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