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  • runrob68876
    Hello Group: I just posted a screenshot of a test exposure using my ST8i/ED80 setup in the runrob folder. Each exposure is 360 sec., dark frame subtracted,
    Message 1 of 5 , Mar 28, 2013
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      Hello Group:
      I just posted a screenshot of a test exposure using my ST8i/ED80 setup in the "runrob" folder. Each exposure is 360 sec., dark frame subtracted, and column repaired. Why is my luminance of the same exposure so different from my red exposure? In the luminance, the smaller stars are much "tighter" and similar to my red filter result, but the brighter stars appear overblown. Is this a focus issue or is there something else going on ? Looking forward to hearing your insight.
      CS Bob R. http://rcfotos.selfip.net/Runyan
    • Stan
      ... That s a real screenshot! (try pressing the Alt-PrtScn keys then paste into Paint or other graphic software). ... To see a real comparison -
      Message 2 of 5 , Mar 29, 2013
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        --- "runrob68876" <runrob@...> wrote:
        > I just posted a screenshot ... in the "runrob" folder.

        That's a "real" screenshot! <g>

        (try pressing the Alt-PrtScn keys then paste into "Paint" or other graphic software).

        > Why is my luminance of the same exposure so different...

        To see a real comparison - identically scale each display. A display image is not the actual data but rather it is a transformation of 16 (or 32) bit data to an 8 bit "image". There is an enormous number of potential transformations (images) contained in the original data. Some of those potential images have bloated stars and some have tight stars and some have no stars at all.

        Stan
      • Stan
        (continued) Examining each data set will reveal that the filter removes a great deal of information. The filtered sky background will be substantially
        Message 3 of 5 , Mar 29, 2013
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          (continued)

          Examining each data set will reveal that the filter removes a great deal of information. The filtered sky background will be substantially diminished. The filtered stars will be dimmer and thus seem "tighter" at any particular scaling (when compared to the unfiltered image with same scaling). Different colored objects (e.g. stars) will have different relative intensities. And so on...

          Stan
        • Ron Wodaski
          Stan, I thought you might be interested to hear about this new technology for one-shot color (if you haven t heard of it already, that is). Obviously, it s
          Message 4 of 5 , Mar 29, 2013
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            Stan,

            I thought you might be interested to hear about this new technology for one-shot color (if you haven't heard of it already, that is). Obviously, it's intended for the terrestrial camera market, but it is interesting nonetheless, if nothing else, for the sophisticated use of technology:

            http://bit.ly/XL11J2

            Ron Wodaski



            On Mar 29, 2013, at 8:39 AM, Stan <stan_ccd@...> wrote:

            > (continued)
            >
            > Examining each data set will reveal that the filter removes a great deal of information. The filtered sky background will be substantially diminished. The filtered stars will be dimmer and thus seem "tighter" at any particular scaling (when compared to the unfiltered image with same scaling). Different colored objects (e.g. stars) will have different relative intensities. And so on...
            >
            > Stan
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          • Stan
            ... I caught word of it from DP Review (a good source of info):
            Message 5 of 5 , Mar 30, 2013
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              --- Ron Wodaski <yahoo@...> wrote:
              > ... technology for one-shot color
              > http://bit.ly/XL11J2

              I caught word of it from DP Review (a good source of info):

              http://www.dpreview.com/news/2013/02/04/panasonic-promises-high-sensitivity-sensors-using-micro-color-splitters

              It is basically a micro version of the 3-CCD scheme used by some high-end video cams.

              Stan
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