Question on Focusmax starting point and ACP

[Joel Hatfield]

My sweet spot for my focuser is right around 10,000 on Focusmax. I had the focus start point in Focusmax settings around 9700. I've found that if autofocus fails for whatever reason, usually clouds, it would revert back to 9700. This would turn out to be a problem later in ACP on the next evening when the focuser was at 9700 and in very poor focus. This would cause a failed plate solve and then a failed autofocus due to not being on the proper focus star.

I went into settings in Focusmax and changed my start point at 10,000 and saved the profile. I also went into filterstate.txt in ACP Config and changed the 9700 to 10,000. My question is since I saved the starting Focusmax start point at 10,000 if it fails an autofocus will it always revert the focuser to 10,000 now? If it's at that point my plate solves should be ok down the road on the next night I do a run. With it in poor focus to start it puts things in a loop where it fails a plate solve and then autofocus, etc. By leaving the starting point at 10,000 in Focusmax should it fail it should default to that point and will ACP load that starting point for the focuser if it's the last focuser position at the start of a plan on the next night? I guess if autofocus is successful all night then it should be in a good focus point on the next night.

Thanks,
Joel


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[Bob Denny]

ACP should restore the focuser where it was on the previous night. Changing FilterState will simply tell ACP a lie about where it finished its previous run (whenever that was, maybe 10 minutes ago or three weeks ago), and that will be erased at the end of every run and replaced with the filter/focus state ending that run. Here's what FocusMax's Return to Start does (underlining mine):

When enabled will send the focuser to the previous starting position before the autofocus routine was initiated if the final HFD exceeds the Max HFD setting (typically the Best Focus Position of the last successful autofocus run). This is a useful feature for all night robotic observing sessions where thin clouds could influence the autofocus routine and cause it to leave

Note that you have a choice of how FocusMax starts out (regardless of where the previous focus left the focuser). Have a look at FocusMax Help, Tabs, Setup, FocusStart for a detailed explanation of the three modes.