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Message: <blockquote data-quote="Holger Merlitz" data-source="post: 3648200" data-attributes="member: 84262">Dear Gijs,Thanks a lot, so they found that an Al coating would almost eliminate that problem. P-coatings, however, as introduced by Zeiss in 1988, have always been dielectric. Obviously, the price of having 2 (Abbe König) or even 3 Al coated surfaces would have been too high to take, in terms of transmission losses. Most interesting seems another fact: The disadvantages of roof-prism binoculars, with their loss of resolution, have not prevented their success on the consumer market, on which they effectively eliminated the Porro binocular already prior to the introduction of P-coatings. Cheers,Holger</blockquote>