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    Re: Sextant Collimation Error
    From: Frank Reed
    Date: 2020 Jun 27, 21:52 -0700

    Early octants often had two sight peeps separated by 1-1.5 cm horizontally. A metal shade could slide over one or the other of them. This was equivalent to the riser on sextant scopes (both historically and today). The line of sight (line of collimation) was still expected to be parallel to the frame but at two different levels.

    The small size of the peephole on early octants served as "poor man's eyeglasses". If you are somewhat near-sighted and normally wear glasses or contacts, try poking a small hole in a bit of cardstock, maybe 2-3 mm across, and look through it. Notice how your visual acuity greatly improves!

    Frank Reed

       
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