Archived posting to the Leica Users Group, 1996/12/01

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Subject: focus/eye problems
From: "Edward Gosfield III, MD" <gosfield@dolphin.upenn.edu>
Date: Sun, 01 Dec 1996 09:23:14 -0500

Greg wrote:

>You might also consider having an eye examination. People normally get
>far-sighted as they age... and it affects one's ability to focus... even a
>rangefinder camera.

>It happened to me twice, over the last dozen years... both times gradually,
>and imperceptably... and both times, my focus was "fixed" and sharpened by
>new eyeglasses."

Even if your distance prescription is accurate, you might still have become
presbyopic (sorry--it means unable to focus at close distances). The
(annoying) cure is bifocals.  You will use the distance portion of your
specs for looking through viewfinders.  This has happened to me recently,
and I had to put +1 diopter correction lenses on my Nikons (SLR) and Fuji
670 (RF), to allow my eye to focus comfortably and sharply at infinity.  But
for some reason my M3 has not become so uncomfortable to focus or view
through my distance prescription, and I have remained accurate with it
unmodified.

Does anyone know if Leitz used (?use) the same -1 diopter standard/default
viewer power, (and 1 meter virtual distance for viewer image) which is used
by Nikon, Fuji, and, I am told, most other camera makers?  Has this changed
with M models over the years as finder mag. changed?

ted gosfield

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mailto:gosfield@dolphin.upenn.edu