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Half my processed image looks different to the other half - ASI6200MC Full-Frame Cam
I have a strange issue that I can't seem to track down.
I am using an ASI6200MC Pro Full Frame camera. On processing images last night (Ha-Oiii Color) I noticed exactly (it appears to be exactly half) of my image is processed differently than the other. I can see a delineation line. The attached pic is obviously reduced andsuper brightened to try and show the problem more clearly.
- 10 min subs as 16-Bit Flats
- Flats 22K ADU + DarkFlats
- Master Bias
Right, so maybe just an screenshot of the masterbias? I just need to see the quality of it as some sensors also have problems with using the shortest exposure for a bias, which is especially an issue with CMOS sensors. As your sensor is a relatively new one, I'd advice to make the bias frames at about 0.1 seconds as a minimum or use dark-flats.
Flats I'd also advice at around 32000 ADU.
As soon as you said about the Bias I'm giving the process another go and it didn't make a difference.
I've tried 16K, 22K, 26K and 32K ADU Flats (and associated DarkFlats) as only had this camera for 48 hours so still trying to work out what is really required so no changes.
Given this is appears to be a 50% split, are dimensions of the FITS a factor? Whilst I've had mosaics processed in APP before, is this a 4k limit somewhere, given 4096 is around about half of the 9k wide resolution of this?
I'm going to just put this on hold for now as it could very well be the data captured - though I can't see it clearly at all in my individual subs. I just processed another target from the same night, further away from the bright moon, and it appears to be fine. Same optics/setup/length of exposure, etc. So for now I'll re-test on a moonless night if the stars align in a couple of weeks!
Ah right, some residual gradient in the background maybe. Light pollution correction doesn't help this at all? I always advice to really stretch the image in the preview window, over-saturate the backgound as well and then slowly start with 5 boxes around the image, then add some more when it seems the gradient model looks ok (which you can check with "show corrected image" button). This might show a light source (the moon) somewhere on the side of the image. Which then would be a good correction model. I'm always looking for the background to become nice and even.