Unfortunately, lens design isn't as easy as 1-2-3.
There are always trade-offs in lens designs, especially
in zoom lenses.
Constructing a well corrected lens (or even an "L" lens)
gets more difficult at extreme maximum apertures. Features
like internal focusing and two-touch zoom just add to the
challenge.
Correcting for a small center part of the front element
is easier and less expensive than correcting for the full
size of the front element.
Lars
> What's the advantage of having a constant aperture zoom then? Aren't we
> losing useful aperture at the shorter end if we are limiting ourselves to
> the center?
>
> confused,
> -e
--
Lars Michael [EMAIL PROTECTED]
87GT http://www.larsmichael.com/
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