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INDI Library v1.9.8 Released (29 Sep 2022)

Bi-monthly INDI Library released with new drivers and bug fixes.

Autofocus - What to do without Big Stars

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What are people doing when imaging a target without large stars? Imaging the Wizard last night and Autofocus just can't find a star big enough for Ha or Oiii. So last night I slew to a nearby large star (Caph), focused and slew back. But of course this isn't very "Auto-ish" :)
3 months 2 weeks ago #85467

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I use "full field", bin 2x2, crank up the camera gain and increase the exposure time.

I was imaging the Wizard nebula last couple of sessions at f/9 with a 5nm duoband filter, and focusing was quick and easy.
The following user(s) said Thank You: David Tate
3 months 2 weeks ago #85469

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Likewise i imaged the wizard at f7 with a quad band filter and had no issues finding a star. Binned 1x1 2 second exposure


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3 months 2 weeks ago #85472

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I didn't think of the "Full Field", figured it did a full field when it lost a star.

I'll look at the gain too.
3 months 2 weeks ago #85474

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I haven't experienced the problem yet. But a more or less good solution could adding a dedicated target for focusing to the scheduler upfront. Enable focusing for this target, select the single sequence option and execute a very short capture that you could ignore later. After this, add your intended target to the schedule.

HTH
Wolfgang
TSA-120 + FSQ-85 + ONTC 10"F4 Newton (+ epsilon-160 on Japan trip) | Avalon Linear + M-zero | ASI 1600mm pro + 6200mm pro | KStars/INDI on Raspberry Pi 4/Intel NUC
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3 months 2 weeks ago #85476

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Thanks Wolfgang... I can't do that, since I'm not using the Scheduler (I know, I need to get on the stick and start using it).

I think my problem might be that it's using a small window and regular gain (and experimented with 1x1 binning). I'm going to go high gain, full window and 2x2 binning.
I've normally been using a Bahtinov mask, enter the offsets and I'm done. But I've noticed lately after a flip, I really need to focus again. But I really don't want to get out of bed to do it ;)
Last edit: 3 months 2 weeks ago by David Tate.
3 months 2 weeks ago #85518

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Taking the advice, I cranked up the gain... went to 2x2 (which was normal) and night before last was great. Nice and tight stars.
Last night, even when the autofocuser (AF) completed after many attempts, I had fairly out-of-focus stars. So back to the Bahtinov mask and making sure my offsets are updated and AF is unchecked.

BTW, any ideas what to do when the AF routine gives up? The whole process just seems to stop. Maybe go back to the original set focus position and keep imaging?
Last night I had to shut down , disconnect, stop and reconnect everything to get it imaging again. I tried restarting the camera driver (via the button on the CCD Tab). The imaging process seems to think the AF is doing something, but switching to the AF tab, it's doing nothing.
3 months 1 week ago #85677

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I guess you aren't focusing with the Bathinow mask on narrow band, right? Why not doing the same with the focus routine?
TSA-120 + FSQ-85 + ONTC 10"F4 Newton (+ epsilon-160 on Japan trip) | Avalon Linear + M-zero | ASI 1600mm pro + 6200mm pro | KStars/INDI on Raspberry Pi 4/Intel NUC
3 months 1 week ago #85685

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Right now I am using a Bathinow mask. It's simple, gets you spot on. Use the offsets per filter and you're good. But it means you have to physically get to your scope. I'm seeing after a M/F my focus is getting pretty poor. And at 2am, I hate having to get out of bed to re-focus :S So I really have to get the AF working.

And right not I'm only focusing Lum/Ha/Oiii. I'm actually not using Lum... turning out to be a waste of time for me. Ha & Oiii have given me great results.

Tonight, I'm giving it another try.
2 months 3 weeks ago #86218

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