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In article <NEBBKHCFDGIGIJEHDJFCOEMNDJAA.firstname.lastname@example.org>, Paul D. DeRocco <email@example.com> writes >This is interesting info. Are these rolloffs caused by the random variations >in the grain size? Or is it related to diffusion in the emulsion? > Its not so much variation of grain as the finite size of the grain that causes this, but diffusion (caused by imperfect photon absorption) also plays its part. This results in the MTF being a function of the emulsion thickness, which is why colour films have much poorer resolution than monochrome film and why the MTF is always worse for the red layer (bottom emulsion) than the blue (top emulsion). And, of course, when you start working at fast apertures with thick emulsions the limited depth of focus means that there is no requirement for the lens to even approach diffraction limited resolution. All in all, you have to work damned hard to justify sampling at more than 4kppi, but there is no justification for sampling at 40kppi. -- Kennedy Yes, Socrates himself is particularly missed; A lovely little thinker, but a bugger when he's pissed. Python Philosophers - Turn off HTML mail features. Keep quoted material short. Use accurate subject lines. http://www.leben.com/lists for list instructions.