Archived posting to the Leica Users Group, 1997/08/04

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Subject: Re: 50 Summicron DR Update
From: ABreull@aol.com
Date: Mon, 4 Aug 1997 09:00:03 -0400 (EDT)

In einer eMail vom 04.08.1997  09:21:27, schreiben Sie:

>>I believe the lens you're talking about is the rigid Summicron lens made
>>from 1953 to 1956 and having 4 of its 7 elements made from lanthanum
>>glass, a rare earth glass. 

Leitz lens numbers  and year:

1952     N= 79 Summicron collapsible prototypes (Sumitar *)

year          from               to
1953         1 051 001       1 124 000
1954         1 124 001       1 236 000
1955         1 236 001       1 333 000
1956         1 333 001       1 459 000
1957         1 459 001       1 548 000

Dennis Laney [(1995-2): Leica Collectors Guide. Hove Collectors Books,
p130-136],
says also, that the rigid Summicron has been "identical in all details" to
the screw  version (p 132), and that this version was available till 1957.

The best performance was at f4.0 (p 132). Distance was given first in meter,
then in meter _or_ feet, later meter _and_ feet.

Screw version 1953 to 1963, first bajonett version 1954 to 1968, DR M
bajonett 1956 to 1968, 1969 2nd computation, 1980 3rd computation (better
performance, specially at close distances, p136).

Weight (7 lenses) screw version: 220 g, rigid version: 285 g. 

Maybe someone knows the weight of the 6 lens Summicron. Than you (maybe) can
deduct, whether you have the 7 or 6 lens version.

- -Alf