SharpCap Forums

Hi, I tried to PA my mount tonight, but no matter what I did, I had loads of rectangles on my screen but no solving. The gear I'm using is a 3 inch 500mm FL refractor with a lodestar guide cam. I pointed the RA axis of my MESU 200 mount at Polaris by standing behind and sighting it. Perhaps it wasn't within 5 degrees.

I tried different sky positions by rotating RA and it was apparent that most of the 'stars' were electronic artifacts (changing the focus position confirmed this) and I couldn't find a way to subtract that out.

Perhaps I'm being a bit ambitious trying to PA with sharpcap from scratch? Is it better to use sharpcap to fine tune PA once I get the mount close with for instance PHD2 PA?

thanks for help
Paul

Hi Paul,

so first the hot pixels being detected as stars - recent versions of SharpCap have a 'suppress hot pixels' checkbox in the polar alignment star detection settings - make sure that is on, and if you are still having trouble, turn up the noise reduction setting which should smear out the hot pixels enough that they are no longer being detected. In particular, you need to make sure that the stars in yellow boxes (those are the ones being used for alignment) are not hot pixels.

The field of view is on the small side (0.7 x 0.5 degrees), but should be OK. If you have a shorter focal length scope, a reducer, or a camera with a larger sensor it might be worth trying as a way to get a better field of view. If you can get about 1-2 degrees in each direction that would be optimal.

Finally - are you within 5 degrees or so of the pole? That's usually possible to achieve with a compass and just setting the mount altitude equal to your latitude. If you are not sure, grab an image to file and upload it to nova.astrometry.net to get plate solving co-ordinates. You can also use a local plate solving engine if you have installed the datafiles down to that (fairly narrow) field of view.

hope this helps,

Robin

ok, thanks Robin, I'll make some improvements to fov and try again.
Paul