On Aug 25, 2006, at 12:32 PM, Toralf Lund wrote: > I a way, yes, but with a "crop" sensor those pixels near the edge > simply > won't be there at all. I'd prefer a slight fall-off, I think...
The issue is not confined to just a slight fall-off of illumination. With non-perpendicular light paths onto a sensor, diffraction around the edges of the photosite wells at corners add up to make chromatic aberration and moire which is difficult to correct, reducing resolution and quality. > Also, don't you get the same kind of problems with a e.g. DX-size (!) > sensor and a lens that's sufficiently wider to give an equivalent > field-of-view? Not if your lens design for the digital sensor is formulated to correct the ray trace so as to make the edge/corner rays more perpendicular to the sensor plane. This is done with a couple of correcting elements well behind the primary lens groups. Without a swinging mirror to deal with, fixed lens digital cameras with optimized lenses use correcting elements to align the light path with elements that very closely approach the sensor, minimizing photo-site well diffraction and moire effects, corner light fall off, etc. Godfrey -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net
