180mm 1:1 Di macro 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. A focal length of 180mm, 1:1 (life-size) macro reproduction, a fast, constant F3.5 maximum aperture and an optical formula featuring two LD (low dispersion) glass elements combine in a lens perfectly suited for extreme close-up shooting with an extended front element-to-subject working distance. The SP 180mm F/3.5 Di's characteristics also lend themselves to indoor, close-range sports shooting and beautiful environmental portraiture. A special FEC (filter effect control) function reintroduces ease to the use of a polarizing filter. Canon and Nikon mount-variants feature a focus ring with instantaneous switching between auto and manual focus for fine-focus adjustment.