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Message: <blockquote data-quote="henry link" data-source="post: 3180188" data-attributes="member: 6806">I find the transmission numbers puzzling too. It's hard to account for the high transmission of the 30mm models or the differences between models with the same number of glass to air surfaces and the same prisms. Are the figures theoretical, based on the number of surfaces, glass thickness and coatings, or actual measurements? If measurements, then how many pairs where measured? Do they represent transmission at 550nm or the peak transmission wherever that occurs on the spectrum?I do appreciate the effort at a very thorough spec sheet. How many other manufactures supply any transmission figures at all or the number of elements and groups in their designs or both the storage and functional temperature ranges.Henry</blockquote>