Abstract: An infrared ranging system for a battery-powered camera uses a light-emitting diode and associated pulse circuitry for producing a single ranging flash concentrated by a lens into a narrow cone of light generally centrally located in the field of view. The diode is powered by a capacitor bank charged in parallel and discharged in series to provide the necessary current pulse to the diode from a 2.0 volt system. The received pulse is concentrated on a photosensing diode by means of an infrared-passing lens to produce a voltage pulse related to amplitude of the reflected light, and hence to the range to a centrally located object in the field, this pulse being processed to set the state of one or more range-indicating latch circuits. The state of the latch circuits is used to govern the final setting of a driven adjustable focus lens. The system is equally applicable to setting the camera aperture in flash mode wherein the aperture is a range-dependent function.