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Re: Lunar Scopes
From: Joel Jacobs
Date: 2005 Feb 12, 22:48 +0000

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" <robert_gainer_2@hotmail.com>: --------------

> 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!
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