NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: John Karl
Date: 2012 Aug 11, 09:26 -0700
For those who want the left and right-hand images spread across the whole field of view, you'll get exactly that by using a prism scope with the half-silvered mirror, instead of the Galilean scope. Each image fades out gradually on their far side, just like Jim W. desires. This optics is explained in my book. I particularly like this arrangement the best, but the the disadvantage is that it's hard to find a low power prism scope.
This works exactly the same with the Freiberger half mirror (half mirror, not half silvered!). I mounted a small co-linear 7x18 prism scope on my Yacht sextant. This is some kind of a sportsman's, or naturalist, scope made by Eagle Optics, about an inch in diameter. As a plus, its color and finish match the sextant exactly, and it fits into the case while attached to the sextant.
Yes, I agree the vernier is no big deal, but the size and shine of the drum is. But to keep all the math consistent I like to work everything to the tenth of a minute, realizing of course that the final result will likely be off by more than that.
JK
----------------------------------------------------------------
NavList message boards and member settings: www.fer3.com/NavList
Members may optionally receive posts by email.
To cancel email delivery, send a message to NoMail[at]fer3.com
----------------------------------------------------------------