Archived posting to the Leica Users Group, 2005/10/25

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Subject: [Leica] Re: Jupiter 8 Lenses
From: msmall at infionline.net (Marc James Small)
Date: Tue Oct 25 15:28:38 2005

At 11:43 AM 10/25/05 -0400, Benjamin Marks wrote:
>>
>> Anyone experienced focus problems wide open with a J-8 or other USSR
>> glass? Rumor was that the roller cams in the USSR RFs were built to
slightly
>> different tolerances than the SM Leicas so that wide open and close up
focus
>> was a problem. Any anecdotes?

This isn't so, Ben.  There were problems in mounting Prewar FED lenses on
LTM bodies and the reverse, but that was caused by the same problem which
Canon was to have with the mount:  true LTM is 39mm in diameter and the
thread is 26 turns per inch Whitworth -- Leitz was a microscope company and
Whitworth was long the standard thread used on microscopes -- while the
Soviets and Canon simply churned out gear in what they THOUGHT was LTM 39mm
by 1mm DIN.  FED learned the truth during the War and Canon got it sorted
out by the time of the Korean War.

Now, Nikon did use a cam slope on its RF cameras different from that used
on the Zeiss Ikon Contax progenitor.  This can cause minor difficulties in
focusing longer-focal-lenth lenses.

Marc

msmall@aya.yale.edu 
Cha robh b?s fir gun ghr?s fir!

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