Archived posting to the Leica Users Group, 1997/08/01

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Subject: LTM and Contax RF 1.5/5cm Sonnar lenses
From: Marc James Small <msmall@roanoke.infi.net>
Date: Fri, 01 Aug 1997 10:30:19 -0400

Patrick

Thanks for the number, 2744913, from your 1.5/5cm CZJ Sonnar T.  Our best
guess is that this lens dates from 1941.

I have a similar lens, 2724549, as well as a Contax RF version, 2677302,
all dating from the same year as your lens.  The LTM lens uses more
aluminium in the mount but is otherwise apparently identical to the Contax
RF lens save for the camera mount.  It is similar also to my early (1939)
factory-coated 2554180 in Contax mount.  (This last lens is most
interesting -- it was purchased in 1939 mounted on a Contax III body here
in Roanoke, Virginia, from the old Roanoke Photo-Finishing Company:  so
hungry was Nazi Germany for foreign exchange that they sold a few of these
early coated lenses overseas, although regular consumer production of
coated lenses did not commence until after the War.)

The 1.5/5cm Sonnar originally opened only to f/8;  by the mid-1930's, they
had cautiously increased this to f/11, as the uncoated version was prone to
flare when fully stopped down.  With coating, they eventually made the lens
go to f/22, which your 1941 lens should have.

The Postwar Oberkochen (Zeiss-Opton, Carl Zeiss) design is somewhat
different and I doubt if the lens rings could be switched to your lens.

Marc


Marc James Small
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