Your All Screen Gain Calculator (“SGC”) and Easy Calculator for Screen and Image Size (“ECSIS”) are quite useful (I created a similar screen size calculator before discovering yours and it proves the math. However, your format is much better, and the use of Excel’s protection and error condition features are very clever). Now to my point - as I attempt to tie screen size, gain and ft lamberts together. Let’s assume:
1) 35.88 sq ft screen size (default from the ECSIS at B12).
2) 2.07 screen gain (default from the SGC at J30).
3) 531 calibrated lumens (from http://www.projectorreviews.com/epso...erformance.php
– Theater Black with low lamp power).
4) Ft-lamberts = lumens / screen square footage x gain.
Then calculated Ft-lamberts become(s):
(531 / 35.88) * 2.07 or 30.63 ft-lamberts
Do you agree with the forgoing?
Assuming (again for illustration) the ideal is 16 ft-lamberts (from http://en.wikipedia.org/wiki/Footlambert
), and that all factors above are fixed other than gain, one should shoot for a screen with gain of ~1.1 calculated as follows;
(16 / 30.63) * 2.07 or 1.081 (~1.1)
Do you agree?
I also understand that much more goes into the selection of a screen as additional factors come into play (i.e. ambient light), but I wanted to pause and see if I am on the right track.