# 18 Jul, 2018 14:20
After calibrating Light Frames I got this weird effect on the corners of the image. Is it something normal, or am I doing something wrong in the process? In the image bellow you can see the effect I am talking about and the setting I am using.
# 18 Jul, 2018 15:19
If we are not careful during our calibration workflow in PI, sometimes a bias might be twice subtracted which will lead to over/under correction.
Also, problems will occur if we underexpose our flats and/or use the wrong light source . Please have a look at:
regarding image calibration, and at:
regarding flat frame acquisition.
I hope you find the above links helpful and resolve your flat issues
# 19 Jul, 2018 00:33
Because of the vignetting (effects on the corner) I would say it's a flat calibration problem. It could be that your image has no vignetting and your Masterflat has it? Also the other way around may lead to the same problem.|
Also when you take flat frames you must use the exact imaging train you used to take the lights. Removing a reducer, changing its distance before taking the flats may cause this kind of problems.
And as Die Launische Diva said, a flat too dark may not provide enough vignetting correction.
# 19 Jul, 2018 20:33
Die Launische Diva thank you for the links. It's very
Andrea Alessandrelli looks like both of may images has vignetting.
I still really don't what can I do in order to avoid this:
# 20 Jul, 2018 07:42
|It looks like your imaging train has so much vignetting that no light reaches the corners. If this is the case, calibrating could be a bit difficult. Did you check if your sensor is out of bounds off the lighted area?|
# 20 Jul, 2018 10:30
Hi everybody. I just figured out how to fix it. I was not using Debayer process. I've just used and that weird effect on the corners gone away.|
I really appreciate all feedback here because I was learning a lot.
Thank you all!
# 21 Jul, 2018 14:49
|If you calibrate your dark with your bias, so you can uncheck « calibrate » under your masterdark|
# 24 Jul, 2018 01:37
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