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  #1  
Old 24-08-2018, 09:59 PM
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Lognic04 (Logan)
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Ha filter + SGP autofocus = no likey...

Hi all,
Having such an odd issue.
Using HA with my 1600 for the first time, the autofocus is just not having it!
40 seconds or 10 seconds, no Difference...
Gain 139, using ZWO 7nm filter with SGP
Issue here is that the graph is just all over the place regardless of what happens, i think because it is just too dim. but 40 secs?!
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  #2  
Old 24-08-2018, 10:46 PM
DJT (David)
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What Mag star? 40 secs seems a tad excessive..
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  #3  
Old 25-08-2018, 06:51 AM
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peter_4059 (Peter)
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Have you considered autofocusing using just the Lum filter and then applying filter offsets for the other filters? You can manually focus each filter using a Bahtinov mask to work out what offsets you need for your filters. That's how I have set up SGP and I think if you look on the SGP forum you will find this is quite a common approach for people using narrow band filters.
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  #4  
Old 25-08-2018, 07:12 AM
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Slawomir (Suavi)
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Hi Logan,

I also had to initially fine-tune settings to get reliable autofocus with SGP and narrowband filters. What works for my 3nm and CCD with small pixels is binning 2x2 for autofocus and 30-second images, plus min star size is at 4. Step size for the motor should stay the same as you had with LRGB filters.

These settings work reliably for me for both bright nebulae and also for star fields without any nebulosity.

Focusing with Lum and applying offsets would be faster though due to shorter exposures for a Lum as opposed to narrowband.
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  #5  
Old 25-08-2018, 08:39 AM
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Lognic04 (Logan)
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Maybe that's my problem, min star size was 10
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  #6  
Old 25-08-2018, 12:02 PM
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Lognic04 (Logan)
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Doh! Was imaging in 8 bit last night...
The frames are usuable anyway, good thing it's clear tonight!
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