9 out of 10 points and recommendedFantastic sharpness and over all image quality!!!hard to find, some CAs at 17mm, noisy AF... nothing signifficant
First of all I have to say that I feel so sorry for those who got a bad copy of this lens. This lens is simply fantastic! It works perfectly on my EOS 30D and since I got it in December 2008, I am more than satisfied. What I have noticed after using it for some time, I completely stopped using the sharpen function in my photo-editing software.reviewed September 29th, 2009 (purchased for $250)
Yes, it has some minuses; first regarding image quality, there is some visible distortion at 17mm, but it is not anything to really worry about. Still it is better than most other lenses at 17mm.
Also there are some CAs at 17mm, but also nothing that significant.
Mechanical part, the front ring turns during AF focusing. I think it is no problem to get used to, I consider it negligible.
The AF is noisy, well, unless you are a spy, who cares that it is noisy. Zooming is not very smooth, well, since it does not effect the image quality, I don’t care.
The built quality, of course it is not like Canon L, Tokina Pro or Sigma EX, but it is good enough. If you are not a professional who throws their equipment around and if you take at least some care about your equipment, there is no problem. I am a big tourist and cyclist, I take my camera with accessories everywhere. I have a special camera bag (case) specially attached to the handle bars of my mountain bike (which by the way is an excellent case, you can take out and put back in your camera very quickly). Of course the inside of it is filled with soft material. I have been riding in any heavy terrains with my camera + the Tamron 17-50 attached since I got it and no problems. If by chance it does break, it is not as expensive as many other lenses.
It’s range, if it can be considered as a disadvantage, yes it could be better. But greater range = lower image quality. Simply, you can’t have it all. Beside the distortion + a bit of field curvature and CAs, all the rest is negligible to me. Really, over all important is the image quality.
Now for the pluses; AF speed, I was so afraid that it would be slow and I was very pleasantly surprised. Of course it is slower than USM which I was used to, but it is by far not as bad. I have no problem catching moments.
Its whole range is F2.8, simply that is always an advantage in lower light conditions.
Sharpness in the whole range is really superb! Regarding this parameter, this lens is a true masterpiece. How to describe it... center sharpness (and smoothness) is totally excellent, a bit farther from the center, still excellent and far edges... almost excellent (at 17 and better further on). A huge plus is that the difference in center and edge image quality (sharpness) is really small compared to most other wide angle-zoom lenses. Another big plus, Most other lenses that start at F2.8, the picture quality at 2.8 is significantly worse than at higher F-numbers. This Tamron, it is only slightly worse and unless you look really closely, you can consider that difference as negligible. Also a plus regarding this, most wide angle-zooms reach their best performance at F8-11, what can be very limiting in many situations. This Tamron, it is best at F4-5.6!
Bokeh (out of focus blur) is quite nice for a wide-zoom lens.
Flare is very well controlled.
Vignetting is small, nothing to really worry about.
Compatibility with internal flash, in total darkness it is slower, the flash must pre-flash up to about 2 seconds in some cases for the lens to focus, but in the end it is accurate. Compatibility with external flash (I use Canon EX 430) absolutely no problem, always fast and accurate.
My conclusion; the image quality is one of the best from among all wide angle-zooms ever built. I took pictures at events where other photographers used Canon L lenses (17-40 and 24-70) after comparing our photos, not a dramatic difference, but the image quality of my was visibly better! Considering the almost funny price I bought it for... no comments. I am not a professional, but I am very sensitive to image quality. Image quality is over all most important. Everything else comes in second place and that is what this lens is about. My final words: HIGHLY RECOMMENDED!!!