I suppose he's not meaning tinted Reticle Glass, which to be bring up as kinda sunglass. He means a Filter like
for Nightfighters there where Filters like this availlable, it could be easily attached over the the Revi-lens itself.
Fl.52119 Rotscheiben-Linse
- Nachtjagdversion Revi C/12D.
http://www.cockpitinstrumente.de/instrumente/Flnummern/52000-52999.htmhttps://www.sas1946.com/main/index.php/topic,10911.msg118458.html#msg118458I applied to my Nighfighters were I could in the.mats (Uhu, Bf110G-4...)
These Red Filters are documented to be in use (Books about nighfighters in lw service etc.) , but I never heard or read them being availlable in Blue or Green? Doesn't make sense for me. As I'm a hobby Photographer with my own small labor I can only suggest a Red filter in the darkroom when I work with b/w cold film developping. For colour you can use red, but I have old AGFA Filterplates for my lamp in Yellow-Green and Orange, which are marked as special Filters for colour-film laboratory. For photography there are plenty filters availlable in different saturations Yellow, Orange, Red, Green, Blue, gives some nice effects if used the right way, i.e. Orange in hazy wheather.
Do you have a source for those Blue or Green filters?