----- Original Message ----- From: "Richard M. Koolish" <kool...@bbn.com> > A spherical film plane would eliminate one of the cosine squared factors in > illumination, but leave the other one.
That's right, it eliminates the one COS^2 factor to account for "inverse square law", also eliminates the one COSINE factor to account for the pinhole covering more area due to the light falling obliquely. The fall-off is then reduced to just one COSINE factor, the one that accounts for the aparent smaller pinhole area as we move off axis. > I think that in a cylindrical camera like an oatmeal box, the illumination > is even more uniform because the edges of the negative get closer to the > pinhole, at least in one dimension. Good observation. For the original poster of the question that type of camera is not an answer, tho, as he is more concern with "sharpness" rather than fall-off. > Paper or film won't bend around a tight sphere, only a cylinder. One > photographic telescope design that astronomers use is called a Schmidt > camera, ...stuff deleted I like to know this type of details! Thx for the info and link. Guillermo
