A lumen is a unit of measurement that quantifies the total amount of visible light emitted or falling onto a surface. It helps photographers, videographers, and lighting professionals determine how bright a light source is and how it will illuminate a scene.
Understanding lumens is important for controlling exposure, selecting appropriate lighting equipment, and achieving desired photographic effects. By knowing the lumen output of a lamp or flash, photographers can accurately plan lighting setups for studio work, product photography, and low-light conditions.