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  1. #1
    Join Date
    Nov 2014
    Location
    Brühl, Germany
    Posts
    138

    Default Scheduler Autofocus Position

    Hello and happy new year!

    after the scheduler has started up the observatory it is doing an initial autofocus operation.

    -Is there an option to do this focus operation nearby the next target in plan? The scope runs over half of the sky and comes back after focusing.
    -Is there an option to skip this initial autofocus operation?

    best regards Sascha

  2. #2
    Join Date
    Feb 2012
    Location
    Charlottesville, VA
    Posts
    885

    Default

    Hi Sascha:

    ACP and Scheduler offer two different ways to autofocus, and you can take your choice:

    1) Within ACP, if you focus for each object, it will do an autofocus star search within 15 degrees of the object, but typically will be much closer. So in that case, you can set the Scheduler periodic autofocus to 0 hours (which will turn it off), and you can focus per object. That is, when you enter your Projects into Scheduler, check the "Autofocus" box.

    2) Within Scheduler, you can set the periodic autofocus. I have mine set to two hours. (Scheduler, Configure menu). In that case, you want autofocus unchecked in your individual Scheduler projects. When Scheduler autofocuses, it does three things of note: 1) it focuses at high altitude, typically 70-80 degrees. 2) It focuses at T=0, and then periodically according to your setting. (T=0 when I startup, and every two hours thereafter, in my case.) 3) If the first autofocus fails, it will go back to the previous focus position, image your first object, then attempt another autofocus even if T < 2 hours.

    I've tested it both ways, and I can tell you it works MUCH better for me using Scheduler's periodic autofocus rather than ACP's nearby focus. The reason is that focusing at high altitude is much more reliable. If you're shooting something at Altitude = 20, the autofocus is less reliable as you focus through the greater air mass. So I use the Scheduler periodic autofocus, and leave the autofocus boxes unchecked in my Scheduler projects.

    Other people might have different strategies.

    Best,

    Rob
    Rob Capon
    (Self-appointed) "Executive Director"
    Stillhouse Mountain Observatory
    Charlottesville, VA
    ----------------------------------
    RCOS 12.5 with SBIG STL11000M
    Televue NP101is with SBIG ST8300
    Paramount ME with SkyX
    Techn. Innovations PD10 with Digital Domeworks
    Robofocuser
    ACP with MaximDL and FocusMax

  3. #3
    Join Date
    Oct 2005
    Location
    Mesa, AZ
    Posts
    33,158

    Default

    Thank you very much Rob.
    -- Bob

  4. #4
    Join Date
    Nov 2014
    Location
    Brühl, Germany
    Posts
    138

    Default

    Rob, thanks for your detailed description! I will figure out which of these methods is better matching for me.

  5. #5
    Join Date
    Nov 2014
    Location
    Brühl, Germany
    Posts
    138

    Default

    Hy Rob,

    I have one additional question. I decided to use your number 2. but ACP is doing the first initial Autofocus with the clear filter and if the next scheduled plan is in Ha the focus position is probably wrong due to different filter. I checked the Box Focus on filter change in ACP but i think that box has no effect when i am using the scheduler. I think the only way to get that problem solved is to install a focusser with stepper motor (i have a normal Motor without steps installed) and use the offsets in filterinfo.txt right?

    best regards

    Sascha

  6. #6
    Join Date
    Feb 2012
    Location
    Charlottesville, VA
    Posts
    885

    Default

    Hi Sascha-

    Yes, that's how I do it. I ran the script FocusOffsets.vbs to get the focus offset for each filter, which created the filterinfo.txt file. All of the focusing is done with the clear filter, and ACP sends a command to adjust the Focuser whenever you change filters. It's seamless and goes on behind the scenes.

    As a practical matter, my filters are pretty much ParFocal and my offsets are very, very small. During the night, the Focuser might move 5-10 ticks, and my filter offsets are 3-7 ticks. So the movement is in the noise level.

    For reference, I'm using Robofocuser, and the Focuser is on the secondary mirror of a Ritchey-Chretien.

    Best,

    Rob

  7. #7
    Join Date
    Nov 2014
    Location
    Brühl, Germany
    Posts
    138

    Default

    Thanks Rob! May i ask you which brand of filters you are using?

  8. #8
    Join Date
    Feb 2012
    Location
    Charlottesville, VA
    Posts
    885

    Default

    Hi Sascha-

    I'm using a set of Astrodon ParFocal filters, 50mm unmounted for an SBIG-STL11000M camera. You might want to call Astrodon directly to get their advice on which filters would be best for you, and if they have an Ha filter that's ParFocal with the CRGB set. They're known for their expertise and service.

    http://www.astrodon.com

    Best,

    Rob

  9. #9
    Join Date
    Oct 2005
    Location
    Mesa, AZ
    Posts
    33,158

    Default

    Sascha - Now that you are a customer you can use the premium sections. Would you like us to change your last name spelling here to match the license = "Schueller" (with the 'e')? This would change your login username.
    -- Bob

  10. #10

    Default

    Dears,

    I just started using ACP expert and tried to use FocusOffets script. It focuses the reference filter (clear), but fails to focus Ha with error message "Star too dim". The reason ACP considers star too dim is that it is out of focus (offset between clear and Ha is 4000 in FLI and it appears to much to refocus when switching from clear to Ha).
    Any way to override such gap?

    Regards,

    Saulius

 

 

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