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Message: <blockquote data-quote="Binastro" data-source="post: 3366934" data-attributes="member: 111403">I don't remember measuring any Pentax 6x7 lenses, so I don't know. Kodak Aero Ektars 7inch and 12inch f/2.5 for 5x5 K24 camera and 9x9 inch. 7 elements. elements 5 and 6 thorium glass.Rare 8inch f/1.5 also. Very heavy night lens.Many Kodak lenses contained thorium glass. Also many other makers.Some of the large approx. 40mm focus Kodak eyepieces were radioactive, some not.Possibly some shorter focus also?Rare old Minolta MC fitting 100mm f/2 lens is radioactive.Nikon, Minolta, Zeiss, and Leica lenses only rarely used radioactive glass. I didn't find any Russian ones.Usually 50mm and less as stated. More often rear lenses. It is possible the daughter products may be more radioactive after time.The white reflections on the Aculon are either uncoated, or cemented surfaces.Only the coloured reflections are coated surfaces.I don't think the prisms, which have flattish reflections, are coated either, so not 90%, probably 70%.But still very useful binoculars.Even some old 7x50 uncoated Leitz binoculars give lovely views because of careful design and  very high quality optics.Some Porroprisms, even cheap ones are 90% if fully multicoated correctly including prisms.</blockquote>