200 to 500mm Di ultra telephoto zoom lens. The Tamron SP designation is reserved for lenses developed with special emphasis on extraordinary photographic performance. Engineers are free to innovate in an uncommon atmosphere where optical performance comes before price, resulting in lenses that satisfy the demands of discerning photographers. Extreme photographic conditions call for extreme, specialized optics. Distant and elusive wildlife, birding, team sports, motorsports and surveillance are just a few of the photographic conditions that demand both zoom versatility and extreme telephoto power. APS-C-sensor photographers will enjoy super-telephoto magnification, with a picture angle range approximating a 310-775mm lens on a 35mm film or full-frame DSLR. Featuring LD (low dispersion glass) to combat chromatic aberrations and an internal focus mechanism that maintains a fixed barrel length when focusing, the SP 200-500mm provides high telephoto magnification accompanied by the sought-after perspective compression effect that draws even greater attention to subjects. While not a small lens, when compared to other similar focal lengths, the SP 200-500mm is an easy choice for outdoor enthusiasts who often must hike great distances with their gear, in search of their subjects.