The Tamron AF18-200mm F/3.5-6.3 XR Di-II LD Aspherical (IF) MACRO 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. 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.
XR (Extra Refractive Index) glass design reduces various aberrations to the absolute minimum and achieves remarkable downsizing at the same time. In addition, three hybrid aspherical lens elements and two LD (Low Dispersion) glass elements are used to accomplish effective compensation of on-axis and lateral chromatic aberrations, a critical factor to enhance the optical quality in digital photography.
Lens features Internal Surface Coatings (i.e., multiple-layer coatings on cemented surfaces of plural elements) and new multiple-layer coating technology on ordinary elements in order to minimize reflections that occur when light enters through the front element and to reduce image degrading effects caused by the imagers themselves.
The Zoom Lock prevents unwanted barrel movement when carrying the lens/camera combination. Design has been improved by adding a gold-colored band between the focus and zoom rings to enhance the appearance and make it stand out as a Di-II lens. The rubber patterns of the zoom and focus control rings have been improved at the same time to compliment the digital camera design style and to provide better handling.