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Taking dark frames
Posted: Sun Jun 20, 2021 6:13 pm
by jazzin
I want to create a HaRGB image and have already taken a set of dark frames with an Ha filter on my camera. Is It necessary to take another set of darks when I shoot my set of RGB images which are going to be of the same length or can I use the same darks I shot with the Ha filter?
Re: Taking dark frames
Posted: Sun Jun 20, 2021 6:48 pm
by sdbodin
Same 'black' light as far as I am concerned. E.G. no light is a dark, or am I missing the definition. BTW, I have ditched all my cal frames, all they do is add confusion, no data is added.
Clear skies,
Steve
Re: Taking dark frames
Posted: Sun Jun 20, 2021 7:23 pm
by STEVE333
You need the same Gain, Offset and Exposure Time. If those are the same for the Ha and RGB filters then the same Darks will work for all four.
Steve
Re: Taking dark frames
Posted: Sun Jun 20, 2021 8:57 pm
by jazzin
STEVE333 wrote: ↑Sun Jun 20, 2021 7:23 pm
You need the same
Gain,
Offset and
Exposure Time. If those are the same for the Ha and RGB filters then the same Darks will work for all four.
Steve
Thanks for the reply Steve! That's what I thought but just wanted to be sure!
Re: Taking dark frames
Posted: Sun Jun 20, 2021 9:18 pm
by carastro
Dark is a dark, whatever filter you use, so long as it is the same length and temperature and settings if CMOS as the light frames. Remember is you do binning for some filters your darks will need to be binned as well.
If you have set point cooling you can create a library of darks and keep re-using them.
Carole
Re: Taking dark frames
Posted: Mon Jun 21, 2021 3:12 am
by STEVE333
carastro wrote: ↑Sun Jun 20, 2021 9:18 pm
Dark is a dark, whatever filter you use, so long as it is the same length and temperature and settings if CMOS as the light frames. Remember is you do binning for some filters your darks will need to be binned as well.
If you have set point cooling you can create a library of darks and keep re-using them.
Carole
Thanks Carole for remembering to include:
Steve
Re: Taking dark frames
Posted: Mon Jun 21, 2021 9:22 pm
by Stuart
Dark frames don't even necessarily need to be the same length of time. They can theoretically be scaled. (I personally don't do that but I know it can be done)
Re: Taking dark frames
Posted: Mon Jun 21, 2021 9:25 pm
by XCalRocketMan
Stuart wrote: ↑Mon Jun 21, 2021 9:22 pm
Dark frames don't even necessarily need to be the same length of time. They can theoretically be scaled. (I personally don't do that but I know it can be done)
Beware, some cameras/sensors have issues with scaling. Those with noticeable amp glow cannot (generally) be scaled very well. My ASI1600 has this problem. My ASI2600 on the other hand, with no amp glow at all, can easily have the darks scaled.