I don‘t know which camera you used, but even if it was the ASI294MC in „unbinned“ mode (best case) you have an FWHM of 4“ and only 2 stars are measured. There are too few stars visible to judge the field and the two stars that PI can measure are very bloated. The single corner star I see in the top left shows significant off-axis aberration (probably astigmatism). The method you describe means a full disassembly, a huge investment of time. My experiments with using the DSI method were far quicker with acceptable results.
There has been terrible seeing for a long time and It is the ASI183MC pro at 1365mm .37"/pix bin 1. The disassemble is only because of my conditions and was not different than when you clean the mirror which in fact I did as it was a second hand scope. If I have to collimate again I do not have to disassemble. Everything is now in place and I know they work.
The problem I see on many of these discussions is that everyone wants perfection with the easy button. It is not going to happen. As a design engineer I know how many hoops I jump thru to make things look easy to the end user.
I did the disassemble mainly to confirm my thoughts and to take the mystery out of the way. Now I know how the scopes are actually built and design features I did not understand before. Case in point: the use of the center screw, the "bad GSO focuser design that wobbles" that does not wobble and is actually not that bad and, the focuser attached to the back plate that is not a bad thing. In fact, I find it is a good thing if you find the way to use it to your advantage which I did.
I use this RC as learning prototype in case I want to buy a larger/expensive one.
Yes I see the elongation by zooming 1:1 but the rest of the field looks pretty good to me. I think I am at the point of diminishing return and trying to finetune this scope further with a coarse thread screw is a waste of time.
I also try to find an adapter from coarse to fine thread but, they do not exist with the thread pitch on the scope. That would have been sweet.
Edited by MikeECha, 20 July 2021 - 06:38 AM.