I collimate each imaging session to ensure that I get the very best out of my scope. Most of the top imagers suggest at least checking the collimation each session. Yes, while it is a very good scope it does have its flaws. SCT's do hold collimation very well but little knocks can cause small deviations, as does weather conditions. So I like to fine tune the colllimation. Usually no more than 1/16 of a turn. I have seen SCT's that have never been colimated, they look good at 200X but when you whack a barlow in the image degrades so much due to the collimation.
Dave, unfortunate but true: you will have to re-align your finder just about each time you move your primary......That's one of the many reasons why it's best to get it as perfect as you can using the cheshire before hand. If youv'e already done this, hopefully you won't be far away from perfect collimation.
Even tracking doesn't help here. At the mag a 5mm EP gives you, & you move the primary screw 1/16th turn, thats usually enough to throw the star out of the FOV....then you have to find the star again, centre it, re-align the finder! It really is an exercise in frustration......the patience & precise movement of a surgeon is needed lol.
30 years ago if my collimation was out by just a little bit it would take on average 1-6 hrs to get it right.....If it was freezing out, I'd end up sweating like a pig from my temper on the border-line of throwing a tantrum the size of everest!
I suggest you stick with the 12mm & get it the best you can perhaps. You can check with the 5mm......but it's up to you weather U wanna attempt tweaking using the 5mm..I don't suggest U try it @ 5mm until your more familiar with doing it..
Thanks Paul. Just wondered.
Will have to relay message to our guys next Ob. session, as they have, AFAIK,never collimated their SCT's.. L.
ps. Maybe that's why I prefer the views thru my DOB.
I can verify what Paul said, my SCT was collimated perfectly on delivery but as winter approached the collimation had changed significantly. Like Paul, I check the collimation every time, easy when you have Bob's knobs or similar.
L.
