Here is a little cheat-sheet I made for myself to calibrate my projector at various gamma settings. It includes the relative luminance numbers of my projector at its native settings.

Here is a little cheat-sheet I made for myself to calibrate my projector at various gamma settings. It includes the relative luminance numbers of my projector at its native settings.Thank you. So in that case your 50 IRE/%stim measured 21% of your 100 IRE. So, if your 100 IRE was 10 ft-lamberts, then your 50 IRE would have measured 2.1 ft-lamberts. And people can see that your 10 IRE/%stim measured less than 1% of your 100 IRE, which is how it should be when properly calibrated. Obviously 1 IRE should be way dimmer than 10 IRE and so 1 IRE would be way dimmer than 1% of the light level for 100 IRE. Hopefully we can put to rest the misleading stuff about digital not having gamma and 50 IRE meaning the ft-lamberts should be 50% of 100 IRE.

--Darin

Havent read all 17 pages so I might be repeating something, but if you were to actually to ge the 12 ft lamberts, I would say its enough. The problem is that sometimes these projectors are tested and measured in facilities where you can never duplicate the results in your own room so if you actually measured and got 12 you will be doing great. Getting 12 based on the specs may or may not be enough

That's the trick. And without a light meter you have no idea what you've got. I was shocked when I finally bought a light meter and checked my old H79 with it's original bulb. It seemed a little dim but watchable. It was about 6 foot lamberts!!

I much prefer the look around 18 FL.

Projector Brightness Advice:
Home cinema users - you can skip this whole article, as all you need to know is that brightness isn't really important for home cinema, which is why there are very few quality home cinema projectors over 1200 lumens.


From this great site:

http://www.projectorpoint.co.uk/Projector-Brightness-Advice.htm


I went to the site and used their calculator. Assuming no lights on and no light coming into the room -- with intricate images and a screen of 9' width, their calculator says I need 1,500 to 2,200 Lumens. Their calculator contradicts them.

I went to the site and used their calculator. Assuming no lights on and no light coming into the room -- with intricate images and a screen of 9' width, their calculator says I need 1,500 to 2,200 Lumens. Their calculator contradicts them.

That sounds reasonable to achieve 16.5 foot-Lamberts or better on a 1.0 gain screen - which I would recommend, anyway. :p

According to the screen set-up calculator at this site;

http://www.accupel.com/

1,500 Lumens x 1.0 gain at 9' wide yields 32.88 fL from screen.

2,200 Lumens x 1.0 gain at 9' wide yields 48.22 fL from screen.

So, that site;

http://www.projectorpoint.co.uk/Proj...ess-Advice.htm

Seems to be all over the map. They say "don't worry about brightness because you don't need that much for home theater," but their calculator recommends 1,500 to 2,200 which is a LOT of lumens and they say you don't need that much brightness but their recommendation comes out to 32.88 to 48.22 fL from screen, which is really bright.

According to the screen set-up calculator at this site;

http://www.accupel.com/

1,500 Lumens x 1.0 gain at 9' wide yields 32.88 fL from screen.

2,200 Lumens x 1.0 gain at 9' wide yields 48.22 fL from screen.

So, that site;

http://www.projectorpoint.co.uk/Proj...ess-Advice.htm

Seems to be all over the map. They say "don't worry about brightness because you don't need that much for home theater," but their calculator recommends 1,500 to 2,200 which is a LOT of lumens and they say you don't need that much brightness but their recommendation comes out to 32.88 to 48.22 fL from screen, which is really bright.

Wasn't the question do you want a screen brighter than 16 ft lamberts or not? You need a degree in Star Trek to follow what this has turned into :rolleyes:

To answer the question posed.....I prefer quite a bit more. There is some research that indicates that double the 12-16 fl (that is suitable in the COMMERCIAL environment) is preferable; a series of articles by John Bishop in Widescreen Review, which included a statement that Joel Silver had come to a similar conclusion in his research namely. All this not to mention that if you calibrate for 12-16fl, by the time your bulb is ready to be replaced, you're most likely well under that number. With 24-32fl, you have some room to account for the bulb getting progressively dimmer.

The 20fL figure Joel recommends is for HD material only. SD is prone to compression artifacts and image noise which will show up more if higher fLs are used, so unless it doesn't bother you, 12fL is more than enough in a light controlled room (commercial theaters are around 7 to 9fL even though the standards recommend 12fL +- 2fL for film, and +-1fL for digital theater).

Have you measured your fLs Scott? You may be surprised what it is if you haven't.

Gary

The 20fL figure Joel recommends is for HD material only. SD is prone to compression artifacts and image noise which will show up more if higher fLs are used, so unless it doesn't bother you, 12fL is more than enough in a light controlled room (commercial theaters are around 7 to 9fL even though the standards recommend 12fL +- 2fL for film, and +-1fL for digital theater).

Have you measured your fLs Scott? You may be surprised what it is if you haven't.

Gary

I haven't. But I've been around high-end video enough to make an educated guess. I'd say I'm at about 14fl or so. And I'd like it to be much brighter...like when my bulb was new :p And you take the good with the not so good, and I'd suffer a little more noise in what little non-HD material I watch.

Unless you've actually measured some set ups, you won't really have a good enough idea to know what you're seeing regardless of how many unmeasured setups you've seen - the eye is very adaptive so very low fLs look brighter than you think - 3 to 4fL is a lot more watchable than you can imagine - for example, I was calibrating a pj for someone and noticed that at 100 IRE the time between readings (using continuous measures in the calibrating software) was a lot longer than usual, and more akin to lower IREs. I measured the pjs output and found that he was getting around 3fL. Whilst I knew the image wasn't bright, I didn't realise it was that low.

Your typical plasma/direct view TV are around the 30+ fLs

Gary

And how many of these "20+ ftL is desireable" recommendations take into account a <2x width viewing ratio? Intuitively I could see 12ftL looking a lot different when it takes up the majority of your field of view than when it takes up a much smaller portion.

And again, Gary has a very good point, most people have no idea what their picture is in terms of ftL. I know I was rather surprised when I finally measured my IN76 and got 9ftL. And sitting in front of my W5000 right now (which is plenty bright), I can confidently say I have no idea how bright it is, because I haven't measured it to figure it out.

And how many of these "20+ ftL is desireable" recommendations take into account a <2x width viewing ratio? Intuitively I could see 12ftL looking a lot different when it takes up the majority of your field of view than when it takes up a much smaller portion.

And again, Gary has a very good point, most people have no idea what their picture is in terms of ftL. I know I was rather surprised when I finally measured my IN76 and got 9ftL. And sitting in front of my W5000 right now (which is plenty bright), I can confidently say I have no idea how bright it is, because I haven't measured it to figure it out.

Buying a AEMC CA813 light meter, which I learned about here on AVS, was extremely helpful and informative! Especially since my projector has 2 bulbs and a variable powered iris. I've been able to keep the picture at 16 - 18 foot lamberts now for 660 + hours of operation, first by using one bulb at a time, then 2 bulbs, and as they age I open the iris a little. A light meter can help you know how your bulb is holding up over time too. No more guessing games for me !

Oh ya, we are sitting around 1.25 - 1.3 screen widths, depending on which electric screen we are using ( the 16:9 or the 2.35:1 ) !

I exclaimed, "This is not rocket science!" And you already have the answers! Enjoy your picture and sound. I'll be here, working for Sony, Barco and Christie to make their products better for everyone. :)

I sure hope not! Given your posts here, it sounds like you think 50IRE should be half of the luminance of 100IRE. Whoops! Keep your hands the hell off my projectors!

Go back and check (instead of jumping all over my typos at the first opportunity). The final figure is 5 ft-Lamberts, half the light level of 10 ft-Lamberts, set out in the question. 5 is half of 10!

Wow. Just....wow. :rolleyes:

Have you ever measured any type of video display of ANY kind in your entire life? Ever!?

I'm fine with 7-10ftLs. Bright and smooth with the W5000. Concerning the other topic 50 ire is about 20% of 100 ire. This is at my lowest level and at 400+ hours, but remains consistent regardless of light levels. http://i524.photobucket.com/albums/cc330/coolrda/Measures-1.jpg

I can confidently say I have no idea how bright it is, because I haven't measured it to figure it out.

Well said!

...Concerning the other topic 50 ire is about 20% of 100 ire.

No surprise there. Visually, half-gray is 18%. Thus 18% gray cards...

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.
What do you do when you go outside where the light level is far higher and probably not attenuated enough by sun glasses to bring it down to indoor levels.

The way you talk you should never drive a car because the light even with sun glasses will be too high for you to see anything.

When you go outside, everything is bright, not just a "small" portion of your field of view.