Guiding drift - what's up?

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Re: Guiding drift - what's up?

Postby rwg » Mon Aug 17, 2015 11:39 pm

Update...

Further experiments this evening have revealed that I definitely have issues with my focus drifting - leaving the scope just tracking for 10 minutes drifts from pinpoint stars to little donuts :(

I'm assuming the cause of this is the focuser creeping rather than anything like thermal expansion of the tube, so I'm back to 'what to do about the focuser?' I don't want to try and adjust the guiding issues while the focuser is giving me grief in case the guiding drift turns out to be due to the focuser problem in some way...

Now, the focuser I have is a dual speed crayford - very similar to the model being taken apart here : http://polluxchung.com/gso_crayford_fix/, but the drawtube is a very glossy lacquered black instead of raw metal silver.

I'm wondering if the glossy finish (which includes the flat area that the crayford drive grips onto) is the cause of the problem - just not enough friction to hold the focuser steady against the steady pull of even a light camera. If that is the case, then maybe Dion's oilstone mod for the Skywatcher crayfords would help - although the reason being to provide a slightly rougher surface rather than to flatten out a curved one.

Does that sound sensible or is there anything I've missed?

cheers,

Robin

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Re: Guiding drift - what's up?

Postby rwg » Tue Aug 18, 2015 11:53 am

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