Derk,
From WW II through the 1970's anti-reflective coatings on binoculars were made of extremely thin layers of Magnesium Flouride which gave the objective (front) lens of the binocular a dark blue color. If you examine the objective lenses of your Bausch & Lomb Zeiss and Kershaw Binoprism No. 2 Mk. 2, they should appear clear because these binoculars did not have anti-reflective coatings. I'm pretty sure the lenses of your REL 7X50's are coated, and I think that they will look a lot more blue than those of the two earlier made glasses. I'm not so sure about the monocular, however. Does the color of its lenses look more like those of the REL or the Kershaw? Also, the early anti-reflective coatings on binoculars were fairly soft so it is not unusual to see rub markings on the interior of the lenses caused by careless cleaning. Unless severe, these usually don't noticeably affect viewing. Modern anti-reflective coatings, by the way, usually have a brown/gold or greenish color.
Frank
|