The Tamron 70-200mm f/2.8 Di LD (IF) Macro Lens is a telephoto zoom lens that has a large maximum aperture of f/2.8 which remains constant throughout the zoom range. It also offers an excellent "close-focusing-distance" minimum of just 3.1' (0.95 m) throughout its entire zoom range, with a maximum macro magnification ratio of 1:3.1 at f=200mm. When mounted on an APS-C sensor size digital SLR camera, it provides a focal length equivalent of 112-320mm.
Di (Digitally Integrated Design) is a designation Tamron puts on lenses featuring optical systems designed to meet the performance characteristics of digital SLR cameras. Features like LD glass elements and Internal Focusing put this lens in the same category as the much bigger and more expensive professional Tamron lenses.
LD Glass
Two LD glass elements reduce various aberrations while minimizing the fall-off of light at the corners
Internal Focus
The lens neither extends nor contracts physically when focusing; all moving elements are contained within the lens barrel
Di Design
Digitally Integrated (DI) design lenses are designed to meet the performance characteristics of digital SLR cameras
Tripod Collar
The tripod mount (included), detachable in one touch, is made of magnesium alloy that reconcile lightweight and high rigidity, resulting in enhanced balance and ease of use in hand-held shooting