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Message: <blockquote data-quote="brocknroller" data-source="post: 3309185" data-attributes="member: 665">Being that some people think CA does not exist or does but is a “non-issue,” I wonder why more and more roofs from entry level to mid-priced to alphas contain ED glass these days? I guess it must be a fashion trend, or at least it must seem that way to those who can’t see CA or who are not bothered by it. Those who do see CA and who find it distracting know why many modern roofs have ED glass (though, as the mentioned in the OP, it doesn’t always work perfectly for everyone). Obviously, it can't be a small minority who are bothered by CA, otherwise, sports optics manufacturers wouldn't bother to use ED glass. At the heart of it, the reason binoculars show CA is that they are "fast" optical systems, and the higher the magnification, the more you're likely to see CA. With roof prism binoculars, there's also another reason. Optics experts have commented on these forums about why internal focus roofs, particularly those with a negative lens focusing elements, exhibit more CA than earlier roofs with external focus. I didn't read that the SuperDuty wears glasses, but Mark makes a valid point about polycarbonate lens eyeglasses. I used to have them and they added gobs of CA. They're convenient because the lenses are light and thin, but they're not good for use with optics if you're bothered by CA.Pily also makes a good point in that as we grow older our eye lenses deteriorate (harden, grow cataracts), and that, too, can add CA to the view.However, the fact that SuperDuty sees more CA in one ED roof than another ED roof suggests that it's not his eyes so much as it is the optical design of the binoculars. Not all ED glass is created equal, nor does ED glass work with all optical designs equally well, and as Bill said, if you want to suppress CA, you might end up with other optical properties or aberrations that might be undesirable.What Steve suggested is the best solution, if you are distracted by CA, put CA suppression at the top of your list of attributes you desire in a birding bin, and try to live with the trade-offs.Here's a list of bins that I found suppress CA well in the centerfield for my eyes: Celestron 10x50 Voyager EDNikon 8x30 M7Nikon 8x32 SESwarovski 10x42 SLCZeiss 8x32 TerraZen Ray 7x36 ED2The best out of these was an $1,800 roof, the 10x42 SLC, which despite my best efforts, I could not get to show CA in the centerfield under the most demanding conditions. So it's not that they can't make a $2000 roof with good CA suppression in the centerfield (and with 10x, no less), it's that you have to try different models and find out which work best for you. Brock</blockquote>

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