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Dual Clusters near Antares

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Posts Made By: David Borenstein

December 1, 2011 07:18 PM Forum: Reflectors

Elliptical Out-of Focus Star Images

Posted By David Borenstein
I just bought a Newtonian on Astromart. In-focus star images are nice points. But out-of-focus images are ellipses rather than circles. Does this symptom point to a specific adjustment needed (ie primary mirror, secondary mirror) or might there be several causes?

January 23, 2013 12:17 AM Forum: Ask rating questions here

Rating Error

Posted By David Borenstein
Charles Ryder and I (David Borenstein) just completed a flawless transaction involving an Astro-Tech AT72 scope (Ad. 808134). I entered a 5-star rating for Charles and he tried to return the favor but accidentally hit the 2-star button in error. How best can we undo this error?

December 2, 2011 02:51 PM Forum: Reflectors

Elliptical Out-of Focus Star Images

Posted By David Borenstein
According to the operating instructions for my Cheshire sight tube, elliptical out-of-focus star images is a first and definitive test for any kind of mis-collimation. Put another way, if out of focus star images are circular, chances are the scope is properly collimated and no further adjustment is necessary. I guess now I have to find out which mirror needs a tweak.

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