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Old 05-12-2010, 10:29 PM
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dugnsuz (Doug)
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Best Method for combining Darks?

Hello all,
With this poor weather overhead I am getting a library of darks together.

A simple question - with Images Plus, what is the best method for combining the dark subs? (They're 12 x 10min iso1600 subs)

I just used the default Average combine in IP, but I recall H in a not so recent thread talking about another method - Median perhaps?

Can't be too complicated, just wondered if there's a gold standard?

Cheers
Doug
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Old 05-12-2010, 10:45 PM
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Octane (Humayun)
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Median is your friend.

H
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Old 05-12-2010, 11:20 PM
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dugnsuz (Doug)
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Cheers H
Doug
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Old 06-12-2010, 09:27 PM
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philiphart (Phil Hart)
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I use Median too for darks, but in practise if you try both I'd be willing to bet you can't see any difference between the two!

Getting the right stacking type becomes more important as you have a smaller number of longer exposure subs with very low noise levels. With a DSLR, even cooled, I think you'd be hard pressed to tell the difference (that's been my experience when I try different settings).

In ImagesPlus, you can also choose just to do the high/low pixel correction without subtracting the dark frame from everything else. Unless your sensor has amp glow or some other structured (non-random) noise other than hot pixels, this is also a good option.

Phil
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Old 10-12-2010, 01:07 PM
jase (Jason)
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I've used a Sigma Reject, Median, and Clip min/max algorithms and couldn't spot any difference. I've settled on using Median for all calibration frames today including sky flats. Light frames is a different story.
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