Exposure meters are devices used to measure the intensity of light in a photographic situation. They help photographers and videographers determine the correct exposure settings, such as aperture, shutter speed, and ISO. Exposure meters are available for a variety of needs, such as measuring reflected light, measuring the light hitting the surface of a subject, or precisely controlling the light from a flash.
These devices are used especially in studios, landscape photography, and film production, where light control is critical.