NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Box Sextant Magnifier
From: Bill Morris
Date: 2013 Nov 20, 01:12 -0800
From: Bill Morris
Date: 2013 Nov 20, 01:12 -0800
Noel, the focal length of mine is about 23 mm, it is plano convex (convex towards scale) and the free aperture is 10 mm. In use, your eye should be as close as possible to the lens and the lens scale distance will be about 25 mm, depending a little on your vision. A lens of 25 mm focal length will do the job and it will need to be about 12 mm in diameter to allow for mounting. Try surplusshed.com
Bill Morris
Pukenui
New Zealand
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