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Signal=Light - (Dark + Offset)/Flat Light - (Flat Dark + Flat Offset)Based on this I have only been using Light, Dark, Flats and Dark Flats. Does anyone have any further insight on this? Should we be using Bias only, Bias AND Dark Flats or Dark Flats only? The DSS tutorial suggest that we should be using Bias frames?
Here, "Dark" refers to the thermal noise signal of the imaging camera; i.e., the noise signal that varies in proportion to temperature, ISO, and exposure length. Note, however, that any exposure we take with a digital camera contains the Offset, and "Darks" are no exception. So, if we define Dark' to be an exposure of some length with the body cap in place, then Dark' = Dark + Offset, and, similarly, Flat Dark' = Flat Dark + Offset. Plugging these values into Equation 4 yields the following simplified form:
Signal = Light - Dark'/Flat Light - Flat Dark'
And just to make things even simpler, let's drop the prime indicators (the apostrophes) that we stuck on "Dark" and "Flat Dark", and just remember that by "Dark" and "Flat Dark" we mean frames captured with the body cap in place but with the same ISO and exposure length as the Lights and Flat Lights, respectively.
The Dark Frames are used to remove the dark signal from the Light frames (or the Flat frames for the Dark Flat frames).http://deepskystacker.free.fr/english/faq.htmSo as we all know we remove the dark signal from the Light frames by taking Dark Frames of the same exposure time, temperature and ISO as the Light frames (only with the cap on). Am I reading the part in parenthesis as the Dark Flat frames are used to remove dark signal from the Flat frames? This leads to the question, based from Jim Solomons Cookbook, that Offsets are not needed because they are already contained in the Dark Frames that we take.
Note, however, that any exposure we take with a digital camera contains the Offset, and "Darks" are no exception.http://www.saratogaskies.com/articles/cookbook/index.html#BackgroundBias/Offests defined:
The Bias/Offset Frames are used to remove the CCD or CMOS chip readout signal from the light frames. Each CCD or CMOS chip is generating a readout signal which is a signal created by the electronic just by reading the content of the chip.http://deepskystacker.free.fr/english/faq.htm
The only case that does not need bias frames at all is when there is no dark scaling and both light and flat frames are dark subtracted.Agreed! Therefore since I use DSS with NO scaling I just use Flat, Dark Flat, Lights and Darks. I've got a brain cramp now. Thanks for contributing to this I know it is helping me further understand this concept.