From the discussion It sounds like a Cheshire (like mine) may not be the best tool for collimating a secondary although it can be used. Since this is the only tool I have this is what I used and it seemed to work pretty well. (with help from Vic, Don, Asbytec & others!)
Wondering out loud here:
- If a star test (real star) shows a good airy disk pattern, the primary must be well collimated, yes?
- Does the good star test automatically mean the the secondary is also well collimated, yes/no/maybe?
- Is this question going to take me down an optical rabbit hole, yes?
As always, many thanks to all for sharing the knowledge.
Well, it might not be the best tool for it - others may have differing opinions here, on this subject.... but it can work. I've used it to good sucess in my F/8 scope, but I also have a few other tools at hand to confirm alignment, a 1.25" AstroSystems Lightpipe, a 1.25" AstroSystems autocollimator (not really needed on my F/8 scope) Celestron Combo tool, and lastly an Orion laser that was way the heck out of alignment, which I've since heavily modified. (collimated, removed the 45 degree window, and added an aperture stop.)
I mostly use the Cheshire/Lightpipe - then check with the laser. When they agree, I collimate the primary with the Lightpipe. Keep in mind that at F/8, collimation is rather easy, and forgivable to an extent, but I also have a F/3.6 Schmidt-Newtonian, which is a real bear to collimate.... hence the extra tools like the autocollimator.
And I agree, I've definitely learned a ton about collimation from the gurus here, (Don, Vic, Sixela, JasonD... etc.) without them.... I'd probably have no hair left. It get's easier the more you do it, then it eventually just clicks, like an ah-ha! moment.