Abstract: In an automatic control apparatus for controlling the quantity of light from a flash device, a first photocell device, responsive to the light from the flash device, is serially connected with a second photocell device, responsive to light reflected from the photographic object, and the output from the second photocell device is integrated and used for energizing known apparatus for preventing the light generated by the flash device from reaching the photographic object to optimize the light illuminating the photographic object. The second photocell device has a lower output than the first photocell device, thereby enabling the output from the second photocell device to determine the light measurement. The first photocell functions as a gate in response to the direct light emission from the flash device to prevent spurious and undesirable actuation of the second photocell device.The first and second photocell devices may each be phototransistors or photodiodes.

Abstract: Spectral output of lamp is controlled by a combination of color filters and dual photocell which monitors the spectral composition of the radiant energy from the lamp and compensates for change therein by automatically varying the power applied to the lamp to provide constant spectral output.

Abstract: The invention concerns a firing device for a number of electric valves, particularly thyristors. Each thyristor control path is associated with a firing circuit with a detector for electromagnetic radiation responsive to a transmitter which is controlled by a firing control signal and is equipped with a radiating device which energizes the individual detectors. To transmit the firing control signal with sufficient strength, a transmitter with a radiator is provided which is arranged in the focal line of a reflector designed as a partial elliptical cylinder. The individual detectors are disposed in a line which is aligned essentially parallel to the focal line of the reflector.

Abstract: A digital light responsive switching circuit in which a plurality of photosensors are respectively responsive to different sources of illumination and in which the electrical input channels are independent and each operative to provide digital output signals representative of sensed illumination levels.

Abstract: The invention concerns a firing device for a number of electric valves, particularly thyristors. Each thyristor control path is associated with a firing circuit with a detector for electromagnetic radiation responsive to a transmitter which is controlled by a firing control signal and is equipped with a radiating device which energizes the individual detectors. The detectors are arranged close together in a plane perpendicular to the radiation direction of the radiator. In order to obtain latitude in the arrangement of the detectors, the radiator is designed so that it furnishes a parallel-ray bundle of radiation and the detectors are spatially arranged relative to each other, such that they are exposed to the parallel ray bundle without mutual shadowing upon projection in the direction of the radiation on a projection plane which is perpendicular to the radiation direction.

Abstract: A wireless multiflashlight apparatus simultaneously illuminates a subject by flashlight rays emitted from a main flashlight device mounted on a photographic camera and at least one additional flashlight device located at suitable position away from the main flashlight device. In the main flashlight device is provided a flash tube arranged to emit substantially two or more flashlight rays at a predetermined time interval therebetween upon the shutter operation of an associated camera. In the additional flashlight device are provided a decoder for producing an outlet signal only upon receipt of the flashlight rays from the main flashlight device through a photo-electric conversion element and an amplifier, and a flash tube operative to be triggered only by the output signal from the decoder. The additional flashlight device is protected from inadvertently flashing even upon reception of any flashlight rays from other flashlight devices than the associated main flashlight device.