Sadly 3D is a game changer when it comes to brightness, a projector that’s a veritable “light canon” for 2D viewing on your sized screen, may well be underpowered for 3D, at least a little. A dim picture certainly was, and probably still is, the number one complaint about watching 3D movies in today’s typical local Cineplex or other movie theaters.
Things are getting better, though. First gen 3D projectors using active shutter glasses were very lucky if they even achieved just 25% of the brightness of the same projector doing 2D. Note: Basically all under $25,000 3D capable home projectors sold in the US use active shutter glasses, although Europe, I understand, is a bit different. We certainly haven’t gotten to 50% yet (considering one glasses lens is closed while the other is open, starts you out with a 50% maximum. But even with the shutter open, the glasses don’t pass 100% of the light, or very close to it. They all look like lightly tinted, almost sunglasses, with the active shutter open.
How many 2D lumens does it take for good 3D? This might be a good question, since no one is measuring 3D lumens, nor is there any real standards for doing so.
The bottom line on crosstalk on these non-DLP projectors is the brighter the image, the more the crosstalk. I have yet to find one of these 3LCD or LCoS projectors that doesn’t have a noticeable amount of crosstalk at their brightest, but often a middle setting is clean enough to be rarely noticeable, and the low setting should be comparable to a DLP.
I generally consider LCD and LCoS projectors to be acceptable in their “middle” glasses positions, so I will discuss assuming that. Please assume that with the same number of lumens to start, that middle setting will be brighter than a similar lumen DLP projector. Thus the bright 3LCD projectors tend to be, by far, the brightest for 3D.
Assume a 1.3 gain, since that’s what my screen is, and that’s typical of many popular screens. Screen size is how large a 1.3 gain screen to get “acceptable” but hardly great brightness. Even with these numbers there will be more than a few people who think 3D is too dim to watch.
I find LCD and LCoS projectors with 1000 “brightest mode” lumens to do a good job on screens under 100” diagonal. By comparison, the brightest of this year’s projectors – measured brightness are typically around 1900 – 2300 lumens, and they do a respectable job filling my 124” diagonal screen for 3D. I could certainly push the Epson 5020UB I have here, out larger, to say, 140 inch diagonal, but that would definitely be approaching “too dim” for most folks (1.3 gain screen).
Keep in mind to get the same brightness to your eye as you would have with a 100” screen, on a 130 inch screen of the same gain, you will need 69% more lumens! That’s because it’s 1.3 times larger in each dimension, that’s 1.30 x 1.30 = 1.69 compared to 1.0 x 1.0 = 1.0. and 169 is 69% greater than 100.
Most LCoS and home theater DLP projectors (Sony’s HW50ES, VW1000ES and some extremely expensive 3 chip DLPs notwithstanding) top out in brightness somewhere between 750 and 1200 lumens), and vary from not really acceptable doing 3D on a 100” screen to pretty darn good (Think that Sony HW50ES as darn good at that size.) I have a few friends who like 3D well enough, but if I put something on, at 100” diagonal, and the projector has less than 1000 usable 2D lumens, they just won’t watch, for more than a few minutes. It’s not crosstalk, it’s not content, it’s brightness.
I’ll say it again, the top complaint about 3D in the movie theaters is brightness. Myself, I avoid conventional 3D movie theaters like the plague. Instead, if I’m going to watch 3D, I stick to IMAX theaters, which in general, seem brighter at 3D.