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Message: <blockquote data-quote="henry link" data-source="post: 3347206" data-attributes="member: 6806">I totally agree about Zeiss marketing. They seem to supply ever less useful information.I've looked through everything I could find and still don't know what "Ultra-FL" means, but I'm sure it doesn't have anything to do with the HTultra glass types, which are just more recent HT glasses with even higher transmission (I think mainly in the UV). None of the HT or HTultras are FL types.Ultra-FL lenses might mean, as Lee suggested, nothing more than the use of two FL lenses of the same type as the one FL lens in the HT or it might refer to the use of Schott's recently developed N-FK58 XLD, which has a higher Abbe number than the other two FL type glasses in the Schott catalogue. In either case, since the designs of the SF and HT binoculars are so different, it's impossible to know whether "Ultra-FL" affects an improvement or is just needed to prevent the CA performance of the simpler SF objective from being worse than the HT.Henry</blockquote>