incidentielichtmeter

An incidentielichtmeter, commonly called an incident light meter, is a device used in photography to measure the amount of light falling on a subject. Unlike a reflected-light meter, which gauges light reflected from the subject, an incident meter reads the illumination that actually reaches the subject. This often yields exposure settings that are more consistent across different subjects and colors.

Construction and use: It consists of a light sensor behind a white, translucent diffuser dome. The dome samples light from the scene, and the device is held at the subject’s height with the diffuser directed toward the main light sources or toward the camera, depending on user convention. The meter is set to the film or sensor ISO and provides an exposure value (EV) or a recommended aperture for the current ambient light. Many meters also offer a flash (strobe) mode, measuring the light from lighting units and computing the correct power for a given ISO and distance.

Compared to reflected meters, incident meters avoid biases caused by bright or dark subjects and are especially useful in portraiture and scenes with challenging tonal ranges.

Limitations and notes: The reading assumes the subject receives roughly even, diffuse illumination. Extremely directional lighting, strong shadows, or unusual scene geometry can reduce accuracy, and field meters must be oriented correctly to sample the scene's light.

History and brands: The concept emerged in the mid-20th century with products from Sekonic, Gossen, and others. Modern digital models often integrate with cameras and flash systems.