9 out of 10 points and recommendedPrime like sharp images, Fast Zoom, Smooth, Light weightNo silent motor & little more plasticy
The Tamron AF 17-50mm f/2.8 SP XR Di II LD Aspherical [IF] is a very serious performer capable to deliver very sharp images at all focal lengths. Vignetting and distortion are about average for a lens in this class. CAs are a bit on the high side towards the short end of the focal range.reviewed May 17th, 2012 (purchased for $350)
Unfortunately the lens suffers from strong field curvature at 17mm which may push the corner portions out-of-focus. The level of distortion is about average in this class whereas vignetting and lateral CAs could be somewhat better.
Mechanically the lens isn't top notch but it compares very well to other lenses in this price class. Thanks to the very moderate price tag the lens is highly attractive and definitely worth a deeper look when shopping for a quality standard zoom lens for any APSC DSLR and it's also a very interesting alternative to the genuine OEM standard zooms.