textdes?DB=EPODOC&IDX=TW270736B&F=0&QPN=TW270736B

I already had it out with Reincarnate over the absurdity of insisting it's "12 Ftl or bust" but have a new experience to relate.

I just picked up a Marantz S4, which is "known" as a dim projector. At 18' back shining on a 105" 1.1 gain screen, projector central calculates I'm at 9 ftL. However, the bulb has only 300 hours left and I'm zoomed in all the way, cutting down lumens even more.

So maybe I'm at 6 or 7 FtL. If I'm lucky.

The picture is easily bright enough. My room is light controlled and I'm more interested in critical film watching than sports with the lights on, so "bright enough" is subjective, but I don't think anyone coming over to watch a movie would complain about not being able to see what's going on.

So again, I side with those who say that the 12 FtL "requirement" is a load of crap. I am sure there are very valid reasons for the SMPTE folks deciding this was an important number, but in real world application I truly believe 12FtL would be way too bright (but a great number for daytime viewing).

If my image was anything over 9, it would induce eyestrain, heighten the rainbow effect and room reflections back onto the screen would be a serious issue. At 12, it would be a joke.

The other "critical film viewing" enthusiasts who have chimed in all seem to agree that as long as you're at 7FtL you're fine. My new experience once again confirms this.

I just can't imagine going with an 85" 3.0 gain screen to pump up the brightness to such ridiculous levels.

Anyone reading this thread and wondering if their image is going to be bright enough without 12 FtL should stop worrying. Daytime sports viewing is one thing, but if you're a videophile after image quality and like to watch movies in the dark, I think you'll rarely come across a situation with ANY projector where you think your picture is too dim.

If you were a videophile you would want to see the image. I guarentee you are not seeing what the source material is presenting at your levels.

likewise I dont know of any audiophiles that turn it up to 1 and say wow. Anything louder would cause ear strain.

you are simply hiding the flaws of the source material and your projector with a dim image.

how do you guys go outside?

I have my wife and videophile obsession. What more do I need? :D Seriously though. It's all about how much light that enters your eyes. Your eyes weren't designed to look at such a bright image in front of you only the screen width. Outside, light comes at you from all angles. Your eye can handle that much light outside, it can't handle that much light concentrated on such a small area as a screen in pitch blackness that bright.

Well, I'm sure a non-videophile neandertal, for I like it at 20+ ftL with an aged lamp, therefore much more than this to start out. Thank God for the HiPower!

Back on topic.

The nature of this thread is subjective so let's not attack each other for their answers to the original author's question.

Based on my experience brighter is better to an extent. I have had the same 120" painted screen for about 2.5 years now and I started with a Sony HS-51 which was bright enough in the first 300-500 hours but then I noticed it was simply too dim and no longer enjoyable to watch. I then got a Panasonic AX100 as I really wanted a projector with enough lumens for watching sports with the lights on as well as maintain proper illumination for more of the bulb life with the lights off. I am now at almost 900 hours on this projector and while I now run the projector in high lamp and vivid Cinema it still has enough lumens for me. I have not measured the lumens yet but if I use a few of the reviewers measurements of almost 600 lumens in Cinema 1 in econo mode when the bulb was new I was at about 14ft lamberts which was good. After 900 hours I am now in Vivid Cinema mode with bulb on high which yealed almost 1100 lumens when new and if we assume 60%, or 660 lumens now, I should be getting just a little more than 14 ft lamberts. So in a light controlled room with white walls I would say 14 ft lamberts is good enough.

But wait, so in my plan to put in a 140" wide 2.35 to 1 scope screen I needed a brighter projector so I got an Infocus IN83. I am now shooting the IN83 onto the same 120" diagonal painted screen. And with the bulb in econo mode with the iris open all the way I should be getting between 900 to 1000 lumens at D6500 setting based on the measurements of the IN82 and the IN83 is brighter. 900 lumens would give me 20 ft lamberts and honestly because the black levels and ANSI CR is so much better than the AX100 it looks fantastic. I don't want to spoil myself so I have clamped the IRIS down to about 66 from 100 which is still brighter than my AX100 was at the estimated 660 lumens and I love it. My thought is that I can open the IRIS up and move the bulb into high as it ages to maintain the same lumens over the life of the bulb.

So is 20 ft lamberts too much, no in fact with the right contrast ratios it looks great! But is 12 ft lamberts enough, yes I think it is. I do plan to cover my walls and ceiling in black and calibrate my projector so I will report back on what ft lamberts I find acceptable in that environment.

Dangc, you made my point! In almost all cases, people who are after the brightest image are NOT concerned with the most detailed image; you yourself said you like to watch sports with the light on, and you enjoy your projector in "vivid cinema" mode. ALL projectors have similar modes, and they are designed to offer more lumen output at the expense of contrast and image detail.

In addition, at 20 Ftl, you must be getting a high amount of reflected light back onto the screen, destroying any possibility of reference video. Assuming you're even watching with the lights out, that is.

And please, while it's absolutely fine for people to prefer a big, bright image with punch over a dim, videophile's dream of reference cinema, let's not try to fool ourselves by saying you're bright, 20FtL image is just as detailed and contrasty as the person with the 7FtL image because it simply is not. I'm not saying it's impossible, but it would be very, very rare and only under the most exacting conditions.

People simply need to choose "bright image" or "reference video" and while many will tell you they have both, ultimately most of us end up falling somewhere in between.

Mojo: have you noted some of Art Sonneborn's posts in this thread? I don't think anyone could accuse him of not being a dedicated videophile.

Miller: Yes, I just went back and read through his posts... he basically thinks a 12FtL image is just scraping by and 20 is more like it... he also agrees with Joe Kane who thinks we need to stop using high power screens to make up for dim projectors, citing that high power screens don't work in many setups.

That's tough, because the vast majority of Reincarnate's suggestions require a high power screen! Art believes that a 2000 lumen projector is the answer.

I don't know what Art's setup is like, but to get a very bright videophile image, the first thing you're going to need is a VERY high output projector that doesn't sacrafice contrast or black level to get it. Those are few and far between (if there are ANY), as all the high lumen models (from the reviews I have read) give up image quality in favor of lumens.

In fact, all the current crop of high end projectors (that I am aware of) offer moderate output at best, and the ones that DO offer more light (like the Epson UB) do so -again- in a mode that makes some quality sacrafices.

But assuming you were to find a videophile light cannon, THEN you would absolutely have to have a strictly tailored room (i.e. painted batcave) or else you'd lose any possibility of a good picture - even a 10 FtL image is going to produce enough room reflections to wash out the picture.

How many "12FtL or die" proponents out there have a high output projector that retains black level AND a painted room to go with it? I'd like to see THAT poll go along with all the people who prefer a high FtL image.

This is why I say that the vast majority of people who choose high brightness are not watching anything close to a reference image.

A "reference image" requires good contrast and black level, two things very difficult to achieve with a high output projector in anything remotely like a normal living room.

Mojo: I believe Art's pj is the SIM2 HT5000, truly a light cannon (and also $ cannon!). And you might note that he has observed the HP screen to be exceedingly good if your configuration is appropriate for it (i.e., pj mounted near screen center, no viewers outside the sides of the screen, etc.)

For reasonably priced pj's (i.e, < 10K) and moderately large screens, I think the HP screen is a good solution. It certainly is for me (RS1 on a 126" diag HP), but my room arrangement is optimal for it.

Art uses a perfed AT ST130 screen. That loses some light. Is that 20 ftl what would be produced if his screen were a ST130 with 1.3 gain without perfs?
We measured Art's image at over 20 footlamberts off of the screen surface, using a Minolta LS-100 spot luminance meter. This eliminates the variable of perf vs. non-perf.


Ken Whitcomb

This debate is beginning to resemble the ever popular plasma vs. lcd fracas.

Tryg responds to Mojo's comments by suggesting he is losing detail by limiting on screen luminance to less than 12fL. It seems to me this is provable enough: the brightness/black level/image quality ratio is just another way of describing contrast levels. If Mojo's contrast level is lower at 7 than 12 fL, then he has lost detail. If not, not. This assumes color accuracy hasn't degraded but that isn't detail per se, I don't think.

I for one can suffer immediate and occasionally painful eye-strain viewing LCDs in a bright Best Buy showroom! On the other hand, I have never experienced eye strain in a theater, which should theoretically be maintaining at least 12fL. So Mojo and reio-ta, a question: do you experience eye strain in movie theaters? (Perhaps you no longer go, I have friends with full home theaters who never do.)

I think there's another way of looking at Tryg's audiophile comparison. It's not exactly true for audio that louder is always better. Once the system exceeds a certain volume threshold, fidelity is lost. Is there an analogue for videophiles? Is there, for example, a point at which black levels begin to crush shadows or peak light output crushes highlights? In my view, maintaining that kind of fidelity would be more important than establishing a minimum screen luminance level.

Having said that, it's clear that there are significant differences between theaters public and home. In some ways, home theaters can exceed the visual quality in public theaters, but are inferior in others. So should we design with public theater recreation in mind? I don't know that that question has an obvious answer.

One thing I've been wondering is how people are measuring their light output. Are they taking the manufacturers maximum output spec and calculating footlamberts from lumens?

If so, the actual measured output could be significantly different.


Ken Whitcomb

No, I don't get eyestrain in a theater, but as Reio pointed out, theaters have dim lighting at all times.

But eyestrain is only a minor point; if I could have a brighter image and not make any quality sacrafices, I'd happily for for it (although I still think 20FtL would be ridiculous).

And this is where the audiophile analogy comes in - just as going too loud degredates fidelity, going too bright degrades video quality (either by clipping white detail or losing blacks as a result of increased lumens or room reflections). Of course, those with very high end speakers can have the best of both worlds, just as those with very high end home theaters can have both.

But the vast majority of people on this forum who believe "brighter is better" are NOT using $10,000+ projectors or have black walls. People who read Reincarnate's suggestions may think they HAVE to have 12 FtL or they won't be happy and as a result will end up with a bright but poor image.

Myself and others are simply providing a counter-argument. And it's fun!

I'm not sure I understand how people can say you don't see the full picture and loose detail at lower footlamberts... when I make adjustments with test patterns, I see the full greyscale and pluge. When I adjust with real-world material, I make sure I am dialed in to see every last bit of shadow detail; if I'm seeing all the picture information on the DVD, what am I losing?

I don't think anyone can argue that it's far easier to produce a high quality image at lower lumens... so again it becomes a question of what is the balance that would make most people happy?

The few people in this thread who have measured their footlamberts (and they are all people who value image quality above all) were surprised to discover that their image was darker than they thought (meaning they assumed their nice, bright picture was at or near the 12 FtL number, but it was actually closer to 7). To me this proves that people are satisfied with less brightness than they think they need.

In turn, people should take Reincarnate's 12 FtL formulas with a grain of salt and understand that not only are images under 12 FtL completely satisfying, they make it MUCH easier to produce a QUALITY image.

One thing I've been wondering is how people are measuring their light output. Are they taking the manufacturers maximum output spec and calculating footlamberts from lumens?

If so, the actual measured output could be significantly different.


Ken Whitcomb

I use the CA813 light meter: hold the probe right up to the screen (pointing at the pj) and read fc; multiplying this by the screen area (in sq ft) gives the lumens.

i am doing a conservitive 13ft lamberts with a sony g90 on a 103" silverstar
that has been calibrated by ken w.

i am doing a conservitive 13ft lamberts with a sony g90 on a 103" silverstar
that has been calibrated by ken w.

I estimate the silverstar to be 2.7 gain. What figure are you using?

Also does the CRT do a good job with the silverstar? any issues?

I estimate the silverstar to be 2.7 gain. What figure are you using?
Arli is giving a measured rather than computed number. The measurement was taken from the viewing position with the Minolta aimed at screen center on a 100IRE window pattern.

Also does the CRT do a good job with the silverstar? any issues?
While I am not a fan of the Silverstar for CRT, it seems to work pretty well in Arli's installation. The biggest issue I notice is light falloff in the corners.


Ken Whitcomb

Myself and others are simply providing a counter-argument. And it's fun!

In turn, people should take Reincarnate's 12 FtL formulas with a grain of salt and understand that not only are images under 12 FtL completely satisfying, they make it MUCH easier to produce a QUALITY image.
Yes, it is fun having point and counter point! I also relish in the ironies - as in the above SIM2 patent application where the manufacture literally trashes their current expensive "one-chipper" products. It doesn't get any better than this! Besides its nice not having to push buttons to make a point.

It's great to see potential front projector owners take into consideration the reduced lumen output from bulb aging before they make there purchase. Lupin3 deserves special mention with his fine reasoning and putting up with my sarcastic humor. He's got my shtick here figured out. Darn!

Now finally, even Greg Rodgers adds a little calculation program to draw people away from the rather embarrassing facts presented here, some of which are based upon his WSR projector measurements. If he would only include the SMPTE brightness standard with screen size with an aged bulb calculations in his WSR reviews that would gladly put me out of business here. However I realize that commercial pressure may prevent that from ever occurring.

In any event people in the industry have to earn a living. If I wasn't satisfied with my RS1, I'd buy another bright (but not too expensive) projector, as excellent LED powered projectors are at least a year+ out.

The lopsided brightness poll results speak for themselves. Everyone should determine their own brightness preference before purchasing. Resist sales pressure and realize that the Internet can be tailored.
Lastly 12foot-lamberts brightness is on the low side of the SMPTE standard, and should be followed unless there is a good reason not to.

Lastly 12foot-lamberts brightness is on the low side of the SMPTE standard, and should be followed unless there is a good reason not to.

This is interesting, because I would bet the farm that the VAST majority of projector owners who have made even the slightest attempt to callibrate their image for contrast and quality (even just using Video Esssntials) are NOT watching a 12FtL image.

Are you saying that no one has been enjoying a proper image?

I'd also guess that the vast majority of reviews we have seen from the pros have been based on watching <12 FtL.

The simple fact is it is VERY hard to produce a callibrated, 12 FtL image on a normal gain, 100" screen, which is what most people are using.

So, the "good reasons not to" follow SMPTE standards are:

- Projectors that offer high lumens without sacraficing image quality are hard to find

- Most people want a screen larger than 80"

- High gain screens can affect image quality and only work well under very strict circumstances

- An image 12FtL or brighter will produce a lot of bounce light; projection like this requires a room with dark walls or reflected light will ruin the image

These are very good reasons why most people CANNOT follow this standard.

Of course the other, simpler reason is that the vast majority of people enjoying home theater have done so with an image under 12 FtL and they have been very happy.

While I am not a fan of the Silverstar for CRT, it seems to work pretty well in Arli's installation. The biggest issue I notice is light falloff in the corners.

Ken Whitcomb

Thanks Ken.

I'm a little suprised its only getting 13 foot lamberts from a G90. What am I missing? I've seen people say 13 fl from matte white screen with a G90. What is the size of the screen?

Of course the other, simpler reason is that the vast majority of people enjoying home theater have done so with an image under 12 FtL and they have been very happy.

define very happy.

It's been proven time and time again whether your in circuit city looking at rear projection units, or a dedicated theater, if shown a brighter image basically everyone chooses the brighter image as having higher picture quality.

videophile shmideophile.

This is more nonsense talk. What is a videophile? someone with a huge ego, a chip on their shoulder and a more opinions on minuscule minusha that most of the world can care less about?

The same tests have been presented to wine tasting experts when blindfolded. They often choose box wines like Almaden as their favorite.

You either like what you like, or you pretend to like what others like.

... Look at the poll. The masses have spoken and they say 12 ftl or bust too! There's enough 12+ votes to over-ride your veto power!

Those people SAY they PREFER an image over 12FtL but they have no idea if their picture actually is 12 FtL!!

I'd guess less than a dozen of those people in the poll actually have a meter and measured the results.

Many people who DO take a measurement are surprised to find that their "bright" picture is substantially under 12FtL.

I agree that people enjoy a bright image... I'm just saying it takes LESS than 12 FtL give people the bright image they enjoy.

And Tryg is right, people always pick the brighter image, but it's a snap decision. That's why the manufacturers always ship TVs with a default setting of overly high contrast and brightness - so when the store whips one out onto the floor, it will look "better."

I'm not quite sure where we draw the line between videophile and "people who just want to enjoy their picture," but I'd guess most people who bother to frequent AVS would prefer NOT to have contrast so high it distorts the image and brightness so high their black level is 50% grey.

Those people SAY they PREFER an image over 12FtL but [i]they have no idea if their picture actually is 12 FtL!!

I have been thinking that through this whole thing and I am sure you are right. I have not measured mine yet but I will be soon.

Also, I agree that although a bright punchy image is very appealing I still crank down the brightness to strike a good balance between black level, overall picture quality and enough brightness to make a sunny day on screen look like a sunny day.

I also only watch sports with the lights on in the brighter modes that typically compromise color balance more than anything. I watch movies with the lights off in the modes that strike the best balance I mentioned above. And yes those white walls have to go and so they are. I am going to cover the ceiling and walls in black commando cloth. After doing this I fully expect to be able to live with 12ft lamberts or less with greatly improved blacks, detail, and generally improved picture.

I just stumbled on this; I haven't visited the home page of this forum for a bit.

This is (in my opinion) not a valid topic. Here's why:

Everyone will like a brighter picture compared to a dimmer one. That's the way our eye works.

However, is it right?

If you believe (I do), that any art should be viewed under the conditions set by the artist, then you should view your films at the EXACT level dictated by what was used during the editing, mixing, etc...

And Tryg, you audio analogy doesn't hold water. THX developed the specs for theaters so that people could hear (and see) the films the way I mention above. If you are playing too loud (or too soft), then it isn't right. Reference level exists in audio. It is there in video too. There is nothing wrong in saying that you "like" something better if it is wrong; don't imply that it is "better" though. People like the sound of tube amps too, I'm one of them. But they aren't any where near as accurate as their solid state counterparts. I still like them though. But I would never sacrifice my credibility by trying to convince anyone that they are better. They're not. And neither is a picture brighter than it is intended to be.

During Academy Awards season, Academy Standard screening rooms all across the country are calibrated every day to 12. My guess is that they are all the time, but during awards season I know this for sure. So voting members can view and decide on things like art direction, cinematography, etc... properly.

And by the way, most IMAX screens are about 6-7. I don't hear too many people saying that because the rooms are so big you need more light there.

If your room is good, all the light will get to your eyes. Remember, outside of Art, many of us lived with CRTs on way too big screens happily for many years. We just had to be smart about room design. Now we have 2x, 3x, 4x, the brightness and people think, "cool I can not have to live in a cave now". WRONG. Making your room really dark will help the image more than adding ANY amount of lumens to the mix. It's also easier to do and cheaper too.

Have FUN!

This is interesting, because I would bet the farm that the VAST majority of projector owners who have made even the slightest attempt to callibrate their image for contrast and quality (even just using Video Esssntials) are NOT watching a 12FtL image.

Are you saying that no one has been enjoying a proper image?

No, as you said that.
However with current technology many people are not seeing 12fl especially as their bulb ages. That my friend is the purpose of this thread. (Reviewers are well aware of this limitation and also why they use small 80-90" 1.3 gain screens).

The poll results can be interpreted to also imply that the majority of owners want a brighter screen :):) :)
It all adds up my friend.

With careful planning you can have your cake and eat it too. I lead by example.

In the future LED powered projectors will turn the market upside-down. Until then I agree with Dan Miller that we are collectively living in the Dark Ages ;)

But isn't this brightness question altogether ambiguous?

Unless "brightness" also takes into account ambient light, it has no specific meaning. That is, if poll respondents do not provide contextual information about their theaters, we have no way of knowing whether they mean that 12fL is too dim for daylight viewing or bat cave night-time viewing. Mojo and reio-ta illustrated this in their responses to my question about eye strain at public theaters. This of course is beyond the question of whether the majority of respondents actually know what their screen luminance is.

So we are left with the only accurate measure of brightness usability: contrast. Outside the question of contrast, brightness is purely a function purpose, with daytime sports and tv viewers requiring higher screen luminance than bat cavers viewing movies. This again leads us to the question of whether it is in our interests to exactly replicate public theater viewing conditions, or to advance the art.

Dan Miller usefully points out the fact that films are designed to be viewed in a reference context. Unfortunately, this context is usually the lowest common denominator in terms of public theaters, and it does not represent the full range of what is actually captured on film. Even this fact is deceiving, as there is much variation in public theaters, between theaters using film and between those and digital theaters. It is unlikely that any two theaters showing the same film will provide identical contexts for viewers.

If 12fL is necessary, so must be theatrical contrast ratios. Thought you were enjoying those Blu-rays on that expensive Kuro? Not really. The blacks are too dark and the contrast ratios much, much too high.

The fact is, home theater is now the driving force in setting the reference criteria for theatrical viewing. Home theaters continue to grow in sophistication while reducing in price, whereas public theaters generally continue to decline in sophistication and increase in price.

Far from the dark ages, this is a renaissance for home theater hobbyists.

Why have LEDs been incorporated into RPTVs but not FPs?

But isn't this brightness question altogether ambiguous?
Why have LEDs been incorporated into RPTVs but not FPs?
All excellent points which is why I seldom go to the theater. Home displays can be both brighter, sharper and with better contrast. Film has about four times the resolution of lowly 1920*1080p but is seldom optimized to see it.
Theater operators will cut even corner they can and force you to watch 30 minutes of commercials while eating grossly coated popcorn. The studios are of little to no help here either. :mad:

The 4k digital projectors have a difficult time maintaining sharp registration as the optical, mechanical and temperature errors seriously degrade the resolution. More promising will be when a single 80-100" flat panel can accept two 2560*1600 sources for a combined 5120*1600 (aspect ratio 3.2!) resolution. Use the next generation format of blu-ray players and on with the show.

However looking back in three years from now will be a night and day difference. The color purity and spectral flatness of LED's will blow away the peaky spectral response of UHP lamps. Green is the worst offender and needs to be greatly filtered which reduces brightness. TI and SIMS2 already know they need to drop their color wheel as it limits brightness way too much.
However it is a double edged sword at increasing the brightness will also increase the apparent dither/switching noise.

In the meantime keep your eyes on the new 10" deep Mitshubishi LaserVue line for the family room. However I'd bet now that there will be too much banding artifacts and noise. We shall see.
In the meantime go try out the 150 lumen LED flashlights for $14 at Sam's Club.

If you believe (I do), that any art should be viewed under the conditions set by the artist, then you should view your films at the EXACT level dictated by what was used during the editing, mixing, etc...I don't know what levels are used for everything, but the monitors for mastering are supposed to be set at over 30 ft-lamberts, with a light in the room.

--Darin

And Tryg, you audio analogy doesn't hold water. THX developed the specs for theaters so that people could hear (and see) the films the way I mention above. If you are playing too loud (or too soft), then it isn't right. Reference level exists in audio. It is there in video too.

This is nonsense. Anyone can claim "reference" for anything. I dont care if it's how much kool aid you should mix with water to be "optimal" as described by the manufacturer or anything else. The bottom line is what the "experts" in the black helicopters tell you is best, often times doesn't make the users happy. What makes them happy is what they want.

Dan,
Aren't you the guy that used to say that it would take an incredibly high quality lens to resolve 1080p?

;)

Good points, reincarnate. I recently saw The Other Boleyn Girl on a digital projector at a public theater, and all I can say is that the image was terrible. Extreme barrel distortion with it's significant focus issues on the bottom fifth of the screen, and in fact an image that never quite seemed properly focused at all. Why pay $10 or more to see it in the theater when you can own it for $30 or less?

Strictly speaking, 35mm film can contain even more than 4 times the resolution of a 1080p signal, and much more color information than we can see now (though hopefully Deep Color and wider color spaces will help with this). This goes to the point of reference quality, as it depends on which context is being referenced. Theoretically, we could (and probably do) have different masters for public and home theaters. The idea of seeing what the director wants us to is dependent on where we sit.

From my point of view, then, I want to maximize the photographic quality of the images I can display. We are familiar with the typical measurements said to be most important; contrast ratio first, resolution second, and color accuracy and black levels and so on. I think its strange that sharpness is never really mentioned, as its very important to overall image quality. But where should brightness be on this list, and why?

...From my point of view, then, I want to maximize the photographic quality of the images I can display. We are familiar with the typical measurements said to be most important; contrast ratio first, resolution second, and color accuracy and black levels and so on. I think its strange that sharpness is never really mentioned, as its very important to overall image quality. But where should brightness be on this list, and why?
Brightness should be set above the level above where the eye begins to loose its color response. Most eyes (just like a camera lens) offer better image quality when the aperture/pupil is stepped down an f-stop or two.
This takes more light rather than less.

This thread has been around long enough now that I don't even remember how I voted. :)

Ok so I decided to do some digging around online and found a few interesting tidbits related to the SMPTE standard...

Essentially, this quote from one of the many white papers I found on the subject reflects what I read many times:

In an average commercial motion picture theater, a level of 8 to 10 foot lamberts would be expected, while in a good quality theater, a level of about 12 foot lamberts might be expected. The SMPTE has recommended a level of 16.5 foot lamberts, but this is not achieved in practice.

So most of us see movies in theaters between 8 and 10, sometimes at 12 if we're lucky.

In a Kodak document on the subject, they went out of their way to hammer into theater owners that "brighter is better!" and suggested that making it higher than 16 FtL would please audiences even more! They actually even admitted that, at brightness levels that high, there would be lighter blacks levels and you would see more shadow detail than the film makers intended, but who cares, brighter is better!

I'm paraphrasing, but they really said that.

The most interesting addendum to the brightness debate was this, from another white paper:

The contrast ratio between the projected image and the ambient light level falling on the screen should be at least 5:1.

This is necessary for the eye to perceive a real impression of brightness. If this contrast ratio is not achieved, the projected image will not be considered of adequate brightness level.

This is a fairly obvious concept, but it underlines than no matter how bright your image is, unless you maintain contrast, it doesn't matter. People who are pouring 12Ftl of light onto their screens at home without a black room are certainly destroying their contrast with ambient reflections.

And on THAT subject, a test on another website was done to measure the effects of ambient light on contrast. They measured 145:1 in a totally black room, but when as little as 1.3 FtL of ambient light (room reflections) was introduced, the contrast ratio dropped to 41:1!

The moral of the story? Good contrast is more important than high brightness, and high brightness makes it difficult to maintain good contrast!

I've never gone to a theater and felt the picture wasn't bright enough, and according to what I have read at least SOME of the movies I have seen were projected at 8FtL.

So if you're running 8FtL at home, you're as bright some movie theaters and 8FtL makes it much easier to control reflected light.

SMPTE reccomends 12fL +or-2fL for film, +-1fL for digital theater IIRC. Max range can be as much as 22fL. 16fL is usually without film in the gate, and 12 with.

Gary

The most interesting addendum to the brightness debate was this, from another white paper:

The contrast ratio between the projected image and the ambient light level falling on the screen should be at least 5:1.

This is necessary for the eye to perceive a real impression of brightness. If this contrast ratio is not achieved, the projected image will not be considered of adequate brightness level.

This is a fairly obvious concept, but it underlines than no matter how bright your image is, unless you maintain contrast, it doesn't matter. People who are pouring 12Ftl of light onto their screens at home without a black room are certainly destroying their contrast with ambient reflections.

And on THAT subject, a test on another website was done to measure the effects of ambient light on contrast. They measured 145:1 in a totally black room, but when as little as 1.3 FtL of ambient light (room reflections) was introduced, the contrast ratio dropped to 41:1!Are you sure that light was room reflections from light that came from the projector and not one or more other light sources? They are very different things as far as this question. I think the 5:1 above must have been talking about other light sources with their ambient light statement, since 5:1 just from room reflections isn't realistic even in something as difficult as the ANSI CR checkerboard. 40:1 is more like it from just room reflections (not other light sources), although a screen can give more than that even in a white room (by using gray and/or directionality).

Going along with what you said, I have little doubt that 10 ft-lamberts with no other lighting and dark surrounds will make the images look brighter to most people than 20 ft-lamberts from the projector, with lots of other lighting on or coming in and hitting the screen. So, if you want the same perceived brightness as a theater with 12 ft-lamberts and enough other lighting (like lighting on the wall) brightening the room and screen up, you don't necessarily need to hit 12 ft-lamberts.
The moral of the story? Good contrast is more important than high brightness, and high brightness makes it difficult to maintain good contrast!That last part isn't the case. High brightness from the projector helps maintain good contrast ratio. As far as reflections the brighter doesn't change that ratio. But as far as other light sources in the room, a brighter projector helps fight those to maintain higher CR off the screen. Screens are a little more complicated. A darker screen by itself doesn't help fight other light sources, but it does help fight reflections.

--Darin

Man you guys are good! Its nice to see people not acting like they have invented the wheel. Were finally cooking as one can achieve 16.5fl with a nice sized screen and very high contrast 15-30,000.

Here are my system calculations:
With a aged bulb the JVC RS1 in normal lamp mode
Di-Lite High Power with 2.5 gain
sqrt(14 * 595 WSR measured lumens * 2.5 screen gain) = 144 inches maximum diagonal screen size, 14ft best THX viewing distance

With a aged bulb the JVC RS1 in high lamp mode
Di-Lite High Power with 2.5 gain
sqrt(14 * 703 WSR measured lumens * 2.5 screen gain) = 157 inches maximum diagonal screen size, 16ft best THX viewing distance

Since my Da-lite HP screen is about 120", the peak brightness is well over 12fl at low/normal power mode even with aged bulb, high contrast/best picture mode.
So you can have it all today - if you ignore the inventors. This is why I'm satisfied long term, with no need to punish myself with the never ending urge to upgrade.

Lastly the larger the room the less influence the side walls will have. Grey porous unpainted cinder block is actually very neutral and is quite good at not reflecting light. Common ceiling rafters are effective too. I only needed to use outdoor black carpeting on the basement floor to not be bothered by stray reflections. :)

Di-Lite High Power with 2.5 gain
...
So you can have it all today - if you ignore the inventors.You can. Your guests? I'm a fan of the HP and use it myself, but how many people do you think can get 2.5 gain in your room? Are you sitting on each other's laps? 2.5 gain has to be pretty close to the projector as far as angles. 15 degrees off angle and I believe it is under 1 for the gain (although I don't recall the exact values on the gain curve for that screen).

Where is your projector compared to your viewing position?

--Darin

Good point, perfectly expressed! Why I view it from the top of the stairs through three strategically placed mirrors. Sometimes reflections are useful silly :cool:

videophile shmideophile.

This is more nonsense talk. What is a videophile? someone with a huge ego, a chip on their shoulder and a more opinions on minuscule minusha that most of the world can care less about?



A videophile is someone who wishes to push the envelope in quality presentation irrespective of what "most of the world" cares about. Folks like Joe Kane who works very hard to set the bar high and standards worth aspiring to.

You can go on caring most about what most of the people of the world want.:D I hope your least common denominator mentality doesn't catch hold on this forum.

It sounds like you aren't the go to guy when we want to see what striving for excellence is all about.

Art

A videophile is someone who wishes to push the envelope in quality presentation irrespective of what "most of the world" cares about.
Art

Is the ultimate destination $5000 power cords, green pens on the DVDs, overprice electrical outlets, ceramic HDMI cable pedestals and giant granite blocks we put our projectors on? ;)

We're pushin the envelope now baby! :D

We have a new winner for need for brightness! I just got this PM

"Tryg I just finished reading your screen post and was very impressed. I just got a new Digital Projecton Dvision 30 (4500 L dual bulb). The largest screen I can put in my HT is a 110". I like to watch sports with some lights on and also movies. Do you still think the Vutech Silverstar is the way to go?"

I calculate 337 foot lamberts. :)

Thats hilarious.

Is the ultimate destination $5000 power cords, green pens on the DVDs, overprice electrical outlets, ceramic HDMI cable pedestals and giant granite blocks we put our projectors on? ;)

We're pushin the envelope now baby! :D

No and people like me would not recommend any of that. Your exaggerations won't cover the absurdity of the post of yours I previously quoted.

Just asking ,Tryg, in your mind would you put Kane's work in the same category as that list of snake oil you posted above ?

Art

It's interesting to me that no one has as yet been able to qualify the demand for more foot Lamberts.

Only reincarnate has responded to this, although he didn't quite answer the question. Where would you put brightness (in terms of screen luminance) in an ordered list of picture quality elements? Why?

Darin earlier suggested that increasing screen luminance was one way to increase contrast ratio. Yet, isn't this misleading? Increasing screen luminance tends to raise black levels, no? Since currently black levels are easier to excel at than the kind of brightness being demanded in this thread, the most efficient way to increase contrast is by lowering black levels. The pj industry's technology development at the moment illustrates this.

So it seems to me that, with regard strictly to picture quality, increasing contrast is more important that screen luminance, and indeed that luminance can measurably reduce contrast.

There's many industry polls that show brightness is #1 priority. At least acrosss the board. That's why pricing unit historically has been related to output. It's only recently that contrast has been equal and more important for those on AVS ;)

Also current tech isn't trying to get to black levels by making projectors dimmer. It's just a by product of the bulbs/engine they use. No engineer starts with a target of 200 lumens "so the black levels will be good"

Just asking ,Tryg, in your mind would you put Kane's work in the same category as that list of snake oil you posted above ?

Art

Why is he about to quit? That's what Lenvinson did

It's interesting to me that no one has as yet been able to qualify the demand for more foot Lamberts.

Only reincarnate has responded to this, although he didn't quite answer the question. Where would you put brightness (in terms of screen luminance) in an ordered list of picture quality elements? Why?

Darin earlier suggested that increasing screen luminance was one way to increase contrast ratio. Yet, isn't this misleading? Increasing screen luminance tends to raise black levels, no? Since currently black levels are easier to excel at than the kind of brightness being demanded in this thread, the most efficient way to increase contrast is by lowering black levels. The pj industry's technology development at the moment illustrates this.

So it seems to me that, with regard strictly to picture quality, increasing contrast is more important that screen luminance, and indeed that luminance can measurably reduce contrast.

Well ,I don't know about the word qualify here. Personally , I'd place contrast above luminance ,no doubt ,but even contrast can't save you if the luminance drops too far. I saw a 3D presentation in Chicago using two DLP projectors last weekend. I would have preferred a non 3D of the film since the detail visible at 2X the luminance (dropping the glasses and observing the difference) was more engaging than the 3D effects.

Art

There's many industry polls that show brightness is #1 priority.

Show me one that has anything to do with theater. And this one doesn't count. Let me see something with SMPTE's name attached to it. Or DCI's.

You cannot equate the business projector market with the theater one.

Brightness is better for business. They don't care about PQ.

The reason brighter projectors cost more is that bulbs and power supplies cost more. Not because they are better. Just because they are brighter.

In our line, as you pay more CR goes up, not lumens. I think that might be Sony's and JVC's as well.

In our line, as you pay more CR goes up, not lumens. I think that might be Sony's and JVC's as well.

Damnit, JVC isn't toeing the line

Seems to me that brightness (i.e., # of lumens, or ftL) and CR are orthogonal attributes. For a given CR, as you increase ftL both white level and black level increase, and CR obviously remains the same. So one would like to have CR a high as possible, to resolve all the features in the pic, and then have ftL up high enough (e.g., ~ 20 ftL) so the the pic is vibrant and striking (esp. for older eyes!).

Seems to me that brightness (i.e., # of lumens, or ftL) and CR are orthogonal attributes. For a given CR, as you increase ftL both white level and black level increase, and CR obviously remains the same. So one would like to have CR a high as possible, to resolve all the features in the pic, and then have ftL up high enough (e.g., ~ 20 ftL) so the the pic is vibrant and striking (esp. for older eyes!).

millerwill you get it! unfortunately projector design can't always maximize the net benefit of CR. They have to choose a bulb for their engine that gives them good results based on design. Yes in theory CR remains constant, but in practice a brighter bulb can cause even more light scatter that you might assume witthin the engine thus reducing CR even further. So you are still left with a light engine that is designed for reasonable range of bulb brightness and architecture.

There's many industry polls that show brightness is #1 priority. At least acrosss the board. That's why pricing unit historically has been related to output. It's only recently that contrast has been equal and more important for those on AVS ;)

Also current tech isn't trying to get to black levels by making projectors dimmer. It's just a by product of the bulbs/engine they use. No engineer starts with a target of 200 lumens "so the black levels will be good"

Tryg, are you really suggesting that brightness is more important to image quality than contrast? Or sharpness, or resolution, or color accuracy? I would be amazed if you can provide a single industry poll to support that. My suspicion is that you can cite polls showing an industry emphasis on increasing brightness as a means of maintaining market competitiveness, but that is not at all the same thing.

I never suggested engineers were intentionally lowering screen brightness in order to achieve higher levels of contrast. That's what calibration is for.

Nevertheless, while contrast ratios have grown by leaps and bounds, with manufacturers resorting to ever more distorted attempts to claim the biggest numbers, lamp technology hasn't grown at anything like the same rate. So there is a clear emphasis in the marketplace on contrast over brightness.

I think we're all in agreement, even Mojo and reio-ta to an extent, that brightness is good and that more can be better. Want to maintain that black level at a higher luminance level? Get a bigger screen (twist my arm). But my question is essentially, brightness at what cost?

If all other things were equal, adding brightness would generally be a good thing. But all other things aren't equal. We still have to pay for all the various capabilities of our display devices. What would you rather pay for? For myself, I realize contrast ratios are a way of defining the appearance of brightness in a given scene, in a way that also affects many other elements of picture quality, from sharpness to color accuracy. As a one time painter and a photography enthusiast, I would much rather see Deep Color widely implemented than a general increase of a couple hundred lumens across the board in pj output. If I could have both, I'd take them.

The reason I'm asking these questions is that there seems to be an unquestioned assumption by the devotees of brightness in this thread that 12fL is a necessary minimum. It's not that I disagree with this per se, but I am curious as to why.

Seems to me that brightness (i.e., # of lumens, or ftL) and CR are orthogonal attributes. For a given CR, as you increase ftL both white level and black level increase, and CR obviously remains the same. So one would like to have CR a high as possible, to resolve all the features in the pic, and then have ftL up high enough (e.g., ~ 20 ftL) so the the pic is vibrant and striking (esp. for older eyes!).

Very well put, thank you! I've been trying to say that for several posts now, but haven't done so as eloquently or succinctly as you have.

In studies that have investigated human perception and preference regarding image quality, Contrast has come first in determining general preference, ahead of resolution/color accuracy and even brightness. In blind tests - and I've read some that were done with industry display professionals as well, - comparing the subjective effects of resolution, color accuracy, brightness etc, it was the display with higher contrast that people most chose as having the better image. I used to have links to a bunch of this stuff but I lost them when I switched computers. :(

But you can see this trend where such controlled tests are performed. Even in the Home Theater Magazine's recent blind-test shoot out of display technologies, where the type and brand of display was hidden from the panel, a Pioneer plasma came out on top. It was the only lower resolution (non-1080p) display in the test (a fact people didn't know during the test), but the majority of viewers found it's picture quality most impressive due to it's greater contrast (especially black level) over the competing displays.

I've also seen the differences between high brightness/resolution and high contrast/good black levels plenty of times. Many times I've compared a plasma with very good contrast ratio and superior black levels to a brighter and/or higher resolution display. In brighter lights the brighter display can look as good or better and sharper. But when I turn the lights down it's amazing how things can change, when you allow the advantages of the better blacks/higher contrast kick in. At that point the higher contrast picture looks "better" insofar as it appears more dimensional and often enough it can even look sharper in lots of content. Which is not surprising because contrast plays a significant role in allowing our eyes to delineate images and thus plays a role in perception of image sharpness.

So, personally, after plenty of looking into this subject both from reading professional literature and my own experience, I appreciate the effects of higher contrast and deeper black levels and would choose those parameters over "brighter."

FWIW.

Why is he about to quit? That's what Lenvinson did

Maybe because the least common denominator folks like you. In my opinion there are perfomance parameters that can be improved on that the most people in the world thought process wouldn't cut it for. I doubt really that you believe yourself some of the things you say on these forums.

And you didn't answer my question but instead side stepped it. People like Kane add to the body of knowledge and allow performance improvement. This is based on engineering and science not snake oil. I hadn't heard that Levinson made video projectors.:rolleyes:

I see excellence as a desirable goal it appears that you see mass affordability as the desired goal.



Art

I'll take that one step further. While I admire Joe and his work tremendously, perfection is all areas is extremely difficult while there are certain things that make huge differences and are much easier to obtain.

In the world of high end (both audio and video), the goal is to become immersed in the performance. Not the Sound. Not the Picture. The Content. And any distractions are a bad thing.

The reason we were thrilled with CRT for so many years was because it forced us to have really good rooms. And even though the ANSI was low (both brightness and CR), it was high enough because absolute black was perfect.

Human nature likes brighter. That is why this poll is unfair. ANY time there is an A/B the brighter picture wins. That means ABSOLUTELY nothing.

Take two identical projectors with exactly the same specs and put a bigger bulb in one of them so that you get 50% increase in brightness. Your eye would be drawn to the brighter picture, because psycho-visually that's the way we work. But I promise you that all things being equal except brightness, you are more likely to enjoy the lower output projector over the long run easier, because it will have better black level and even though during high APL scenes you would never notice that, when the picture gets dark, you will, and that will immediately pull you out of the presentation, reminding that you are watching an imperfect device. The other one is just as imperfect, but assuming that you have a balanced set of specs to begin with, you might not notice it.

High end is not about doing more stuff right, but less stuff wrong. And elevated black level is one of them.

More polls will show that high CR is way more important than high brightness, if given the choice.

In my system, I get about 10 ftL with the iris closed and around 16 with it open. Right when I make the switch I like it brighter. That's normal. But the knowledge that I gain twice the CR makes me close it, and I never ever find myself wishing it were brighter DURING a movie, only upon making the change.

The best thing ANYONE here can do is fix your room to absorb screen generated light. It will make a bigger bang-for-the-buck than any amount of luminance increase you can get.

Just my 2 cents.

Very thoughtful post, Dan. Interesting that it almost sounds to me that you are making an argument in favor of the RS2. ?

Darin earlier suggested that increasing screen luminance was one way to increase contrast ratio.No, I said:
High brightness from the projector helps maintain good contrast ratio.in response Mojo_LA's post about ambient light and:
The moral of the story? Good contrast is more important than high brightness, and high brightness makes it difficult to maintain good contrast!
Yet, isn't this misleading? Increasing screen luminance tends to raise black levels, no?First, I didn't say screen luminance, I said "from the projector". Consider the Sharp 20k with Greg Rogers' measurements for high brightness and high contrast ratio modes:

High brightness: 720 lumens and 1900:1 on/off CR
High CR: 309 lumens and 7260:1 on/off CR

Add the equivalent of one lumen worth of other lighting and the high brightness mode gives close to 720:1 on/off CR off the screen, while the high contrast mode gives close to 309:1 on/off CR off the screen (I don't feel like doing the exact math right now :). So, lower on/off CR. Try these 2 modes in a room with no other lighting, but with white walls. With the high brightness mode using a screen that has a 0.43 gain gray layer in addition to whatever the screen used for the high contrast mode has, so that the ft-lamberts for white are the same. Now, even though the high CR mode likely has a little more ANSI CR than the high brightness mode coming out of the projector, I bet that the ANSI CR off that screen with the 0.43 gain gray layer will be higher. The reason being that both screens reflect the same amount of light into the room (since the darker screen is getting hit with over twice as much light), but when those reflections come back to the screen, the darker screen then kills more of those reflections and so the reflections wash out those images less.

There are also cases where considering a matte white screen compared to a screen with directionality (like the Da-Lite High Power), the screen with directionality will increase ANSI CR off the screen to a viewer at a high gain screen position by giving more gain to the projected light than the average gain for the reflections around the room and will also give more on/off CR off the screen with other lighting added that is off angle (so lower gain than the gain for the projected light). A black level can go up at the same time as the CR goes up. Like with the High Power and off angle other lighting. If the white level doubles and the black level goes up 20%, then the CR went up.
Since currently black levels are easier to excel at than the kind of brightness being demanded in this thread, the most efficient way to increase contrast is by lowering black levels. The pj industry's technology development at the moment illustrates this.That was largely the case before, but dynamic irises changed that to some degree. An iris can only go so closed before things like color uniformity get hurt. So, there are cases where a dynamic iris gives more CR and more lumens than if the engineers just tried to give max CR without a dynamic iris. As an example, if a dynamic iris was to be added to the JVC RS2 it could have both more lumens and more total on/off CR. More lumens because they could open the lens more for white than the RS2 is currently, and more CR because the total on/off CR is basically the instantaneous CR with the iris closed times the multiplier for the reduction in white level from iris open to iris closed. The ANSI CR might go down slightly (although not likely much), but the CRs in many images would go up.

The new Planar 8150 is a single chip DLP that gets both high lumens and high CR because of its dynamic iris. They could have chosen other tradeoffs and along part of the curve less lumens for more CR, but the same thing that is giving them high CR (the dynamic iris) is giving them more lumens for that same CR compared to just closing a couple of non-dynamic irises down.
So it seems to me that, with regard strictly to picture quality, increasing contrast is more important that screen luminance, and indeed that luminance can measurably reduce contrast.Going for more luminance can reduce CR or it can raise CR. Depends on the design, where you are starting from, and multiple factors. But, in the face of ambient light from other lighting, more luminance from the projector is very likely to increase the CR off the screen.

--Darin

This is an interesting thread, and I've enjoyed the posts. There are some significant pieces missing, though, from this discussion that must be considered, and may well take the discussion in the thread a new direction. Let's see.

The biggest problem I see here is that pretty much everyone is viewing this from the perspective of the display calibration/setting being the ultimate variable. Although some have admirably mentioned/cited SMPTE and others, even they have missed some major points that affect this subject in a huge way.

First, let me point out that 12 ftL is not "optimum;" it is minimum tolerance. 14 ftL is the nominal. If anyone really cares for the technical explanation, I'll see if we can provide it.

Unless, I've missed someone else covering these in the posts, there are a couple of technical reasons why the 12 ftL to 22 ftL range exists. It has nothing to do with how dark the environment is; it is presumed reasonably dark as others have cited. It has to do first with a technical issue of the relationship of the spinning shutter and the brightness of the lamphouse. If the lamphouse produces too much light (I forget the actual number, but it is a little above what will render 22 ftL), the 24fps image will begin to result in big problems (strobing, if I recall properly). So, luminance was set to a level that was under this limit. Film labs have established priniter light specs that create nominal densitiy of prints to provide nominal (faithful to the original) luminance, contrast, and color saturation at the "nominal" lamphouse output (that results in about 14 ftL). Theoretically, the labs could print more densely for a brighter presentation, but there is the strobing issue. So, we are kind of locked into that luminance range in cinemas (for film presentation). Review cinemas at the film labs and studios are calibrated to the nominal luminance with extremely low/tight tolerances. Of course, we hardly have a prayer of seeing it at that level at most of our local theaters :( We have an excellent chance to see it that way at home!

That's film, and we are looking at video at home. What affects how we translate that? Again we have to consider that the post houses that do the HD tranfers are "translating" the nominal original material to a different medium with the intent of being as faithful as possible to the nominal review cinema presentation. These facilities are using professional monitors well calibrated to a nominal set of specs. Fortunately, the post production suite can actually improve some characteristics of the oringinal film, and deliver us a BD that is faithful to the digital intermediate (DI) rather than just the print in the review cinema. But how bright can we expect to take that image without creating more problems than we are fixing with higher luminance? Do we even have the capability of displaying at home a faithful picture if we have calibrated our displays significantly brighter than the professional specs. When we pump up reference white luminance to 30+ ftL and try to hold on to proper blacks, are we screwing up the intended gamma, contrast, and other qualities?

Front projector manufacturers (such as JVC and others) have the task of deciding where to land with regards to the capabilities of their products based on some reasonable performance specs. I think it is realistic and reasonable for they and us to use nominal specs from DCI/SMPTE and maybe even review room tolerances as a reference. When I hear lots of complaints about "bright corners," gamma, contrast, and similar anomolies, I wonder if that is because that particular display is being asked to perform outside its designed capabilities which are presumably designed to reasonably perform best at or reasonably close to profesional specs that render a faithful representation of the source material.

Every HT owner may calibrate their displays to their own subjective criteria, but it is resonable to exepect that there may be compromises for doing so. Some folks really like to use their HT as a lab for experimenting; it's part of the fun of being an enthusiast. But all I ask, as a member of the community of people that create the things we are watching, is to realize that motion picture technology has been around and been evolving for a century. Things are where they are sometimes for a reason. In some instances, the spec exists for a reason that forced a compromise. I don't think it is unreasonable for us to expect the possiblity of some specs being modified for the home theater envirionment, but that is a slippery subject because there is no standard for the home viewing environment or display properties. THX has made an admirable effort over the last couple of decades to help find some translation for the home environment, but that is evolving, as well. I doubt that any particular standard will ever be acceptable in all HT circumstances. The way I see it is that we should get the most out of that century of motion picture evolution (that now is beginning a hybrid relationship with digital imaging technology) by referencing, to the max extent, the nominal specs for the created media with regards to viewing envirionment and picture qualities. In the normal evolution of technology, we will probably see reference luminance creeping up a bit. But because 35mm projection is going to be around for a long time to come, it will be a slow transition. Home theater will not be able to depart with a leap ahead of the professional production and exhibition standards.

I don't have an all-encompasing conclusion to offer on this subect. Give me a great pj well calibrated to 14 ftL - 16 ftL in a well light controlled room, and I'm a very happy camper. As most of you know, I believe the advent of high native on/off CR is a huge advance in the ability of display technology to more faithfully reproduce photographed content. If my pj can achieve that, and my environment and images can conform closely to the professional benchmarks, I'm doing about as well as can be done.

Seems to me that brightness (i.e., # of lumens, or ftL) and CR are orthogonal attributes. For a given CR, as you increase ftL both white level and black level increase, and CR obviously remains the same. So one would like to have CR a high as possible, to resolve all the features in the pic, and then have ftL up high enough (e.g., ~ 20 ftL) so the the pic is vibrant and striking (esp. for older eyes!).You might find that with enough CR the ~20 ftL for white become fatiguing or distracting (like going from dark black to something very bright) and then need to make a tradeoff between raising the black level or lowering the white level.
At that point the higher contrast picture looks "better" insofar as it appears more dimensional and often enough it can even look sharper in lots of content. Which is not surprising because contrast plays a significant role in allowing our eyes to delineate images and thus plays a role in perception of image sharpness.Yep. I was just talking to somebody the other day about how a lower resolution image can actually look like higher resolution than an image that is higher resolution, if the lower resolution image has a lot more CR.

--Darin

You might find that with enough CR the ~20 ftL for white become fatiguing or distracting (like going from dark black to something very bright) and then need to make a tradeoff between raising the black level or lowering the white level.

--Darin

Well, now that my lamp is aging, I think I'm down to between 15 and 20 ftL on my HP. It still looks very nice to me, so maybe I'll learn to like it down there as you more experienced guys are pointing out.

Darin, I think I see your point now. Sorry for the confusion. Yes, as ambient light increases, it increases the floor of the overall level of blacks the pj is capable of. Yes, once this has occurred, increasing overall brightness will restore that lost contrast.

Your example of an iris is interesting, particularly in light of Tryg's comment about engineers not reducing light output to increase contrast ratio. But of course, that is exactly what irises do.

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Cam Man, I really appreciate your thoughtful and detailed post! It explores in depth many of the issues we have touched on in this thread, particularly the contextual differences of watching films in a public or a home theater. I wonder if I might impose on you somewhat to learn your opinion of why 14fL is really nominal?

I wonder if I might impose on you somewhat to learn your opinion of why 14fL is really nominal?
Not to put words in your mouth :) but your question needs to be broken in to two parts: Why is 14ftL the nominal spec, and why do I agree with it?

It took a while to find it, but I finally found the source from communication I had on a forum for production professionals. A fellow pro was telling how DP Gordon Willis used to bring a "screen brightness meter" to the lab and other screening rooms to measure their screens (projector lamp on, no film in gate). He mentioned it was amazing how often lamp voltage was too low. He mentioned that he thought that Gordon was looking for 14 foot-lamberts uniformly across the screens (might have been 16 ft-L). I piped up and posted "16 fL is correct for an empty gate. Amazingly, a totally clear piece of film (full white) drops that 16 fL to 12 fL. I don't recall the uniformity spec for film, but they are probably the very close to the same for digital cinema. Tolerances are based on "nominal" and tolerances for review rooms, and theatrical. DCI has established similar specs for digital cinema. Nominal calibrated white luminance at the center is 14 fL with +/-0.7 fL review room tolerance, and +/-3 fL in theaters. Nominal uniformity at corners and sides is 85% of center, review room tolerance of 80% to 90% of center, and theatrical tolerance of 70% to 90% of center. You can find the pdf with all these at http://www.dcimovies.com/DCIDigitalCinemaSystemSpecv1_2.pdf Table 11, page 67."

A very interesting and educational follow-up post was made by a fellow from a film lab: "A clear gate at 16ftL is reduced to 14ftL by a piece of film with density 0.06, while film of density 0.12 will take it down to 12ftL. A well-processed print should be somewhere between these, but a lot closer to 0.06 - giving 14ftL. The DCI spec of 14ftL is designed to give the same results as an on-aim film projector with good clean film in the gate."

So, there you have the explanation of where 14ftL comes from; the horse's mouth, no less. 14ftL is the nominal spec. Whether we choose to use it at home or not is the question. For obvious reasons, my background leads me to follow the professional spec at home.

Believe it or not, there is a lab here or there that will actually set their projectors at 5 or 6 ftL because they believe that they should follow suit with the neighborhood cinemas, otherwise prints that look good in the lab would be too dark in front of an commercial audience. That's nuts! Let's not lower the benchmark there or at home. Nominal specs for viewing environment and image qualities exist for good reasons.