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PHD Re-calibration

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#1 Rac19

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Posted 30 June 2020 - 08:09 PM

I am new to PHD and have a question about calibration.

 

It seems that PHD automatically saves and restores calibration data for each combination of guide-scope/camera.

 

I can't find anyway to explicitly initiate calibration, it apparently happens automatically. In my case I found that some of the configuration under Advanced Settings was incorrect (namealt the guide-scope focal length and the camera binning).

 

Does PHD automatically recalibrate after ANY Advanced Settings are changed? Maybe I was just a bit impatient, but after noticing for some time that the "cal" indicator was red, I did a few things to try to trigger a re-calibration. I cleared the calibration data, unchecked "Restore calibration data automatically" (in Advanced Settings) and restarted PHD.

 

A few things happened to make me think that re-calibration had occurred. PHD asked me if I wanted to restore calibration data automatically, the "cal" indicator turned green and the calibration chart changed.
 

Any clarification that anyone can offer on this subject would be appreciated.
 

Also, the binning was set to 2x, possibly by default, and I changed it to x1. Is there any improvement in tracking with binning configured? Clouds didn't really allow for meaningful testing but the PHD chart appeared to fluctuate more widely with binning set to 1x. It did seem to be settling to a tighter band with time but them the clouds rolled in.



#2 vnc1218

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Posted 30 June 2020 - 08:14 PM

You can force PHD to re-calibrate by pressing shift while clicking on the green crosshair button.  You should do this near the meridian and around Dec 0 for best results.

 

 

This link will have pretty much everything you need to know about calibration: https://openphdguidi...tic_Calibration


Edited by vnc1218, 30 June 2020 - 08:23 PM.

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#3 Rac19

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Posted 30 June 2020 - 09:02 PM

You can force PHD to re-calibrate by pressing shift while clicking on the green crosshair button.  You should do this near the meridian and around Dec 0 for best results.

 

 

This link will have pretty much everything you need to know about calibration: https://openphdguidi...tic_Calibration

Thanks, I searched Calibration in Help but it didn't seem to take me to that section. I will try it again on the next clear night.



#4 lantosque

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Posted Yesterday, 10:43 AM

Thanks for providing the calibration link.  I have been imaging for 10 years, but am still a beginner.

I have started using SGP and Phd2 and am having real problems because of calibration.

 

I have thought of everything.  Could it be that the moon is nearly full?



#5 Fernando134

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Posted Yesterday, 11:39 AM

I am new to PHD and have a question about calibration.

 

It seems that PHD automatically saves and restores calibration data for each combination of guide-scope/camera.

 

I can't find anyway to explicitly initiate calibration, it apparently happens automatically. In my case I found that some of the configuration under Advanced Settings was incorrect (namealt the guide-scope focal length and the camera binning).

 

Does PHD automatically recalibrate after ANY Advanced Settings are changed? Maybe I was just a bit impatient, but after noticing for some time that the "cal" indicator was red, I did a few things to try to trigger a re-calibration. I cleared the calibration data, unchecked "Restore calibration data automatically" (in Advanced Settings) and restarted PHD.

 

A few things happened to make me think that re-calibration had occurred. PHD asked me if I wanted to restore calibration data automatically, the "cal" indicator turned green and the calibration chart changed.
 

Any clarification that anyone can offer on this subject would be appreciated.
 

Also, the binning was set to 2x, possibly by default, and I changed it to x1. Is there any improvement in tracking with binning configured? Clouds didn't really allow for meaningful testing but the PHD chart appeared to fluctuate more widely with binning set to 1x. It did seem to be settling to a tighter band with time but them the clouds rolled in.

Following advice of much more experience imagers than myself, I run a PHD2 calibration before every imaging session.


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#6 ks__observer

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Posted Yesterday, 02:24 PM

If you go to "Modify Calibration" >>"clear calibration" -- PHD2 will rerun calibration when you start guiding.

PHD2 suggest calibrating near meridian, I don't think it is that critical to do that.


Edited by ks__observer, Yesterday, 02:24 PM.


#7 Stelios

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Posted Yesterday, 02:43 PM

How often you calibrate depends on which way you guide.

 

If you guide using ST-4 (the cable from your camera to the mount's "Guide" port), then you should calibrate every time you change target (and PhD2 *will* do that by default).

 

If you guide using "pulse" (aka ASCOM) guiding, with a mount connection to your computer and no ST-4 cable, then you only need to calibrate *once*.

 

That calibration *should* be done near meridian and celestial equator, because that's where RA motions are most obvious and there's least atmospheric image distortions. Once done, you can reuse that calibration (even over multiple sessions) as long as the *guide* camera is not rotated with respect to the scope RA axis. In any case, avoid doing your calibration near the pole. 




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