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PHD calibration problem

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#1 Michael Morris

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Posted 16 October 2019 - 06:28 AM

I have a new (to me) Skywatcher AZ EQ6-GT mount.  On it, I have mounted a Skywatcher 80ED with a standard Skywatcher 9 x 50 finder converted into a guide scope using a 'finder to C-mount' adaptor.  I use a Starlight Xpress  Lodestar 2x guide camera screwed directly on the C-mount adaptor.

 

I've always found that my mount calibration seems to take ages when using a finder/guider (10 minutes +).  However, with the new mount it takes so many steps to calibrate that PHD2 runs out of time and calibration fails.  If I try it using PHD version 1, calibration is successful, but still takes ages to complete.  I am using 3 second exposures and the calibration step size set to the maximum value that the software will allow.  I have checked and PHD2 is definitely moving the mount on each step, just not enough.

 

What am I doing wrong?



#2 happylimpet

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Posted 16 October 2019 - 06:35 AM

Can you increase the guiding rate? On EQMOD you can change it from (for example) 0.1 to 0.5x sidereal rate.


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#3 mbocca

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Posted 16 October 2019 - 06:48 AM

Michael,

 

You may have the Telescope/Camera configuration incorrect in PHD2. It is expecting to move a certain amount during the calibration. If the configuration is incorrect, the calibration will take too long. For my setup (714mm scope with 3.2um pixel camera), the calibration move about 20 steps to achieve a distance of 25.

 

You may want to create a new configuration using the Wizard. The two pieces of info needed is the telescope focal length in mm and the camera sensor information. 

 

Good luck.

Mike

 



#4 Tapio

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Posted 16 October 2019 - 07:02 AM

You should use calibration step calculator:
https://www.theastro...4/phd2-tutorial



#5 AXAF

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Posted 16 October 2019 - 07:16 AM

I find that if I am calibrating near the north celestial pole, the calibration times out due to an excessive number of steps. This happens early, when stepping in the west direction. I believe that PHD2 best practices recommends choosing a target near the celestial equator, and towards the meridian, during initial calibration. I presume that this orientation would require the least number of steps in a given direction to calibrate. This may well not be the source of your problem, but may help to eliminate one possible contributing factor.



#6 Michael Morris

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Posted 16 October 2019 - 07:35 AM

Can you increase the guiding rate? On EQMOD you can change it from (for example) 0.1 to 0.5x sidereal rate.

Thanks, I'll check what I have and adjust it accordingly, then give it a try.



#7 elmiko

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Posted 16 October 2019 - 07:14 PM

Also , when you select a guide star and begin looping click the manual guide in the tools tab. Click on the west button until you see the star move. Then click on the north button until you see the star move. This removes any backlash which is common in these mounts. Then begin the calibration. 

Also set the step size to 14 in the brain icon.


Edited by elmiko, 16 October 2019 - 07:15 PM.


#8 Peregrinatum

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Posted 16 October 2019 - 10:15 PM

Decrease the PhD2 exposure rate to decrease calibration time.


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