The Tokina 12-24mm f/4 AT-X 124AF Pro DX II Lens is exclusively designed for use with SLR cameras that use the smaller APS-C size sensor. This lens provides a super wide-angle zoom range, ideal for the tightest of interiors, as well as for dramatic landscape photography. This updated inchIIinch version benefits from improved multi-coating technology, which helps to reduce reflections that can cause flare and ghosting. The Focus Clutch Mechanism feature - a signature of Tokina PRO series lenses - provides a faster, smoother autofocus operation, with a smooth manual focus action not normally found in autofocus lenses. Two aspherical elements are incorporated in the lens design, to correct for spherical aberrations. It also incorporates internal focusing to prevent deterioration of the optical quality at close distances and to eliminate rotation of the front barrel during focusing. Equivalent focal length in 35mm terms when used on a digital camera is 19-38mm. Note! NOT recommended for 35mm film or digital inchfull-frameinch SLR cameras ? Fast, ultra-wide angle zoom lens with a constant f/4 aperture ? Two aspherical lens elements minimize distortion, especially at the periphery, for superior optical performance ? Fast internal focusing with the one-touch Focus Clutch Mechanism ? Long focus travel for easy, accurate manual focusing ? The rounded diaphragm opening (9 blades) makes out-of-focus elements appear more natural