There are four types of operation for lens iris, that are：
(1) DC drive auto iris
(2) Video drive auto iris
(3) Manual iris
For DC drive type, the iris is controlled by the circuit inside the camera;
For Video drive type, the iris is equipped with an amplifier inside and is operated by the video signal and DC power supply from the camera;
For Manual type, the iris is manually adjusted over the adjusting ring on the lens;
For P-iris type, the iris is precisely controlled by stepping motor, which optimizes the iris opening under all lighting conditions and generate the better contrast, clarity, resolution and depth of view of the image.