First shot after CCD repair - M83 - odd star shapes
After a long layoff (the ST2000 developed nasty banding and it had to go back to the US to have a capacitor changed, then it was summer - then work, family poor w/x etc got in the way) I finally got my kit out again this week (!) and took this shot.
I used the GSO RC10 fitted with an AP CCD67 reducer and the ST2000 with a CFW10 and I cannot seem to get the spacing/focus quite right. Please have a look at the star shapes in the corners two are ok and 2 are not. I think this is a problem with orthagonality but it could be the FR out of true or the focuser or collimation or some horrid combination of all of those. I am at a bit of a loss as to how to debug this issue and would welcome some hints. I have a moonlite focuser that allows the FR to sit in a range of spacings but am not sure if I can set tilt accurately - perhaps it is better to screw the FR to the nosepiece with the right spacing.
I have used spark plug gap adapters to pack out tilt with a focal reducer successfully in the past. Its trial and error. Use focus mode in CCDSoft taking continual focus images and try shimming different spots until you get it sorted. It might only take 10 minutes.
What you'll find is its a pretty thin shim required. You are highly magnified there. My CDK17 and Proline 16803 makes an M83 image much smaller than that.
Omera centure looks good with lovely colours. There seems to be some slight elongation in the bottom left of the Jewel box. but much better than M83. What did you do to correct it?
I am not 100% sure - collimation was one thing - if was off - but I also re-seated the camera, I found the compression ring in the draw tube had rotated - allowing a thumbscrew to force the camera offcentre when tightened. A bit of both I suspect. Anyway it forced me to collimate the scope so I have learnt from that.
