This Sigma 12-24mm F4.5-5.6 lens has a large variable angle of view from 122° super wide-angle (at 12mm/diagonal axis) to 84.1°. The 4 Special Low Dispersion (SLD) glass elements enable effective compensation of color aberration, which is a common problem with super-wide angle lenses. Features an inner focusing system that keeps the length of the lens unchanged while controlling aberration; a minimum focusing distance of 11" at all focal lengths; and it's equipped with a Petal-type hood to block out extraneous light. For use with Nikon cameras. 3-13/32" dia.