On Mon, 2 Sep 2002 12:53:56 -0400, mms@xxxxxxxxxxxxxxxxx wrote:
>Zuiks,
>
>Using a recently bought OM-2, I noticed that my 50mm lens would focus beyond
>infinity. Must be the lens, I thought, but it works fine on my other OM's.
>Do I have a mirror offset of some kind? Loose prism? I can't see any way to
>adjust the mirror stop.
>
>I was focussing on some Mtn. peaks about 20 mi. distant, which is about as
>close to infinity as it gets around here.
>
>Any ideas?
Even if "loose", the prism can be ruled out. Three things can cause
this:
(1) Lens flange incorrect distance from film plane;
(2) Mirror out of alignment;
(3) Focussing screen in incorrect position.
First, when you focus critically on infinity, is the image on the film
in critically sharp focus? If it is then it can only be (1). It's
more if an inconvenience really, since you can't just "hit the stop"
and assume it's infinity.
If the image is *not* in focus then reseat the focussing screen (the
easy bit first :-) and see if that cures it. If it's not that then it
can only be the mirror.
AFAIK collimation of the lens/body is a fairly routine operation that
could be combined with a CLA.
The "infinity stop" really is very convenient, I agree. The lack of it
is an irritation on the E-10, whose manual (motorised) focus takes it
beyond infinity and there is focus shift on zoom. I've had a few
blurred distance shots where manual focus has been necessary
(insufficient subject contrast to operate AF) and vague focus
indication on the screen (no focus aid) leads to wrong infinity
setting.
Regards
John Gruffydd (Mold, Wales, UK)
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