Archived posting to the Leica Users Group, 2000/02/13
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]I don't think we are talking abou the same thing. According to the MTF charts pictured in the pdf brochure on the APO 90 downloadable from Leica, the curve for the 40 lpm at f2.8 never dips below 65% until you get about 10 mm from the center of the frame. Then it dips to about 60 until very close to the frame's edge. At f5.6 it stays around 73% until around, well, almost right to the edge. Of course the 5.6 valus is better; it is for every lens. But the f2 curves are no slouch. It would be interesting to compare these curves to the earlier Summicron, but I can't find any. The best thing to do of course is to compare photographs, not charts. For me, the photographs taken with my APO 90 at f2 show a significantly superior performance compared to any other wide open leica lens I own. Dan C. At 08:55 PM 13-02-00 +0100, dominique pellissier wrote: >########### >Yes. >At full aperture, the contrast is 52 %. At 5.6 : 72 %. Great difference. >By comparison (yes, i know, it's not very rigorous to compare lenses of >different focal lengths) the 2.8/180 apo gives 82 % at full aperture and 82 >% at 5.6. >Now, let's see the CDI tests for these 2 lenses. >For the apo90 : good (center), good (edges) at full aperture and excellent, >very good at 5.6. >For the apo 2.8/180 : very good, very good at full aperture; same results at >5.6. >The 2 tests are corroborated. > >Leica writes : " The overall performance measures up to the legendary LEICA >APO-MACRO-ELMARIT-R f/2.8/100 mm from the LEICA R system." >It's true. But not at full aperture for the 90.