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I was out last night dodging the clouds and trying to get my head round the auto focus routine. From a Lazy Geek video I was attempting to find figures for backlash. The routine works (checked with a Bahtinov mask) but the shape of the curve is far from smooth.
Anyone got any tips?
Anyway, I had to get up at 05:00 this morning so I couldn't stay up late, which was a pity since it was very clear. So after a last look about the sky I went to bed thinking about parabolic curves!
Regards
Graeme
Re: Capturing with NINA
Posted: Wed Dec 16, 2020 2:21 pm
by Juno16
Hi Graeme,
Sounds like a backlash issue.
Just curious if you use backlash overcompensation? Not sure of the terminology in N.I.N.A., but I watched a James Lamb video after I had issues with my new (at the time) ASI EAF focus motor. I had trouble getting the right backlash measurement.
James used N.I.N.A.'s methodology to employ this method with APT (what I use). Works great!
What happens is that every time that the focuser moves outward, the software (N.I.N.A or APT) setting adds additional movement outward, then moves the focuser the same amount inward to somewhat cancel out the backlash. In APT it is called "Final Inwards Move".
These are my settings below.
I am sure that this is an option in N.I.N.A., but not sure if it is called "Overshoot".
The process is described in N.I.N.A. documentation below.
Cheers for the link Jim. I was aware of the document but I've never really studied it! Geezers don't read manuals! So, after reading it, things made more sense! NINA uses Overshoot and Absolute compensation methods. I had been trying large backlash figures, 90, 100, 120 etc but then testing at 0 gave a horizontal line on the graph of only 30! So I set the backlash to 30 and it seems to be working fine now!
Cheers for the link Jim. I was aware of the document but I've never really studied it! Geezers don't read manuals! So, after reading it, things made more sense! NINA uses Overshoot and Absolute compensation methods. I had been trying large backlash figures, 90, 100, 120 etc but then testing at 0 gave a horizontal line on the graph of only 30! So I set the backlash to 30 and it seems to be working fine now!
Regards
Graeme
You are right Graeme, geezers don’t read manuals!!! I have read more with AP than anything else in my life!
Great news! Yeah, I as frustrated with backlash too. I look at YouTube when I am on the treadmill and came across James’s video and couldn’t wait to give it a go. Having the ability to focus at the laptop and having a sensitive response to small adjustments is an awesome tool.
Let me know how AF in N.I.N.A. Works out. Looking forward to the feature in APT.
Cheers!
Re: Capturing with NINA
Posted: Wed Jan 27, 2021 7:39 am
by AstroBee
If you can post a screenshot of the graph, I can help you diagnose this issue.