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Stellavita guiding calibration issues.

ToupTek StellaVita Sky-Watcher Evolux 62ED Sky-Watcher EQM-35 Pro Guiding Calibration
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Eric Gagne avatar
Eric Gagne avatar
Hello,

I am having issues calibrating guiding on my StellaVita.  It's a new rig, I took it out for the first time last night.   The hardware is:
  • QHYCCD Minicam8
  • Skywatcher Evolux 62ED (400mm, 358 with 0.9x reducer)
  • ZWO ASI120MM with ZWO Mini guide scope
  • ZWO EAF
  • Skywatcher EQM-35 Pro mount.


A video from Touptek I saw on youtube shows the calibration steps will go up until it reaches a distance of 25.00.  My issue is that it's moving extremely slowly.  I let it go up to over 25 steps and it hardly moved at all.  The default calibration step size in the guide settings is 750.  I changed it to the max allowed value of 6000, it helped a bit but still after 25 steps the distance was just around 10.

Does anyone have suggestions as to what I could try ?  I'm beginning to wonder if it's an issue with the Stellavita+EQM-35 combination.
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Astro Hopper avatar
Astro Hopper avatar
Same here, guiding calibration does not work as it should.
But, how did you get MiniCam 8 to work with Stellavita. Mine does not recognize filterwheel?
Eric Gagne avatar
Eric Gagne avatar
New firmware update released Friday fixes the filter wheel.
Astro Hopper avatar
Astro Hopper avatar
Thank you for the update on update smile
Eric Gagne avatar
Eric Gagne avatar
It looks like calibration is highly dependant on where the scope/mount are pointing.  Last night I was trying it near Polaris after polar alignment and homing the mount.  Tonight I slewed to M81 before starting it and it’s much better.  It only needed 10 steps to reach the required distance. The whole calibration was completed in about 5 minutes
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Alex Nicholas avatar
Alex Nicholas avatar
I have no experience with the EQM35, however, this I can tell you.

Guiding calibration will be faster if you do it near the pole, because movements of the mount result in much smaller angular changes in pointing. This is sub-optimal for calibration, as it is not a 'true' representation of the characteristics of the mounts movement.

Technically speaking, calibration should be done at a declination of 0° +/- 3~4°, and within 10° of the meridian for the best calibration results. Calibrating close to the pole will always result in a sub-par calibration result, either you will be unable to successfully reach the calibration step target, or it will take an incredibly long time to do so. 

So, I would recommend calibrating on the celestial equator, within 10° of the meridian for the best results.
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NeilM avatar
NeilM avatar
I don't have a Touptek, but I do have an older EQM-35 and it has a huge amount of backlash which I (mostly) removed by making adjustments with an Allen key (several YouTube videos on this).  If I remember correctly when I first got it (used) I couldn't get it to calibrate at all.  After backlash adjustment, I was able to calibrate the guiding, and I now get good guiding with the rig.

If your EQM-35 is new, then presumably it shouldn't have too much backlash "out of the box" but you might wasn't to check it (you can do this visually by sending forward and reverse move commands and seeing if there is a delay in movement)
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