Hello
Is it important to have the same Black Level values for the Darks/Offsets/Flats and for the Light frames?
Many thanks.
Eric.
Darks and Black Level
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Re: Darks and Black Level
Hi,
it's important that they match between
light frames and dark frames
also between
flat frames and dark flat frames
but there is no need for the light frames to match the flat frames.
cheers,
Robin
it's important that they match between
light frames and dark frames
also between
flat frames and dark flat frames
but there is no need for the light frames to match the flat frames.
cheers,
Robin
Re: Darks and Black Level
Thanks.
For someone like me, who is not doing livestacking, isn't it better to always set the black level at zero as I'll address the black level later anyway during post-processing? This way I would ensure that my dark library is robust over time (providing I use a BP value of 0 as well).
Regarding the "dark flat frame", is it what is also called "biases" or "offsets" or something else (I only run lights, darks, offser/bias, flats)?
Cheers.
Eric
For someone like me, who is not doing livestacking, isn't it better to always set the black level at zero as I'll address the black level later anyway during post-processing? This way I would ensure that my dark library is robust over time (providing I use a BP value of 0 as well).
Regarding the "dark flat frame", is it what is also called "biases" or "offsets" or something else (I only run lights, darks, offser/bias, flats)?
Cheers.
Eric
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Re: Darks and Black Level
Hi Eric,
yes, you can often use bias frames in place of dark flat frames in most circumstances (unless you take long exposure flats), so in that case the black level should be the same between flat frames and bias frames.
The choice of zero for black level may be fine, but you will need to check. The way to test is to take full length dark frames at the settings that you propose to use and then check that the histogram of the dark frames is separated from the left hand side of the graph. If you test and the peak extends all the way to the left, increase the black level until it is separated. Once you have found that black level, you can use it for all imaging.
cheers,
Robin
yes, you can often use bias frames in place of dark flat frames in most circumstances (unless you take long exposure flats), so in that case the black level should be the same between flat frames and bias frames.
The choice of zero for black level may be fine, but you will need to check. The way to test is to take full length dark frames at the settings that you propose to use and then check that the histogram of the dark frames is separated from the left hand side of the graph. If you test and the peak extends all the way to the left, increase the black level until it is separated. Once you have found that black level, you can use it for all imaging.
cheers,
Robin