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Ioptron gem45 mount

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#1 McEwen52

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Posted 18 September 2020 - 09:41 PM

I need phd2 settings for gem45 my tot rms error is fluctuating to much .50 to .70 up to 1.70 but i have round stars.Any suggestions.



#2 Michael Covington

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Posted 18 September 2020 - 10:25 PM

Run  Guiding Assistant and PHD2 will determine its own settings.



#3 petert913

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Posted 18 September 2020 - 11:25 PM

Anything under 1sec is good enough for me. 


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#4 micky7890

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Posted 19 September 2020 - 12:40 PM

For my GEM45 I run the guiding assistant for 300 sec (120 sec min.) and I just apply the recommendations. If you have round stars I wouldn't mess with the settings too much.



#5 Ken Sturrock

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Posted 19 September 2020 - 01:04 PM

...but i have round stars.Any suggestions.

Step away from the mount and enjoy your round stars.


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#6 Michael Covington

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Posted 19 September 2020 - 03:05 PM

Yes, if it's working that well, it's working quite well indeed.  Remember that guiding accuracy is dependent on the steadiness of the air.  Here are my criteria:

2.0" RMS - Acceptable with shorter-focal-length gear
1.5" RMS - Acceptable when the air is rough
1.0" RMS - Good
0.7" RMS - Excellent
0.3" RMS - You are miscalculating something! :)   Guidescope focal length may be set wrong in PHD2.

If you think there's still a problem, we'll need your PHD2 log file and a description of your equipment.



#7 cyendrey

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Posted 20 September 2020 - 01:10 PM

I had an email exchange with PHD2 support after requesting some suggestions for initial settings for my new GEM45.  To summarize his instructions:

  • Get a good polar alignment.
  • Create a new profile in PHD2; there are so many algorithm interactions/AI inputs in PHD2 that a new profile is the only way to get a 'clean' starting point.
  • Go through the camera and guide tabs of the Advanced section and insure that the information on you guide scope/camera/pixel size are all accurate (it should have picked up the camera information when it connected to the camera, but still verify).  This will automatically populate the appropriate minimum step size for calibration.
  • Select a star/location near the Celestial equator and the meridian (I typically go a few degrees east of the meridian to avoid the possibility of a flip during the Calibration and Guide Assistant runs.
  • Preferably, let the mount auto select the guide star, then start the calibration session.
  • Correct issues/problems (if any) identified in the calibration.  If you move/change the guide scope or guide camera, you MUST recalibrate.  Once the issues are resolve, run another calibration.
  • After a successful calibration, start guiding, then run the Guide Assistant.  There will be two runs; the first a minimum of two minutes (or until PA error stabilizes, which ever is longer).  I typically go one worm rotation instead so that that PHD2 gets a full look at the worm PE.  For the GEM45 that is 400sec.
  • Implement the Guide Assistant recommendations/settings.
  • Start guiding, and run the Guide Assistant again, this time for 20-30 minutes.  This will provide a more 'fine tuned' set of recommendations/settings.

Slew to your target for the night and start imaging/monitoring the guide performance.

I followed these steps Friday night  and after I started imaging, the guide performance remained below .7a-s total rms error for all my targets.  For the two closer the the NCP (in/around Cassiopeia), they were below .5 a-s at times and averaged below .6a-s RMS.  The Orion Nebula target, being further south, average .65 a-s ttl rms error.

 

You didn't indicate your configuration; just keep in mind that your guide scope fl should be at leat 30% of your primary OTA fl and the pixel resolution should confirm well to the pixel resolution of your primary OTA/camera. 

 

My rig:

Skywatcher Esprit 100ED w/ZWO ASI294MC Pro

Guide scope/camera:  Altair MG60 w/ZWO ASI120MM-S


Edited by cyendrey, 20 September 2020 - 01:20 PM.

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