Camera Lens Parts: Automatic Aperture Coupling Lever

Of all the film camera lens parts, one of the most important and least understood is the automatic aperture coupling lever. When this is working properly, you never pay it any mind, but when something goes wrong with it, you quickly realize the great impact it has over your photos. What it does is control the aperture opening. You could either allow the camera to automatically select the aperture, or you could manually control it and decide what f-stop you would be using.

How an Aperture Works

Exposure is dependent on film speed (ISO in digital cameras), the aperture and the shutter. The film speed dictates how much light is needed for exposure. The aperture controls how much light passes through the lens to the photographic medium, and the shutter determines how long that the film is exposed to the light for. On a film camera, the aperture is controlled on the lens by the aperture ring, which then controls the aperture coupling lever. If something went wrong with the automatic aperture coupling lever, then it would cause your processed film to either be over or under exposed.

Aperture on Digital Cameras

On today's digital cameras, the aperture is controlled through the camera's settings instead of a ring on the lens. However, the aperture itself is still located within the lens. It receives it's signals through the electric connector strip that allows information to pass from the camera to the lens.