"Wandering" polar-scope issue

For those who need help choosing a setup or want further advice on how to improve their own setup
Post Reply
User avatar
Posts: 1417
Joined: Mon Oct 12, 2009 7:47 pm
Location: Bolton

"Wandering" polar-scope issue

Post by rwilkinson » Sun Mar 26, 2017 11:46 am

I've noticed during my imaging sessions this week that my declination-drift has been poorer than usual, so I was suspicious that the polar-scope which I use for alignment needed re-setting.

But when I checked it this morning (using the antenna on top of the street-lamp across the road as my reference-point), I found that my target was "wandering" around the reticule as I rotated the polar axis, but never returning to the same point. :?

After stripping it down, I discovered the problem: the collar which locks the polar-scope's helicoid focusser (see picture) had worked loose, and there was then enough play in the thread that the objective-end was "drooping" under gravity!
The focus-locking ring on my polar-scope
polarscope.jpg (125.02 KiB) Viewed 7632 times
After I tightened this collar, the 'scope was good and solid again and when I re-fitted it in the axis, the fixed target described a small circle in the reticule. I've now re-calibrated it so that there's very little movement in the target, and even tightened up some slack in the polar axis whilst I was at it.

Post Reply