Abstract: A battery power indicator for a DC to DC flyback converter is responsive to the current flowing in the secondary winding of the converter's transformer. In one embodiment the power indicator is lighted when the battery is weak but not dead. If the battery is good, the indicator is bypassed and remains off. In a second embodiment, the indicator is lighted to indicate a good battery and when the power capability of the battery drops below a predetermined level, the indicator turns off.

Abstract: The same recording head or heads may be employed to record both an information signal and a synchronization word signal. Where at least two recording heads provide overlap intervals in the recording of the information signal, the synchronization word signal may be recorded in such overlap intervals. Upon playback, the synchronization word signal may be employed to control at least part of the reproduction of the information signal.

Abstract: Electronic flash apparatus produces a variable amount of flash illumination corresponding to pre-flash photographic conditions, i.e. subject distance, film speed, ambient light intensity, etc. Circuitry, which has a threshold adjustable in response to a pre-flash signal relating to the flash illumination required for the photographic conditions, monitors energy as it is delivered to a flash tube to produce flash illumination, for activating quenching circuitry to limit the discharging of a flash capacitor to an amount of energy corresponding to the pre-flash signal.

Abstract: A camera having electronic flash apparatus for flash photography includes a rangefinder for measuring distance to a subject to be photographed, and circuitry for regulating a DC to DC converter to limit charging of the flash apparatus to a voltage corresponding to flash illumination that is necessary to effect a predetermined flash exposure of a subject situated at the distance measured by the rangefinder.

Abstract: A fixed-focus camera provides flash photography of normal-range subjects beyond a near distance which is limited by depth of field and flash overexposure. A proximity sensor, in response to detecting that a subject to be photographed is closer than the near distance, causes an override mechanism to establish an exposure aperture which is smaller than the aperture normally set for flash photography. This reduces the near distance at which both depth of field and flash exposure are acceptable.

Abstract: A clamp device for a switching transistor of a D.C. to D.C. converter is non-conductive when the converter is ON. When the converter is turned OFF, the clamp device is placed in a standby state that clamps off the switching transistor and draws no power from the battery. When noise occurs the clamp device momentarily enables the converter, but only while such noise is present.

Abstract: A DC to DC flyback converter for charging a capacitor in which the maximum current supplied from a battery to the converter's transformer is determined solely by the battery recovery voltage, circuit resistances, the transformer turns ratio and semiconductor junction voltages.

Abstract: Power distribution circuitry for battery-powered apparatus having multiple energy-consuming loads, such as a camera having an electronic strobe flash unit and a film drive motor, enables the loads to be actuated independently without drawing battery current simultaneously. This limits peak battery current which can extend the useful life of the battery.

Abstract: A quenchable electronic strobe flash unit has a light-responsive integrating circuit for causing the light emitted by a flashtube to be terminated when the integrating circuit senses a predetermined amount of light. A light-level sensing circuit measures the intensity of the ambient light. A threshold-setting circuit, responsive to the sensing circuit, causes the amount of light needed to be sensed by the integrating circuit for terminating the flash in bright ambient light to be, for example, twenty-five percent of the amount of light required to be sensed for terminating the flash in low ambient light. Thus, for subjects within the maximum range of the flash, when ambient light is relatively low, a desired exposure is due primarily to flash light, and when ambient light is relatively high, a selected portion of the desired exposure is attributable to flash light which is, for example, twenty-five percent of the full-flash light output.

Abstract: An exposure control circuit of the type adapted to produce an exposure termination signal after a time interval related to a time integral of light intensity includes general purpose lag compensation responsive to the absolute change in light intensity from the beginning to the end of exposure measurement for adjusting the time interval, whereby lag compensation is provided in ambient, flash, or fill-flash modes without the need for external mode switches.

Abstract: Exposure control apparatus provides an exposure program in which an exposure aperture is related to shutter speed to produce an optimum compromise between both exposure parameters. The exposure control apparatus comprises a diaphragm defining an exposure aperture of variable size, and a shutter comprising first and second selectively movable shutter blades for sequentially uncovering and covering the exposure aperture, respectively, during an exposure interval. Shutter speed is varied automatically by moving the second blade a variable time before commencing movement of the first shutter blade. The second shutter blade and diaphragm are coupled together by a control member such that the aperture size as well as exposure interval are varied in proportion to each other prior to an exposure. A movable latch member operably associated with a level-sensing light-sensitive circuit latches the diaphragm in an aperture regulating position which is functionally related to scene light intensity.

Abstract: An electronic flash unit for use with cameras having a flash lamp firing mechanism adapted to fire flash lamps in timed relation with the operation of a camera shutter. An electronic time delay circuit coupled to the flash lamp firing mechanism energizes a flash unit trigger circuit to fire the flashtube in synchronism with the camera shutter. A voltage-sensitive switching element renders the delay circuit operative once the flash unit firing capacitor is charged above a predetermined level. With this arrangement, the flash-firing mechanism cannot energize the flashtube trigger circuit when there is insufficient firing capacitor voltage.

Abstract: An electronic flash unit includes a housing having an elongate passage. An electrical plug having a pair of contacts electrically connected to the flashtube-firing circuitry is movably mounted in the passage to locate the contacts at varying positions relative to the housing. The flash unit further includes a camera mounting bracket that is adjustable relative to the base of the housing. A ratchet mechanism prevents a control button operatively associated with the bracket and an electrical control switch from closing the switch to energize the flashtube-firing circuitry when the bracket engages the housing base.