Features:

• The 11-20mm has a new proprietary optical design that uses three aspherical lens elements (2 all-glass molded and 1 P-MO lens). Three SD (Super-low Dispersion: FK01 and FK03) glass elements achieves superior contrast and sharpness, and corrects for spherical aberrations.
• This compact ultra wide-angle zoom lens has a bright, constant F2.8 aperture making viewing and auto focus possible in low light situations but still maintaining portable size and weight.
• Tokina’s exclusive One-touch Focus Clutch Mechanism allows the photographer to switch between AF and MF simply by snapping the focus ring forward for AF and back toward the lens mount for manual focusing. The lens is also designed to stand up to the rigors of daily use by photographers in a wide variety of shooting conditions and environments.