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 and image control, giving you greater creative control. The 17-50mm f2.8 XR Di II VC lens delivers impressive sharpness and contrast over its entire focal-length and aperture range, and at its maximum aperture of f/2.8 produces beautiful images with a shallow depth of- field and 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 hand-held photography, even when shooting in low-light conditions, giving you greater photographic freedom.
Tamron’s Technical Terms
Tamron Di II Lenses
Di II lenses are designed for exclusive use on digital cameras with smaller-size imagers and inherit all of the benefits of Tamron’s Di products. These lenses are not designed for conventional cameras and digital cameras with image sensors larger than 24mm x 16mm.
XR Glass is a special type of glass with a high index of refraction. XR Glass allows for a more compact lens construction in terms of length and diameter, as compared to a lens made of customary glass with the same luminosity and optical performance. The focal length of an XR glass element is shorter than that of customary glass, so that the barrel of an XR lens can be shortened. As a result of the shortening of the barrel, the actual opening consequently becomes bigger and the lens diameter can also be reduced (see picture). The luminosity of the lens remains the same in spite of the smaller diameter.
The VC (vibration Compensation) mechanism is a Tamron development which ensures an effective compensation for camera vibrations. Especially hand-held, low-light and tele photography is susceptible for camera shake and consequent blurred results, due to the required longer shutter speeds. Under these photographic conditions the VC mechanism can unfold to its full efficiency.