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Old 24-08-2016, 07:56 PM
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Location: Sydney
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Originally Posted by Joshua Bunn View Post
If your rark frames are the same duration as your light frames, my understanding is you do not need to take bias frames, as when you subtract the dark from your light frame, of the same duration, the bias is subtracted with the dark (its in the dark frame).

However, if you chose to have your dark frames longer than your light frames, you will need to do adaptive dark subtraction, in which case you will need to subtract the bias first, then your dark frames are scaled.

I do find though you get more reliable flat fielding if you do either a bias subtract on the master flat at the time of calibration or a flat dark subtract. I do both. On some systems or in light polluted imaging conditions flat fielding is a bit of an art and it can make a huge difference.

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