FEATURE REQUEST: autofocus before Autoguider starts


When automatically running sequences, is it possible (or have an option) to run autofocus before starting up the autoguider?

using an OAG which requires reasonably good focus to acquire star for autoguiding.

however, i often have a couple hours waiting until the target starts, and by then it’s pretty far out of focus.

The auto sequence now is start up autoguider followed by autofocus. I’m wondering if that order can easily be switched, or have an option to autofocus prior to autoguider starting up




+1 - Yes, please.

I had asked for this a couple of years ago:

If we get a good focus before PHD2 auto-selects its guide star, we are less likely to end up with a saturated star and more likely to end up with the “best” guide star. This applies to changing targets too: any time a new guide star needs to be auto-selects and focus needs to be done, please do the focus first!

  • Shane


Even before plate solving, sometimes the focus is so off that it doesn’t work.


Yes, +1 to that.

It amazes me how well PS2 is sometimes able to work with de-focused stars at all. But other times it just cannot cope. De-focused stars is often a problem for me if it has been a long time (ie. weeks) since last session - an all too common occurrence here. Probably because seasonal changes means diff temp etc.

If running unattended (as I often try to do) this stops the sequence before it really gets going.



Bumping this as it continues to cause me issues.

I am currently running a sequence that waits 2 hours for the target to be up (and for it to get dark). By the time it does so, the temperature has dropped 15 degrees and the scope is not is good focus. PHD2 picks the best star, then autofocus runs and that star ends up being very saturated. That star would not have been picked if it was already in focus. My normal 0.5 arc-second guiding turns into almost 1 arc-second.

– Shane


Yep - unfortunately i have to stay up and monitor focus until an hour or so before it starts.

it would be great to switch that order


I’ll add my voice to this request as well. I’d already mentioned the need to “slew - focus - center” a target rather than the current “center - focus” approach which causes plate solving problems.

I should probably start another thread, but what I’ve been thinking would be very helpful (and hopefully not too major of a task to accomplish) would be to have the ability to add ANY event to the sequencer, just like an exposure. There are certain events tied to sequencer items already, so some of that could be accessed just with a “null” event that doesn’t actually take any images. Anyway, just a thought. I realize there are challenges to using something like this in addition to any coding challenges.




I requested the same several years ago. In the meantime, I have a workaround. I put in a dummy target leading up to the real target start time. This does not have centering enabled and just takes heavily binned images every 10 minutes or so. The AF triggers are common for the sequence and it has the effect of nailing the focus right up to the real target. It fixes another issue for me too, with my RCT, I get more accurate focus if the focus point is within a click either side. In this way after a few AF runs, it has it zeroed in.


Pretty similar to my work around. Still requires ‘manual’ intervention.

I slew to a random patch of sky (land target from hand controller) and work the autofocus there till it is refined.

Once that is done a solve and synch, only then do I start the guiding.