Hi!

I now tried this, and I seem to just get an long loops of moving in's and moving out's with the same step until it finally reports an error. I also have to set the Initial step size quite low to not get errors like this
[2020-01-19T19:09:49.966 CET DEBG ][ org.kde.kstars.indi] - FCUSB1 Focuser : "Error: Invalid range for FOCUS_TIMER_VALUE. Valid range is from 0 to 5000. Requested value is 20000 "
[2020-01-19T19:09:52.093 CET DEBG ][ org.kde.kstars.indi] - FCUSB1 Focuser : "Error: Invalid range for FOCUS_TIMER_VALUE. Valid range is from 0 to 5000. Requested value is 10000 "
[2020-01-19T19:09:58.382 CET WARN ][ org.kde.kstars.ekos.focus] - Focus GSL error: invalid argument supplied by user

The last line persists even with a small initial step size.

I use a FCUSB focuser.

Best Regards,
Søren

I also use FCUSB, did so just last night with the latest stable version and did not have that problem. What is your initial step size, what's the maximal step size, what is the maximal travel and what is the tolerance setting? Which algorithm did you choose? Linear v3, polynomial, iterative?
What focuser are you using? Can you provide logs?

Polynomial and iterative seemed to work fine, the failure was for the linear. There is somewhere a limit of 5000 on the maximum step, which I go above if I set initial step to what I use in polynomial and iterative (2000). If I set initial step lower the algorithm does something, but it does not reach focus.

I don't have more from the logs than the above, sorry.

This was with the nightly build, as the latest stable give me a focus error when moving inwards, which seems to have been fixed, but the nightly does not.

The linear algorithm in the nightly builds currently is under development. If you send me a PM with your email address then I’ll be happy to add you to the email conversation between Jo, Hy and me about this.

Ok, thanks for letting me know. I will stick to the stable from now on. I hope the focus error fix will appear soon in the stable release, this was the only reason to use the nightly.

I think I need to get a lot more under control with my equipment before I can contribute anything, but thanks for the opportunity!

No need to revert to stable as long as you are aware of the potential issues with the linear algorithm. You said that polynomial and iterative work so that’s great.

As Wouter said, he, Jo and I are iterating on improving this algorithm, but would be happy to get additional testers.
I think things are better with the latest nightlies (the most recent one will show "v3" on the menu where you select the algorithm: "Linear (Experimental v3)"

One of the weaknesses is that you need to select an appropriate step size--ultimately we should have a "wizard" for that, but until things are more mature, I think it should be done by hand.

Søren: As I am not familiar with your particular configuration I can't recommend anything, but probably each step size might be the kind of small steps you'd use manually when you were somewhat close to focus. If you go too small, though, the algorithm can get caught in the noise of the focus system.

Søren: I suspect you weren't using the latest release, because there was a bug in there a week or so ago that caused that last output line. Are you sure you're using v3?

Pit: join in!

Anyway whoever does want to provide feedback, please have logging to a file turned on with at least verbose, file and focus logging enabled.

Note, you don't have to waste a nice evening to do these tests. If there are clouds, so it's not the ideal evening to image, but there's a patch of clear sky, you can try a few autofocus rounds pointing at that patch.

Thanks,
Hy

Hy, I'd love to, but as I wrote in my last mail (did you actually get it?) I'm in Sweden at the moment, without a telescope
So I'm only following the discussion, but cannot do much testing...

Ekos focus module says "Linear (Experimental) v3".

The initial step is described, in the "mouse over help", as a step that give a noticeable change in focus, so this is what I typed in, i.e. much bigger than I would use to pin-point the focus. I will try to go for a smaller value next time.

I will keep my nightly updated and try again when weather permit and report back.

I have updated everything and it shows "v3" and I still get errors in the log:
[2020-01-22T19:28:27.334 CET WARN ][ org.kde.kstars.ekos.focus] - Focus GSL error: invalid argument supplied by user

I also get these:
[2020-01-22T19:28:27.354 CET DEBG ][ default] - WARNING: bool Phonon::FactoryPrivate::createBackend() phonon backend plugin could not be loaded
[2020-01-22T19:28:27.354 CET DEBG ][ default] - WARNING: Phonon::createPath: Cannot connect Phonon::MediaObject ( no objectName ) to Phonon::AudioOutput ( no objectName ).
[2020-01-22T19:28:27.355 CET DEBG ][ default] - WARNING: bool Phonon::FactoryPrivate::createBackend() phonon backend plugin could not be loaded
[2020-01-22T19:28:27.355 CET DEBG ][ default] - WARNING: bool Phonon::FactoryPrivate::createBackend() phonon backend plugin could not be loaded

The V-curve looks kind of strange, with two sets of points at the same two x-values. It also writes only
2020-01-22T19:39:27 Focusing inward by 1250 ms...
2020-01-22T19:39:24 Focusing outward by 2500 ms...

in the log window. It does not change these values (initial step is 250, but I think it would be better with a larger value. But then I get errors from fcusb like Error: Invalid range for FOCUS_TIMER_VALUE. Valid range is from 0 to 5000. Requested value is 20000").

And it does not converge.

Polynomial focusing seems to work OK.

Can you please include the log and I'll have a look?

Also let me know the kind of telescope and focuser you're using.

BTW, is yours a timer-based focuser (which focuser is it)?
I've recently discovered that there is an issue in the V3 algorithm with timer based ones.

Thanks,
Hy

The logs simply repeatedly displays the messages I have shown above, I dont think you will get much more out of it...

Yes, it is a timer based focuser, fcusb focuser, so that may be the issue.

Let me know if I should try something specific next time.