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Old 20-11-2012, 08:56 AM
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Geoff45 (Geoff)
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Geoff45 is offline
 
Join Date: Jul 2006
Location: Sydney
Posts: 2,399
Elongated stars have more than one cause, so finding THE cause is a process of elimination. First thing to check is: Are they elongated exactly E-W? If so then is is probably a guide error. Does the orientation of the elongation change in different parts of the sky? Probably flexure if it does.
You don't need a long focal length guidescope as the algorithm for computing star position is accurate to a fraction of a pixel. Putting on a barlow will at best do nothing and at worst provide an additional source of flexure.

Geoff
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