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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Longitude by calculator -theodolite
From: Paul Hirose
Date: 2013 Jun 23, 15:15 -0700
From: Paul Hirose
Date: 2013 Jun 23, 15:15 -0700
Bruce J. Pennino wrote: > Stars are not so easy because there is no internal light on the theodolite and I can't see the cross hairs at twilight. Hold a small flashlight so your index finger protrudes into the beam. Position the finger just ahead of the objective lens so it's in the field of view. This provides enought backlight to see the crosshairs. By showing more or less finger you regulate the illumination. For a workaround when the instrument has no reticle illumination, some old surveying books recommend shining the light straight into the objective from a point outside the field of view. That works, but my method gives more even illumination, easier control, and less light in your eyes. --
