So with my latest rig, a 12" TPO RC, and AP focal reducer, Auto focus has been working well until suddenly the last few nights I seem to have doughnuts, and even had one sequence where I could see them getting larger as the sequence continued.
So, loose focuser assumed but it seems solid as a rock, so I’m a little stumped.
SGP is set to autofocus every 0.8 degrees, and I see in the log it can see the focuser temp but I don’t think the temp has ever changed that much in an event/filter (yet).
In the meantime I do see that SGP (and ccdstack2, for that matter) seem to be struggling with giving good, or ZERO HFR numbers for doughnuts, so it seems I should try to get that sorted as well as looking for a mechanical issue.
I have “Disable Smart Focus” checked, since I have a center obstruction. Should I try with it unchecked?
I have, left over from previous rigs, “Minimum star diameter at 1x1 (px)” set to 4 but not sure what this should be. I’m imaging, via an CCD67 focal reducer and 2x2 bining at 0.92 arcsec/pixel and assuming seeing is no better than 2 arcsec. What should my minimum star diameter be and will this help detect doughnuts?
Anything else I should try to avoid ZERO HFR results with doughnuts?