At 09:15 AM 5/18/99 -0400, Tomoko you wrote:
>Joel,
>Do your Vivitar (?) extension tubes automatic aperture closing and opening?
>
>With Olympus extension tubes, earlier ones were manual aperture. With those,
>you can stop down the aperture prior to shutter release, which would
eliminate
>vibration in the lens due to aperture movement.
>
>Tomoko Yamamoto
Tomoko, yes the Vivitar extension tubes are auto, so that if aperture
stopdown is a culprit in vibration to the lens, these tubes might
contribute in some way to the problem.
However, the OM-1 and OM-2S, both of which I used for my test frames of the
striped orchid with 200/f4 and extension tubs, are quite different in terms
of how their mirror lockup works vis a vis aperture stop down. There is no
way to prefire the aperture stop down on the OM-1, even though you can
manually lock up the mirror. Timer prefire on the OM-2S locks up the
mirror as well as stops down the aperture.
The fact that the results with OM-1 and OM-2S were indistinguishable
suggests to me that the stopdown of the aperture prior to exposure is a
non-issue.
Joel Wilcox
Iowa City, Iowa USA
< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
|