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Old 23-09-2009, 06:33 AM
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multiweb (Marc)
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Join Date: Oct 2007
Location: Hinchinbrook
Posts: 18,333
Quote:
Originally Posted by pmrid View Post
Do you mind explaining how you arrived at the figures mentioned - 53.5 and 56 mm? Is it just trial and error or is there a formula?
Yes Peter, trial and error. I took pictures of Alpha Crux centered on the CCD chip and run the subs through CCD Inspector measuring the spacer with an digital caliper.

Quote:
Originally Posted by pmrid View Post
Also, with the adjudtment rings, did you buy them as a set from Peter Tan or did he have them made up to your design and specifications? Obviously, the idea strikes me as a good one - using the final threaded adjuster with the little lock ring. If someone isn't making this as a set they probably should.
Peter.
I originally bought the solid spacer he sells for the QHY8, But I couldn't shorten it. I did some test by moving the spacer away and I was over correcting so I figured I had to shorten the distance and in order to do that I needed a shorter spacer. I wasn't ready to stuff around with different lengths rings so I worked out this spacer and send him the drawing see if he could do it and it worked a treat.

I googled all over the place for one and nobody made any. I was really surprised because to me it's just common sense to have an adjustable spacer for field flateners or coma correctors rather than fixed length rings.
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