I've been in the audio/video rental and staging arena for many years now and I have always assumed that when you stacked two identical projectors you got twice the lumen output at the screen. The image is not "twice as bright" but it is noticeably brighter. My point is that if you stacked say, two 5K projectors you would get the same results as if you used one 10k projector of the same quality.
But recently I've had two people who have been in the business for awhile tell me that that is not true, that stacking, for example, two 5k projectors would only be the equivalent of one 7k or 7.5k projector. My experience and common sense tell me that this is wrong, but I don't know the math. Can anyone enlighten me on this subject? Perhaps direct me to a paper or article that deals with this?
If I'm wrong, I want to know and if I'm right I'd love something in writing to back me up.
Thanks to all