Canon 17-55 f2.8L vs Tamron 17-50 f2.8 VC for 7D

[Section31]

I just bought my wife a canon 7d, an upgrade from an XS. I want to buy her a nice lens for it, looking at these two lenses. They seem similar as far as specs go, but a huge price difference. Can you guys offer some advice please.

Much appreciated.

[sbsbennett]

I have the Tamron and love it. It is noisier than the Canon, but tack sharp. I use for portraiture quite a bit. Pretty versatile for landscapes as well.

Steve

[shnitz]

Image quality with the Tamron 17-50mm, or the new Sigma 17-50mm f/2.8 OS for that matter (not the older 18-50 as much), is pretty respectable. Definitely worth the price for many people. This website, while not the end-all as far as lens tests, is well-respected and considered to be balanced:
Canon 17-55mm
Canon EF-S 17-55mm f/2,8 USM IS - Retest @ 15mp / Review
Tamron 17-50 VC
Tamron AF 17-50mm f/2.8 SP XR Di II LD Aspherical [IF] VC (Canon) - Review / Test Report
As the reviewer notes, the previous version of this lens, the non-VC version, is optically better. Tamron tried to update their lens by just adding it as a feature, instead of restarting from the ground up, and it has led to some issues. Sigma, on the other hand, has a new lens that is completely better in every way than their old lens. I have the non-VC version of the lens, and I love it and see no reason to step up to the name-brand version.
-Sigma 17-50
Sigma AF 17-50mm f/2.8 EX DC HSM OS - Review / Test Report

VC, OS, and IS are all just different terms that mean image stabilization

[arich]

This is one of my absolute favorite lenses and it kills me that its EF-S. I always refer to it as razor sharp.

7D: 2.8, 1/2000, 1600ISO

[photo_day]

I am very glad I bought Tamron 17-50, I would recommend to everyone.