Abstract: An improved automatic focus system wherein circuitry is provided to inhibit the focusing function when the scene being viewed provides too little contrast for satisfactory operation.

Abstract: An improved automatic continuous focus system of the spatial image correlation type determines whether focus correction is needed and in which direction and moves the lens with a proportional drive in accordance with these determinations. The focus motor may be operated continuously for large focus errors to allow smoother lens motion and faster response without increased motor requirements, a large active scan duty cycle may be provided, minimum drive pulses may be utilized for zero focus errors so as to overcome static friction in the lens drive and improve the focus accuracy and electronic debouncing of switches may be accomplished.

Abstract: A digital continuous focus proportional controller for an automatic focus system of the spatial image correlation type determines whether focus correction is needed and in which direction and moves the primary optical member or lens with a proportional drive in accordance with these determinations.

Abstract: An automatic continuous focus system of the spatial image correlation type determines whether focus correction is needed and in which direction and moves the lens with a proportional drive in accordance with these determinations.

Abstract: An automatic continuous focus system includes means for inhibiting movement of the primary lens unless each focus control signal within a predetermined time requires position correction in the same direction.

Abstract: An automatic continuous focus system of the spatial image correlation type includes means for inhibiting movement of the primary lens if the correlation signal lacks a sufficient amount of variation.

Abstract: An improved trigger circuit for triggering an electronic flash apparatus and for energizing a remote sensor is disclosed.

Abstract: An automatic continuous focus system of the spatial image correlation type determines whether focus correction is needed and in what direction and moves a lens in accordance with these determinations.

Abstract: An automatic focus system of the spatial image correlation type uses a dual scan technique. During a first scan, the amplitude of the major extremum in the correlation signal is stored. During the second scan, this stored amplitude is used to pick out the point of best focus.

Abstract: An automatic single focus system of the spatial image correlation type uses two scans to position the primary lens. During a first scan, the amplitude of the major extremum in the correlation signal is stored. During the second scan, this stored amplitude is used to pick out the point of best focus.

Abstract: An automatic continuous focus system of the spatial image correlation type uses a dual scan technique.

Abstract: A correct exposure annunciator for electronic flash apparatus includes an indicator which is turned on when the voltage on a capacitor is less than a predetermined value. The capacitor is discharged in response to a control signal which indicates that proper exposure has occurred. The capacitor is then recharged until the voltage on the capacitor attains the predetermined value and turns off the indicator.

Abstract: An electronic flash apparatus includes a correct exposure annunciator which operates if light received from the subject exceeds a predetermined percentage of the required illumination.

Abstract: An improved remote light sensor for use with an electronic flash unit is disclosed. The remote light sensor generates a termination signal to terinate the light provided by the flash unit when sufficient light is received from the scene being illuminated.

Abstract: False triggering of the flash termination switch in a series termination electronic flash unit as a result of contact bounce is eliminated. Gating means inhibits the contacts from triggering the flash termination switch unless a voltage at a selected point in the circuit has attained a predetermined value. False triggering of the flash ignition as a result of noise present on the synchronization switch line is also inhibited.