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73939Re: [ccd-newastro] Re: Do Dark and Bias Frame patterns change as the camera gets older over time?

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  • Mark Acker
    Feb 5, 2014
      I think one thing that differs here is that you operate from a perm setup, while I am mobile only, which I probably should have made more clear. It's not practical for me to take darks as soon as I finish a night of freezing my whiskers off. :)  Also, I only cool to a multiple of 5 degrees, with the exception of 1, 2, 3 minutes for things like M42.  Frankly I'm not at all sure that I could recognize the difference in darks taken 3 degrees off from the lights anyway, which is why I stick to predominately multiples of 5.
      Mark Acker

      From: Mike Dodd <mike@...>
      To: ccd-newastro@yahoogroups.com
      Sent: Wednesday, February 5, 2014 9:47 PM
      Subject: [ccd-newastro] Re: Do Dark and Bias Frame patterns change as the camera gets older over time?

      Mark Acker wrote:
      > I think most take darks no more than about every 6 months or so.

      I used to do that, and kept a library of darks. But I stopped when I
      found myself cooling the camera to temperatures that didn't match my
      "standard" camera temperatures (e.g., -15C, -20C, -25C). If I could
      reach, say, -18C in the camera, I wouldn't have a dark to match. So I'd
      set the camera to -15C, "wasting" any reduced noise that extra 3 degrees
      would have provided.

      This also applied to exposure times. A library of 10- or 15-minute darks
      isn't much help if I can make 17-minute light exposures one night.

      Instead, I began taking a set of 10-15 darks immediately after my target
      went behind the trees. I keep these darks with the light frames, and use
      them just for processing that target. I'm always assured of darks with
      the correct exposure and temperature.

      In short, I found maintaining a good dark library to be not worth the
      effort, especially when I started using ACP automation software, which
      will take my darks without any action on my part.


      Mike Dodd
      Louisa County, Virginia USA N37.58.23 W77.56.24

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