Archived posting to the Leica Users Group, 1992/04/10

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To:, leica-users
Subject: Re: lenses
From: (Kevin Burke)
Date: Fri, 10 Apr 1992 08:56:52 -0400

In Gunther Osterloh's "Leica M: the Advanced School of Photography" there are
several drawings showing the evolution of Leitz 50mm lens development
over the years. One drawing shows an early 1950s version of the
Summicron with 7 elements all having indices of refraction in the 1.6 -
1.7 range. The drawing for the redesigned version of the late 1960s has
6 elements (I think) but indices of refraction above 1.7. What does this
all mean? The text doesn't elaborate but better performance is implied
along with smaller size as a feature.

Laney's book "Choosing and Using Leica Lenses" shows
contrast/edge-spread graphs for a 50mm Summicron versus a 50mm Summitar
(again, my memory may be failing me).  In general, the Summicron really
shows its stuff at the edges of the frame.

- Kevin (