A very interesting thread you have started here Don. I never realised that sensor size was a factor, apart from the degredation that arises from the extra enlargement needed with small sensors. As I understood it, degradaion due to defraction arises from bending of the light rays close to the perimeter of the iris. The smaller the iris the larger the ratio circumference/area of the iris, therefore, a larger proportion of the light rays get bent (defracted) with small apertures. The theoretical maximum resolution of a lens in lines/mm is 1600/f number. In practice this resolution is not achieved, but with a well corrected less it is approached after stopping down 2 stops.
John
Last edited by John; 20-06-06 at 10:11.
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