The Tamron AF 18-200mm f/3.5-6.3 XR Di-II LD Aspherical (IF) Macro 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 18-200mm f/3.5-6.3 XR Di-II is a high power zoom lens designed exclusively for digital SLR cameras using the more compact (APS-C) digital size image sensors. The focal length of this lens is equivalent to approx. 28-300mm in 35mm format.
Designed as an "all-in-one" lens, it will meet almost all photographic opportunities without changing lenses.
The 18-200mm zoom lens realizes an MFD (Minimum Focus Distance) of 1.5' (45 cm) over the entire zoom range by the employment of a new optical/mechanical design configuration. Since the maximum magnification ratio at f=200mm is 1:3.7, you can enjoy close-up photography easily and conveniently.
Note: 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.