Quote:
Originally Posted by Terry B
I don't have a PMX but have seen similar problems with Dec guiding with my tak mount.
If I turn dec guiding off and only guide on RA there will be a very slow dridt one way depending on how good the polar alignment is. I can go for ~20 mins with little drift evident. Superimposed on the drift will be almost random movements both directions due to seeing changes. If the Dec guiding is set too sensitive the guider will then bump the mount 1 direction. Sometimes it will overshoot and then try to bump it back. This will take time though due to the backlash in the dec system requiring more then 1 bump of the guider to move it back. This can set up the pattern you see.
I have also had occasions when a cosmic ray hit or interference has occurred on the guider and the mount has reacted wildly to this pushing the mount a long way and then it overshoots correcting it.
I mostly turn dec guiding off to overcome this problem.
Cheers
Terry
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Thanks Terry. That's very helpful input! I'd better tighten up my polar alignment. I'm finding that azi is quite difficult to nail when one is close. On the MX often I will move the required tics (from T-Point) and the mount actually hasn't moved. I might need to run 50 points in T-Point just to figure that out and then start over. I am able to chart moves photographically in altitude but when I tried the same trick in azi it failed big time. I'm not quite sure I understand why. Can anyone here provide a method for verifying say a 1 arcmin move in azi photographically?
Thanks,
Peter