NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Night shots useing refected light
From: Doug Royer
Date: 2004 Jan 30, 15:53 -0800
From: Doug Royer
Date: 2004 Jan 30, 15:53 -0800
Joel,my personal sextant is a Tamaya MS-733 and it always goes to sea with me.I ordered and picked it up in Japan many years ago.It has some customised features that a person can get only if ordered and bought in Japan.Look in the archives,early to mid '03,as I discribed it and the extras I got. Some of the Astra IIIB sextants may also have polarizing shades.I've used those while on duty and recall doing this very thing with one. Speaking of the Astra,I was in a local equipment store a few days ago when a Lt. and a Master Chief came in and bought 4 brand new Astras from the owner.I asked the M.C. about it and he stated they were being placed on 2 Navy ships getting ready to deploy for training.$480.00 each. -----Original Message----- From: Navigation Mailing List [mailto:NAVIGATION-L@LISTSERV.WEBKAHUNA.COM]On Behalf Of Joel Jacobs Sent: Friday, January 30, 2004 15:16 To: NAVIGATION-L@LISTSERV.WEBKAHUNA.COM Subject: Re: Night shots useing refected light Doug, You may have said earlier which sextant you're using with Polarizing shades. If you did, I missed it? I've seen some Japanese sextants fitted with them, but know of no others. To the best of my recollection, Tamaya never offered them, at least until 1979. Joel Jacobs ----- Original Message ----- From: "Royer, Doug"To: Sent: Friday, January 30, 2004 3:55 PM Subject: Night shots useing refected light > Peter,I can't explain what causes the phenominon you described.You are right > that the true horizon doesn't match the reflection.I've never done one from > a small vessel so I can't comment on if the height of eye has anything to do > with it either.It does appear mostly on those nights when there is little > breeze,seas are calm with clear atmospheric conditions. > On nights with the light from a 3/4 to full moon one can make out the > differance between the sea and sky even when the moon's altitude is fairly > high and quite a large number of degrees in arc either side of the moon's > azimuth.As the moon gets closer and closer to the horizon(setting and > opposite when riseing)the reflected line of light gets more and more intense > untill the moon's light is refracted enough and the white light turns to > orange. > Useing the polarizing shade,sometimes useing both the horizon and index > polarizing shade or a combination of all the shades if both the light of the > moon and the reflected light is strong,helps in seeing the black line you > mentioned.