Abstract: The photographic shutter has two curtains cut out of a sheet of synthetic material. The flexible return of the curtain is ensured by two drum springs engaging with pinions carried by the end of the rollers. The setting of the shutters may be effected by wheels which may be completely disconnected from the setting mechanism. Release may be effected electrically by electro-magnets.

Abstract: A photometer for providing a measurement of shutter speed or aperture setting corresponding to a preselected value of the other comprises a photodiode supplying a voltage proportional to the logarithm of the measured light intensity. This voltage controls the frequency of an oscillator supplying pulses to a counting circuit during a time interval set by a timer.

Abstract: A process for controlling the closure of a diaphragm includes measuring the light intensity with the diaphragm fully open and memorizing a value related to the correct diaphragm opening. The diaphragm is then progressively closed while sensing the intantaneous light value. The memorized and instantaneous values are compared to determined proper diaphragm opening.

Abstract: The lamps of two slide projectors are each supplied by the secondary winding of a transformer. Each secondary winding has a half-wave rectifier and a current-control element in series with its lamp. Terminals are provided for bridging the rectifier and current-control element to enable each projector to be used separately. The two secondary windings and rectifier can also be connected to form a full-wave rectifying unit with a median terminal feeding the two lamps each in series with its current-control element, to enable projection of a series of slides with simultaneous fading-in and fading-out of successive slides.