The Tamron SP AF17-50mm F/2.8 is a lightweight, compact, fast standard zoom lens that features the Di-II design, which means it is exclusively for digital SLR cameras. Portrait shots are made beautiful with the natural out-of-focus effect characteristic provided by the fast F/2.8 aperture. Additionally, a broader photographic expression through the use of faster shutter speeds as a result of the maximum aperture offers enhanced photographic pleasure. The lens boasts one of the best close-up shooting performances in the class of fast standard zoom lenses and features an F/2.8 maximum aperture throughout the entire zoom range, to ensure stress-free photographic shots at all focal lengths and distances. The Minimum focus distance of 10.6 inches makes it easier than ever to enjoy the creative combination's of wide-angle and macro photography. Superior images can easily be achieved because of the workmanship in the construction of lens by the use of three elements of XR (Extra Refractive Index) glass, two Hybrid Asperical lens elements and one element of LD glass. The LD (Low Dispersion) glass element effectively compensates for chromatic aberration and provides high-contrast and outstanding image quality. The SP means the lens is from the Super performance series which provides high performance through its' outstanding design specifications. The special internal surface coatings eliminates the ghosting and flare. The result is a product to ensure that you get the superior performance you need from your digital camera.