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Message: <blockquote data-quote="Binastro" data-source="post: 3367487" data-attributes="member: 111403">The Aero Ektars with a yellow spot on the front near the serial number are factory coated.They made large numbers and had to have many coated by independent labs.First hard coated U.S. lenses 1940.There is also the 6inch f/2.5, not found I think in the U.K.And the enormous 48inch f/6.3.The K24 5x5inch camera is the U.S. version of the British Williamson F24, which used the Dallmeyer 8 inch f/2.9 Pentac, 5 inch f/4 Ross 6 element wide angle. Also 14inch and 20 inch and rare 3 1/4 inch or near EWA.The Kodak 38mm or so WW2 eyepiece was supposedly used on the 200 inch Palomar telescope. 75deg approx.Hard coated, some radioactive some not or minimally.</blockquote>