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Old 25-10-2013, 12:59 PM
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2stroke (Jay)
The devil's advocate

2stroke is offline
Join Date: Jul 2011
Posts: 816
Originally Posted by Merlin66 View Post
Every CCD frame taken includes the Bias....
I've been following the recommendations given in the AstroArt guide (p135) since moving into CCD work.
-Subtract a (master) dark frame a 5-10 image stack ( average or median combine) at the same temp and exposure as the lights.
- Divide by a (master) flat field (also corrected with it's own dark frame), a 5-10 image stack ( average or median combine)

This does away with the need for separate Bias frames (unless you're trying to scale your darks ie use a stack of ten minute darks to replicate a 40min exposure......)
Yer i scale darks in maxim when needed, though arn't subtracting the bias twice or are you dividing the whole image data by the master light value after subtracting you your dark. That seems weird as i thought it was

cal'd data = Sub - (Dark with bias data included) - ((Flat with bias data included) + (Bais frame as you have subtracted it twice))

Can you explain how your doing it with maths is it

cal'd data = (Sub -(Dark with bias data included)) / (Flat with bias data included)

so like if you had a pixel that was warm and its value was 102 for your dark inc bias value, your bias value was 2, your flat was 204 and your sub was 2000

(2000 - 102)/204
1898/204 = 9.3~

hmm that dosent seem right lolz, have a cold atm and doped up so help a brother out lol, i'am now expert either and i know you sure as hell have a vast experience please show me your maths.

Last edited by 2stroke; 25-10-2013 at 01:29 PM.
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