whichlens.com - Lens Reviews

Specs:

If you are after a high quality wide angle zoom (<17mm) for under $1000, you have three choices, the Canon 17-40, the Sigma 17-35 and the Tamron 17-35. Please note, the Sigma 17-35 reviewed is the latest EX DG version, NOT the older version as pictured by Amazon. The EX DG is a better lens than its predecessor and uses a smaller filter size (77mm) as well. If you are willing to go over $1000, there is the Canon 16-35mm f/2.8L, probably the best zoom lens in this range, coming top of the pack in all the samples. We added this one in since you might be interested in seeing what extra bucks might get you.

At the wide end, the Canon and the Tamron are neck in neck in terms of sharpness at all apertures. Up until f8, the Sigma lags behind. At the telephoto end, the Sigma leads followed by the Canon then the Tamron.

The 50% crops are arranged Canon, Sigma, Tamron horizontally and f4, f8 vertically. On the wide crops, the Sigma and Tamron also have f2.8 crops.

Article updated with more crops and Canon 16-35mm f/2.8L:

Bokeh quality is a subjective issue, sample images are available.

Pros and Cons

All three lenses have their strengths, but I would give my vote to the Tamron as the best balance of price and performance. The premium for Canon will get you slightly better build and fast and silent USM autofocus but I can't justify the extra $200. The Sigma has silent HSM autofocus but it is painfully slow and is behind the others in terms of image quality meaning too. We are most likely dropping Sigma from the recommended lens list.

What else to consider?
For $1400, you could also include the Canon 16-35 f2.8, the 17-40’s more expensive and faster bigger brother. As you can see from the samples, the 16-35 is an outstanding lens if you can afford it. It has sharpness to rival primes and is f/2.8 through its entire range. If you were to count 18mm as wide angle, you could add quite a few more lenses onto the list such as the Sigma 18-50 f2.8. As for lenses not on the Whichlens.com recommended list, the Canon 17-85mm f/4-5.6 IS USM is a possibility but I would not consider the 17-85’s performance in the 17-35mm range on par with any of the lenses listed above.

Questions? Comments? To Mark please.