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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

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    Re: Simplified Bris Sextant
    From: Greg Rudzinski
    Date: 2012 May 8, 07:58 -0700

    GB,

    I count pixels during the editing procedure in iPhoto. The 200 mm lens (used for sunsets) on my Canon DSLR works out to .0975 minutes of arc per pixel for small angles in the center field. Large angles need to be corrected for geometry and lens distortion in a more complex manner (lots of posting in the NavList archives on this). Measuring with calipers to .001 of an inch or 0.1 mm directly on a lap top screen works but is less precise. A filtered properly exposed image of the Sun taken high in the sky can serve as the standard solar diameter using available almanac information for solar diameter minutes of arc.

    Greg Rudzinski

    [NavList] Re: Simplified Bris Sextant
    From: G Becker
    Date: 8 May 2012 05:32
    Greg,

    Do you count dots or pixels?

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