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Originally Posted by graham.hobart
1/ polar alignment
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No, otherwise all your stars would rotate around your guide star.
Quote:
Originally Posted by graham.hobart
2/ collimation
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It maybe a contributor. If you made a circular (cardboard) disk larger than the secondary holder and centred it in the ota, you should be able to tell.
Quote:
Originally Posted by graham.hobart
3/ coma
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No, nor does it look like a spacing issue, otherwise the stars would be distorted symmetrically around the field centre.
Quote:
Originally Posted by graham.hobart
4/ flexure
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It is not flexure between the guide scope and imaging ota, otherwise all the stars would be equally distorted.
The one thing it does look like is focal plane tilt (with maybe a little collimation error) The easy way to test this is to note your best focus position for each corner of the frame. It should be the same for all 4 corners. This is best done after you have eliminated the possibility of collimation error.
best
c