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    Re: Compact Lightweight Metal Sextants - Freiberger Yacht vs. Astra IIIB
    From: James N Wilson
    Date: 2012 Aug 11, 10:14 -0700
    
    Greg:
     
    I don't see how it could help with a dim star. There I want a full silvered mirror. What I'm proposing is, instead of a sharp dividing line between silvered and clear, have a gradual change. Thus you could move the image laterally for best viewing.
     
    Jim Wilson
     
    On 10 Aug 2012 21:09:49 -0700 "Greg Rudzinski" <gregrudzinski@yahoo.com> writes:

    Jim,

    Cassens and Plath has a hybrid whole horizon option that is half silvered in the middle and clear on the sides. This should improve early twilight and dim star observations.

    http://www.cassens-plath.de/katalog/index.html?startpage=90


    Greg Rudzinski


    [NavList] Re: Compact Lightweight Metal Sextants - Freiberger Yacht vs. Astra IIIB
    From: James N Wilson
    Date: 10 Aug 2012 20:25
    
    John:

    I agree with many of your sextant comments, except that I have no use for verniers on the micrometer drum. Their ostensible increase in accuracy is questionable, and they introduce the possibility of reading from the wrong end of the vernier, introducing an eleven minute error.

    I deplore the idea of eliminating the clear glass on the horizon mirror. I've found it handy with Sun and Moon shots. I also dislike "whole horizon" mirrors, finding the horizon difficult to discern at twilight. Has anyone produced a horizon mirror with a gradation from full on the right to zero on the left? That sounds handy. Should I patent the idea?

    Jim Wilson

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