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Message: <blockquote data-quote="henry link" data-source="post: 1428049" data-attributes="member: 6806">I see that this thread has been provided with a blizzard of cut and paste "information" with sketchy attribution and no links. Alas, much of it is marketing poop, speculatiion or irrelevant to the binoculars under discussion.Kimmo, I think we can be pretty sure that the ED glass in the Chinese binoculars is FK61 (Vd=82), which is reported to be as cheap as normal glass and made in large quantities by the Chinese glass producer CDGM. I recommend that those with an interest in "ED" glass types read a recent thread on the Refractor Forum at Astromart.com titled "More Schott FK61 Shennanigans" here: <a href="http://www.astromart.com/forums/viewpost.asp?forum_post_id=649964&poll_id=&news_id=&page=5" target="_blank">http://www.astromart.com/forums/viewpost.asp?forum_post_id=649964&poll_id=&news_id=&page=5</a>Roland Christen of Astro-Physics has posted some excellent information there and on other threads has dealt with the Fluorite vs ED question and many other topics. I'm sorry to say new visitors may have to pay a $12 registration fee to view the forums. I believe Dennis is already a member.When it comes to CA in binoculars we don't have to resort to speculation based on the little we know about glass types or design. The relative correction of longitudinal CA among binoculars is easily seen at boosted magnification (see the photos in post #1 of the thread below). Transverse CA is trickier, but can be evaluated in a controlled test with a target like the one seen in post #11 of the same thread.<a href="http://birdforum.net/showthread.php?t=134310" target="_blank">http://birdforum.net/showthread.php?t=134310</a>Henry</blockquote>

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