For use in reflected-light color photography a diffuse light source has been developed which has an annular geometry (347×140 mm in diameter) and coaxially surrounds the optical beam of recording. The light source has a luminous peak intensity of 200 Mcd and emits a flash with a duration of 180 ns FWHM. The principle of operation is based on a chain of nine V-shaped light-emitting gliding sparks, each consisting of at least 50 interstitial copper electrodes for the generation of micro gliding discharges. They are all connected in series and driven by a modified nine-stage Marx-surge generator. Substituting each V-shaped gliding spark by two U-shaped Xe-filled flash lamps doubles the light output as well as the flash duration.