OT: Question for Royal Navy binocular grogs

[panzerwilly2]

Hello, I have a pair of Barr & Stroud 7X CF41 7X50 binoculars that I inherited from my Grandmother. She was married to a British Army Officer who served in WWII. I looked up the binocular's serial number and they were manufactured in 1945. They work wonderfully, but I have a question. They have a red, yellow, and green filter switch for both lenses. In what circumstances would each be used? Sun, fog, night etc... thanks!

[JeffroK]

Barr & Stroud 7X CF41 7X50

The green and yellow filters were meant to increase the contrast of a grey ship against a blue sky and sea while the grey filter was to flatten contrast when looking into bright sunshine or a searchlight beam. This information is thanks to William Reid's fascinating book, " ' We're certainly not afraid of Zeiss' Barr & Stroud Binoculars and the Royal Navy", ISBN 1-901663-66-3, NMS Publishing Limited (National Museums of Scotland), 2001.
https://www.flickr.com/photos/binocwpg/ ... 3234405689

[panzerwilly2]

Thanks very much! I'll take them house boating this summer and see if I can spot any U-boats

[JeffroK]

Treat them well, they appear to be worth a bit on the market.