A zoom lens mechanism foldable and retractable to be used in a digital still camera to control zooming of the zoom lens uses programmed data written in a micro controller unit (hereinafter referred to as MCU) instead of the conventional cylindrical grooved cams that are usually used to mechanically control zooming of a zoom lens of a digital still camera, and the assembly of the second lens group is rotatable inside the lens barrel, and the first lens group can be folded and retracted into the space provided by the rotation of the second lens assembly.