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The telescope in question is a Skywatcher 130 Dob with a rotating focuser tube (that is how the focus is adjusted), so I get two results:
If I tighten the laser in place and rotate the focuser tube with the laser, the laser is pretty much steady on the primary.
If I do not tighten the laser and turn it around loosely within the tube, then the laser dot is not steady on the primary - but I would not really expect that due to the 'wobble' from not being tightened.
It's a bit annoying because obviously I purchased the damn thing to get it just so, now there's no way of telling what makes it better or worse!
How drastic are the differences between having it spot on or slightly outside the centre ring in practice?
Should I get a star out of focus and see whether the rings are concentric as a guide? Is that a good test to determine whether the scope needs collimation?
Cheers!
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