The Tokina Opera AF 16-28mm f/2.8 FF is the perfect super-wide angle zoom lens for photographers who specialize in landscape, architecture, documentary, environmental portraits, and night sky image captures. With a constant f/2.8 aperture throughout the entire zoom range, the lens provides excellent sharpness and improved contrast suitable to today’s high-resolution cameras. This model is specially designed for use with Nikon F mount cameras. The lens uses an improved auto-focus system for fast and accurate AF and maintains the exclusive one-touch focus clutch mechanism for easy switching between AF to MF. Additionally, the directional rotation of the focus ring matches the proprietary direction of Canon lenses. Image Quality The lens incorporates a complex optical design, with 15 elements in 13 groups. Using three aspherical lenses including a large aspherical P-MO element and 3 all-glass molded Low-Dispersion (SD) elements, the lens effectively suppresses chromatic and spherical aberrations. The large front element provides super-low distortion and low light fall-off for straight lines and minimal exposure vignetting – perfect for architectural, landscape, and astrophotographers. One-Touch Focus Clutch The new 16-28mm f/2.8 FF is designed for a great user experience and to give photographers the confidence to create beautiful images. The lens includes a newly designed Silent Drive module using new GMR magnetic auto-focus (AF) sensors for faster, smoother, and quieter AF than the previous generation. The One-Touch Focus Clutch Mechanism makes switching from AF to manual focus (MF) simple. While in AF mode the user only needs to snap the focus ring back toward the camera to engage “real” manual focus control. This gives the photographers an authentic tactile MF feel with hard stops on either side of the focus range like traditional manual lenses.