Информация в оригинале от известного авторитета в Новом Свете по ED-HD стеклу и птичника.
I think Newfie probably holds the record for starting new threads, but at least he didn't get run off by the troll monitor like another newbie did last year whose only "crime" was his abundant enthusiasm and curiosity about binoculars.
His question seems like a legitimate one, and harkens back to early discussions I've had on BF about how reports of CA seemed to pick up markedly at the turn of the century as more and more roofs were designed with internal focusers and lead-free glass.
After reading some technical reports by Ohara, a major Japanese optical glass maker, on how their early attempts at making lead free glass were unsuccessful, in that they were not on par with the lead optical glass they made, and that it took some time and experiment to come up with the right combination of cost-effective lead substitutes to get their lead free glass "almost as good" as their lead glass, I began to think that lead free glass was the culprit behind the increase in CA reports, particularly after noting the increase in CA in the Nikon HGL vs. the HG.
In a rare moment, Henry "speculated" that the internal focusing elements might be the culprit rather than the lead free glass. This was plausible to me, because before ED glass, I had always noticed more CA in the roofs I've tried than porros of similar quality.
Then there was a pile up of naysayers on how lead free glass was just as good as lead glass, with Abbe numbers to prove it.
Of course, what these posters missed was that my suspicions were about early lead free glass, not the lead free glass in current production.
The matter of what caused the uptick in CA reports in the early 2000s (Stephen Ingrahm was even blamed) was never resolved, although, as mentioned, more recent Abbe numbers from Schott and Ohara proved that if any subpar lead free optical glass had been used, the latest lead free glass was up to par with lead glass and was not the culprit.
It became a moot point because now many manufacturers use ED glass to their roofs.
However, as Henry and others have pointed out, not all ED glass is created equal. Some are better quality than others, and this also shows up in the numbers. But AFAIK, only one company, Minox?, reveals the type of ED glass they use. So it's impossible to objectively compare one to the other.
What you're left with is subjective observations about bin A controls CA better than bin B, but since other factors beyond the ED glass can contribute to an increase in CA, it's impossible to know what role the quality of ED glass plays in this.
However, speaking from experience, the ED bins I've owned or tried at length, which included the Celestron 10x50 and 9.5x44 ED porros, Swift 8x44 ED and 804 Audubon ED, Promaster 8x42 ED, and ZR 7x36 ED2 all did a better job at controlling CA than the non-ED bins in similar configurations that I compared them with.
Of particular note was the 10x50 ED, which showed no fringing around crows perched on tree limbs against bright, gray winter skies. The ZR 7x36 ED2 also presented a very clean image in the centerfield and to a good degree out from center.
But to get to newfie's question, beyond reducing annoying color fringing, the big advantage of ED glass in the improvement in color saturation and contrast. According to the experts, about a 15% increase, enough for the discerning eye to see the difference.
For me, ED glass enhances my birding experience. However, if Nikon added ED glass to the SE, the image would be so sharp, it might cut your eyeballs.