Quote:
Originally Posted by Slawomir
Hi Simon.
Astrophotography is not easy, and that's the best part of it! 
As for your graph, it seems to me that your mount is managing to correct traction for periods of time and then occasionally you get large drifting.
If I was to guess, I would say that there might be some play in your gear; maybe the focuser is not rigid, or tube rings, or maybe you have large backlash? Also, if any of the cords catches up on something it may also stuff up guiding.
Patience and perseverance will be your best allies in solving this issue |
All of the above and, make sure your clutches are tight (but not over tight).
However if you are seeing it once every 3-4min, then that sounds about right for a full gear rotation. Take a look at the gears to make sure they mesh properly, set the scope up inside and let it run in tracking mode and watch to see if there is any slippage.