I don't think there is any adjustable part on the focusing screen holder. I
have seen two OMs and a Nikon FA which had slight focusing problem. I fixed
them by adding a 0.15-0.2mm tape under the mirror. I found most of the
"reasonable good" condition used cameras had quite "clean" focusing screen
(of course except scratches) and also the focusing screen holder area are
usually free from dirty.
I don't see why the change in mirror position has less effect then off
position focusing screen due to dirty. By looking at the construction of the
mirror rest pin, I would say the factory use it to control the focusing
accuracy.
C.H.Ling
-----Original Message-----
From: WKato@xxxxxxx <WKato@xxxxxxx>
To: olympus@xxxxxxxxxxxxxxx <olympus@xxxxxxxxxxxxxxx>
Date: Saturday, September 30, 2000 1:48 AM
Subject: Re: [OM] Focus discrepancy in OM-4T: Solution sought
>The mirror angle and distance does not change the lens to focus screen
distance very much. There are shims under the holder for the focusing screen
that adjust the screen-lens distance. But before sending the camera in to be
adjusted I would take out the focusing screen and clean the edges and also
clean the upper surface where the screen fits in the mirror box. It takes
very little to change the focusing distance. Also, unless the focusing
distance was incorrectly set up in the first place, there is little that one
could do to upset this adjustment. Even if the lens flange to film plane
distance were changed by some type of impact, this would not necessarily
change the lens flange to focusing screen distance.
>
>Warren
>
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