Abstract: An electronic circuit for sampling a digital pulse train signal and providing a replication in place thereof during a selected holding period includes a binary counter and register for counting and storing a clock pulse of substantially higher frequency than the sampled digital pulse train together with control gates for inhibiting the counter from rolling over in the event that the period of the sampled digital pulse train becomes so long that the maximum binary count capacity of the counter is reached. The sampled digital pulse train signal is preferably provided by the scene light detecting and integrating circuit of a photographic camera apparatus and the holding period during which the digital pulse train signal is substituted by the replicated signal corresponds to the flash fire duration of a strobe.

Abstract: An automatic focusing control apparatus focuses subjects in any one of a plurality of different camera-to-subject distance ranges by transmitting a sonar ranging signal and at the same time displacing an objective lens to move through a plurality of different focal positions corresponding respectively to the different camera-to-subject distance ranges, and thereafter detecting an echo signal from a subject and utilizing the detected echo signal to provide a specially timed control signal to ultimately stop the displacement of the objective lens at the appropriate focal position corresponding to the distance range in which the subject is located.

Abstract: In an exposure control system in which the instant in which the scene light is first admitted to a film plane from a shutter blade mechanism at the commencement of an exposure interval must be precisely and accurately determined for subsequently controlling the instant of flash fire and/or other exposure control functions utilizing digital scene light integrating techniques, there is provided an arrangement for prebiasing the light integrator to provide an output therefrom within an operative range of voltages immediately prior to detection of first light at commencement of the exposure interval in order to eliminate any potential errors which might otherwise result in the detection of first light at the commencement of the exposure interval or any other scene light related measurement resulting from the integration lead time required for the digital type of light integrating arrangement to reach its operative range of voltages.

Abstract: An exposure control circuit for a photographic camera is provided for determining the camera-to-subject range directly by sonic ranging and for automatically responding to the sonically determined subject range to provide either a shortened maximum exposure interval time out period under conditions where the photographic subject is located far enough from the camera as to be just beyond the effective range of the flash or within the effective range of the flash but without sufficient reflectance to effect the termination of exposure solely as a function of scene light integration or an extended maximum exposure interval time out period under conditions where the photographic subject is located far enough from the camera as to be far beyond the effective range of the flash where there is likely to be little or no reflected flash light.