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    Re: Current Sextant Manufacturers
    From: Bill Morris
    Date: 2012 Mar 30, 13:15 -0700

    Alex

    > Now, I am convinced that SNO-T Kepler telescope is by far superior
    to the "standard" modern Galileo sextant telescope in all conditions
    that I tested.<

    Comparing like with like, a 6 x 30 monocular with the SNO-T inverting (Keplerian) telescope, the fields of view are pretty well identical, but, looking with both simultaneously at a patch of overcast sky, the SNO-T gives a noticeably brighter image. Since the human eye can just detect a doubling in brightness, this gives a distinct advantage for twilight sights, not because of the brightness itself, but because of the implied increase in contrast at the horizon, which improves with even modest increases in brightness.

    >SNO-T standard Kepler 6x is comparable to a prizmatic 8x30,
    but has larger field of view and a small fraction of its weight and bulk.<

    Not really, unless 8/11 is a small fraction...

    C Plath 4 x 40 Galilean scope 130 grams
    SNO-T Inverting scope 160 grams
    6 x 30 monocular 220 grams

    The main advantage is the bright, wide field of view, but for a beginner trying to pick out a particular star at morning twilight, the inverted view is disconcerting.

    Most bronze frames are less rigid that most aluminium alloy frames. A notable exception is the Husun three circle frame, which is as stiff as the best. I suspect however, that the differences in stiffness are of little practical importance, until the sextant is dropped. Bronze frames bend. Alloy frames break (an unlikely scenario).

    You mention that I may be responsible for the rising price of SNO-Ts, but I fear that the sales of my book have not been so great as to make this likely. I am not a rich man and the book sales are unlikely to make me one :-). My impression is that over the last five years the prices of all micrometer sextants have been rising and vernier ones (except genuine antiques) have been falling slightly, but this is only an impression.

    Bill Morris
    Pukenui
    New Zealand

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