A control used exclusively to zoom the lens in and out. It is on the left side of the lens when the camera is viewed from the user's perspective (i.e., from the rear). This control is added to cameras with high-power zoom lenses to make it easier for the user to operate the zoom control while supporting the lens and supplements the zoom control in the vicinity of the shutter button. If both controls are operated simultaneously, the latter takes priority and the former is ignored.