Posted By Eric Planalp
I bought one of those run-of-the-mill laser collimators that everybody sells; the one with the 45-degree angle face visible through the side of the unit.
I use a Discovery 10" f/5.6 dob with the standard focuser and a focuser upgrade is not an option at this time.
Even with the laser unit firmly set-screwed into the drawtube, and as much slop taken out of the focuser mechanism as possible, everything just still seems too sloppy to achieve a good collimation. A slight touch on the laser unit will send the beam dancing 1/2" back and forth across my primary.
If I don't find some way to take the play out of the stock Discovery focuser and where the unit slides into the focuser, am I wasting my time with it?
It seems like most of the play comes from where the unit slides into the focuser, even with the setscrew tight. With just one setscrew, it just pivots around it. If I had two setscrews, how would I know the unit was perfectly centered in the focuser.
I toyed with the idea of wrapping a very thin piece of foil tape or something evenly around the part of the unit where it slides into the focuser to "shim" it.
Anybody have any thought or ideas about whether #1. I'm being too picky. #2. There's a way to solve the "slop" problem without buying a better collimator or focuser, or #3, if I should just sell the laser collimator and go back to eyeballing or using a Cheshire system.
(I would note that the first and only time I used the unit and then observed,I just did a quick "get the beam back in the hole" by adjusting only the primary and the views were nice and on a good night the star test was about as good as one gets.)