NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Observations with pocket sextant in the Baltic CROSS POST
From: Alexandre Eremenko
Date: 2006 Jul 3, 13:48 -0500
Dear Red,
> Is your eyepiece filter just an inset or filter glass?
The back end of the telescope has a thread,
and this is where the eyepiece filter
(which is missing) should be attached.
The eyepiece filter should be a simple brass ring
with matching thread inside, and a piece of dark glass.
You can see the type of sextant I am talking about on
http://americanhistory.si.edu/collections/navigation/object.cfm?recordnumber=1197881
and
http://americanhistory.si.edu/collections/navigation/object.cfm?recordnumber=1197882
In the pictures you see telescopes sticking
out of the cylindric sextant body.
On the back end of this telescope a filter should be screwed on.
The diameter of the telescope is less than 1 inch.
> complex no doubt?) Can you point me to a URL where I can see a similar
> instrument on the web?
> Perhaps because they were manufacturing their
> new frame instead of sticking to
> the old type similar to C&P?
The story mentioned several times on this list
was that they tried to stick to the traditional
process of manufacturing a brass sextant frame whose purpose
is to relieve inner tension in the material.
The process was very complicated and the price of a sextant
was more than $2000 at the tame they had to discontinue the manufacturing.
> That is, you splurge to buy one if you want one--but
> that's "want" with no true practical need.
Sure. I can buy a new Cassens-Plath for $1300 or so,
or something really nice and old on e-bay for about the same
price. The problem is that I take a risk in both cases.
The risk that the sextant will not be of the highest quality
I want.
(It took me almost 2 years of observations to conclude that the
new SNO-T, a sextant of high reputation, I bought 2 years ago,
does not perform according to its specifications, and moreover,
I had it checked by BOTH Freiberger and Cassens-Plath and they did
not find any defect. If Cassens and Plath tests their own
sextants by the same standards... how can I be sure that a new
Cassens+P performs better?)
But of course I understand your comparison with "Ferrari market".
It does not serve any practical purpose indeed. But people
have all kinds of weird hobbies. "Backyard navigation" is one of them.
Alex.
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To , send email to NavList-@fer3.com
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From: Alexandre Eremenko
Date: 2006 Jul 3, 13:48 -0500
Dear Red,
> Is your eyepiece filter just an inset or filter glass?
The back end of the telescope has a thread,
and this is where the eyepiece filter
(which is missing) should be attached.
The eyepiece filter should be a simple brass ring
with matching thread inside, and a piece of dark glass.
You can see the type of sextant I am talking about on
http://americanhistory.si.edu/collections/navigation/object.cfm?recordnumber=1197881
and
http://americanhistory.si.edu/collections/navigation/object.cfm?recordnumber=1197882
In the pictures you see telescopes sticking
out of the cylindric sextant body.
On the back end of this telescope a filter should be screwed on.
The diameter of the telescope is less than 1 inch.
> complex no doubt?) Can you point me to a URL where I can see a similar
> instrument on the web?
> Perhaps because they were manufacturing their
> new frame instead of sticking to
> the old type similar to C&P?
The story mentioned several times on this list
was that they tried to stick to the traditional
process of manufacturing a brass sextant frame whose purpose
is to relieve inner tension in the material.
The process was very complicated and the price of a sextant
was more than $2000 at the tame they had to discontinue the manufacturing.
> That is, you splurge to buy one if you want one--but
> that's "want" with no true practical need.
Sure. I can buy a new Cassens-Plath for $1300 or so,
or something really nice and old on e-bay for about the same
price. The problem is that I take a risk in both cases.
The risk that the sextant will not be of the highest quality
I want.
(It took me almost 2 years of observations to conclude that the
new SNO-T, a sextant of high reputation, I bought 2 years ago,
does not perform according to its specifications, and moreover,
I had it checked by BOTH Freiberger and Cassens-Plath and they did
not find any defect. If Cassens and Plath tests their own
sextants by the same standards... how can I be sure that a new
Cassens+P performs better?)
But of course I understand your comparison with "Ferrari market".
It does not serve any practical purpose indeed. But people
have all kinds of weird hobbies. "Backyard navigation" is one of them.
Alex.
--~--~---------~--~----~------------~-------~--~----~
To post to this group, send email to NavList@fer3.com
To , send email to NavList-@fer3.com
-~----------~----~----~----~------~----~------~--~---
