A versatile wide-angle zoom for Canon APS-C-format DSLRs, the AT-X 11-20mm f/2.8 PRO DX Lens from Tokina offers a 17.5-32mm equivalent focal length and features a constant f/2.8 maximum aperture for maintained brightness throughout the zoom range. One P-MO hybrid aspherical element and two glass-molded aspherical element work in tandem to minimize distortions and control various aberrations while three SD ultra-low dispersion elements reduce chromatic aberrations for increased clarity. A multi-layer lens coating has also been applied to further enhance overall light transmission and color accuracy by suppressing lens flare and ghosting. Well-suited to working in a wide variety of situations, this ultra-wide zoom covers an array of wide-angle perspectives while maintaining consistent illumination for working in challenging lighting. Benefitting the usability, a one-touch focusing clutch permits quick switching between autofocus and manual focus modes, and an internal focusing design maintains the overall length of the lens during use. The medium-torque focusing ring further benefits precise handling by allowing for refined control when manually focusing. Additionally, this lens sees the incorporation of a nine-blade diaphragm, which contributes to a pleasing out-of-focus quality when employing shallow depth of field shooting techniques.