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Message: <blockquote data-quote="kabsetz" data-source="post: 3665575" data-attributes="member: 10167">Dennis,You are jumping to conclusions here. The 10x42, according to Canon's own literature, has two "UD" elements in each optical tube, one as the middle element of the three-element objective lens, and the second in the eyepiece. To my knowledge, fluorite crystal is not mentioned anywhere in context with the binocular. UD is a bit ambiguous designation, but typically whenever fluorite crystal is being used, it is pronounced so loudly that you cannot miss it - not hidden between the lines.Also, as has been implied in some of the posts in this thread, HD or Fluorite does not increase light transmission. Yes, it is typically only used in some of the most sophisticated optical designs, which typically also have premium multi coatings and therefore high transmission, but there are exceptions such as Kowa, which does use true fluorite in some of their optics but does not have as high transmission as some other optics such as Swarovski that don't use fluorite crystal lenses.Kimmo</blockquote>