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02/26/2005 09:36:29 PM · #1 |
I just wanted to pick someone's brain. Looking at the Canon website and at this 70-200mm lens. I noticed thath the f/4L has a Fluorite element and 2 UD Elements. However the f/2.8 has 4 UD elements. From what I have read, I thought that the fluorite elements were better.
I also read from a Canon brochure that 2 UD elements almost eqaul the performance from 1 fluorite element. I know that there is a method to the madness. I'm just curious as to why they wouldn't use the fluorite element in the more expensive lens?
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02/26/2005 09:41:52 PM · #2 |
Just a guess, but it may be that the slower (f/4) lens makes the use of fluorite a bit more economical, since the fluorite element will be smaller.
The f/4 version is at least as good, possibly a bit better optically than either of the f/2.8 versions, by the way. It's about as good as a zoom gets. Not that I regret going with the 2.8 version, after all, that extra stop is a big deal.
All in all, I'd rather avoid fluorite. Think of it as a crystal of salt, which is exactly what it is (calcium fluoride). Fluorite elements are therefore somewhat delicate.
Message edited by author 2005-02-26 21:42:57.
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