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Message: <blockquote data-quote="kabsetz" data-source="post: 1427894" data-attributes="member: 10167">Just a note,The quote in Dennis' post #16 above, from the astronomy forum, discusses differences between crystalline fluorite and "ED-glass" -types, as the fellow clearly states. It has no bearing on the potential similarities or differences between the Zeiss FL binoculars and the Chinese ED binoculars. As far as I know, crystalline fluorite is not used in any birding binocular model by any make. In spotting scopes, it is used by Kowa in the 823/4 and 883/4 models. For their binoculars, Zeiss states that in the FL series they use optical gass containing fluoride. Among "ED" glasses, there are several types available and being used, and manufacturers usually do not offer much if any information on just what glass types they use. Even if they did, we could hardly predict the final image quality very accurately from the data since there are so many factors influencing it. From what I have read on the net, the Chinese ED binoculars use an optical ED glass manufactured in China and available there for local optics makers for a very competitive price, thus the low pricing of these binoculars. But, I don't know what the optical properties of this glass are. If somebody does know, it would be interesting to hear it (Kevin P. perhaps?).As far as benefits/lack thereof of using "ED" objectives in binoculars, I'm rather in agreement with Dennis. Of all the binoculars I have used, tested or tried (and even owned, although this last group is rather small compared to many who contribute on this forum) I have definitely most enjoyed the ones that attempt better-than-achromat color correction. The image I see in the couple of Hawke ED's I have tried does have a color purity similar to what the Zeiss FL offers to my eyes. But there are plenty of people who do not see or notice differences in chromatic aberration levels and seem to be entirely happy with non-ED binoculars.Kimmo</blockquote>

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