That was my issue in the end as well, the position of the guide tube was not ideal, I changed it from the finder shoe to under the dovetail and this gave me the best results confirmed by PHD2 guiding assistant.

Still minor variation between consecutive runs as well, in the few arc minutes though (<5) and mostly on the RA axe, I think that is due to other factors that probably change from one run to another like wind, flexures, gear meshing, etc.

In any case this is now totally usable and will finally take me away from the looong PHD2 drift alignment method I was using until now.

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Like magic! I set the FL to 120mm ignoring the warning message in Ekos and was able to get similar PA error both in Ekos PA and PHD2 drift alignment.

The routine I followed was to first run PHD2 drift alignment and guide assistant first, which reported an error of 6’5”.

Then I run Ekos PA and before adjusting the knobs it reported an error of 4’5”, a bit of a gap but much better than my previous tries.

Then I adjusted to 0’5” in Ekos and run a second iteration which confirmed the same error practically. I then run PHD2 guiding assistant and got 1’5” error.

So in my case there is something like 1-2 arcminutes of deviation between both, for me enough to use the much faster Ekos PA routine. I was able to confirm it by taking same 5mins pictures with perfect round stars.

So in my case it seems the wrong FL was the error, I hope this helps others.

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kobu replied to the topic 'Inconsistent polar alignment results' in the forum. 12 months ago

I usually do 2-3 runs of the new PA routine with Ekos (no polaris view) and find it very consistent between runs, maybe some differences of max 1’ between iterations. I’ve run the routine close to the pole and in other regions using my guide scope with 120mm FL and the guide camera QHY5LIIM. I have to say though, that I need to set the FL to 128mm in order to match the FOV reported by Ekos, seems strange to me to have this 7% difference, however plate solving is working fine with this FL so I have been using that since the beginning.

However I then run PHD2 guiding assistant (setting FL as 128mm as well) and the error reported is much higher. In my last try after getting under 1’ error with Ekos i got 45’ of error in PHD2, which I think was correct as the drift was evident. I then run drift alignment in PHD2 and got under 3’ error so I was able to continue with my imaging session. Unfortunately I wasn’t able to run Ekos PA right after to get the error reported as it refused to plate solve any image (didn’t happen to me before)

Any ideas of what could be the issue? Maybe related to the FL not being set correctly?

In my next session I will definitely run PHD2 drift alignment first and then try Ekos PA, without touching the knobs but just trying different FLs to see if can get close results between both methods.



Let me first say thank you for such a great piece of software and specially for this new polar alignment method, a life saver for all of us that don’t have direct view to Polaris.

I’ve successfully used the method to get under 1’ error, having tried at different sky locations (I have a clear view NE-East-South).

After doing the polar alignment I use PHD2 for guiding so I usually run Guiding Assistant to confirm the PA error. The problem is that there is a huge misalignment between both, yesterday for example I finished Ekos PA under 1’ but when I run PHD2 guiding assistant it reported 42’, and I think PHD2 was right as the drift was evident. After that I run the drift alignment in PHD2 and I was able to get under 3’ of error which was good enough for imaging. Unfortunately I wasn’t able to measure back the PA error in Ekos as it refused to plate solve giving a timeout (never happened before)

What could be causing this deviation? My only guess is that there is some error in the configuration. Camera and focal length setting were set equally in both, however my guide scope has theoretical FL of 120mm, but when I did plate solving in Ekos for the first time it reported 128mm based on the FoV calculation, so I set it like that since the beginning. Seems strange to me that there is a 7% variation between the manufacturer theoretical FL and the real one, maybe this is the error?

Any suggestions? This is driving me nuts, it takes me forever to do PHD2 drift alignment, min 1h, so it would be amazing if I could use Ekos and have PA done in 10min.



Hello, let me first say thanks for such a great piece of software, the combination of kstars/ekos/indi has done everything "easy" for a starter like me. I never thought I could be possible to take nebula photos from my backyard, and definitely this is thanks to the hard work all the developers are putting on this.

Now, I still have issues with polar alignment with Ekos. I don't have a view of Polaris so my only possibilities are plate solving polar align or drift alignment. I couldn't use the previous polar alignment method in Ekos without Polaris so I started using drift alignment in PHD2 which takes me to a consistent total RMS between 0.20-0.35, enough to take up to 10min pictures without star trails with my setup. However this takes ages to do, I spend at least 1h-1.30h to achieve the needed accuracy, so when I saw the new polar alignment feature I was really excited as it could drastically reduce the time I was taking for a proper alignment.

I'm able to run the process without issues, have tried close to the pole region and east or west, I have clear view of the sky from North-East-South and a little portion from North to West. In many cases, and after 2-3 iterations, I'm able to get polar aligned with less than 1' of error. However, then I run Guiding Assistant in PHD2 and I get a much higher alignment error. Last night, I got under 1' in Ekos while PHD2 was reporting 42', which is a huge difference. I could actually see the drift happening and stars where not sharp. I then drift align again in PHD2 and got a good 3' error which was fine in my pictures.

What do you think it could be happening, why such a difference between both tools? Any feedback would be highly appreciated.