Archived posting to the Leica Users Group, 1999/03/09

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Subject: Re: [Leica] Summicron 35/2 wide open
From: apbc <>
Date: Tue, 9 Mar 99 18:03:12 +0800

>Perhaps I 
>have a good sample, but my 35 summicron is quite sharp off center at 
>f2, but often, I find that I have missed the focus by a bit.


This is true and due to the curvature of field of the non-ASPH Summicron. 
It is particularly apparent in the 1-3m range at wide apertures IME. 
Still it is not a big problem in practice. The ASPH lenses are 
specifically designed to address this (dis)advantage. Field curvature is 
also evident IME with the 50 summicron (slight) and summilux (quite 
distinct), 75 summilux (quite strong). Given the focussing system of the 
Ms it seems somehow more likely that the main subject will be pretty 
central usually so it is not often apparent that field curvature is 
present IME. Stopping down covers it up usually...



Adrian Bradshaw
Editorial and Corporate Photography
Shanghai, China