The collimator is not very snug in the focuser, it certainly has some wiggle, so however the screws are tightened will determine how the laser sits. That would be the cause then. There is no compression ring unfortunately, making things worse I suppose.
The collimation instructions mention that one should makeshift a collimation cap if one does not have a collimation tool, and the rest is on mirror adjustment etc. - but it's all standard.
Apart from the wiggle, can I still assume that if a laser shot straight into the centre of the primary comes out into the target of the collimator, the procedure is successful?
I.e., when I then reinsert the laser, re-adjust secondary and primary mirrors to fit again, am I just re-aligning them to the angle of the laser beam but the net result is the same, i.e., centring the mirrors successfully both times but in different positions?
I am German and this inaccuracy kills me inside
Quote:
Originally Posted by barx1963
Hi
There are a couple of things that spring to mind. The focuser is often a weak point with less expensive scopes, but if the laser point is not moving when you rotate the focuser, that eliminates one possibility. The other is how snug is the fit of the collimator in the focuser before tightening the screw? It ideally should be fairly snug, if it moves around a bit that is a likely cause.
My old laser that was a less expensive one had a bit of play, when I upgraded to my Howie Glatter model, it was much snugger and the difference in repeatability was very apparent.
Also does the focuser have a compression ring ( a little piece of metal, usually brass that distributes the tension of the screw around the eyepiece) or does the screw contact the side of the eyepiece/collimator barrel directly?
Last comment, did the scope come with any instructions regarding collimation?
Malcolm
|
It's the same scope, the Heritage - I've actually screwed the focuser all the way in so as to eliminate the slop for collimation purposes...
I bought that scope for its portability and would like to take it to dark sites and then collimate on-site prior to using it as the suspension in my car is probably not going to do me any favours when taking it somewhere in the Hinterland.
Quote:
Originally Posted by CJ
Hi
Those helical focusers have a fair bit of slop in them which might account for your varying results with a laser. You could try using some plumbers ptfe tape to tighten up the fit but it's probably not really necessary for visual use. I found my 130 dob, the Heritage model, pretty good optically, given the price and the design philosophy. That focuser was a bit annoying though.
|