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I found this post from Paul Hirose valuable.  This is indeed a
pleasure of  using interest group lists.
Thanks
Brian W

He wrote

       illuminating [theodolite] 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.
>...
>paulhirose@earthlink.net (Paul Hirose)

Brian Whatcott
   Altus OK                      Eureka!

   

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