A photometer is described for measuring the peak brightness of light flashes 0.3 &mgr;sec in duration and 10−3in.2in cross‐sectional area. A telescope and beamsplitter arrangement permits convenient and rapid aiming. The light flashes are sensed by an RCA 931‐A multiplier phototube, and the resultant electrical signals are transmitted to a pulse lengthener with appropriate 0.1‐&mgr;sec rise time circuitry. A single transient will fully deflect the output meter for a period of five seconds.