Re: AP900 Gto Auto-Guiding woes.
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The only scope I have ever owned that didn't suffer from differential
flexure between a piggyback guide scope and the main scope is my AP
130EDF-GT. That is why I ONLY use off-axis/radial guiders any
more.
Over in the Meade Yahoo groups that I haunt (I also have a 16"
LX200GPS) I am constantly amazed over how many scope setups I see where there is
an under-mounted SCT combined with a small Chinese refractor and a floppy
focuser riding on its back. And not an OTA counterweight anywhere in
sight.
Of course I rarely see any images taken with those
scopes...
Christopher Erickson
Consulting Engineer Summit Kinetics Waikoloa, HI 96738 www.summitkinetics.com From: ap-gto@... [mailto:ap-gto@...] Sent: Friday, October 14, 2016 8:44 AM To: ap-gto@... Subject: Re: [ap-gto] Re: AP900 Gto Auto-Guiding woes. Vince, you want the guide scope/camera to be fixed relative to the
back of your imaging scope. Ideally mounted on the focuser but with your scope
that seems impractical. You could try a second pair of rings that are lower
profile around the big tube and move them back as far as possible.
What is the focal length of your imaging scope? AP makes a very elegant
guider holder that mounts on the focuser. I'd talk to them about that vs. what
you're trying in the photo if that set-up is suffering from flexure.
BTW - I imaged for years with a 350mm focal length Borg 60mm guide scope
mounted to the top plate on my AP155. I was able to stabilize it fine and never
had an oblong star in all the years I did that. You should be able to do what
you're trying but it may need to be more securely attached than what I see in
the photo. In my case, I had the guide camera, an ST-402ME, sitting firmly on
the top plate of the cradle holding the AP155. The rear ring of the cradle
nestled up against the focuser. The front of the Borg 60 was held in a Losmandy
3-point ring and the body of the Borg 60mm was held in a second Losmandy 3-point
ring. The three points were tightened down really hard.
I'll try and get a photo of this set-up.
Stuart
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Stuart Heggie
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