there are so many posts about RC collimation that one gets lost... I ask for your help understanding if I'm right direction or not.
I used CCD Inspector and the famous DSI collimation procedure to **** my GSO RC8 collimation, both at native FL and with AP 0.67x reducer (actually the TS version at about 82mm, so a little more than 0.67x).
What I found is that at native focal lenght collimation is OK, my conclusion is that I don't need to do anything more to improve it: DSI method shows balanced and round defocused stars all over the frame, CCDI shows good values. See pictures in next post.
Using the reducer, things becomes much more questionable: DSI method shows unbalanced, non round stars across the frame; CCDI return uneven plots. See pictures in the further post.
So I conclude that the reducer lowers image quality and maybe has something wrong.
Then my points are:
- Curvature % shown by CCDI are not as low as hoped, in both configuration. But, at native focal lenght the difference between min and max FWHM looks thin enough for me. So I would not worry about it. Do you agree?
- Do you agree that my instrument collimation is actually good enough, or should I improve it?
- I'm a little surprised that the reducer worsens results so much. Actually, the impact on my final deep sky picutres is probably not that huge, but CCDI and DSI method suggests something is not ok. On the other hand I wouldn't do anything since my OTA at native FL looks ok, concluding the reducer is not good enough. Do you agree with my conclusion / is all of this normal in you experience?
Thanks everybody for your support.