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    Re: Long Range Desert Group navigation
    From: Paul Hirose
    Date: 2002 Feb 2, 22:48 -0800

    "Dr. Geoffrey Kolbe" wrote:
    >
    > I have a surveying theodolite, but there is no way of illuminating the
    > cross hairs.
    
    
    One old surveyor's trick for making Polaris observations at night is
    to hold a flashlight just outside the field of view and shine it into
    the telescope objective lens.
    
    You can also place the tip of your index finger, illuminated by a
    flashlight held in the same hand, so it protrudes into the field of
    view. I like this method a little more, but either one is quite
    effective for making the reticle visible without washing out the star.
    
    Many theodolites have a small "lollipop" in the telescope, easily
    visible through the objective lens. It's made of thin metal and is
    normally turned edgewise. For crosshair illumination, you turn the
    lollipop 45 degrees. That causes its round tip, at the center of the
    telescope tube, to intercept a light beam supplied through the side of
    the tube and deflect it back toward the reticle. The light comes from
    the circle illumination optics, so the lamp and power source need to
    be operating. Or you shine a flashlight into the illumination port.
    
    Someone in the Sextants group may know more about this.
    http://groups.yahoo.com/group/Sextants/
    
    --
    
    
    paulhirose---.net (Paul Hirose)
    
    
    

       
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