NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Peter Fogg
Date: 2006 Jan 25, 13:46 +1100
Which sextant is this, Mike?
Did the polarising filters come as
standard? If not, how did you add them?
From:
Sent: Wednesday, 25 January 2006
1:28 PM
To:
NAVIGATION-L@LISTSERV.WEBKAHUNA.COM
Subject: Re: Sextants with
Polarizing filters
I use a sextant with a polarising filter on both the index and the
horizon glass. They provide excellent filtering and I often use them alone - no
other shade glasses. They are, as has been noted easily adjustable so it's easy
to get specific brightnesses. This is particularly good when doing lunars - you
can balance very easily the relative brightness of the other object with the
moon.
It is important to note however that even good polarisers change the index
error when used. I know that the manuals say that this can happen with any
shades but I have only ever measured it with polarisers - maybe it has to do
with the two pieces of glass in each filter. In any event IE must be measured
with the filters in place - orientation does not seem to matter.
Regards
Mike
