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Basic questions...

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  • Daniel Fafard
    Hi group, I ordered today the QHY9 CCD camera. I would like to know: How many darks is recommended to do with a CCD? When doing Ha...Do you do Ha only or we
    Message 1 of 5 , Feb 27, 2010
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      Hi group,



      I ordered today the QHY9 CCD camera.



      I would like to know:



      How many darks is recommended to do with a CCD?



      When doing Ha...Do you do Ha only or we must do L + Ha?



      Thanks for your help,

      Daniel Fafard
      Québec, Canada
      Lat: 46° 2' 50" Nord, Long: 73° 28' 35" Ouest


      "Découvrez la beauté du ciel"

      Sites Web: http://www.astronomeamateur.ca
      http://www.notrejardin.ca
      http://www.flickr.com/photos/dreamdan












      _________________________________________________________________
      Voici Téléphone WindowsMD.
      http://go.microsoft.com/?linkid=9708128

      [Non-text portions of this message have been removed]
    • john hendry
      Hi Daniel I have the QHY8 and that seems to work pretty well now that I have got it all sorted out. I use Nebulosity for calibration and it has a Bad Pixel
      Message 2 of 5 , Feb 28, 2010
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        Hi Daniel



        I have the QHY8 and that seems to work pretty well now that I have got it all sorted out. I use Nebulosity for calibration and it has a 'Bad Pixel Map' option made from a single dark frame of the same duration as the light frame. As it is a cooled camera and I aim for -15C to -20C chip temperature I have a library of them for my normal exposure lengths. If using standard dark frames then a couple of dozen is plenty, I used to take about 15. I always use a bias frame as well, but not too sure if this is useful or not.

        The Ha images can be very nice on their own, and/or used as a luminance frame in LRGB work.

        Whatever you do, have fun anyway



        Cheers



        John



        > To: ccd-newastro@yahoogroups.com
        > From: daniel.fafard@...
        > Date: Sat, 27 Feb 2010 23:38:00 -0500
        > Subject: [ccd-newastro] Basic questions...
        >
        >
        > Hi group,
        >
        >
        >
        > I ordered today the QHY9 CCD camera.
        >
        >
        >
        > I would like to know:
        >
        >
        >
        > How many darks is recommended to do with a CCD?
        >
        >
        >
        > When doing Ha...Do you do Ha only or we must do L + Ha?
        >
        >
        >
        > Thanks for your help,
        >
        > Daniel Fafard
        > Québec, Canada
        > Lat: 46° 2' 50" Nord, Long: 73° 28' 35" Ouest
        >
        >
        > "Découvrez la beauté du ciel"
        >
        > Sites Web: http://www.astronomeamateur.ca
        > http://www.notrejardin.ca
        > http://www.flickr.com/photos/dreamdan
        >
        >
        >
        >
        >
        >
        >
        >
        >
        >
        >
        >
        > _________________________________________________________________
        > Voici Téléphone WindowsMD.
        > http://go.microsoft.com/?linkid=9708128
        >
        > [Non-text portions of this message have been removed]
        >
        >
        >
        > ------------------------------------
        >
        >
        >
        >


        [Non-text portions of this message have been removed]
      • Mike Dodd
        ... I like to take at least 7 dark frames, and often as many as 20 or 25. This allows using a statistical-combine (e.g., Sigma reject) to eliminate cosmic ray
        Message 3 of 5 , Feb 28, 2010
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          > I ordered today the QHY9 CCD camera. [...]
          > How many darks is recommended to do with a CCD?

          I like to take at least 7 dark frames, and often as many as 20 or 25.
          This allows using a statistical-combine (e.g., Sigma reject) to
          eliminate cosmic ray hits or other bad data from individual frames.

          > When doing Ha...Do you do Ha only or we must do L + Ha?

          I do just H-a, unbinned.

          Hope this helps.
          -----
          Mike

          Mike Dodd
          Montpelier, VA USA
          http://astronomy.mdodd.com
          http://NotWhatIVotedFor.com
        • Daniel Fafard
          John, Mike, Thanks for these advices. I m eager to try it out. Clear sky! Daniel Fafard Québec, Canada Lat: 46° 2 50 Nord, Long: 73° 28 35 Ouest
          Message 4 of 5 , Feb 28, 2010
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            John, Mike,



            Thanks for these advices.



            I'm eager to try it out.



            Clear sky!

            Daniel Fafard
            Qu�bec, Canada
            Lat: 46� 2' 50" Nord, Long: 73� 28' 35" Ouest


            "D�couvrez la beaut� du ciel"

            Sites Web: http://www.astronomeamateur.ca
            http://www.notrejardin.ca
            http://www.flickr.com/photos/dreamdan














            To: ccd-newastro@yahoogroups.com
            From: napier58@...
            Date: Sun, 28 Feb 2010 09:11:57 +0000
            Subject: RE: [ccd-newastro] Basic questions...






            Hi Daniel

            I have the QHY8 and that seems to work pretty well now that I have got it all sorted out. I use Nebulosity for calibration and it has a 'Bad Pixel Map' option made from a single dark frame of the same duration as the light frame. As it is a cooled camera and I aim for -15C to -20C chip temperature I have a library of them for my normal exposure lengths. If using standard dark frames then a couple of dozen is plenty, I used to take about 15. I always use a bias frame as well, but not too sure if this is useful or not.

            The Ha images can be very nice on their own, and/or used as a luminance frame in LRGB work.

            Whatever you do, have fun anyway

            Cheers

            John

            > To: ccd-newastro@yahoogroups.com
            > From: daniel.fafard@...
            > Date: Sat, 27 Feb 2010 23:38:00 -0500
            > Subject: [ccd-newastro] Basic questions...
            >
            >
            > Hi group,
            >
            >
            >
            > I ordered today the QHY9 CCD camera.
            >
            >
            >
            > I would like to know:
            >
            >
            >
            > How many darks is recommended to do with a CCD?
            >
            >
            >
            > When doing Ha...Do you do Ha only or we must do L + Ha?
            >
            >
            >
            > Thanks for your help,
            >
            > Daniel Fafard
            > Qu�bec, Canada
            > Lat: 46� 2' 50" Nord, Long: 73� 28' 35" Ouest
            >
            >
            > "D�couvrez la beaut� du ciel"
            >
            > Sites Web: http://www.astronomeamateur.ca
            > http://www.notrejardin.ca
            > http://www.flickr.com/photos/dreamdan
            >
            >
            >
            >
            >
            >
            >
            >
            >
            >
            >
            >
            > __________________________________________________________
            > Voici T�l�phone WindowsMD.
            > http://go.microsoft.com/?linkid=9708128
            >
            > [Non-text portions of this message have been removed]
            >
            >
            >
            > ------------------------------------
            >
            >
            >
            >


            [Non-text portions of this message have been removed]





            _________________________________________________________________



            [Non-text portions of this message have been removed]
          • hilary15xx
            Hi Daniel, There probably is no good answer to your question. It depends on what you are photographing. If the target is very bright, it will cover up the
            Message 5 of 5 , Feb 28, 2010
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              Hi Daniel,

              There probably is no good answer to your question. It depends on what you are photographing. If the target is very bright, it will cover up the dark frame noise, and then a single dark frame might be enough to eliminate hot pixels. If the target is very dim, then more darks will be needed to keep the sky noise down. I have heard it said that a good rule of thumb is to take as many darks as you do lights; but that can be an daunting task. (Maybe I made that rule up myself!) For what it's worth, I typically use 15 frames, and that seems to be enough for my typical targets.

              You might want to look at my SimCCD program, which can give you a feel for what the impact will be if you use too few darks. A beta test version of the program is available at http://www.darklights.org/simccd/.

              Take care,
              Hilary

              --- In ccd-newastro@yahoogroups.com, Daniel Fafard <daniel.fafard@...> wrote:
              >
              >
              > Hi group,
              >
              >
              >
              > I ordered today the QHY9 CCD camera.
              >
              >
              >
              > I would like to know:
              >
              >
              >
              > How many darks is recommended to do with a CCD?
              >
              >
              >
              > When doing Ha...Do you do Ha only or we must do L + Ha?
              >
              >
              >
              > Thanks for your help,
              >
              > Daniel Fafard
              > Québec, Canada
              > Lat: 46° 2' 50" Nord, Long: 73° 28' 35" Ouest
              >
              >
              > "Découvrez la beauté du ciel"
              >
              > Sites Web: http://www.astronomeamateur.ca
              > http://www.notrejardin.ca
              > http://www.flickr.com/photos/dreamdan
              >
              >
              >
              >
              >
              >
              >
              >
              >
              >
              >
              >
              > _________________________________________________________________
              > Voici Téléphone WindowsMD.
              > http://go.microsoft.com/?linkid=9708128
              >
              > [Non-text portions of this message have been removed]
              >
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