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QHY294 C PRO - Gain/Offset - Flat Field using NINA Flat wizard

CMOS Refractor Astrophotography
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#1 dbologna

dbologna

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Posted 13 April 2021 - 12:19 PM

Hi All,
I recently bought the QHY294C PRO CMOS camera and I'm looking for the right setup for Deep Sky photography. My old camera was a QHY8L CCD and I was quite comfortable using APT as acquisition software. Now the new camera is not supported by APT and I am using N.I.N.A.
Analyzing the graphs of the QHY294C PRO camera I identified the gain value at 1600 (low noise) with offset 0. With NINA's Flat Wizard I have generated two series of flats by setting 'Histogram Mean Target' first to 50% and then to 33% (of 65k ). Using the two flat sets I was not able to correct the lights, vignetting and dust spots are visible. Analyzing the flat files with Pixinsight's Statistc I get the following information:
a) single flat file 50% of FWC : mean = 33511, minimum = 556, maximum = 61416
b) single flat file 33% of FWC : mean = 22060, minimum = 532, maximum = 65476
Is there a procedure that allows me to understand if a flat file is correct and can be used to define a master flat for the correction of the lights? Verifying that the mean value for flat files is 50% or 33% of the full well capacity seems to be insufficient to define that a flat is correct. I am waiting for your suggestion.
Thanks
Dimitri



#2 dbologna

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Posted 20 April 2021 - 03:42 PM

Hi all,
I wanted to raise another problem with the QHY294 PRO camera, if you use it as gain 1600 and offset 5 the generation of a flat field at 50% of the FWC (per gain = 1600 the  FWC is 14300ADU). For these ADU values the exposure times are 0.3 seconds. It seems that the QHY294 PRO camera chip has problems generating images with sub-second time. Someone tried to generate the flat field for this camera.
Thank you
Dimitri




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