Camera Lens Parts: Iris

Much of the design of a camera is based on the human eye, and one of the most important camera lens parts is the iris. In the eye, the iris is the colored part. It is made of muscle, and it expands and contracts, depending on the brightness of the surrounding light, in order to allow only a certain amount of light into the pupil at any given time.

The Camera Opening

In a camera, the opening is called the aperture, and the iris controls how much light comes in to expose the image. The iris is a series of leaves of metal that open and close in a contracting circular or expanding circular motion. If it’s overly bright, you could close down (sometimes called “stopping down”) to make sure too much light doesn’t get through and overexpose the image. If it’s too dark, the iris can be opened up to allow more light in. 

Auto or Manual

One of the benefits of a manual iris is that it lets you determine how bright or dark their picture will be. Perhaps the image is perfectly lit, but if you allow more light in, you can overexpose the background and focus on the well-lit subject of the picture.