zoom camera objective / machine vision

There are various types of auto-iris: DC, video and motor-controlled. The DC irises are regulated directly by the camera (DC iris = galvanometer). The video-controlled iris is controlled by the electronics of the lens. The camera supplies the lens with the operating voltage and the video signal for balance. Motorised irises are still sometimes used with motorised zoom lenses and so the iris can be manually controlled via an external control without having to come into contact with the lens itself.