Abstract: A device for controlling the termination of light emission by a flash device including means for detecting the light reflected from the subject being illuminated by the flash, integrating means connected to the detecting means for providing a flash termination signal when the total amount of light received by the detecting means reaches a predetermined value, and flash termination means connected to the integrating device and to the flash device for terminating the delivery of electrical energy to the flash device when the signal from the integrating device reaches its predetermined value. The flash termination device is preferably constituted by a novel gas-filled, arc-producing element having identical, unpolarized electrodes and an internal or external triggering electrode.

Abstract: Circuits and auxiliary elements for use with a device for controlling the emission of light pulses from a flash unit, which light pulses are produced by the discharge of current pulses from a capacitor, the device including a light sensing element for receiving light produced by the flash unit and reflected from an object in the light path. One such circuit includes a switch which is selectively operable to permit control of termination of the emission of light pulses at either one of two light intensity output levels. Another circuit permits one light sensing element to normally trigger the emission of a light pulse in response to a light pulse from a remote unit, and to be selectively connected to subsequently control termination of such emission. One such element is a special gas filled switching tube having two internal electrodes for triggering conduction through the tube in response to a low voltage.

Abstract: A lens having an equivalent focal length variable between predetermined limits where the lower limit is less than the diagonal of the image frame and where the lens comprises four lens groups of positive, negative, negative and positive powers, respectively, and the first three groups mounted from the object end are movable in unequal relationship to vary the focal length while all four groups are axially movable in fixed relation to each other to focus the lens.

Abstract: A wide aperture long focus photographic lens having internal aberration compensation and comprising an objective which is movable for focusing and a rear lens which is stationary with respect to the film plane and has an equivalent focal length which is substantially longer than the equivalent focal length of the overall lens.

Abstract: Circuits and auxiliary elements for use with a device for controlling the emission of light pulses from a flash unit, which light pulses are produced by the discharge of current pulses from a capacitor, the device including a light sensing element for receiving light produced by the flash unit and reflected from an object in the light path. One such circuit includes two zener diodes for providing threshold voltages for use in comparing the output of the light sensing element. Another such circuit compensates for nonlinearities in the response of certain components of the device.

Abstract: A telephoto photographic lens having internal aberration compensation and comprising an objective which is movable for focusing and a rear lens which is stationary with respect to the film plane. The rear lens has an equivalent focal length greater than that of the overall lens and may have negative power which presents a slight change in the equivalent length of the overall lens when the lens is close focused.