the tokina at-x 12-28 pro dx has a super-wide to semi-standard zoom angle as versatile photography. we gave a follow focus gear on such lens to make suitable videography more by dslr.
follow focus works effectively by making a focus ring having a clutch system on mf. the feel when manually focusing has moderate sense of torque in the focus ring, enabling precise focusing.
yabo亚博平台af/mf switching is accomplished by the simply sliding focus clutch ring forward and back on the lens barrel. when photographing normally (taking photos), auto-focus can be used.