On Thu, Sep 28, 2006 at 09:49:53AM -0400, Mark Roberts wrote: > J. C. O'Connell wrote: > > I have never used ANY wide angle lens on film (24mm equiv or wider) > > On ANY film format (35mm thru 8x10) that didn't have softer corners > > And edges than in the center. That is simply the nature/physics > > Of optics. Even the very best W.A. optics always perform better in the > > center if that is your "standard". The wider the lens (say 17 to 20mm > > equiv) > > The more pronounced the difference will be....I don't think this is > > A "fault" of FF DSLRS whatsoever.... > > Especially with SLR's, where the presence of the mirror requires > retrofocus lens design that prevents the "angle of light striking the > sensor" to even be significantly different between normal and wide angle > lenses. (And the difference between light hitting the corner of an APS-C > sensor and the corner of a full-frame sensor is less than 1.5 degrees > anyway.)
You might want to check that again. By my calculations, even assuming the rear nodal point of the lens is at the register distance of 42mm, there's a difference of over seven degrees in angle of incidence. Since, for wide angle lenses (which are the lenses where this is a problem) the nodal point is even closer to the film plane, there will be an even larger difference in angle. -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net
