NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Basics of computing sunrise/sunset
From: Hein Bodahl
Date: 2009 Jun 19, 10:47 +0200
From: Hein Bodahl
Date: 2009 Jun 19, 10:47 +0200
On 18.06.2009 19:49, Brad Morris wrote: > Hi Douglass > > I use a sextant from about 1920. A wonderful device, identical to the one used by Worsley on his famous boat journey. > > Should I be worried about the filtering qualities of my shade glasses? > > Would there be a way to check to see if my shade glasses are up to the mark? > > Best Regards > Brad If you got a digital camera you could probably use a IR-pass filter to take a picture of the sextant filter with a sunlit background. If it blocks out IR the sextant filter would turn up dark in the picture on long exposures. IR-pass filters go for about than $15 on ebay. I guess 650 or 720nm is a good choice. Hein --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---
