Canon 17-55mm or sigma 18-35mm ?

thamer08 wrote:

Curve ball, Sigma 17-50 f2.8 OS, fantastic lens, very comparable to the 17-55 (I've shot both side by side on a 7D), far less money.

thanks for your replay

sigma 17-50 also nice lens but it looks cheap build compared to canon and tamron also i read this lens has bad copies

This is so far from the truth it's just nutso to me.  The build of the Sigma is much better than the Canon.  The mediocre build quality of the Canon is it's biggest downside, the build just doesn't live up to the near 1000$ L price level. (though it's on sale now for 830$)

As for bad copies, I don't know about that, where did you read that someone took a large sample size of this lens and reported a statistical value for "bad" copies?  Or do you mean that you read reviews online?  I think there are more Sigma lenses with issues than Canon lenses, but I doubt it is by a huge margin.

I have not collected up 1000 of these and tested them either though, so there's that.  The couple of copies that I've used have been excellent, but that's of very little statistical relevance.  Up to you, but for my it was clearly the best lens I owned for my 7D, even better than my 70-200 f4, also true for a couple of close friends.  My one friend told me he was upset when he bought it because now he just doesn't use his other lenses.

The Canon is just as good (better in corners at f2.8, worse in the center), but larger, worse built, more expensive, and you buy the hood separately.  I think you'd be happy with either one, honestly, it's just that one is 830$ and the other 570$.