Archived posting to the Leica Users Group, 2016/09/17

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Subject: [Leica] How did 50mm become the "normal" lens for 35mm cameras?
From: amr3 at (Alan Magayne-Roshak)
Date: Sun, 18 Sep 2016 00:00:39 -0500

On Sat, 17 Sep 2016 Philippe <photo.philippe.amard at>wrote:

>Just remembered a conversation heard years ago between M enthusiasts here,
they were debating on the actual FL of varied Leica 50mm - >and got out
impressive differences between luxes, crons, elmars, etc
>Anyone knows more about this?
In "Camera 35" magazine Oct/Nov 1961, Arthur Kramer wrote about how E.
Leitz dealt with variations in focal length:

"...variations in focal length, if they are to provide critical sharpness,
must be compensated.  Here's the astounding way in which Leitz accomplishes
this.  For every Leica lens there is a *series* of focusing mounts which
contains the proper cam and thread pitch to provide accurate [RF] tacking.
As many as 18 mounts are available for certain lenses. Focal length
variations which fall outside or between the values  for which mounts are
available are rejected.  In this way, tolerances come closer to approaching
zero than in equipment where this is not done."

Alan Magayne-Roshak, Senior Photographer
University of Wisconsin-Milwaukee Photo Services
UPAA Photographer of the Year 1978
UPAA Master of the Profession 2014
amr3 at

"All the technique in the world doesn't compensate
 for an inability to notice. " - Elliott Erwitt