I have been reading this thread with a great interest but having a hard time to fully understand. I'm trying to improve the guide accuracy. Overall, it's not so bad at around 1.0 RMS but as the others reported, sometimes it goes over 1.8 and sometimes it's as good as 0.6. On the last two nights, I tried to change the settings (Calibration step, Max RA/DEC duration, Aggressiveness for RA and DEC, turning on/off "Guide Camera Bin2" and using or not using dark library for guide camera, guide exposure 1 second and 0.5 second, guide camera gain from 48 to 100) within ASIAir Plus but I didn't see any improvement. It's more like random in terms of RMS. The only tendency I experienced so far is that RMS would be better when the scope looks to the north sky (away from the equator), which sounds reasonable.
Looking at my chart, the Max & Min Periodic Error looks good. Very small. But the zoom-in chart shows more zigzag curves than others' charts. So, I'm wondering the randomness is due to this zigzag curve and it would be hard to get a stable, accurate guiding at around 0.5-0.8 RMS?
I currently use a Nikon 180mm camera lens with ASI533MC Pro on AM5 with ASIAir Plus. Guide scope & camera is ZWO ASI120MM Mini & ZWO 30F4 Miniscope. I do polar alignment as good as 0.5 arcseconds. So, RMS 1.0 is fine with the current setting but I will get a much longer refractor (around 800mm) in the future. That's why I want to achieve a better and stable RMS. And I live in the central part of North Carolina under Bortle 4 if that matters.
What numbers should I use for the guide settings? Should I use the "Bin2" feature and dark library? Or should I return it and get a replacement as my copy is not well built and impossible to achieve, say, 0.5 RMS? I bought it in June 2023. Any other suggestions / recommendations are highly appreciated!!
