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    Tinkering with Davis sextant scope
    From: Rolf Vainio
    Date: 2011 Apr 8, 22:13 -0700

    Modified my Davis sextant by replacing the original scope with a piece of Japanese optics.

    The modification quadrupled the amount of sky in my view while simultaneously increasing the magnification from 3x to 4x.

    The scope has a 12.5 degree field of view , the literature mentions 21.9 cm at 1 meter (corresponds to 657 yd at 1000 ft).


    Installing was uncomplicated:
    - Tape was attached to the sextant to protect it during the operation, dismounted the original scope cut the feet from the sextant frame with a fine toothed saw and than used a file and a knife to level the area.
    - My general spares- box contained a rifle scope which fitted perfectly on the scope without any modifications to neither. ( 30 mm scope mount from EAW Germany ).
    - The plastics in the sextant was too thin for the scope mount , therefore added a piece of 2mm aluminum sheet to beef it up.
    -The scope was placed slightly forward from the outer edge of the frame for the sextant to fit the Davis box with scope mounted . Only one hole had to be drilled to the sextant frame.

    First observations:
    - Works as expected, picture is impeccable giving a great feeling of presence.
    - Sighting is easier, I do save time, which is nice when sighting outside in the cold and hawing to warm up hands in mittens in between.
    – I have now tried both whole horizon and traditional half mirror and found that using a traditional mirror became easier due to increased leeway.
    -I paid more for the new scope (€88) than for the used Davis Mark 25 (€80) but consider the pennies well spent, the improvement is substantial and contributes to making sighting training sessions more enjoyable .

    Three pictures of installation attached

    Rolf Vainio

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