Hi Steve,
The big moment for me was deciding to remove one of the big countersunk screws. When the mirror didn't shift or fall out I was happy
The skywatcher documentation I got with the scope was pretty useless, so I had to look around. I'd assumed the small screws were for locking only, and all the adjustment was done with the large screws. This page put me on the right track:
http://www.ioptron.com/v/Manuals/610...ollimation.pdf
I did a rough adjustment looking through the front, to get the main alignment straight. I then used a defocussed star at 77x magnification to tune further.
It really helps to have a widefield eyepiece and diagonal. I rotated the diagonal until the areas where the defocussed star rings were closer together were in the same position as the collimation screws.
After collimating here I then went to 168x magnification. This is more challenging, and having a tracking mount really helps, as the image shift is significant with even the slightest screw adjustment. I was constantly using the direction pads on my hand controller to keep the defocussed star centred. At the moment the collimation is 90% there at this magnification. The next step is to go to higher mags and keep tuning. It's really interesting to see the defocus rings as they collapse into the focus point. I think this is the level at which the really fine tuning can take place.
I lost the star once after making too large an adjustment, and there was no easy way to get it back in the eyepiece. The finder scope quickly becomes out of alignment as the primary is shifted, so its necessary to keep readjusting the finder.
At one point the collimation got way out, and I lost touch with what was happening. I had to start all over again the next day, from the rough adjustment through the front.
The lightbulb moment was when I realised that my goal when adjusting was to move the outermost defocus ring, rather than move the centre points. After this it came together very easily.