[Leica] Focus index mark on LTM lenses

["Doug Richardson" <doug@meditor.demon.co.uk>]

My recollection from the days when I first used Leica screw lenses and
cameras is that when a lens was mounted, its focussing index mark was
at the 12 o'clock position. Looking at screw cameras at a recent
camera fair, I noticed that all had index marks at the 1 o'clock or 2
o'clock position as seen from the front of the camera.

I assumed this to be due to half a century of wear to the camera mount
or the rear face of the lens, but removing the lens on several cameras
showed no obvious scuffing or signs on wear on the body or the lens.

My curiousity aroused, I checked my own equipment - a IIIb I
inherited, and a IIIg I purchased recently. In both cases, the focus
index was at 1 o'clock. However when I removed the standard lens from
both, and tried the wide angle and 13.5cm, both had index marks at the
traditional 12 o'clock position. So if it's the result of wear,
presumably it must be the lens which wears and not the mounting ring
on the body.

Perhaps LTM equipment has always shown variations in index-mark
position, and I was just lucky that in the 1960s mine all gave the 12
o'clock position.

Regards,

Doug Richardson