Autoguiding slowly out of alignment... help appreciated

[Obi Wan Ken00bi]

Dear SGL,

I'm using PHD together with a 8x50 guidescope and a QHY5L 2 mono cam and a ST4 cable attached tio the autoguiding port of my mount. Yesterday evening it seemed PHD couldn't keep up with scope/mount  (which was probably a little out of alignment itself). The N-distance kept creeping up. Should I re-align the mount or use more aggressive settings on PHD. And which settings to change if needed?

Some help would be appreciated, tonight is the last good imaging night due to the moon phases :-)

Cheers!

Obi

[kens]

Posting the log file would help. But at a guess are you using uni-directional Dec Guide Mode South?

[michael8554]

Hi Obi

For the moment set Dec Guiding to Auto so that it corrects in both directions.

Set Dec Agr to 100, Hys to 10, and Dec Max Mo to 2000.

If it now keeps up with the Dec errors but the graph is now large sawtooth movements, back off Agr by 10's until the sawtooth smooths out.

Then experiment with increasing Min Mo, so that the mount reacts to errors before they get too large.

Finally alter Hys and Ag in small amounts for best results.

http://openphdguiding.org/man-dev/Trouble_shooting.htm

Michael

 

[opticalpath]

If you don't spot something quickly in the PHD settings, I would go back a step: assess how the mount is tracking with guiding switched OFF.  It can be difficult to distinguish between problems caused by guiding, and problems due to basic mechanical or other issues with the mount.  You can end up trying to fix basic mount setup problems with guiding - not ideal.

Set up PHD to track a guide star but with guiding corrections switched off.  Then the (not) guiding log or graph will show you the UNguided tracking performance of your mount.  If that reveals significant tracking problems, you should address these first.  Only when unguided tracking is as good as you can get it should you switch guiding back on to assess and optimise guiding performance.

Adrian

[knobby]

Check p.a. and balance too, guiding can't correct if things are too off in the first place 

[Obi Wan Ken00bi]

Great feedback!

I will try everything tonight, starting with the new values from Michael and also try to isolate the problem if it occurs by switching off guiding (knobby and Adrian's tips).

Thanks a lot. SGL is a great community :-)

[knobby]

Hope it goes well !