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Re: [ccd-newastro] Re: Exposure time for luminescence images

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  • Mark Striebeck
    Thank you for the explanation - makes sense. MarkS ... [Non-text portions of this message have been removed]
    Message 1 of 8 , Feb 11 1:11 PM
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      Thank you for the explanation - makes sense.

      MarkS
      On Feb 11, 2013 11:19 AM, "Stan" <stan_ccd@...> wrote:

      > **
      >
      >
      > --- Mark Striebeck wrote:
      > > What I'm interested in is the relative exposure time
      > > (sub, but also overall) of luminance vs. rgb.
      >
      > Lum sub-exp time should be determined by its own criteria (e.g. "sky
      > limited") and has nothing to do with the sub-exp times of the RGB. Any
      > sub-exp L/RGB ratio is happenstance and irrelevant (though once you settle
      > into an imaging regime, that ratio will become somewhat constant).
      >
      > The L/(RGB) ratio of TOTAL exp times is important but as the prior msg
      > stated, the dynamics are not quantitatively well understood and so most
      > people experiment to find a ratio that works for them. That ratio can often
      > be a result of circumstance; for true resolution it is highly advantageous
      > to shot Lum when the seeing is good and fill-in the color data when the
      > seeing is otherwise not useful.
      >
      > Basically the ratio of total Lum time to total RGB time determines the
      > balance of color fidelity vs. image definition/depth. Pure RGB produces the
      > highest color fidelity and color-definition but also produces poor depth
      > and resolution. Pure Lum (otherwise known as grayscale or B&W) produces the
      > greatest depth, contrast and resolution. A strong Lum with under-done
      > coloration data can produce washed-out/undifferentiated colors.
      >
      > Stan
      >
      >
      >


      [Non-text portions of this message have been removed]
    • hilary15xx
      Hi Mark, You might want to try my SimCCD and Exposure Planner utilities. They can be used to give a recommended exposure time for that part of the image that
      Message 2 of 8 , Feb 15 8:33 AM
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        Hi Mark,

        You might want to try my SimCCD and Exposure Planner utilities. They can be used to give a recommended exposure time for that part of the image that is most important to you. For example if you want to get a good signal to noise ratio in the tidal tail of a galaxy, you can select that region and these utilities will tell you how many subs to take. You can find more information about these utilities at
        http://www.darklights.org/simccd/index.shtml

        Hilary

        --- In ccd-newastro@yahoogroups.com, Mark Striebeck <mark.striebeck@...> wrote:
        >
        > Hi,
        >
        > I found some interesting articles about how to evaluate the different
        > exposure times for the RGB images. But I couldn't find anything how to
        > determine the exposure time for the luminescence images. Is there a general
        > rule or are there good sources to read up on it?
        >
        > Thanks
        > MarkS
        >
        >
        > [Non-text portions of this message have been removed]
        >
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