Tokina AT-X Pro 28-70mm f/2.6-2.8 SV DU is an exceptionally fast standard zoom lens with razor sharp optics and constant lens speed for most autofocus 35mm SLR cameras. The internal focusing lens employs a constant f/2.8 aperture enabling focusing and shooting in low light conditions. The internal focusing combined with Focus Clutch mechanism yields quick and silent autofocusing and smooth manual focus. This lens features enhanced multi-coating and High Refraction Low Dispersion glass to improve contrast while reducing flare and ghosting. In addition, the lens features One-touch Focus operation, 16 elements in 12 groups, eight blade diaphragm, 75.3-34.3° viewing field, 0.7m close focusing distance and 77mm filter thread.