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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Observator Mark 4 Sextant
From: Bill Morris
Date: 2008 Aug 14, 02:06 -0700
From: Bill Morris
Date: 2008 Aug 14, 02:06 -0700
Members can read the original patent document at http://v3.espacenet.com/origdoc?DB=EPODOC&IDX=EP0082556&F=0&QPN=EP0082556. Its claim to originality are that the filters are contained safely within the viewing means and that they can be made of cheap material like photographic film, as they do not have to have flat parallel faces, lying as they do behind the objective lens of a Galilean telescope. The index beam and the horizon beam do in fact have separate filters which do not get "filthy" like ordinary ones, nor do they invited destruction at the hands of the clumsy. The filter density can be made continuously variable. Bill Morris On Aug 14, 9:25�am, "Richard B. Emerson"wrote: > I've never seen this sextant before but I looked over the eBay auction > and decided it has one big problem: filters. �As best I can tell there's > no way to use one level of filtering for the index mirror and another > for the horizon. �Things like a bubble horizon are out (unless one's > built in?) as are astigmatizers and varying scope powers. �Of course, > all off that could be built in. �But I'm not holding my breath on any of > that being present. �Good luck with your bidding! �:-) > > Rick Emerson > S/V One With The Wind > > > > Greg Rudzinski wrote: > > � � �Has anyone on the list used an Obervator Mark 4 sextant (Dutch > > made) and how does it compare to other sextants ? There is one listed > > on Ebay right now. > > > Greg- Hide quoted text - > > - Show quoted text - --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---