The Tamron SP 17-50mm F/2.8 XR Di II VC lens for cropped sensor digital cameras covers the very popular 17-50mm focal length range (equivalent to 26-78mm in the full-frame 35mm format ) making it extremely versatile. Its wide aperture provides practical advantages in low-light shooting & image control, giving you greater creative control. The 17-50mm f 2.8 XR Di II VC lens delivers impressive sharpness & contrast over its entire focal-length & aperture range, & at its maximum aperture of f/2.8 produces beautiful images with a shallow depth of- field & smooth, natural out-of-focus areas (i.e. excellent bokeh). The new lens is equipped with Tamron’s Vibration Compensation (VC) stabilization mechanism, which controls the effects of camera shake in three planes. The VC function, in combination with the wide maximum aperture, permits sharp h&-held photography, even when shooting in low-light conditions, giving you greater photographic freedom. Di II lenses are designed for exclusive use on digital cameras with smaller-size imagers & inherit all of the benefits of Tamron's Di products. These lenses are not designed for conventional cameras & digital cameras with image sensors larger than 24mm x 16mm.