QUOTE(azrinarizz @ Jun 15 2010, 01:25 PM)
Sigma 18-200? I suggest you to try the sigma until you satisfied. Tried 5 copies and I gave up!
The lens suffer focusing problems and the sharpness is very moody. Sometimes this range sharp
Tomorrow the other range sharp. Some days, not sharp at all.

If you have the money, go for canon's 18-200 or the 18-135
Both are beautiful lens

true. as what azrinarizz said.
my most used lens, and I've been using the Sigma 18-200 DC OS since 2007!
the IQ can be so good until can be accepted in Shutterstock (damn picky people, more picky than all of you combined!)
http://www.shutterstock.com/pic-54736594/s...background.html but this was at 154mm la. if go 200mm then IQ cacat a bit liao.

and focusing i also kena many times liao, lock focus but no come out what i wanted.
it's still a lens that i don't sell off cos damn useful.
bear in mind i bought this lens in 2007 so there were no Canon 18-200 nor 18-135.
i haven't tried both Canon 18-200 and 18-135 intensively but did shoot a bit with them and thought that they perform better than the Sigma.
let's not forget also, Canon's 18-200 is f5.6 at 200 while the Sigma version is f6.3
given a choice, I'd say people should just get the Canon versions nowadays unless budget constraint.