Help me with my math, when trying to decide whether to go with zoom method vs. A lens. This would be with a 600ES.
First, I'm making an assumption of 1,250 calibrated at mid zoom (splitting difference between projector central and projector reviews -- actually a little closer to the lower projector central numbers). I know it's possible that the number could be a hair lower, but for relative calculations, I had to make an assumption.
For this exercise, I'm assuming a 1.0 gain screen, like maybe the Seymour XD 2.35 -- 132" wide (I might ultimately go with a different material/manufacturer). Also, I will be near max throw, at 21'.
16x9: 56 x 100 - nearly full telephoto, so assuming 15% or so drop in brightness to 1,050 lumens or 27 FL
2.35 74 x 132 - mid zoom, because of bigger area, still 21' throw, lumen output 1,250 or 18 FL
A Lens method
16x9: 56 x 100 - nearly full telephoto, again assuming 15% or so drop in brightness to 1,050 lumens or 27 FL
2.35 56 x 132 - nearly full telephoto, again assuming 15% drop to 1,050 or 20 FL -- (probably 5-10% lower, because of light loss with A-lens, bringing it to about 18-19 FL).
So, it seems like that unless I'm missing something in my calculations, I'm coming up with the zoom method being essentially equal to the A lens method in terms of brightness (I know there could be a separate performance issue in terms of unused resolution in zoom method).
Now, if my math is correct, then I think it's because at 16:9 and using the anamorphic lens, I'm getting the 15% or so penalty of being near full telephoto, and when I use the zoom method for what is essentially a 74 x 132" 16x9 screen, it will move to a mid lens position, which avoids the 15% or so (plus A lens light loss) hit in brightness.
So, do my numbers look correct? Am I correct that in a near max throw situation with the Sony, that from an FL perspective, the zoom and A lens methods are essentially equal?