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Old 19-11-2012, 12:52 PM
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blink138 (Pat)
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discovered flexure!?

hello members
i have been having an absolute ball autoguiding (see signature) all so far with 6.3 reducer
started trying at native f/10 late last week and even though the images look good and bright they have elongated stars! is this the fabled diff. flexure that many people are on about?
would a barlow or powermate on the f/5 guidescope fix it? (if i can get focus)
thanks
pat
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Old 20-11-2012, 07:56 AM
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Geoff45 (Geoff)
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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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Old 21-11-2012, 10:37 AM
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blink138 (Pat)
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thanks for the wise words geoff and your reply
i will see if i can ascertain if it is different in different parts of the sky
i know lodestar is amazing and since it has never "beeped" at me during exposures i assumed that it was guiding perfectly
it seemed to have only happened in f10 and my f6.3 seem very good
pat
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