Haha yeah that was the first thing I checked - I found a few loose screws on the secondary side and thought you beauty, this must be it! unfortunately not to be though. I might pull the secondary spider out again and check it all out to make sure nothing there is loose at all. Interesting idea re the aluminium flat! Something else to look into for sure. I did adjust the clips holding the mirror as well (might have tightened a little too much as I have almost triangle shaped stars - gotta love pinched optics).
Cheers, Mike
Quote:
Originally Posted by astro_nutt
Hi Mike. I had similar problems with my 12 inch dob. First thing I did was check the tube ends and make sure they are tight. Next came the spider holding the secondary mirror. Check the focuser/tube fastenings. Next the clips holding the primary mirror in it's cell. The collimation lock screws for the primary mirror are push against a steel plate which does move when you tilt the scope. I glued a piece of 6mm aluminium flat on the steel plate with a shallow 2mm recess using a 6mm drill under the lock screws. I then drilled the end of the lock screws with a 6mm drill just enough to hold a ball bearing. You will now be able to apply more locking force to the steel plate. I also find that you only need to adjust the locking screws when collimating. I hope this might help.
Cheers!
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