The Tamron SP AF17-50mm f/2.8 XR Di II LD Aspherical [IF] Lens made for the Nikon SLR system incorporates a motor built into the lens itself, which gives it the capability to autofocus with all Nikon DSLR cameras (including the D40 and D40x). In addition, with the motor built into the lens, focusing will be quieter and more responsive.
The Tamron SP AF17-50mm f/2.8 XR Di II LD lens is a lightweight, compact, fast standard zoom lens designed exclusively for digital SLR cameras. The focal length of this lens is equivalent to approx. 26-78mm in 35mm format.
This lens offers an f/2.8 maximum aperture throughout the entire zoom range, to ensure stress-free photographic shots at all focal lengths and distances. Additionally, a broader photographic expression through the use of faster shutter speeds as a result of the maximum aperture offers enhanced photographic pleasure.
Di-II lenses cannot be used with digital SLR cameras using image sensors that are larger than that of an APS-C size imager, or with 35mm film SLR cameras.
Tamron 17-50mm f/2.8 XR Di-II LD Aspherical [IF] Autofocus Lens