Archived posting to the Leica Users Group, 2001/06/02
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]In a message dated 6/2/01 9:15:54 AM Eastern Daylight Time, stiles@s-way.com writes: << (Wide open performance does seem to be a major Leica difference.) Perhaps the ASPH lens performance is weighted to the wide open (where one would be using the lens), and the photodo average neglects this aspect. >> Phil: I think your conjecture is exactly right. Lothar Kolsch, Leica's current chief of lens design, has clearly opted for optical design that favors optimum performance at full aperture. Erwin Puts has emphasized this in his book. Leica wants to furnish users with lenses that can be used wide open without fear of degradation in coverage of the full film frame. That could imply that as lenses are stopped down, medium aperture performance might not match stopped-down performance of other lenses not computed for optimum performance at full aperture. Thus the Photodo average rating. This current design philosophy is precisely what prompts my continued use of the 40+ year-old rigid 7-glass 50 Summicron, described in an article in the current VIEWFINDER magazine of LHSA. Seth LaK 9