Author Topic: Flat Trouble?  (Read 265 times)

Offline james423896

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Flat Trouble?
« on: 2018 December 20 02:33:17 »
I am attempting to calibrate some widefield images I took on my 6D but my flat calibration seems to be ruining the files. If I calibrate the light with a master dark and/or master bias the file looks fine but is heavily vignetted. As soon as I introduce a master flat it goes way off piste and I dont fully understand why. I took the flats in AV mode and they look ok.


Link to folder with files:
https://1drv.ms/f/s!AtooZYq7lKxzgSf2q81jFPWh7bCe

I have never had trouble with flats on my crop bodies, it seems to be a problem with super wide images on the 6d...

Online dld

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Re: Flat Trouble?
« Reply #1 on: 2018 December 20 03:04:01 »
Hello James,

I am also a user of the 6D and lenses with lots of vignetting  :laugh:

Here are my observations regarding your files:
  • Your superbias is debayered.
  • Your flat frames exposure time is too short; it is the same as of a bias frame. Try dimming your light source to achieve a longer exposure time.
  • And your master dark was made with a different ISO setting.

Your first concern is to check how a debayered superbias entered into your calibration pipeline.

Hope this helps!

Offline james423896

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Re: Flat Trouble?
« Reply #2 on: 2018 December 20 08:15:02 »
Thanks, I knew there had to be a wood-for-the-trees thing I was missing! Weirdly all my biases for the 6d were rgb, I must have had a setting wrong when I created them which propogated through all of my calibrated subs.

Thanks