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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Night shots useing refected light
From: Joel Jacobs
Date: 2004 Jan 30, 18:16 -0500
From: Joel Jacobs
Date: 2004 Jan 30, 18:16 -0500
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.