Archived posting to the Leica Users Group, 1997/10/18

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Subject: Re: SM-to-M Adaptors
From: Marc James Small <>
Date: Sat, 18 Oct 1997 08:59:10 -0400

The M cameras have an optical registration 1mm less than that of the LTM
cameras, to allow the 1mm adapter rings to be used with no loss of infinity

There are minor variations in these rings over the years, including a run
of 'serial numbered' ones which none of us can figure out.  Early ones are
marked in cm, later ones in mm, as are the current ones produced by J Uhl
in Germany.

Simply put, though, the rings match the framelines of the camera.

50mm gives 50mm in an M3 and the 50/75 in M2 to M6.  The 90mm gives 90mm in
the M3 and 28/90 in M2 to M6.  The 135mm gives 135mm in the M3 and 35/135
in M2 to M6.  Some were marked '28 - 50' as, in the pre-M4-P days, no
cameras had a 28mm frameline, so an auxiliary finder was used and the 50mm
frameline in the RF/VF was as good as any.


Marc James Small
Cha Robh Bas Fir, Gun Ghras Fir!
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