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    Re: Simplified Bris Sextant (calibration)
    From: Greg Rudzinski
    Date: 2012 May 15, 13:01 -0700

    Bill,

    I just did a trial with two sets of polarizers together at maximum filtering and got a barely visible purple Sun. The attached images compare solar film (orange Sun) to two sets of polarizers together (purple Sun). Settings f11,ISO 100,,1/320s at infinite focus using 50 mm prime lens.

    When in the field I start at f22, ISO 100, 1/4000s in manual mode then slow the shutter down until the horizon is just visible. In iPhoto the image can be adjusted to show the horizon without overexposing the Sun.

    If using a homemade Bris with the naked eye then the reflected image is much less bright than the direct Sun. The polarizers are set to less than maximum for a faint Sun and visible horizon.

    Greg Rudzinski
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