Taking dark frames

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jazzin United States of America
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Taking dark frames

#1

Post 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?
Telescopes: Celestron 6" Newtonian, Orion 8" Astrograph

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sdbodin United States of America
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Re: Taking dark frames

#2

Post 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.

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Steve
Scopes; Meade 16 LX200, AT80LE, plus bunch just sitting around gathering dust
Cameras; Atik 460ex mono, Zwo ASI1600MC-cool, QHY5L-II color and mono
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STEVE333 United States of America
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Re: Taking dark frames

#3

Post 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
Steve King: Light Pollution (Bortle 5)
Telescope + Mount + Guiding: W.O. Star71-ii + iOptron CEM40 EC + Orion Magnificent Mini AutoGuider
Camera: ASI 1600MM Pro + EFW Filter Wheel + Chroma 3nm Siii, Ha, Oiii + ZWO LRGB Filters
Software: PHD2; APT; PixInsight ***** My AP website: www.steveking.pictures
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jazzin United States of America
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Re: Taking dark frames

#4

Post 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!
Telescopes: Celestron 6" Newtonian, Orion 8" Astrograph

Guide scope: 50mm guidescope

Camera: modded Canon T7i, stock Canon T1i

Software: PixInsight

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carastro Great Britain
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Re: Taking dark frames

#5

Post 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
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Scopes: Skywatcher ED80, Skywatcher ED120, William Optics ZS71, Samyang 135MM F2 lens,
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STEVE333 United States of America
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Re: Taking dark frames

#6

Post 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:
  • same temperature
  • same binning
Steve
Steve King: Light Pollution (Bortle 5)
Telescope + Mount + Guiding: W.O. Star71-ii + iOptron CEM40 EC + Orion Magnificent Mini AutoGuider
Camera: ASI 1600MM Pro + EFW Filter Wheel + Chroma 3nm Siii, Ha, Oiii + ZWO LRGB Filters
Software: PHD2; APT; PixInsight ***** My AP website: www.steveking.pictures
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Stuart United States of America
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Re: Taking dark frames

#7

Post 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)
Personal equipment: TEC 140 F7 on Astro-Physics Mach 1 mount. Camera QSI 683ws7. Guide with Vario guiding scope
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Re: Taking dark frames

#8

Post 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.
Scopes Celestron EdgeHD-11; William Optics GT102; William Optics ZS61; Criterion Dynamax-8 SCT
Mounts AP1100GTO mount w/APCCpro; iOptron iEQ30 Pro; Criterion Dynamax-8 SCT
Lenses Hyperstar-III; Celestron 0.7x FR; WO Flat/Reducer 0.8x
Guiding Celestron OAG w/ASI174mm mini; WO 50mm; Orion ST80
Cameras and Filters ZWO2600mm Pro w/Optolong 3nm NB and RGB; ZWOASI1600mm Pro (ZWO LRGB and Astrodon Ha-5nm, Oiii-3nm, Sii-5nm), QHY10, Canon 50D; ASI174mm mini; ASI462MC; ASI120MC
Misc Moonlite focuser on Edge - Feather-Touch focuser on GT102; ZWO EAF on ZS61; ZWO 2" and 31mm FWs; Kendrick Dew System, Temp-est Fans
Software NINA; PHD; APT; BYE; PI; APP; PSP; Registax; FireCapture; SharpCap
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