The Tamron 70-200mm f/2.8 Di LD (IF) Macro Lens is a telephoto zoom lens that is designed with a maximum aperture of f/2.8, which remains constant throughout the zoom range. This lens offers an excellent minimum-focusing distance of 3.1 feet (0.95 m) throughout the entire zoom range, and has a maximum macro magnification ratio of 1:3.1 at f=200mm. When used with an APS-C sensor size DSLR camera, it has a focal length equivalent of 112-320mm. Its Di (Digitally Integrated Design) features optical systems that are designed to meet the performance needs of digital SLR cameras. Its design includes LD glass elements, as well as Internal Focusing, putting this lens in the same category some of the more expensive professional Tamron lenses.