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GPixel 4040 - calibration challenges

buzz

GPixel 4040 - calibration challenges
« on: July 10, 2020, 02:32:18 PM »
I notice that QHY is developing a camera with this sensor. Are you aware that this sensor does not seem to respond to standard calibration (as would otherwise work with a CMOS camera), causing the image to have four distinct quadrants.  The pattern appears in all images, of any exposure length or intensity and so far, do not seem to be able to be calibrated out. My friend has the Kepler 4040 FLI implementation and they and GPixel have so far been unable to explain how to calibrate out this underlying pattern.

By CMOS calibration, I assume to calibrate flats with flat darks, and lights with darks and master flat. No bias frames are used.

Chris Woodhouse FRAS

buzz

Re: GPixel 4040 - calibration challenges
« Reply #1 on: July 22, 2020, 02:20:39 PM »
After 4 weeks, the manufacturer gave up on trying to fix the issue and GPixel were equally puzzled and unable to offer a solution. I hope QHY do a thorough test of this camera that includes real deep-sky imaging and the extreme image stretches that it requires.
Chris Woodhouse FRAS

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Re: GPixel 4040 - calibration challenges
« Reply #2 on: August 25, 2020, 08:30:28 AM »
Hello,
      I think the problem is appearing in the dual 12bit image into 16bit image. This progress will cause the unlinear at some part of the linear curve. And it may cause the calibration failur.

      We have an scientific user who are using our QHY4040 and everything is fine. So I think the QHY4040 can do the standard calibration.   Please note the QHY4040 is using the single chnannel 12bit mode so it should be no this issue.

Best regards,
Qiu Hongyun
Qiu Hongyun