there are "some" who are "L-itists" who can't see anything beyond a
white lens or a red ring or USM. They have brand-blindness and
will accept no evidence to the contrary because of their misguided
presuppositions. There are a few others (besides myself) who have
used BOTH the Canon and Sigma 24-70 lenses for a "substantial"
amount of time, often with various copies and many tests, unlike
some of the posters here. For example, SaltLakeGuy went through 7
copies of the 24-70L and gave up (now has the Tamron 28-75 and
loves it, although he concedes his 24-70EX was the sharpest wide
open but it had focusing problems). Pepe Lepue uses the 24-70L but
has high regard for the Sigma version and has done some good tests
on them. Eugene Powers has both the Canon and Sigma 24-70 on his
1Ds and says the Sigma is 95% equal to the Canon. These are the
kinds of people you want to listen to who can find pros and cons of
EACH lens and offer helpful advice. In my case my current 24-70EX
is the best optically I've had, and that includes being better than
ANY of my previous 3 24-70Ls. Of course, it lacks HSM and
weathersealing, but it also costs over 70% less. It is give and
take, but it is hard to beat the Sigma 24-70 in terms of
price/performance.
Take everyone's advice with a grain of salt, including mine. At
day's end, given a good copy of any of these lenses will provide
you with years of satisfaction. Best wishes. I'm done with this
thread.
--
http://www.pbase.com/fstopjojo/lenstests
“98% of all lenses are better than 100% of all photographers.”
Michael Reichmann