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Star 71 Astrograph

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  • tbird0322
    I just took delivery of the new Star 71 Astrograph, composite FOV image attached. I live near the beach, low clouds and fog have made testing difficult, but
    Message 1 of 9 , Jun 12, 2014
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    I just took delivery of the new Star 71 Astrograph, composite FOV image attached.  I live near the beach, low clouds and fog have made testing difficult, but initial results exceed my expectations.  The field is flat and fully illumated.  Star tests are excellent, and the OTA is built like a tank.
  • dan_kordella
    Looks really nice and I thought about trying one of these myself! Have you been able to check the image scale and confirm that it s actually f/4.9? I know
    Message 2 of 9 , Jun 12, 2014
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      Looks really nice and I thought about trying one of these myself! Have you been able to check the image scale and confirm that it's actually f/4.9? 

      I know there were some major discrepancies with both the GTF81 and GTF102 between their advertised f-ratios and what they actually delivered. 

      Dan
    • tbird0322
      Dan, I use a spread sheet to calculate field of view. Based on pixel size and chip size, I should get about 2 1/2 X 3 1/2 degrees, which the photo shows. I
      Message 3 of 9 , Jun 12, 2014
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        Dan,

        I use a spread sheet to calculate field of view.  Based on pixel size and chip size, I should get about 2 1/2 X 3 1/2 degrees, which the photo shows.  I am not sure how to measure image scale?
      • dan_kordella
        Can be done pretty easily - I use a freeware called CCDcalc. If you tell me the kind of camera you use, I can figure out the image scale and then expected FOV.
        Message 4 of 9 , Jun 13, 2014
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          Can be done pretty easily - I use a freeware called CCDcalc. If you tell me the kind of camera you use, I can figure out the image scale and then expected FOV. 2.5X3.5 deg is pretty wide, so it might very well actually be f/4.9.

          Dan
        • tbird0322
          Dan - I use a Canon XSi DSLR it is 4272 X 2848 with 5.2 micron pixels. Thanks for your input, I will look into CCDcalc. I plan to give it a dark sky test on
          Message 5 of 9 , Jun 13, 2014
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            Dan - I use a Canon XSi DSLR it is 4272 X 2848 with 5.2 micron pixels.  Thanks for your input, I will look into CCDcalc.  I plan to give it a dark sky test on the 21st.
          • tbird0322
            I had the Star-71 in some dark sky last weekend, this is 30 minutes, 3X10minutes), of M101 and the area around it, If The Sky is correct, some of the
            Message 6 of 9 , Jun 26, 2014
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            I had the Star-71 in some dark sky last weekend, this is 30 minutes, 3X10minutes), of M101 and the area around it,  If "The Sky" is correct, some of the galaxies noted are below magnitude 14.  A Canon XSi was used for the image.
          • timm_bottoni
            Looks amazing!!!! I can t wait to try mine. If I can only get a clear night. Thanks, Timm
            Message 7 of 9 , Jun 26, 2014
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              Looks amazing!!!!  I can't wait to try mine.

              If I can only get a clear night.

              Thanks,

              Timm
            • dan_kordella
              I must ve missed your reply. Sorry! If the Star 71 is really f/4.9, your total field of view with your Canon should amount to 146 X 220 arcminutes (rounded a
              Message 8 of 9 , Jun 26, 2014
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                I must've missed your reply. Sorry! If the Star 71 is really f/4.9, your total field of view with your Canon should amount to 146 X 220 arcminutes (rounded a bit). So about 2 1/3 degrees by 3 2/3 degrees - which is about what you got, right? 

                Sounds like a really nice scope!
              • tbird0322
                Thanks, that is exactly what my Excel spreadsheet calculated. Here is one I took this weekend of the area around Gamma Cygni.
                Message 9 of 9 , Jul 1, 2014
                Thanks, that is exactly what my Excel spreadsheet calculated.  Here is one I took this weekend of the area around Gamma Cygni.
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