Hello,
I took down my mini PC and now just use the ASIAIR Pro exclusively on my two refractors and my 9.25 EdgeHD with ZWO gear 294MM Pro main, 290MM guide, EFW, OAG, and EAF. The auto focus routine works great on both refractors but on my SCT 90% of the time it just makes it much much worse. This is due to the mirror shift that happens when the focus is adjusted which makes the stars wobble for a second or two and makes them appear many times larger. If only you guys could add an option to the AF routine to 'wait' X seconds after a focus adjustment step is made before taking the next measurement it would make this problem go away. Other people with SCTs and the AAP have this issue too so please consider my request.

Thank You,
Walter

WalterT changed the title to Help with SCT mirror shift - Please add a "Wait" option to Auto Focus routine.

Celestron tells on their website that their SCTs should be focused by finally turning the focus knob counter-clockwise, so the primary mirror „falls“ into place by gravity. It would be great if AAP could be configured to make the last focuser adjustment counter-clockwise.

I selected "reverse rotation" on the focuser settings and found that the final focus movements changed from clockwise to counter-clockwise on my SCT. I check FWHM often during subs and see very little change over an hour.
Try it.

Steve

    StevenEvan Thanks for the info Steve. Can you share how you check the FWHM in the AAP, and also what about that number tells you if you need to refocus or not.

        WalterT Can you share how you check the FWHM in the AAP, and also what about that number tells you if you need to refocus or not.

        When I first start tracking on my target for the night, after focusing, I'll take a 3 second image in Preview mode.
        When this image loads, I select Tools->Detect Star.
        This will take a sample of stars in the image and calculate and display the average FWHM value.
        This can vary with the seeing on the night but for me is usually around 2 arcsec.

        If your focus drifts while collecting subs the FWHM value will gradually change.

        I'll check FWHM occasionally as the subs roll in. The first sub will be a little higher than 2 arcsec, just because the sub is over a longer time and the mount accuracy is going to play a part, but they are generally around 2.1, 2.2.

        If the subs get to around 2.4 I would probably be rejecting them when processing so I would refocus at this point.

        As I said, I rarely have to refocus the SCT within the hour after auto focus, and AAP is set to finish focusing with a CCW movement and autofocus every hour while ion Autorun mode.

        Steve.

            @tech@zwo Or is there a current solution for SCT users that I'm missing? Thank you.

            a year later

            Grreat Thread with good info just not a single person shared with their AF steps are and Backlash settings. although the reverse Idea was good

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