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Problems getting Autofocus setting right for my narrow band filters.

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#1 MikePaling



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Posted 07 January 2020 - 10:02 AM

Now that I have just started getting into narrow band imaging I am having quite a battle getting the settings on the "Autofocus window"  in Sequence .... especially when trying to use the Oiii and Sii filters. I don't seem to have any problems with all other filters.


I am using an APM 123/738 scope with an Optec FeatherTouch FTF3545 3.5-inch  focuser attached.


Is there anybody out there who can either send me a screen shot of a working Autofocus setting screen  ( or simply list  the most suitable settings ) to be used with the Oiii and the Sii filters.


I keep wasting precious clear skies here in the UK with this issue :-(((


Any help with this would be VERY helpful.


Cheers Mike

#2 MarkS



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Posted 15 January 2020 - 12:45 PM

Why do you want to run AF with these filters? I have never tried to do this, but your problem is perhaps that there is not enough signal in SII and OIII bands of many stars.


The usual  procedure if your filters are not parfocal is to set focus very accurately (AF or manual) on L or R as a reference and then determine the focus offsets for the other filters. This can be done with careful AF or manual focusing on a suitable star field. There is provision in Sequence to record the offsets, which are then applied automatically to to the focus setting for each subframe.


Hope this helps.



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