An extinction meter is an early type of photographic exposure calculator used to measure the amount of light in a scene and help determine the correct exposure for film or photographic paper. These devices were commonly used before modern light meters and automatic camera metering systems became widespread. By assessing how quickly a test element, such as a calibrated strip or visual indicator, "extinguished" under the light, photographers could estimate the proper combination of shutter speed and aperture to achieve a correctly exposed image.
Although largely obsolete today, extinction meters are an important part of photographic history and illustrate the evolution of exposure measurement. Understanding their use can be valuable for collectors, historians, or photographers working with vintage cameras and traditional darkroom techniques, providing insight into how early photographers achieved accurate and consistent exposures.