Quote:
Originally Posted by rat156
OK, so that points to a balance problem more than anything.
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I don't think this is really the problem. I have ensured that the PME is well balanced. I am yet to find a part of the sky where the mount moves. Having said that though I will check just to be on the safe side.
Quote:
Originally Posted by rat156
As the camera/OAG will not be balanced around the axis of rotation, do you run an instrument rotator?
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The OAG is part of the camera and the camera is not that heavy. I don't have a electronic rotator but I do have the Tak one on board. Worth a try at least.
Quote:
Originally Posted by rat156
Could be minor flexing of the imaging train, rotationally. Try with the OAG vertical, so it's not placing any torque on the rotator/nosepiece etc.
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It could be I suppose, especially since I only get this infrequently, then flexure is the most likely cause, however small that might be.
Quote:
Originally Posted by rat156
Additionally, you should notice field rotation between subs, no matter the length.
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Just checked that and no rotation seen. The stars stay in exactly the same position over 4 hours. It has raised another idea though.
Quote:
Originally Posted by rat156
Finding the causes of this stuff can be painstaking, but you have to be barking up the right tree to find the problem.
Cheers
Stuart
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Yes that is the truth. This might well be a focus related issue. The image that is worse has some subs near the end of the run that are less than sharp and that could be part of the problem too. It is not the spacing of the reducer but if the focus just goes out a little this type of aberation can occur from what I know.