atx-i 11-16mm f/2.8 CF from Tokina is a versatile ultra-wide zoom well-suited for landscape, architecture, and interior shooting. Characterized by its bright f/2.8 constant maximum aperture, consistent brightness is afforded throughout the zoom range and benefits working in available lighting conditions. The optical design incorporates a series of aspherical and low dispersion elements, which suppress a variety of aberrations for improved sharpness and clarity. Individual elements are also multi-coated to resist flare and ghosting for greater contrast and color accuracy when working in bright or backlit conditions. Complementing the optics, this lens features a One-Touch Focus Clutch Mechanism for fast changing between AF and MF settings, and an internal focusing design is used for responsive focusing