William:
Hmmm. Nice discussion. Just curious-- did your calculations take into account loss du to the inverse square law? Maybe I'll do some of this today, since I'm kinda laying around doing nothing. Should be easy math as we're dealing with right triangles with flat film planes. My experience with pinhole cameras is limited to cylindrical cameras mostly. It might also be fun to calculate how curved, equidistant film non-planes would affect the apparent focal length of the "lens".
