A lumen second is a unit used to measure the total light output of a photographic source over a period of time. It combines the brightness of the light (lumens) with the duration of its emission, providing a measure of the total amount of light delivered to a subject.
Understanding lumen seconds is important for photographers, cinematographers, and lighting technicians who need to calculate exposure accurately. This measurement helps in determining the correct flash power, studio lighting setups, and consistent illumination for both still photography and motion picture production.