In a message dated 6/4/99 7:55:16 AM Eastern Daylight Time,

<< Can anyone tell me the best way to eliminate shutter vibrations of the OTA
whilst doing astrophotography?
I have a 10" Lx200 and I'm using a Nikon FA 35mm camera >>

I don't think the FA has mirror lockup, but if it does, that's a first step.

Shutter and mirror vibrations are only a problem in fairly short exposures
because: for long exposures (over 1/2 second or so) you can use the "hat
trick" of holding a hat (or piece of cardboard) past the end of the tube,
tripping a Bulb or Time exposure, and using the hat as the real shutter. For
fast exposures such as 1/250 or faster, it's also a non-problem due to the
shutter speed. That middle ground of 1/125 to 1/4 is more problematic.
Mirror lockup and "hand holding" a rigidly mounted camera both help. Squeeze
the camera with both hands, press your face against it, or do anything else
you can to reduce vibration, just as when you hand-hold a telephoto lens for
"normal" photography. You'd think that breathing and shaky hands would hurt,
but it turns out they have fairly low frequencies, and you can apply a lot of
damping for the higher-frequency vibrations of the mirror and shutter.

Good Luck!

John

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