Quote:
Originally Posted by JA
Hi Darren,
You mentioned that your recent planetary videos have had focus issues: Suggesting that perhaps previous videos were OK? If so, what has changed? A new Bahtinov mask? Another remote possibility - is the Bahtinov mask OK, any damage, scrapes etc? Were you previously focusing without a mask and now with? etc....
It may be some coma &/or astigmatism seen through the Bahtinov mask &/or some collimation issues. Any bumps/jolts or falls for the scope lately? What does the star look like without the mask? Is it perfectly symmetrical? Is the star you used in the centre of the frame / on the optical axis? It might be telling to compare the same test you have done, with a star at the centre (on axis) and one towards the edge of the frame. That would help to rule in or out coma/astigmatism issues and point you towards collimation issues.
Best
JA
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Hi JA, Some good questions for me there to look at. In all honesty, the planetary ones have never been that good in focus but are good enough for the eyepiece. I thought it was just me not getting things right.
The bahtinov mask is in good condition, and I don't recall any jolts or anything to the scope. I've previously used the bahtinov mask when I trialed some DSO's (at f12 I was asking for trouble
) and it worked fine then. That was probably a few months ago now.
I'll see if there is a particular axis which is off and see over the field of view. But if I don't have the bahtinov mask on the stars don't appear to be out of shape (at least visually) and I can split doubles no problem as well as not noticing any colour fringing visually.
It's all a little bit of a conundrum. Maybe it is slightly out of collimation - do the effects of this get worse at longer focal lengths? I will definitely defocus a star and see what happens - unless the edgeHD just gets me too excited and I forget
But thanks both for your suggestions and thoughts.