Interesting tidbit about brightness in theaters

That would make a lot more sense, I still don't hear 16, but I could be not hearing him correctly. They must use some very high gain screens, at a native aspect ratio of 1.9:1, they need about 70,000 lumens to light up their screen with 16fl, seeing how their projectors emit exactly 34000 lumens each. I am sure they loose quite a bit after calibration as all of our projectors do, the gain would have to make up the difference.


It is very interesting because their site indicates that a single 34,000 lumen projector can light up a 105ft wide screen, why do they need 2 for a 90 foot wide screen then?


I see similar numbers from barco, they claim that a single 33,000 lumen projector can use a max screen of 105ft wide - and they even say that it tested 16 fl!


Now, even if these cinema projectors, that are ONLY used in cinemas can achieve every single lumen in the specs on screen, after calibration, they would need a screen gain of 2.8 to get 16fl. Seeing how most of these are AT applications, I have no idea how they can get anywhere near that much gain and even if they do, there would be absolutely insane hotspotting across the huge area the audience sits.

A 90 foot wide 1.9:1 screen is 90' x 47'4" which is 4,260 square feet.


4,260 x 16 = 68,160 lumens.


That's 34,000 lumens required per projector.


Now, the reality of 100% power and the rest, certainly could be 'made up', it may not be as better manufacturers tend to specify much closer to 'real world' lumen ratings instead of BS numbers. JVC, for example, in home theater tends to have lower numbers on their projectors, but do a better job with color when hitting those brightness claims.


When considering a $80,000+ projectors it is often important that the numbers claimed aren't such BS numbers as we are used to seeing as the engineering involved really needs to be accurate for the design. Still, with the Xenon lamps in use (typically) you get better color, more stable color, and more stable brightness that burns out more quickly, but provides a solid image throughout the life of the lamps. I would expect that these projectors really need minimal gain from the screen to deliver the image quality expected.


Still, theaters often run much dimmer than what we can achieve at home. They also don't have the contrast numbers we can get at home, or much else. It is a fact that home theater projectors in a good room can pretty easily best the local cinema in overall quality. From sound to image, we can do better.


Still, while I'm not sure they can't hit the numbers discussed, I'm as doubtful as you are that they actually are hitting anywhere near those numbers. Still, 12 lumens per square foot in a good theater environment is a lot better than 20 lumens per square foot in a weak room.

Indeed, if there are two separate sources with the same input, and the listener is not precisely located equidistant from each source, you will have different arrival times for the radiating sounds and, hence, phase interference. Yeah, I guess you could call that a "time alignment" issue. So...


...strictly speaking, you are correct. It's just that the term "time alignment" is presumed to apply to phase-coherency among band-limited radiators within a given loudspeaker module. "Time alignment" as you use it will be an issue for anyone who is not precisely located in the "sweet spot" between the two sources. (And, BTW, is another reason for live sound reinforcement to evolve to discrete multichannel mixing a la Grateful Dead. But I digress...)


To return to the subject at hand (home theater versus commercial cinema), this is likely to be more of an issue in the home because of the close proximity of the radiators compared to the commercial cinema. Which is to say, if you move one seat over in a cinema house, the "time alignment" (as you use the term) will be degraded by a smaller amount than in a typical home theater room, simply due to the smaller geometry of that space.