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    Re: Navigator's Vision,Day or Night.
    From: Tom Sult
    Date: 2009 Oct 05, 19:54 -0500

    I have not seen night vision optic that can focus that close...
    perhaps the military types have... I have a pair of goggles I use in
    my plane at night.
    Thomas A. Sult, MD
    IntegraCare Clinic
    www.icareclinics.com
    tsult@mac.com
    
    
    
    
    On Oct 5, 2009, at 1:39 PM, Greg Rudzinski wrote:
    
    >
    > Byron,
    >
    > Have you ever used electronic night vision optics on a sextant? If so
    > what are the pros and cons?
    >
    > Greg
    >
    > On Oct 5, 9:34 am,  wrote:
    >>  Navigator's vision at day and night.
    >> The way you use your eyes at night is different from the way you
    >> use them during the day. With normal day vision, you train your
    >> eyes to look directly at the target. If you catch something out of
    >> the corner of your eye, you automatically move your eyes to center
    >> on the target. Once you have done so, you can see the target
    >> clearly in color, and detail. In the dark, however, instead of
    >> directing your vision at the area you desire to see, you must learn
    >> to use off-center vision for a very dim light or star.  The first
    >> step in training yourself in night vision is finding a location
    >> free of normal white city lights,   Perhaps your backyard or better
    >> at sea. Wait until your eyes have adapted to the dark; this can
    >> take about 15 to 20 minutes. At this point the sky is black, some
    >> stars are bright, or some dim and you are aware of your
    >> surroundings. Your eyes are accustomed to the dark. If you need a
    >> light to read/write or see a star finder (NAVLIST 9471) use a red
    >> dim light only.  Look at the sky and find a bright star. Now slowly
    >> move your eyes until you see, or think you see, the dimmest star
    >> out of the corner of your eye. Look directly at the star. If it is
    >> a very dim star it will "disappear" when you look at it and won't
    >> reappear until you move your eyes and "look" at it using the off-
    >> center technique. It may well be fuzzy and lack color. But you do
    >> see it. What is happening here is that you are seeing it with your
    >> peripheral vision. Practice this off-center technique until you are
    >> comfortable picking up even the dimmest star.  Binoculars can help
    >> make some of the dimmer stars very bright. But other stars will
    >> disappear when you look directly at them, even with binoculars. At
    >> sea at night, relax and move your eyes slowly just a few degrees
    >> around the sky or the horizon. If you think you see a light, use
    >> the off-center vision technique to isolate your target. If the
    >> light is very faint and disappears, use a slow, off-center eye
    >> motion to pick it up again. Then use your binoculars to pick up any
    >> color details. Practice this off-center procedure until you are
    >> proficient in seeing things at night. When you are in the darkness,
    >> only a trained eye can produce the correct information quickly. In
    >> the day time when you want that good horizon for a star or planet
    >> before dark thickens the horizon try the "Vertical Sextant" NAVLIST
    >> of Sept 28.
    > >
    
    
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