Quote:
Originally Posted by Octane
Leave ICNR off and take dedicated dark frames. You'll thank me later.
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Absolutely correct!!!
(and you can thank Humayun straight away
)
When you subtract your darks from your lights,
the final image will contain the noise from the light and from the dark added together.
In other words, the
ICNR reduction will double the noise.
The fact is that any dark subtraction will add noise to your lights. However, if the amount of noise in your darks is less, the amount of noise added to your lights will be less. The same applies to flats.
To minimise the noise in your darks take multiple darks and stack them. The darks have to be taken at the same temperature as your lights, i.e. straight after. Do not use ICNR.
If you want to know more how it all works, see here:
http://deepskystacker.free.fr/english/theory.htm
Luka