Been looking at TAK FSQ's and trying to decide if I want a Fluorite version or the new ED version. I have read advantages of both but I found an article on Takahashi's site and this is what it said.:
If you seek optical and mechanical perfection in a truly modern telescope, look no further. Takahashi is the answer. Other telescope manufacturers may claim that ED (Extra-low Dispersion) glass is the equivalent of fluorite or that their older designs will work as well. Unfortunately, they are not being honest. While ED and fluoro-crown lenses can achieve Abbe-coefficients approaching fluorite, they tend to absorb more light in the visible spectrum. This means that fluorite yields a brighter, higher contrast image. Leica, Zeiss, and Kowa have all gone to fluorite in their spotting scopes and telescopes to achieve the maximum performance levels their customers demand. Most of them previously used ED glass. Obviously, they know the difference between fluorite and ED. You will too. Takahashi pioneered the use of fluorite in astronomical telescopes and they are still the leader. Accept no substitute. Get the fluorite advantage. Get Takahashi!
Now I have heard that part of the reason they stopped using Fluorite is due to environmental reasons, but that can't be true, being TAK still produces Fluorite scopes. I am just curious if they actually found a better way with ED glass to where it truly is a better color correct glass. Not trying to bash the new Q's I am just wondering why if Fluorite was such a great glass and to read from TAK itself, why they would switch. Seems they are now not being "Honest".
Never really found a good discussion about this online.
So let the debate begin.