Polar Alignment Using a Canon DSLR, Raspberry Pi, and SkyWatcher AZ-GTi

[aditya10]

Hello!

This is my first post on stargazer’s lounge, so forgive me if this is the wrong place to ask. 

I have a SkyWatcher AZ-GTi mount (with a firmware update + eq wedge so that it can run in eq mode). I also have a Raspberry Pi 4 with INDI, KStars, and Ekos tools. I don’t have a guidescope (and my budget is extremely limited), so I was wondering if there was a way to polar align my DSLR using just the software running on the Raspberry Pi. 

I’m also competent in Python, if that could be useful for anything. 

[MarkAR]

Yes, if you set up your camera profile in Ekos you should be able to run the PA that build in to the Alignment module.

[Avocette]

Yes as @MarkAR says, you can use the Alignment module in Ekos to Polar Align with your DSLR. You will need to have downloaded to the Raspberry Pi all the recommended Astrometry files for the FOV (field of view) of your camera sensor and lens or telescope combination. You start with the mount in the Park position (pointing roughly towards the North Celestial Pole) and run the PA routine. Choose an exposure of about 5 seconds. I found that it could take 45 seconds for the 'plate solve' which establishes the precise position of the image, before the mount moves by 15° and another image is captured and then a third final image, before Ekos calculates the error in the mount pointing and tells you that the mount is for instance to the right and below the NCP. The alignment window shows the error as a purple vector on the final image. You click on a suitable star in the image, and subsequently adjust the mount to move the star image to the optimum location. With a DSLR this process takes quite a time since each adjustment step made needs an image to be downloaded and displayed - but in my time I have done it successfully!

[MarkAR]

24 minutes ago, Avocette said:

and subsequently adjust the mount to move the star image to the optimum location

Yes, move the mount alignment bolts not the mount motors.

With a little tweaking I can get under 6" accuracy.