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[OM] The 35-80mm/2.8 Zuiko

Subject: [OM] The 35-80mm/2.8 Zuiko
From: Rich Lahrson <tripspud@xxxxxxxxxxxx>
Date: Tue, 22 May 2001 06:10:02 -0700
OM-4 with mirror and auto diaphram prefire, plus Bogen Telephoto Lens
Support
Aperture  Center    Corner
f/2.8     B+        B-
f/4       A-        B+
f/5.6     A         A-
f/8       A         A-
f/11      A         B
f/16      A-        B
f/22      B+        B
Notes: Differences between OM-1 with mirror lockup and this OM-4 test
are
significant at the 1/3 grade level since they were determined from
paired
comparisons.  The greatest differences are at shutter speeds of 1/30th
(f/8), 1/60th (f/5.6), 1/125th (f/4), and 1/250th (f/2.8), indicating
that
1) shutter vibrations from the horizontal shutter in the OM-1 and
2) automatic aperture mechanism movements significantly degrade even a
lens in the short telephoto range.

@ 80mm setting
OM-1 with mirror lockup
Vignetting = B @ f/2.8,B+ @ f/4
Distortion = moderate pincushion
Aperture  Center    Corner   Popular Photography
f/2.8     B-        C+       C+
f/4       B-        B-       B
f/5.6     B+        B        A
f/8       A-        B        A
f/11      A         B        A
f/16      A-        B        B+
f/22      B+        B        B
Notes: Exceptionally high contrast at f/8, high contrast elsewise.

Hi Gary and everyone!

     I was surprised at your findings at 1/250 and the other
instantaneous
speeds @80mm.  In the real world, surely, most photographers don't
usually lock up the mirror and/or prefire the aperture at these fast
speeds?

     I've got an OM-1n with the standard 1.8.  FWIW, I've been able to
hold in the aperture stop down button on the lens with a piece of tape.

    Do you think this is an effective method?  Or is there still some
differences in the shutter curtains operation between the OM-1s and
the current OM-4ti?  And is this homebrew tape method less effective,
perhaps due to some other internal movements that the prefire
on the OM-4 is able to accomplish?

     Also, what is a Bogen Telephoto Lens Support?

    I don't have to tell all you Zuikaholics, there's one on eBay now.
The specsheet says this lens focuses to 0.6 meters, very useful.
Do some real world users of this lens care to share?

                                        Cheers,


Rich Lahrson

tripspud@xxxxxxxxxxxx








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