Autofocus Frames Show Elongated Stars

Autofocus usually runs fine, but lately I’ve been getting elongated stars in some autofocus frames. It’s like the mount stops tracking, or SCT mirror flop is happening in slow motion. You can see an example here, which is a crop of an AF frame:

AutofocusImage.jpg photo - The Hole in the Trees Skybox photos at pbase.com

The log from tonight’s session is here:

A bunch of AF frames, and almost all of the “confirmation” frames taken at the end of focus runs, show this issue. Any ideas?

Kevin

It’s unlikely, even without a guider, that 5 sec AF frames would result in elongation unless you have a massive error in polar alignment or are possibly having colimation issues. Unfortunately (fortunately?) nothing looks odd in the logs. Do you see this behavior when the mount is in certain positions or does that not seem to matter?

Argh. I finally figured it out: my imaging train was unthreading itself! The reducer had started unscrewing itself, and thus the entire imaging train including the OAG, from the SCT visual back. Probably due the heat wave a couple weeks ago. I fixed that days ago, but it’s only now that I realize what it was doing to my AF frames.

Sorry for the trouble. Back to your regularly scheduled programming.

Kevin