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    Re: Suitable Sextants
    From: Alexandre Eremenko
    Date: 2005 Oct 11, 18:05 -0500

    Joel,
    Yes, you are right.
    Most of my experience was from land.
    And on a small boat (not so small, 42 feet)
    at first I could not use any scope at all,
    just had to do it without scope (and with poor results).
    
    A.
    
    
    On Tue, 11 Oct 2005 joel-jacobs@att.net wrote:
    
    > Alex,
    >
    > Sometimes the proof of the pudding is in the eating.
    >
    > Take a proper Star scope and couple it with a small size horizon mirror, and 
    note the results at twilight.
    >
    > Also take a sextant with small mirrors and use what ever scope you are most 
    comforatble with and try some high altitude sun sights. Note the results.
    >
    > I suggest it will be like your use of an inverting scope on land vis-a-vis at sea.
    >
    > You never notice the difference until you're at sea.
    >
    > Joel
    >
    > --
    > Visit our website
    > http://www.landandseacollection.com
    >
    >
    >
    >
    > -------------- Original message from Alexandre E Eremenko : --------------
    >
    >
    > > Joel,
    > > Thanks. It seems to me that in both cases it is the
    > > diameter of the telescope objective lens that is most relevant.
    > > Provided that the mirror occupies the whole field of view.
    > > Indeed, once this is the case,
    > > increased mirror will not send more light
    > > into the scope. Same about motion.
    > >
    > > So you probably mean that in the old sextants with small mirrors
    > > the mirrors did not occupy the full field of view,
    > > and some of this field of view was thus wasted, correct?
    > >
    > > Alex.
    > >
    > >
    > > On Tue, 11 Oct 2005 joel-jacobs@att.net wrote:
    > >
    > > > Hello Alex,
    > > >
    > > > Large mirrors collect more light and transmit more though the optics which are
    > > an advantage in taking twilight sights.
    > > >
    > > > The second adavantage is that celestial objects tend to move around on the
    > > horizon mirror due to the motion of the vessel or of the sight taker. They also
    > > seem to move more when taking high altitude sights. The larger size mirrors
    > > provide more surface area for the body to dance on before being lost from view.
    > > >
    > > > Also try WD 40, a moisture displacement chemical, to minimize affects of
    > > spray.
    > > >
    > > > Joel
    > > > --
    > > > Visit our website
    > > > http://www.landandseacollection.com
    > > >
    > > >
    > > >
    > > >
    > > > -------------- Original message from Alexandre E Eremenko
    > > : --------------
    > > >
    > > >
    > > > > Dear Joel,
    > > > >
    > > > > > 1. The larger the size of the mirrors, the better.
    > > > >
    > > > > I always read and hear this, but I am not sure that
    > > > > I understand exactly why the larger mirrors are better.
    > > > > Can you explain?
    > > > >
    > > > > > 2. Sextants with enclosed tangent screws
    > > > > > are prone to having them freeze
    > > > > > unless they are cleaned after use when
    > > > > > there is spray.
    > > > >
    > > > > This I confirm, even with my small experience.
    > > > > The remedy is to wash it with fresh water after
    > > > > a spray. And the fresh water is sometimes scarce
    > > > > on a small boat.
    > > > >
    > > > > Alex.
    > >
    
    
    

       
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