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Old 03-09-2020, 07:10 PM
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rbronca is offline
Join Date: Sep 2013
Posts: 36
Can you test without the corrector? The coma and star sizes should be consistent in each corner if the sensor tilt is good. That would quickly rule in or out the corrector.

ASTAP (free) has an Image(CCD) inspector option that will allow you to work with actual numbers whilst your isolating the issue.

Since there are so many different pieces in the chain can you run just the camera and nothing else and start from there and add pieces and see where things go wrong? You may need a good spacer collection.

Is everything screw threaded?

Are you certain the spacing before and after the corrector is correct?


Sanity check time:

Primary mirror cell gap to the bottom of the tube look even?

Secondary mirror gap look even all around? (Use a small mirror to see)

Does the secondary look square to the focuser?

Any slop in the focuser?
Does the elongation change depending on telescope orientation?

Is the spider tight?

You didn't mention which corrector your using?

Does it have any elements that aren't centered, damaged?

The glass etc. should appear to be even all the way around.

I hope it isn't an Orion UK one...

Paul Haese is the local expert on testing wonky Orion coma correctors

Hope this helps you to isolate your culprit.
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