RA fail in PHD

[paler31]

Hi I am looking for some advice and help here.  I have been using PHD to guide my celestron C6 sgt successfully for a couple of years.  I am using a finder scope with a cam attached to that as a guide scope and it works fine with my C6.  However I recently bought a ED80 pro refractor scope which is lighter than my C6 and when I try to set up guiding in PHD I get the error message RA failed star did not move enough.  If I try to take pictures with the scope without guiding I can only manage about  1-2 min before I get star trails.  My question is how can I tweek PHD in order to get it to guide properly.  Any help would be much appreciated.

Regards

John

[IanL]

Well assuming you are using the same finder-guider and camera with both scopes and haven't changed the PHD settings at all, then I'd expect it to work.  It may be that there is something mechanical going on with the mount under the lighter load.

The usual cure for 'did not move' errors is to increase the calibration step size by clicking the 'brain' button.  Making it a larger number increases the length of each guiding pulse during calibration so should produce more visible movement on the guide camera.  What is the approximate focal length of the finder, what guide camera are you using and what calibration step size do you have set?

[Gina]

If Ian's idea doesn't do it and you are using EQMOD/ASCOM for guiding, this is might be the ASCOM settings.  In the extended view, in the top RH corner thare are sliders to adjust the amount the mount moves for each guiding pulse.  This needs increasing.  Another possibility is a bad connection stopping the guide pulses getting through.  HTH

[paler31]

Hi Thanks for replying Guys I am using a different guide scope for the 2 scopes however they are both the same magnification and field of view.  I am using a QHY5 guide camera.  I will have a go at increasing the calibration steps.  This sounds like a good course of action.  I will hopefully get a chance to try it this weekend, there has been so few clear nights here in scotland.

John