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    Re: Digital Image CN Exercise
    From: Greg Rudzinski
    Date: 2010 Apr 5, 07:36 -0700


    The .097 minutes of arc per pixel was not determined by the image example provided but by taking an average of several images from an altitude above 50° in Black and White at 10 mega pixels, 1/4000s shutter speed, ISO 100, f22, through circular polarizers. This number is a constant for this particular 200mm fixed lens. If a 32.00' Sun is measured at 330 pixels this would be good to plus or minus 2 pixels resulting in a range of .0964' to .0976' minutes per pixel. The Hs altitude for the image example would then be within the range of 3° 57.9' and 4° 00.9' (3 minutes of arc). This is the best that can be expected using the Sun as a reference of measurement over a 4 degree field of view. There is of course potential for better results.

    Nothing is worked backwards.

    For extra credit:
    1. Determine the height of the oil platform.
    2. Species, wing span, and distance of the two birds from the photographer.

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