Archived posting to the Leica Users Group, 1997/12/08
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]At 01:21 AM 08-12-97 -0500, Nick Hunter wrote: [smip] > >I know there are aberrations which are not affected by aperture, and that >contrast differences influence sharpness as much or more than resolution. >Have you (or anyone) found differences between lenses used at small >aperture openings which would be noticible in regular use? I believe I have noticed such degradation in quality using enlarger lenses at small f-stops. Enlarger lenses must be capable of very high resolving power to focus on the grain in such films as Kodak Royal 25 ot Tmax 100. When stopped down to f11 or beyond, the lens begins to go past the point where diffraction effects makes it impossible to do this. I have noticed this in my own enlarging. I try to use as large a lens opening as possible (with my APO Rodagon). I am even contemplating getting a ND filter for the lens, to be able to get more reasonable enlarging times. Dan C.