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    Re: Hello and a question about polarizer sun filters
    From: Geoffrey Kolbe
    Date: 2016 Dec 7, 07:40 +0000

    On 6 December 2016 at 23:03, Wayne Hilliard <NoReply_Hilliard@fer3.com> wrote:
    Geoffrey, I can only presume that the manufacturer used the proper material as these were widely used in the Navy etc.

    ​One would hope so, but it is your eyes.... 
    Some filters I found on one particular WWII aircraft sextant, an A12 made by Link which were widely used in the US Airforce, were not up to the job and had to be replaced​. (The filters on other A12 sextants I have - I like the A12 sextant, or rather octant - are fine!)
    What other materials were used in sextants for shades. 

    ​Often, filters with different transmission bands, so a combination of filters that let though blue light and red light, for example, will let through not-much-at-all when combined. 

    Also I just realized that the book that was just delivered today was written by you!  The Long Term Almanac! Looks to be very interesting!

    ​Ah, a man of taste!

    Have fun...

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