To furher suggestions for this middle speed exposure problem, one idea is to try using
the timer delay on the camera (the thing that is supposed to let you run over and get into
the shot). Most, but apparently not all, cameras will raise the mirror right away and then
wait for the timer to expire before activating the shutter. This allows the vibrations from
the mirror slap to die down and the only vibrations left are from the shutter mechanism.
Doesn't eliminate vibrations, but should significantly reduce them.

Phil Freeman

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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.

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