Abstract: A detecting device comprising a projecting optical system for focusing the image of an object to be examined on a focusing glass, a plurality of photoelectric elements which can be set in proper positions on the focusing glass, circuits including level adjusting circuits and for converting outputs from the respective photoelectric elements to binary logical outputs and circuits for converting these binary logical inputs to octonary logical outputs so that the slightest variations of the shape and state of the object can be easily and accurately detected. The respective photoelectric elements can be moved out of the projecting light path as required. The projecting optical system consists of an objective lens system and a projecting lens system so that a magnified erecting image of the object can be obtained on the focusing glass.

Abstract: An automatic focusing device by which the intensity distribution of an image of an object to be photographed is detected by a detecting section having an accumulation mode image sensor with a charge accumulation time in dependence upon the brightness of the object and develop a video signal corresponding to the intensity distribution. A signal processing circuit processes the video signal to determine whether the optical system of the photographing apparatus with which the focusing device is associated is focused or out of focus and when an out-of-focus condition is detected a drive direction signal is developed and applied to a drive to move the lens in a proper direction toward a focusing position.

Abstract: An automatic focusing device having a signal processing circuit for providing a focusing signal and a defocusing signal, or drive direction signal, to move the photographing lens to a focusing position the device is provided with a hunting preventing circuit in which, even if the drive direction signal is developed after it has been determined that the lens is focused on the object, the drive direction signal is made ineffective for a period of time which is shorter when the object brightness is high and longer where the brightness is low, whereby the hunting phenomenon with the lens which is liable to occur with a low brightness is positively prevented.

Abstract: An automatic focusing device in which the intensity distributions of the images of an object which are formed by light beams passing through different portions of an optical system in a photographing device are detected as video signals. A correlation output is obtained from the video signals so that the focusing condition is detected from the peak position of the correlation output. When the peak position is not one for focalization, a drive direction signal is delivered to drive the optical system towards the focusing position. A low contrast detecting circuit is provided in which is counted how many times the correlation output becomes higher than a predetermined level in one focusing condition detecting operation, and when the count value reaches a predetermined value, the drive direction signal is made ineffected, so as to prevent the occurrence of a hunting phenomenon with the optical system.

Abstract: An automatic focusing device comprises a detector for detecting distributions of the images of an object which are formed by two light beams passing through two different points in a photographing optical system and for providing corresponding video signals. The video signals are processed to obtain an output signal representative of a relative positional relation between the video signals for use in establishing the optical system moving direction and the distance of movement of the focusing position, or to determine only the direction of movement of the optical system so that the optical system is moved in the direction thus determined to the focusing position. The automatic focusing operation can be accomplished without using movable members other than the photographing lens of the optical system, or in the case of using a movable member, the focusing operation can be achieved with high accuracy by operating the movable member only once.

Abstract: A nonreflective coating is made up of five or seven layers of optical films provided on an optical element, such as a lens, whose refractive index is in a certain refractive index range for a particular light wavelength. The layers are formed of two materials different in refractive index so that the odd layers have one of the two refractive indexes while the even layers have the other refractive index, and the thicknesses of the layers are suitably defined as functions of the light wavelength.

Abstract: A variable aberration lens system usable not only as a general photographic lens but also a soft focus lens is provided. The variable aberration lens system includes at least a variable meniscus-shaped air space and cementing surface which are respectively concave against a stop provided therein. A very high resolving power and high contrast can be obtained when the variable aberration lens system is used as the general photographic lens, and a photograph in which an out focus image of the background or foreground is fine can be obtained by varying the width of the air space when the variable aberration lens system is used as the soft focus lens.

Abstract: The mirror of a single-lens reflex camera is supported on a swinging leading shutter swung upward by a rotary solenoid, the mirror thus being moved upward from its viewfinding position to its picture taking position, an aperture for passing stroboscopic light to the camera film being formed between this shutter and a trailing shutter held in cocked state by a resiliently urged latch lever. The trailing shutter is then released and swings upward into aperture closing contact with the leading shutter, the two shutters then being lowered to their positions for viewfinding, at which the trailing shutter is again locked for the succeeding shutter operation. The trailing shutter has a stud member fixed thereto which is locked, in the lowered position of the trailing shutter, by the latch lever. A buttressing bracket is provided with which the stud member is brought into contact in its locked state for accurate positioning thereof thereby to assure regular release timing of the latch lever.

Abstract: In the viewfinder optical system of a reflex camera with a film holder which is rotatable to change the orientation of the oblong image on its film, a viewfinder mask orienting device supporting a square focusing screen has two pairs of rotatable masking blades, the two blades of each pair being integrally joined in Vee shape, which are actuated by the rotation of the film holder to operate cooperatively to alternately mask edge parts of the two pairs of opposed sides of the focusing screen thereby to form an oblong viewfinder image and change the orientation of this image to conform to that of the image on the film.

Abstract: Precipitation-hardenable, nitrided aluminum alloys are produced by forming an alloy of aluminum metal at a temperature up to about 800.degree. C with a nitrided mother alloy of a specified composition which has been nitrided at a temperature of 800.degree. to 1,200.degree. C. The aluminum alloys are made precipitation-hardenable by the incorporation therein of a precipitation-hardening component such as copper, zinc and/or magnesium, and the precipitation-hardening component can be contained in the mother alloy undergoing nitridation.