Sigma 311306 is a versatile lens that offers both autofocus and manual focus capabilities. It features Sigma's built-in Hyper Sonic Motor (HSM) for quick and quiet autofocusing. To use autofocus, set the focus mode switch on the lens to the "AF" position. You can also manually adjust the focus by turning the focus ring. The lens also has a depth of field scale that helps you check the depth of field (the zone of sharpness) of your composition. Additionally, the lens comes with a lens hood to help protect the lens from scratches and damage.