Hi Greg
Thanks for the feedback.
If the night is clear on Monday I'll give a polar alignment a go again.
My scope is an ed120and i'm using a modified finderscope as a guide scope, never had flexure issues before and would be surprised.
I'll report back after my tests
Quote:
Originally Posted by gregbradley
An image would help analyse it.
Permanent setups can shift so don't assume it won't because it may have. Wet weather, dry weather can cause soils to change and cause movement. Bumping into your mount can also.
I assume from your post it was once good and then went bad or was it never good?
Elongated stars are caused by:
1. Bad polar alignment.
2. Unbalanced scope (if you have a piggy back system then centre of gravity is high and your setup can be unbalanced at the angle you are imaging at yet balanced when horizontal so check balance at the angles you are imaging at).
3. Cable drag.
4. High periodic error of mount, ie. your mount is inaccurate.
5. Flexure.
6. Poorly setup guide camera, not callibrated, too long exposure times, double star used for guide star, hot pixels picked by software instead of gudie star, guide star too dim.
7. No PEC or PEC done wrong - east/west setting back to front so guider is correcting the opposite of what it should.
8. Mirror shift for SCT scopes.
Are you using a guide scope? Does it flex? What sort of main scope is it?
Elongated stars in corners may be coma not guide errors.
Greg.
|