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Re: [OM] New lens tests posted

Subject: Re: [OM] New lens tests posted
From: "Tomoko Yamamoto" <tomokoy@xxxxxxxxx>
Date: Tue, 27 Jul 1999 18:50:07 -0400
Gary Reese wrote:
>Mike H. writes:
<< I don't know if you've addressed this before, as I'm new to the list, but
can
you explain why the OM-1 shutter has affected some of your lens tests in the
wide apertures only? Why don't they affect the results across the whole
aperture range? >>
>Perhaps there is a jolt that occurs when the camera's auto aperture linkage
>meets the lens rear diaphragm linkage and it can't travel anywhere because the
>lens is set at full aperture.  Likewise, the action might be dampened the
>further the linkage travels (i.e., the more the lens is stopped down).
I have tried to test the effects of the aperture mechanism on the sharpness of
pictures by pushing in the preview button with my finger.  I could not reduce a
fuzziness that way in the frames, but I did experience a jolt on my finger when
the shutter is released.  I would say that the jolt is real.  I don't remember
whether the jolt was bigger at the wide-open aperture.
>At wider apertures, the shutter speed is faster.  Perhaps during the time the
>film is being exposed there are stronger and/or more cycles of residual
>harmonic vibrations at, say 1/250th sec. (= f/2.8), versus 1/8th (= f/16).
Gary, do you have a record of actual shutter speeds you used for those wider
apertures?

Now that you can use the higher shutter speeds with the OM2000 or the OM-4,
would you increase the light level on your map?

Tomoko Yamamoto
mailto:tomokoy@xxxxxxxxx
http://www.charm.net/~tomokoy/



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