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    Re: Simplified Bris Sextant
    From: Alexandre Eremenko
    Date: 2012 May 10, 10:27 -0400

    Greg,
    
    > I only compared 6 observations by counting pixels
    > from the center of the Sun down to or up to the horizon.
    
    Are you saying that cunting pixels from a limb to the horizon
    gives worse results?
    
    > I was
    > disappointed in the inconsistencies.
    
    Well the camera must be distorting too.
    And it is not easy to find how much.
    
    And the glas might be non-flat.
    (The original Bris has very small and relatively fat glass.)
    
    > Another try will be made with the 50 mm lens which will give a bigger
    > field of view to  better determine the reflected image low point
    > relative to the horizon.
    
    Remember: bigger field of view implies bigger distortion.
    A piece of sphere cannot be mapped on the plane without distortion,
    and bigger the piece bigger the distortion.
    I am afraid that measuring this distortion might be a non-trivial task.
    
    Alex.
    
    
    
    
    

       
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