NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: David Pike
Date: 2023 Sep 19, 14:07 -0700
Murray Buckman you wrote:
"I don't think Captain Onedin has his scope in back-to-front at all. I think it is a glass-free sight-tube for teaching purposes (or for finding a star on a rough day to get the estant arm in about the right place)."
I’ve not had chance to test the idea against the Sun yet only using a ceiling light v a curtain rod. It does work after a fashion, even with the front lens in. I was unable to find any other photographs online of the front part of the 2.5x star telescope being used in this way. It’s possible that this is a wrinkle used by some instructors in calm conditions. It would certainly reduce the chances of getting a quick flash of unfiltered Sun. However, I would be wary of using it in rough conditions. One good lurch of the vessel could leave you with a cut around your eye. DaveP
