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I wonder if you could test what's flexing with your lazer.
Attach it to the mirror box pointing up to the secondary cage and see if there's flexure.
It could also be the spider flexing.
-------------- Original message --------------
From: "Greg LaFlamme" <greg.laflamme@No-Spam>
> My 15" f5 also has laser drift when moved from horizontal to vertical but
> in my case it has nothing to do with movement of the primary, its the
> "supply beam" from the secondary TO the primary that shows the error first.
> The red dot will drift horizontally from left to right when the scope is
> moved 90 degrees in altitude about a 1/8" center to center. I believe this
> is caused by slight amount of shear flex in the ota itself (on the long
> axis) but I'm not certain, its a tricky bug to work out and a bunch of
> scopes have this issue. To "cure" it, I collimate the scope while its at
> about 45, this way I split the difference. There is no noticeable difference
> in resolution in my f/5 but maybe it may be noticeable at f/4.5? Not sure...
> I use a 2" Kendrick collimator with a barlowed angled face so I can stay
> back at the primary when collimating it. Every so often I check mechanical
> alignment with a Cheshire.
>
> GML
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GSSP Web Page updated 3/4/08: http://www.goldenstatestarparty.org
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Received on Thu Mar 13 18:59:38 2008