The Feather Touch Zoom Motorized Controller from Camera Turret is used for slow and smooth zooming of a DSLR lens. It is controlled by eight 100 MHz microprocessors in a chip, doing over 100,000,000 instructions/second. Ramping, motor feedback control, and rocker angle filtering are all done simultaneously at lightning speed. This creates the smooth, slow movement of the Feather Touch Zoom while still having the capability of extremely fast movement.
The Feather Touch Controller is useful even for video lenses that can't go smoothly at very slow speeds. The variable speed rocker allows even a DSLR Lens to run slowly and smoothly when zooming. The external slip clutch allows overrun of stops without damage.