Tamron AF016NII-700 SP AF 17-50mm F/2.8 XR Di-II LD SP Aspherical IF Zoom Lens with Built In Motor for Nikon Digital SLR (Black)

This is the kind of lens that makes me wish Canon would understand their market better. Instead of putting out a 17-55mm zoom that everyone can afford, they put out a EF-S non pro lens at a pro price, which has serious quality control issues. Tamron, however, responded.

This lens is quite sharp. It could definately be used for professional purposes. Sharp at 2.8 and much sharper above. After using this lens, the 17-40mm L, as well as the new EF-S 17-55mm, I can honestly say that Tamron beat out Canon in their own game in terms of quality for the money. Great optics, great range, affordable, and a SIX YEAR warranty, as opposed to Canon's weak 1 year warranty. Buy me.

I tested canon 28-105 3.5-4.5, sigma 24-70 2.8, canon 50mm 1.8, canon 18-55 3.5-5.6. I would say this Tamron 17-50 2.8 is my dream lens. I bought canon 28-105 3.5-4.5 for the focal range but was very sad about its softness and returned it. Then I went to sigma. That's a huge, heavy lens and very solid. Based on reviews, it should be very sharp. however, it was not true in my case. No matter how hard I tried, I never got sharp image. I guess I was not lucky enough to have a good copy and returned it in one week. Finally I bought Tamron 17-50mm 2.8. It surprised me from the very first picture. The sharpness is as good as canon 50mm 1.8 prime, the benchmark. Contrast is very good and color too. 7 blade aperture makes very nice blur background. I care so much about sharpness so the lens is my taste. The focusing is very accurate and fast enough, even though not as fast as sigma. Now I never touch canon 18-55 kit lens, the difference is huge. It's true this lens has no IS. But for 17-50mm range, IS is not as useful as for tele lens. The price is excellent considering the top optical quanlity. Now I am feeling I am a pro. :)))

The reasons I choose this lens are:

1. widest angle in the class(most important thing for 1.6X cropping factor sensor camera
2. Very sharp and top quanlity glass
3. light weighted and small and easy to carry
4. 7-blade aperture makes nice background(if you own canon 50mm 1.8 II, you will see its 5-blade aperture makes harsh background)
5. big constant 2.8 aperture through the whole range
6. excellent price

Update: I really think this lens is a godsend to the enthusiast, it performs well and is very light and compact. Carrying this lens for hours compared to the more professional and better built, but heavier, Canon Lenses makes it worthwhile to use especially if you consider the saving you get with this lens.

This lens is probably the most interesting among all the wide angel lenses available to Canon crop DSLR users. It offers the best of everything except for a couple of things here and there. Best of all it's price beats all other lenses in that range. But before I start comparing it to other options here is a basic rating of this lens.

RATING: The lens is well built and surprisingly light and compact. It doesn't have the solid L feel but still has a firm feeling that inspires confidence while shooting. Sharpness is at par with other top quality zooms, so much so that at F8.0 and above it matches many primes. Distortion like chromatic aberration and vignetting are about average. Meaning you would probably have to stop the lens down to 5.6-8.0 to eliminate distortions. Focus is quick and right on though a little noisy. Overall, a very good lens.

RANKING: With all of the above in perspective how does it rank? Compared to Canon's 17-40L 4.0 I think the Tamron come on top. Here is a breakdown of the Tamron strenghts and weaknesses compared to the Canon 17-40L.

Strengths
1. Faster lens (2.8 vs 4.0). That can make the difference between taking the shot or missing in a low light situation.
2. It has a wider zoom range (10mm at the telephoto end).

Weaknesses
1. Flare and chromatic aberration control lags behind the 17-40L.
2. solid build but not as solid as the tank-like 17-40L. Some may find that slightly objectionable after using any L lens for many years.