Quote:
Originally Posted by peter_4059
Interesting idea Sam. Do you think the short guide exposure (<2sec) might cause this approach to not work as well when the seeing is poor?
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It's really a matter of the amplitude of the mount oscillation vs the seeing FWHM. In my experience, poor seeing simply hides these type of high-frequency mount oscillations. With poor seeing, when you plot an unguided log, you just see noise superimposed on a long time scale oscillation.
My idea with shorter exposures is to try and get as many points as possible for good curve fitting, and to feed in pre-emptive corrections frequently. When you're dealing with a 10 sec cycle, you ideally want to be sending corrections every 1-2 seconds.
Quote:
Originally Posted by glend
Rowan Belt Mod on my NEQ6 and it does help
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I agree that a physical solution is definitely the best way to go, it is a mechanical problem after all. Software can only mitigate the problem so far. With a good mount it would be preferable to have a longer guide period, 2 secs plus to average out seeing. Credit to the NEQ6 of course. For most practical purposes, the standard factory build does a pretty good job for astrophotography.
Quote:
Originally Posted by Shiraz
application to the Losmandy G11
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Thanks Ray, that is a good summary. The 10.2 second cycle is the dominant short term cycle on the EQ5/6 mounts. I would imagine the same approach would work on a Losmandy G11, just with a different period. A starting point would be to look at an unguided guide log with good seeing to see what kind of short-term oscillation is apparent.