The main update to this lens is in the Nikon mount, the AT-X 116 PRO DX-II has an internal silent focusing motor to allow the lens to AF on Nikon bodies that do not have an AF drive gear and motor. 

There have also been some adjustments made to the coating for slightly improved optical performance. 

This compact ultra wide-angle zoom has a bright constant F2.8 aperture make viewing and auto focus possible in lower light situations but still maintaining a reasonable size and weight. 

Two Super-Low Dispersion glass elements and two aspheric glass allow the proprietary optical design to achieve excellent contrast and sharpness as well as controlling chromatic aberration. 

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. 

Other than the optical coating change there are no changes to the Canon mount.  The AT-X 116 PRO DX-II for Canon uses the same AF motor and AF drive system as the the previous model.