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.