NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Lunar Scopes
From: Fred Hebard
Date: 2005 Feb 13, 19:34 -0500
From: Fred Hebard
Date: 2005 Feb 13, 19:34 -0500
I am most specifically not intending any insult to Joel Jacobs with the following. He is a fair, honest, scrupulous merchant, in my experience and opinion. With that said, if you do buy another telescope for your sextant for lunars or other high-precision work, it is an excellent idea, in my experience, too check that the telescope is properly aligned when mounted on your sextant. One advantage of the inverting Russian (Cho-T) scopes is that they can be aligned; most prism telescopes cannot be aligned. On Feb 12, 2005, at 5:48 PM, Yourname Here wrote: > > Hello Alex, Bob, and Group, > > I will try and answer both your questions in a way that may be of > benefit to everyone. What I omitt here, I will respond off group if > you have any further interest in discussing it. > > Most all well known contemporary sextants use the same fork or rising > piece design so that many sextant scopes are interchangable with each > other. It is easier to list which sextants most scopes wont fit than > the other way around. Sextants that have a unique design to their fork > are the Dutch Obseravtor, French Poulin, German Freiberger, USN MK II, > and likely some English designs with which I am not familiar. Those > are the ones the three high powered scopes I mentioned will NOT fit. > Therefore, you can conclude they will fit most others. > > That said, the limiting factor to most of the sextants with the same > fork design will be the size of the INDEX MIRROR. Any index mirror > with a vertival demension of greater than 49 mm will hit the top of > the objective lens, and stop the travel of the index arm on two of > these scopes. Both the SNO-T, C&P and all other large mirror sextants > will not read below 41 degrees if the 7 x 50 scope is fitted, or 21 > degrees if the Shonan 6 power scope is fitted. The Tamaya 7 x 35 > scope, because of the smaller diameter of its objective lens will > allow full index arm travel on all sextants other than those I named. > If in doing your Lunar sights, you need the full range of travel, then > make sure you have a mirror the size of the Tamaya MS 1 series > sextants to which all three of the scopes were fitted. > > For Alex, > > The two Tamaya scopes were made in the 1970's. They both are in > excellent condition. The Shonan scope was dropped and there is a dent > in the objective lens ring, but this does not appear to have affected > images as viewed. > > From an old Nautech catalog, the Degrees of View are: > > 7 x 35, 6.5 degrees > 7 x 50, 7.1 degrees > > The Shoan is marked on the scope 6 power, 6 degrees. > > A Russian SNO-M sextant was handy, so I fitted the scopes to it, and > not a SNO-T, and the reseults were as noted. > > I published pictures of these scopes on a Tamaya MS 1 sextant and a > SNO-M sextant. The two higher powered scopes are very rare and you > likely will not come across them, but they are an interestng bit of > sextant history. To view GO: > http://www.villagephotos.com/pubbrowse.asp?folder_id=1217241 > > If anyone wants more information, please contact me off group. > > Cheers, > > Joel Jacobs > > > > > > -------------- Original message from "Robert Gainer" >: -------------- > > > > How much for the 7X50 and does it fit a C&P sextant? > > Thanks, > > Robert Gainer > > > > >From: Yourname Here > > >Reply-To: Navigation Mailing List > > >To: NAVIGATION-L@LISTSERV.WEBKAHUNA.COM > > >Subject: LUNAR SCOPES > > >Date: Sat, 12 Feb 2005 13:32:10 +0000 > > > > > >For those who practice the art of Lunar distances, I have three > rare high > > >powered sextant telesopes, each with a fork that will fit most > contemporay > > >sextants. > > > > > >7 x 35 Tamaya Prismatic > > >7x 50 Tamaya Prismatic > > >6 x 6 degrees Shonan Kosakusho ( WW II searchlight manufacturer) > > > > &! gt; > > > >Joel Jacobs > > > > _________________________________________________________________ > > Express yourself instantly with MSN Messenger! Download today - > it's FREE! > > http://messenger.msn.click-url.com/go/onm00200471ave/direct/01/ > >