Abstract: Two lamps are controlled in that one is off and the other one on or vice versa with fractural transition from one state to the other being controlled by a differential amplifier with integrated, pulse or trigger switch operated Miller integrator. The differential amplifier control circuit elements (transistors, triacs) in separate circuit paths for the lamps. The control is either a direct one (d.c.) or an indirect one through phase shifting of firing pulses in a.c. operated triacs.

Abstract: A photographic camera in which at least one of the two main exposure factors (shutter speed and diaphragm aperture) may be set either manually or automatically. Indicating means is provided, visible in the viewfinder of the camera, to indicate to the user both the exposure factor value which he has set manually (if any) and the exposure factor value which the automatic mechanism would select according to prevailing light conditions, regardless of whether the user plans to utilize the automatic setting feature or whether he prefers to set the factor manually.

Abstract: A cam and follower construction in which a flat plate has a plurality of cam grooves intersecting each other and in which the cam followers are in the form of cylindrical pins or rollers, one in each cam groove. To insure that each follower stays in its own groove and does not accidentally pass into the wrong groove at the point where they intersect, the grooves are made of different widths and different depth, the widest groove having the shallowest depth and the narrower groove having a greater depth. Thus the follower of a wide cam groove cannot pass into an intersecting narrower groove because the groove is too narrow to receive the follower, and the follower of the narrower groove cannot pass into the wider groove at the intersection, because the narrower groove is deeper and the shallower wide groove cannot accommodate it.

Abstract: Timing mechanism for timing an adjustable and controlled interval between commencement of movement of two light obstructing elements of a photographic shutter, such as commencement of movement of an opening blade or curtain, and subsequent commencement of movement of a closing blade or curtain. A cam operatively connected to the first element starts to move upon the movement of that element, and controls the movement of a first pivoted lever. There is a second pivoted lever spaced from the first pivoted lever and adapted to be moved from the movement of the first lever, through an intermediate adjusting member which is moved by the movement of the first lever and which, in turn, causes movement of the second lever. For adjusting the time interval, the adjusting member is movable toward or away from the fulcrum of the first lever, and simultaneously away from or toward the fulcrum of the second lever, thereby varying the transmission ratio from one lever to the other.

Abstract: Mechanism for feeding a picture slide magazine in such a way that picture slides can be taken out of the magazine in the same order in which they are placed in the magazine, for delivery to two separate projector units of a dual slide projector, and then can be returned to the magazine still in proper order. Two indexing gears rotate in opposite directions about a common axis of rotation. Each gear carries index pins or projections which cooperate with a star wheel or modified Geneva gear as the indexing gears rotate, and the star wheel or Geneva gear drives two pinions which engage a toothed rack on the slide magazine. As two indexing pins located relatively close to each other on one indexing gear pass the star wheel, they rotate the star wheel through two increments, to feed the magazine through two steps in one direction.

Abstract: The flap of the case has a frustoconical extension for receiving the lens, but when empty, the extension is folded inwardly by bending at the seam with the flap proper, and by folding about two score lines.

Abstract: An electronic flash unit having the conventional flash tube, storage capacitor dischargeable through the flash tube, measuring device for recording the quantity of light emitted by the flash tube and reflected back from the subject being photographed, a pulse generator responsive to the measured reflected light, and means for quenching the flash in response to a pulse produced when the measured reflected light reaches a threshold value. The present flash unit, in addition to the conventional features just mentioned, includes the novel feature of a light-emitting diode which becomes illuminated when the light measuring means and the pulse generator circuit become operative, thus signalling to the user of the device that the so-called "computer" mechanism has actually operated. Circuit means is provided for extinguishing the light-emitting diode at the proper time.

Abstract: Two sets of lamellas are moved across the image aperture in a photographic cameras, whereby the lamellas of each set move in different but parallel planes. Each lamella is coupled to a crank pin and the pins are, on the one hand, guided for movement in parallel paths to move the lamellas of the set colinearly across the aperture while, on the other hand, the crank pins are being moved by a pivoting, slotted lever in which the pins glide. Guiding of the pins may include use of slide tracks or of linear ball bearings for guide elements carrying the pins.

Abstract: A picture slide projector having provision for automatic focusing (i.e., provision for automatically keeping the projection lens and the picture slide at a constant distance from each other notwithstanding a buckling displacement of the slide under the influence of heat) is provided with means for moving the projection lens axially relative to the picture slide, to an out-of-focus position to produce a fading or dissolving effect on the viewing screen, while the slide is being withdrawn from the slide holder or gate and replaced by another slide. At the same time, the automatic focusing mechanism is rendered inoperative. Preferably also at the same time, the projection lamp is dimmed. When the slide changing operation is completed, the automatic focusing mechanism is rendered operative, and it serves to bring the projection lens back axially to the sharp focus position, the projection lamp being simultaneously brightened.

Abstract: An arrangement for supplying a load with controlled current of a predetermined voltage which remains uniform notwithstanding variations in voltage of the alternating current supply, and notwithstanding differences in the frequency of the alternating current supply. A monostable trigger stage of the switch mechanism is connected to a DC voltage which is proportional to the voltage of the alternating current source, and its resistor which is connected with the capacitive coupling of the trigger stage transistors and determines the reset time of the trigger stage, is connected to a constant DC voltage. The mechanism includes a voltage divider, the division ratio of which is variable by means of a frequency recognition circuit.

Abstract: Electronic flash apparatus of the general type having exposure-measuring and flash-limiting mechanism comprising a light-sensitive element connected in series with an integrating capacitor and a thyristor, arranged so that when the thyristor becomes conductive, it causes a pulse which interrupts or terminates the flash. In distinction from prior flash apparatus of this same general type, the present apparatus has circuitry in which one plate of the integrating capacitor is connected to the collector of a photo-transistor and the other plate is connected to the control grid of the thyristor and to a higher voltage source, while the emitter of the photo-transistor is connected to a lower voltage source.

Abstract: Photographic flash apparatus having a body provided with a cavity for storage of the synchronizing cable, and a mounting bar or rail pivoted to the body in such a way that in one position of the mounting bar, it forms a closure for the cable storage cavity, and other positions of the mounting bar enable the bar to be attached to the camera and enable the body of the flash apparatus to be swung to either one of two positions relative to the mounting bar. Releaseable latch means holds the mounting bar in the selected one of its various positions relative to the flash apparatus.

Abstract: A photographic camera having a lens opening and a finder opening in the housing or casing of the camera, is provided with a cover plate or blind plate to close these openings when pictures are not being taken, to protect the picture taking lens and the finder lens from possible damage and to prevent entrance of dust or foreign matter into the housing. A manually operable slider controls the movement of the cover plate between its closed and open positions and also moves the film transport means or feeding mechanism, to advance the film through the space of one picture area or "frame.

Abstract: Each slide is comprised of an exposure slit defining lamella moved on parallel swinging arms in front of the image aperture, whereby the arms overlap each other in part, as well as the lamella to provide additionally shutter functions for covering portions of the aperture which are to be covered but are not covered by the lamella in any phase of movement or position of deployment.

Abstract: An electronic flash unit for photographic purposes, in which there is a first thyristor in series with the flash tube, and a second thyristor which, in series with a quenching capacitor, is in parallel with the first thyristor. The first thyristor is quenched at the appropriate time, by quenching current from the quenching capacitor, and after the first thyristor has been rendered non-conductive, the second capacitor is also rendered non-conductive by forced commutation. The arrangement shortens the recovery time of the apparatus, as compared with prior art apparatus of this same general type, to such an extent that the flash apparatus may be used with a motion picture camera as well as a still camera, to produce one or more flashes during each shutter-open cycle of the motion picture camera.