At 06:21 PM 7/26/1999 EDT, you wrote:
>In a message dated 7/26/99 2:40:49 PM Eastern Daylight Time,
>jowilcox@xxxxxxxxxxxxxxxxxxx writes:
>
>> Are you saying the vertical shutter (as opposed to the horizontal) is not
>> the culprit in vibration scenarios with the OM-1 because this is caused
>> specifically by the aperture stopdown mechanism? If so, I'm not sure that
>> horizontal shutter isn't part of the problem.
>
>My comment that the horizontal vs. vertical shutter stems from my
>recollection (always suspect, of course) that the OM-4, with a horizontal
>shutter, and the OM-2000 with a vertical one, gave comparable results in
>Gary's(?) tests with both using mirror and aperture prefire. I would imagine
>that the additional action of the aperture mechanism in the OM-1 with mirror
>locked up would be more significant than any differences in the shutters.
>
>Paul Schings
>Coventry, Rhode Island USA
>
Paul,
I can see why you draw that conclusion, and I don't know that it is not
correct. Another possibility is that the electronic shutters may be
"better" than the mechanical one (of the OM-1 at least), and also that the
mechanical vertical shutter of the OM2000 is virtually as good as the
electronic shutters. As I mentioned in the previous note, even
neutralizing aperture stopdown by taping it down (in one case) and testing
with the lens wide open (in another) did not smooth out the OM-1 for me.
Of course, this doesn't eliminate the root problem if it is in the camera
itself.
Gary Reese wrote:
>But vibrations from the mirror ISN'T even a factor in these lens tests. ALL
>tests (well, OK, except for one Vivitar Series 1 test) were done with mirror
>lock-up, be it the OM-1, OM-4, or OM-2000. Instead, by using the self
timer,
>we have as variables the vibrations from the shutter and the automatic
>diaphram mechanism (OM-1), or just the shutter itself (OM-4 and OM-2000).
>
>Looked at another way, here are what the leading models can offer towards
>features that can be used to reduce vibrations:
>OM-1: mirror lock-up only
>OM-2, OM-3(Ti): nothing!
>OM-2000, OM-2S, OM-4(T)(i): mirror lock-up and aperture stopdown (via the
>self-timer)
>OM-2000: shorter shutter travel (vertical)
>
A definitive summary. But to say in the case of the OM-1 that "we have as
variables the vibrations from the shutter AND/OR [instead of just "and"]
the automatic diaphram mechanism" might be a little more accurate.
Joel Wilcox
Iowa City, Iowa USA
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