Light Meters

Photographers use light meters to measure the amount of light reflected by the subject they wish to photograph. The first light meters were hand-held. Later ones were built into the camera.

Light meters help determine the aperture and shutter settings. Once the film speed is set, the light meter measures the average brightness of the subject. This provides the proper aperture and shutter-speed settings. Fully automatic cameras determine the settings.

The two most common metering systems are incident light metering and reflected light metering.

Incident Light Metering

The light meter is positioned at the subject and aimed back at the camera. This type of metering originated with early portrait photography. It is still used in professional photography today.

Reflected Light Metering

The light meter is positioned at the camera and aimed at the subject. This type of metering is more practical when a subject is far away from the camera. Most light meters today use this system, including those built into cameras.

Spot metering is another type of light metering. Placed at the camera position, a spot meter can measure the light within one degree of its target area. This method can have an advantage over reflective metering, which takes a reading of the entire picture area.