Thanks. That's what I thought. Good reason the lens cost more.
Is the glass the same between lenses, say the 28-70 f2.8 and the
35-70 f 3.3-4.5?
No, they use different glass for different lenses. Most of the
time, the 2.8 lenses are the best they make (at least for zoom).
They use the best glass for these lenses, like ED (Extra low
Dispersion) and aspherical (although these aspherical lenses are
used in some cheaper lenses too). Also the optical design can be
completely different. For instance, the 80-200/2.8 has a
designed-in correction for chromatic aberation. A chromatic
aberation is really difficult to achieve. Most of the time they
need more lenses in the system then you normally would need for
just zoom and focus. Therefore you will find those "good" lenses
too be big and heavy.
It's probably not the best description of how it works, but I
believe it is close enough to try to explain the system.
--
The Duke of Jax
(
http://bellsouthpwp.net/o/r/oranje )