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  #61  
Old 27-09-2021, 07:39 PM
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The_bluester (Paul)
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No problem, just I saw a similar problem with my own flats recently and went down a rabbit hole trying to work out why something I had nailed a year ago was suddenly giving me grief.

I use my 2600MC exclusively on 0 gain, and the MM on 0 gain for LRGB and 100 gain only for narrowband, I did shoot NB flats at 100 gain but a rough and ready set of sky flats this afternoon at 0 gain did better than a properly done set at 100 gain! I think it comes down to the loss of resolution where 1e=4ADC or so, the quantisation error was just too much for it to work.
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  #62  
Old 09-04-2022, 11:02 AM
gb44 (Glenn)
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Calibration frames and ZWO and QHY OSC camera

What a great resource this is. Thanks Martin and Paul.

Ive been having the same issue with my QHY410c OSC camera where the flat frames are causing bizzare colour casts in a vignetting sort of pattern.
Looking at the thread has given me clues and I can see a few actions I can take.

Another question though - I'm getting error reports in DSS and ImagesPlus
where, even though I have shot frames at 6070x4046 pixels, these programs report differing frame sizes (6070x4044) and IP cant proceed. I can acquire the frames at the same size so its not a real problem. DSS does proceed however, so it is a work around. Just makes me wonder why???

Cheers
GlennB
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  #63  
Old 09-04-2022, 12:44 PM
gb44 (Glenn)
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Heres a look at the histogram Im getting.

Maybe just need the singlet over the scope?

GlennB
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  #64  
Old 09-04-2022, 06:46 PM
gb44 (Glenn)
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Thought I'd post a couple of pics that show the results with the poor flats.
Horsehead nebula , 11x270s QHY410c, low gain mode, gain53,9degrees, ED100, SharpCap, dithered. Stacked in DSS.
One processed in SIRIL and noise reduced in ImagesPlus.
Second processed in Startools.

Cropped out a lot of vignetting rubbish...

I tried reducing gain to zero and differing exposure lengths. Gain didnt seem to change the flats but there was some improvement lowering the exposure time towards ADU range 8-12k so I'll work with that.

GlennB
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