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Discussion Starter · #1 ·
Ken,


The new D-ILA models (150HT and 2000SC)in the smaller product line do have improved optics and coatings to actually improve the contrast ratio to the point that the new production spec is 600:1 as opposed to the previous 350:1 figure. Yes, some of the previous units might be able to be tweaked to measure 500:1 but that was not the rule, you just got lucky.


Going much beyond an honest 600:1 in a reasonably priced optical system is probably not going to happen soon, the optics are still too expensive.


Regards,




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Tom Stites

Director, Business Development

Digital Systems Division

JVC Professional Products

"My opinions do not necessarily reflect..."
 

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Quote:
Originally posted by tstites:
Going much beyond an honest 600:1 in a reasonably priced optical system is probably not going to happen soon, the optics are still too expensive.
Tom,


Is this D'ILA specific or are you saying that the contrast ratios of the LCD based XP21N (700:1) and DLP based LT150 (800:1) are exaggerated?


--Les

 

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Hi,


I compleatly agree with KBK and I wonder about this for the same reason (I think.) Obviosly with a 600:1 contrast ratio the blacks should be very, very black. Either that or the whites will burn your eyes. I do think there is some false advertizing here. Maybe there is a high contrast ratio when the contrast in cranked way up but under conditions where you can actually watch the movie without going blind I doubt the contrast ratios still apply.


Anyway, Good Luck,


Brian
 

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Ken:


Interesting points. However, I'm not sure if I'm missing something, or if I just disagree, but I wonder if a lower lumens, higher contrast projector would be something I would even want. Like many others (I think), I prefer viewing with a small amount of ambient light in the room. So, having a projector with totally black blacks, wouldn't help me at all, would it? I need high lumens to get a high contrast ratio, if I want to have ambient light.


Also, this talk of a bright projector "burning out" your eyes has me confused. Has anyone actually seen a projector that is too bright? It seems like your eyes will compensate for any excessive brightness. Even though a 400 lumens projector seems bright enough in a dark room, that's not to say that a 2000 lumens projector will make you go blind. I have a pretty bright projector (a 2000 lumens G20), on a relatively small screen (100" diag). I've never felt it was too bright.


- Dave
 

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Quote:
Like many others (I think), I prefer viewing with a small amount of ambient light in the room. So, having a projector with totally black blacks, wouldn't help me at all, would it? I need high lumens to get a high contrast ratio, if I want to have ambient light.
Dave, keep in mind that your screen will only get as dark as it is with the projector off, so no matter how many lumens or contrast, if you have ambient light you will not have black.


KBK, you are exactly right. Lets make up a lttle math:


Lumens / contrast = black level


In this case the Sanyo XP21 with 2000 lumens and a contrast ratio of 700:1 has a black level of 2.86. But the good ol' Davis DL450 with 450 lumens and 500:1 contrast ratio would have a black level of .9. Probably why it was such an HT success.If you also figure in the very real eqaution of (Projector Output / Sq. Footage of screen) x Screen gain = Foot lamberts, and the SMPTE standard of 15 to 20 foot

lamberts, you start to see where a 2000 lumen projector is really IMHO not ideally suited for a HT but for business where showing presentations with the lights on is THE number one criteria.

This is why I am personally very excited about the Plus piano. With 450 lumens and 600:1 contrast ratio it produces the lowest black level of any reasonably priced projector I know of (.75). With a 92" 52" 1.5 gain screen it will produce 19.56 foot lamberts which is plenty bright in a dark room.
 

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Quote:
Originally posted by Dave T:
Has anyone actually seen a projector that is too bright?
Oh yes! In a totally dark theater, 2,000 lumens looks horrible. But of course with ambient light it probably not to bad.


As for enjoying a movie with the room filled with ambient light, that is the viewer's choice. Some people may enjoy listening to classical music while their kids are playing noisily in the room.



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Mark A. Torre

NEC XG-8"CRT PJ, HTPC, HDTV and loving it! The Torre Home Theater
 

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Come on, let's not get ridiculous about burning out your eyes! Geez! Natural sunlight produces about 130,000+ lumens. A cloudy day roduces about 40-50,000 lumens to reflect off everything around you. Anyone's eyes melt from that?


(P.S. We do have irises for a reason)


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- Tom C
 

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Zoinks! I'm afraid I was completely misunderstood.


"Dave, keep in mind that your screen will only get as dark as it is with the projector off, so no matter how many lumens or contrast, if you have ambient light you will not have black."


Sofa: That was exactly my point. I know the math - I wasn't talking about black, I was talking about contrast. If you have some ambient light, you need high lumens to get contrast. I know black isn't really black, but, as I'm sure you know, your eyes can still be completely fooled, if you still have high contrast.


And, Torre, I said "a small amount of ambient light", not "a room filled with ambient light". I can tell you from personal experience, a G20 in a completely dark room looks AWESOME! What projector did you see that looked so bad? If you saw a 2000 lumens projector in a dark room that looked horrible, it was the fault of something else in the projector, not the lumens.


As tcumbo pointed out, our eyes are used to light much brighter than the brightest of these projectors.


Don't get me wrong - I understand the importance of contrast, and agree that in a black room, absolute black level is critical. I'm just pointing out that high lumens high contrast is better than low lumens medium contrast, and high lumens high contrast can also be better than lower lumens higher contrast, if you have even a small amount of ambient light.


- Dave
 

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Discussion Starter · #9 ·
Not to worry...we are currently working on a 4-chip projector...RGBBk, red, green, blue and black...it will set the industry on it's collective head. http://www.avsforum.com/ubb/biggrin.gif


I can't speak for the claims of others who have higher contrast spec's, I just know what I've measured with a meter at our QC checks. My personal opinion is that until I've measured a few units with a meter under known conditions it's ALL BS.


As "sofacinema" says, you have to do the numbers...what works for you is totally dependent on your viewing environment...you cannot disassociate the projector and the environment. If you want to have black blacks and still be have a decent pic in higher light environments, you may very well have to resort to ND filters on a very bright projector when you're viewing in a dark room.


Regards,




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Tom Stites

Director, Business Development

Digital Systems Division

JVC Professional Products

"My opinions do not necessarily reflect..."
 

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Tom:


Will your RGBBk produce blacker than black? http://www.avsforum.com/ubb/smile.gif


Even in a darkened room, if you have a small room with waf paint on the walls, you get alot of spillover just from the projector.


In this case, do you get better overall contrast ratio by cranking up the lumens and cranking down the screen gain? I know you do with polarized screens, whatever happened to them?


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Alex
 

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I will add another question: are we trying to make a replica of the movie theater in our homes? If the answer is yes, then we need to know how much lumens are the black level in the movie theater, and how much is the contrast.

I know for sure that a crt projector has blacker blacks than a movie theater, maybe a very well calibrated dlp projector looks more similar to a movie theater (we are talking black level) http://www.avsforum.com/ubb/rolleyes.gif


Federico
 

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Funny you should bring this up today; FWIW, this is from the thread entitled "Sharp",
http://www.avsforum.com/ubb/Forum10/HTML/007176.html


about the new 720P DLP:


"The incredible contrast is actually around 1100 to 1, which represents the tip of the doable at the moment. The new DM3

chip with RGBRGB colorwheel and 1280X720 resolution is being used.


The blacklevel was exemplary, really black and differentiated. Simply more details and no sceendoor effect showed(even from 1m away hardly no screendoor, very CRT-like)...."


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Noah
 

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I'd like to take a shot at improving the quality of the optical pathway of a decent DILA. I'm pretty darned sure that I can noticably improve one. In the real sense. The repeatable, real sense. Ie, commerical application. But, every time I call up these kinds of folk, they treat me like a flake, or want me to just blurt it out and give it to them. There ain't no reasoning with people, sometimes.


The only problem, is I would probably get bogged down in re-designing the entire machine. Why stop half way... there's always room for jello.


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Ken Hotte

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[This message has been edited by KBK (edited 07-10-2001).]
 

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...when we will actually see the promise made, actually take place?


What is (and has) ALWAYS been a concern for me, in the world filled with marketing jargon..is the ability to have a specification sound better in one machine over the other, simply due to a misunderstanding.


For instance, 3000 lumen DILA's ae probably not that suitable for home use with average sized screens, where the detail is kept high, with a smaller size of screen. My great concern is that manufacturers are falsely pumping contrast ratio figures, byt relating the contrast ratio to the simple max ouput lumen count. Has the actual black level performance of the design FUNDAMENTALY been altered for the better??


For instance, if you took a two year old DILA with a 1000 lumen rating, and 500:1 contrast ratio, and put it beside a 2000 lumen BRAND NEW design unit (2001 release date) with a 700:1 contrast ratio design, and then... put the same light engine in both units, would the new unit still hold onto it's so called 'improved contrast ratio?"


*Probably NOT*


THIS is the fundamental specification that MUST improve. Otherwise it's just merely cranking of the numbers, and is meaningless.


Driving a PJ with huge light engines so hard that it makes the viewers go blind is no substitute for a true black level and actual improved contrast ratio. I'd really like to see that improved engine. Anyone seen one lately?


Sorry fot he general rant. I'd like some REAL improvements, please!

Have their been any of note, or even mentioned anywhere?


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Ken Hotte

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[This message has been edited by KBK (edited 07-10-2001).]
 

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Quote:

"we are currently working on a 4-chip projector...RGBBk, red, green, blue and black...it will set the industry on it's collective head."


All you'll have to do to get one is sell your house. http://www.avsforum.com/ubb/eek.gif


Chris
 

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Quote:
Originally posted by Dave T:
I can tell you from personal experience, a G20 in a completely dark room looks AWESOME! What projector did you see that looked so bad? If you saw a 2000 lumens projector in a dark room that looked horrible, it was the fault of something else in the projector, not the lumens.


It was (is) a Sharp DLP with a 2,000 lumen rating. And I thought it looked bad for two reasons. 1) Too bright. Yes it did hurt my eyes. I need to have the lights on and dimmed for it not to. Of course I can not watch my 46" RPTV with the lights out either. I actually feel pain in my eyes when a bright scean comes on. 2) Off topic, but the "digital look" of the DLP I did not care for. Rendering of the storm clouds at the beginning scene in "Dinosaur" looked absolutly fake.


That said, I do agree with you that you must have high lumens to get bright whites if you have ambient light. As stated, this helps to fool your eyes into thinking that you are seeing black when a dark grey image is displayed.


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Mark A. Torre

NEC XG-8"CRT PJ, HTPC, HDTV and loving it! The Torre Home Theater
 

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Just got my XP21N today. It meets all my expectations of what a good projector should be, atleast when it is feed with a 480p source.
 

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There is a thing that engineers speak of, when the kinds of current directions towards solutions to contrast ratios is being enacted.


it's called: "Brute Force and Ignorance".


It's certianly not the best solution, just a repeat of the earlier, and expanded to meet. But certianly not any new thinking.


"I hate it when that happens!" --- Billy Crystal, SNL.


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Ken Hotte

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[This message has been edited by KBK (edited 07-11-2001).]
 

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Maybe KBK is subtle and pushing gray paint.


As he knows, one needs to include he reflectance of the screen in estimating black level.


The XP21N should, for example, be used with a dark screen (refectance/gain ~.5) for the best picture.


Even a minor amount of grey is well known to improve the perceived black level by a large amount. A brighter projector keeps the white level from going to hell.




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Ken Elliott
 

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Me? Subtle? maybe. who knows. I never even tought of paint at all when making the above post.


I suspect that within 5 years or less, we will see some digital PJ's that have a different sort of enacting and design of light engine, and thus the greyscreen will go the way of the Dodo bird. Totally unnessesary for our purposes, due to the fact that a real black level has been achieved. You could see that writing on the wall at the very moment the first grey screen was considered. There will be a residual useage about, for bright conditions. Once the black level of digital J's moves more towards a perfect black.. the number and type of greyscreens lessesns,andyou end up with just a few.. that are actually targeted for specific ambient lighting conditions. Like conference rooms, etc. Right now, due to PJ limitations, the black level should be intimately tied to the realizable contrast range of the PJ at hand. Any other solution leaves you with less actual contrast range, as far as the eye sees it. When the Contrast range of Digital PJ's gets high in a great and linear fashion, then low grey, or no grey will be preffered.



Non-linear machine... corrective, non-linear screen.


Linear machine...Linear screen.


Very simple. We are moving slowly towards the linear.


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Ken Hotte

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