GalaxyHunter

6 hours ago, Stu said:

I once completely messed up the collimation on a C925, so the secondary was at a crazy angle. I blame the fact that one of the collimation bolts was rounded off so was not turning, unknown to me at the time. One could just as easily put it down to my incompetence 🤣🤣.

I ended up removing the secondary completely as it was a Fastar compatible one which allowed this easily, and then adjusted it visually so the secondary was level with the base plate, refitted it and then it was close enough to be able to adjust.

Can you post a picture of your unit so we can see what it looks like?

Stu, thanks for that, the scope is an EdgeHD, I just did as you suggested, and true enough the glass was skewed off at a crazy angle.  Now with bobs knobs all tight and with the glass visually flat, I have returned the secondary to the scope and had a look at an improvised artificial star (sun reflection off electricity insulator about a k way), and whilst there is now a recognisable image, a vast improvement on what was previously just a mass of mush, I still can’t distinguish the shadow of the secondary.  I’m going to wait for night and see if a genuine star sheds a little more light on the issue.

GalaxyHunter

I have acquired a second hand 8” SCT.  The scope was given to me by a friend who picked it up at a car boot sale of all places, and just wasn’t getting along with it (he gave up and bought an 8” Newt).  The crux of the problem is that the scope is so far out of collimation that the shadow of the secondary is nowhere to be seen.  I can guess where the shadow is  by virtue of what I can see as a series of connected bright arcs which I can only describe as a stylised impression of a flying swallow.  I have collimated my own SCT on numerous occasions, but have always had a recognisable frame of reference, being the classic out of focus collimation ‘dohnut’, with this scope I really don’t know where to start.  Can anyone recommend how best to recover this situation?

GalaxyHunter