Join Date: Apr 2000
Location: Ottawa, Ontario, Canada
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Actually, if you wanted to reduce hotspotting by moving the projector, you would move it *farther* away. That would reduce the angle of the light reflected at the edges of the screen and direct it closer to the viewing area and less into the walls on the side.
As for the depth of the curve, you should probably experiment with your projector when it is installed (before you make your screen...). Focus it on a screen sample or a wall, then take a piece of paper and hold it at different distances from the wall. See what range of distances produces a sharp image (look for sharp inter-pixel gap) on the paper and that is the maximum depth of the curve you should use. Also, measure at the center, edges, and corners as the results may not be the same (try and stay within the smallest value). Obviously, sharpness is a matter of preference and you can push it a bit, I believe when someone measured an ISCO + D-ILA the depth of field was about 6" (which is quite a bit more than the 1" you want). I don't know what the half-gain angle of the m2500 is, but any kind of curvature will improve your image even though some hotspotting may still be visible.
I assume you are going to construct a horizontally curved screen? In this case it would definitely be achievable and a curve with a depth close to the focal depth you measure will provide an improved image with a wide-oval shaped hotspot rather than a smaller circular hotspot, definitely an improvement. Even if your curve is not perfect it will still provide a better image (as long as you can't notice the imperfection).