Abstract: An automatically focussed optical system in which two arrays of photosensitive detectors have different optical spacings respectively in front of and behind the image plane of the system, and sense different portions of the image. Differences in electrical signals generated by adjacent detectors (C,D and E,F) in each set, and indicative of differences in intensity of the corresponding portions, are processed to generate a focus drive signal (Fd) of a value related to an error in the focus of the image. This signal is used to adjust the focus. Two discrete arrays of detectors (FIG. 2B) can be used or alternatively a single array (FIG. 2D) tilted relative to the image plane can be used. In another example (FIG. 2C) a transparent block is inserted adjacent to a part only of a single detector array to thereby lengthen the optical path length of that part relative to the remainder of the array.

Abstract: A method of adjusting the position of a solid-state scanning element and mounting the same, in a manuscript reading optical block included in a manuscript reading part of a solid-state electronic scanning system is disclosed in which the position of the solid-state scanning element is adjusted by handling the solid-state scanning element itself in a state that an adjustment pattern forming an optical standard and a lens support forming a positional standard of a device are set to an adjustment jig, so that the highest optical sensitivity is obtained, and in which a wiring board is fixed to the lens support in such a manner as using the position of a pin of the solid-state scanning element as a guide, while maintaining the solid-state scanning element in the above-mentioned adjusted state, and then the pin of the solid-state scanning element is fixed to the wiring board using a melt made of solder or the like to make an electrical connection therebetween.

Abstract: A method and apparatus for detecting a focussing error signal of an objective lens with respect to a video disc on which a light beam emitted from a laser light source is to be focussed as a light spot by the objective lens. A light flux reflected by the video disc is made incident upon a detection prism surface which is set substantially at a critical angle with respect to a central light ray in the reflected light flux, and two light fluxes which situate on respective sides of a boundary plane including the central light ray and perpendicular to a plane of incidence, and are reflected by the reflection surface are separately received by two light receiving regions which are divided along a boundary plane including the central light ray reflected by the reflection surface and perpendicular to the plane of incidence. The focussing error signal is derived as a difference between output signals from the two light receiving regions.

Abstract: An apparatus and method for recording optically an information signal on a disk-like record medium as a spiral track or concentrical tracks by modulating a main beam by the information signal to be recorded and projecting the modulated main beam onto the record medium. In order to obtain a tracking error signal, a sub beam is also projected on the record medium at an edge of an adjacent track which has been previously recorded and the sub beam reflected by the record medium is detected by a light detector to produce the tracking error signal which is then supplied to a high pass filter to remove a low frequency component from the tracking error signal.

Abstract: A device for automatically focusing an objective lens includes detecting means capable of detecting the positional relation of the objective lens with respect to an in-focus position at which an image of an object is formed on a predetermined focal plane, means including an electric motor and moving the objective lens toward the in-focus position by the motor, and means for controlling the driving of the motor in response to the detecting means. The control means includes a power supply circuit means for connecting the motor to a power source, a braking circuit means for short-circuiting the two terminals of the motor, and means for alternately operating the power supply circuit means and the braking circuit means to thereby decelerate the revolution of the motor when the objective lens is within a predetermined range near the in-focus position.

Abstract: A focal position detecting optical apparatus wherein a light beam focused by a first optical system is irradiated on an object to be illuminated, focal point images are formed at two foci spaced apart from each other by a cylindrical lens disposed in a path of light beam reflected from the object, and a shielding element having a tip edge making an angle of approximately 45.degree. with an operating axis of the cylindrical lens is inserted at a site between the two foci and at which the light beam has a circular cross section to extract a portion of the light beam travelling between the two foci. The extracted portion is detected by two photodetectors disposed symmetrically with an axis lying in substantially the same direction as the tip edge, and the difference between outputs of the two photodetectors is produced for detection of an actual focal position of the first optical system.

Abstract: An automatic focus adjusting apparatus is provided with a light sensor producing a photoelectric output corresponding to the optical image of an imaged object, an operation device generating control information indicative of the in-focus position of a phototaking lens with respect to the object in response to the photoelectric output, a servo circuit for driving the phototaking lens in response to the control information, and filter means for transmitting the control information of the operation device to the servo circuit and controlling the responsiveness of the servo circuit to the control information.

Abstract: A method and apparatus for converting the intensity of an unknown optical signal (B) into an electrical signal in digital form utilizes two elongated optical attenuators (11, 13), one for the unknown optical signal from a source (10) and one for a known optical signal (A) from a variable source (12), a plurality of photodetectors (e.g., 17, 18) along each attenuator for detecting the intensity of the optical signals, and a plurality of comparators (e.g., 21) connected to the photodetectors in pairs to determine at what points being compared the attenuated known signal equals the attenuated unknown signal. The intensity of the unknown relative to the known is thus determined by the output of a particular comparator. That output is automatically encoded to a relative intensity value in digital form through a balancing feedback control (24) and encoder (23).

Abstract: A system for producing a default signal for an auto focus system whenever the scene being viewed has too low a contrast for the system to operate correctly. The default signal is produced as a function of the out of focus condition of the system so that default occurs when the low contrast value is below a first magnitude when the lens is near a proper focus position but occurs near a magnitude less than the first magnitude when the lens is further away from the proper focus position.

Abstract: A method and apparatus for detecting a focussing error signal of an objective lens with respect to a video disc on which a light beam emitted from a laser light source is to be focussed as a light spot by the objective lens. A light flux reflected by the video disc is made incident upon a detection prism surface which is set substantially at a critical angle with respect to peripheral light fluxes reflected by the video disc, and the peripheral light fluxes reflected by the reflection surface are separately received by two light receiving regions which are spaced apart from each other. The focussing error signal is derived as a difference between output signals from the two light receiving regions.

Abstract: In the disclosed focus detecting system, the focusing condition of an objective lens relative to an object is determined by a number of pairs of radiation sensitive elements arranged in a linear array, and a number of lens elements arranged in a linear array corresponding to the linear array of the pairs of radiation sensitive elements. Each lens element is disposed so that one radiation sensitive element in each pair of radiation sensitive elements is arranged to cause one radiation sensitive element in each pair of radiation sensitive elements to receive radiation from a first portion of the objective lens and to cause the other radiation sensitive element to receive radiation from a second portion of the objective lens.

Abstract: This specification discloses an apparatus disposed in the light beam from an object passed through an imaging lens for producing an output variable with movement of the image of the object by the imaging lens in the direction of the optical axis. The apparatus produces, when the image of the object is formed on a predetermined imaging plane, an output corresponding to a critical value representative of the in-focus of the imaging lens to the object and produces, when the image of the object is formed at a position deviated from the predetermined imaging plane, an output corresponding to the amount of said deviation.

Abstract: In a focusing position detection apparatus for detecting a focusing position by causing rays of light coming from a peripheral portion of an exit pupil of a photographing lens to enter a pair of self-scanning type photoelectric element arrays through a lenticular lens group and then detecting the difference of the phases of the output signals from the photoelectric element arrays, in order to cause the rays of light to enter accurately the pair of self-scanning type photoelectric element arrays, a pitch Po between photoelectric elements which constitute the pair of photoelectric element arrays is suitably changed relative to a pitch P between small lens element which constitute the lenticular lens group, and furthermore, in order to detect the focusing position accurately, the boundary areas in the convex surfaces of the small lens elements of the lenticular lens group are made opaque so that noises in the output signals of the photoelectric element arrays are reduced.

Abstract: Automatic focusing apparatus includes a charge store type photo-sensor. Due to the use of the photo-sensor, the apparatus has an improved response to a substantial charge of an interval of control outputs by change in a time sequence of the control outputs and also has an improved response to a change in a time sequence of servo outputs and a substantial change in an interval of the servo outputs.

Abstract: In the exemplary embodiments, two line-shaped images of a scene are imaged onto two line sensors. The output signals of these line sensors are stored in successive stages of respective shift registers, whereby the distance measurement ensues by means of sequential examination of the correlation of the image element signals as stored by the shift registers. For the correlation examination, a predetermined set of stages of each shift register are read out in parallel for comparison. The image element signals are then alternately shifted in the respective shift registers followed by further parallel readout and comparison steps to locate the segments of the two line sensors having a maximum correlation.

Abstract: An in-focus detector for binocular stereoscope including a pair of left- and right-hand observation optics comprises a pair of beam splitters disposed on the optical axis of the respective observation optics. Each of the beam splitters derives part of observation light out of the associated observation optics and directs it to a reflecting element, which reflects the light onto a light receiver disposed at a focused position. The light receiver produces photoelectric outputs in accordance with the imaging condition of an image of an object being examined, and an in-focus detection circuit responds to these outputs by detecting an in-focus condition.

Abstract: An automatic focusing device and method for a camera in which the distance and direction to the focused position of a focusing lens of the camera are quickly determined after which the lens is moved directly to the focused position without the necessity of carrying out calculations as the lens is moved. Images of an object being viewed through the lens are projected onto first and second sensor groups. The outputs of the sensor groups are digitized then calculations are performed to determine the distance and direction to the position of correct focus. The lens is then moved to the focused position directly in accordance with the computed values.

Abstract: In a method for detecting a focussing error signal of an objective lens with respect to a video disc on which a light beam emitted from a laser light source is to be focussed as a light spot by the objective lens, a light flux reflected by the video disc is made incident upon a detection prism surface which is set substantially at a critical angle with respect to a central light ray in the reflected light flux, and two light fluxes which situate on respective sides of a boundary plane including the central light ray and perpendicular to a plane of incidence, and are reflected by the reflection surface are separately received by two light receiving regions which are divided along a boundary plane including the central light ray reflected by the reflection surface and perpendicular to the plane of incidence. The focussing error signal is derived as a difference between output signals from the two light receiving regions.

Abstract: An automatic focusing apparatus for a camera comprises a first focusing optical system with a half mirror transmitting light from a subject, a second focusing optical system with a mirror to lead another light from the subject to the half mirror and a single focusing element for receiving said different lights thereby focusing detection.

Abstract: Disclosed is a device for detecting an incident position of radiation beam, particularly, its center or center of gravity. The detecting device is provided with a scanning type radiation beam sensing device having a plurality of radiation sensing elements in a linear arrangement, and the sensing device is disposed in such a manner that its radiation receiving surface may be substantially coincided with an incident surface of the radiation beam to be detected. When reading an output from the sensing device, the time sequential output signals from the sensing device are split into predetermined sections, and the signal quantities among the sections are compared. In this way, the position of the center or the center of gravity of the radiation beam on the incident surface is detected with the position corresponding to a split point of the signals as the reference.

Abstract: A colorimeter in which a light source, a collimating lens and a band pass filter are supported by a housing that is movable with respect to a stationary beam dividing assembly in a direction at least substantially transverse to the optical axis of the light from the source. The assembly separates the incoming collimated and filtered light into a sample beam and a reference beam which are directed back toward the housing in directions parallel to the optical axis. The movement of the housing toward or away from the sample produces an increase or decrease in the intensity of the light illuminating the sample and a corresponding decrease or increase in the intensity of the light at the reference detector. The arrangement is such that the apparatus may be readily adjusted to obtain accurate colorimeter readings even for samples having abnormally high or low density characteristics.

Abstract: A method and apparatus employing optical type techniques are provided for use in reliably sensing the juxtapositional relationship between successively relevant portions of an object and a sensing unit that are relatively movable, in accurately maintaining a predetermined juxtapositional relationship between such portions of the object and the sensing unit during relative movement therebetween, and, when appropriate to the application, in also faithfully sensing other information carried by such portions of the object. The method and apparatus are characterized by eliminating any need for mechanical engagement between the sensing unit and the portions of the object to which the sensing unit responds and by utilizing only optical type coupling between such portions of the object and the sensing unit for the transfer of all information to be acquired by the sensing unit from the object.

Abstract: Disclosed is an image sharpness detecting system in which an image formed by an image forming optical system is received by an array of a plurality of optical-electronic transducer elements, and an illumination difference in each individual minute compartment of the above-described image is detected on the basis of the concurrently obtained output signal from a corresponding one of the optical-electronic transducer elements, while all the illumination differences are summed up over the entire area of a sensing region of the above-described image, whereby is obtained a signal representing the degree of sharpness of the image on the above-described array of optical-electronic transducer elements.

Abstract: A focus detecting device has an objective lens, a pair of re-imaging lenses for receiving the light imaged by the objective lens to form a first and a second image, respectively, a pair of focus detecting photoelectric converters disposed near the focal planes of the pair of re-imaging lenses, respectively, the pair of photoelectric converters being adapted to produce photoelectric outputs corresponding to the position changes of the first and second images caused on the photoelectric converters by movement of the objective lens in the direction of the optical axis, and detecting means for receiving the outputs from the pair of photoelectric converters and detecting whether or not the objective lens is in its in-focus condition. The pair of re-imaging lenses are provided so that the F-number thereof in a direction perpendicular to the direction of movement of the images is smaller than the F-number thereof in the direction of movement of the images position-changed on the photoelectric converters.

Abstract: A light measuring device capable of amplifying the difference of the time-sequential pulse output signals from the photoelectric sensor array regardless of the magnitude of said pulse output signals, comprises optical system means; means comprising a photoelectric sensor array having a plurality of photoelectric sensors for receiving the light passing through said optical system means and generating electric signals respectively corresponding to the intensity of light received by said photoelectric sensors as time-sequential signals of a determined interval; means for generating a comparison signal of a determined magnitude related to the output level of said electric signals; and processing means adapted to receive said electric signals and said comparison signal to generate output signals related to the difference of said signals in a sequential manner.

Abstract: A automatic focusing apparatus is disclosed for automatically focusing a focal point on an object substrate wherein the pn junction of an emitting part of a semiconductor ray source itself, has the effect of a pin-hole in order to eliminate a complicated setting of a position of a pin-hole panel whereby variation of the output of the semiconductor ray source caused by reflective ray is detected by a phase detector and the output is applied to an actuator to carry out an automatic focusing.

Abstract: Apparatus and method for adjusting the outputs of radiation responsive detectors to correct for mismatching.

Abstract: A control system for maintaining proper focus of a radiant recording or writing beam, such as a laser beam, with respect to a recording surface, by measurement of the duty cycle of an oscillatory information-carrying signal recorded from the recording surface immediately after recording. The system includes a photodetector for detecting a reading beam used to recover the recorded information, a focusing lens movable with respect to the recording surface to focus the writing and reading beams, a dither oscillator to generate a dither signal employed to move the focusing lens in an oscillatory manner, a duty cycle detector to provide a signal indicative of the duty cycle of the information-carrying signal recovered by the reading beam, and a multiplier for comparing the phases of the duty cycle signal and the dither oscillator signal, and thereby providing a correction signal indicative of the magnitude and polarity focus error.

Abstract: Range finding equipment for use with optical systems utilizing a small number of radiation detectors positioned to receive radiation in first and second patterns from a remote object. The logarithm of the ratio of the output of a first and second detector are compared with the logarithm of the ratio of the output of a third and fourth detector to determine which has the largest absolute magnitude. The system operates to control the range finding circuitry with the largest signal thus obtained.

Abstract: Apparatus for use with range finding equipment in which the radiation from a remote object may be too small to provide for proper operation. A signal which is a function of the logarithm of the ratio of the output of a first and second detector and a signal which is the function of the logarithm of the ratio of a third and fourth detector is compared with a reference signal. If the reference signal is larger than both of the other signals, the system operates to focus at a predetermined position.

Abstract: Range finding equipment for use with optical systems utilizing a small number of radiation detectors positioned to receive radiation in first and second patterns from a remote object. The sum of the logarithm of the ratio of a first and second detector and the logarithm of the ratio of a third and fourth detector is compared with the difference between the logarithm of the ratio of the first and second detector and the logarithm of the ratio of the third and fourth detector to determine which has the greatest absolute magnitude. The signal of greatest magnitude is selected to operate the range finding circuitry.

Abstract: Electro-optical focus detection apparatus for providing a signal indicative of the magnitude and polarity of focus error in a light beam impinging on a surface, such as a recording surface in a recording or playback system. The detector includes a beam splitter for dividing the beam reflected from the recording surface into two reflected beams of equal power, and includes an aperture placed in the path of the two reflected beams. The first reflected beam converges at a focal point before encountering the aperture and the second reflected beam converges at a focal point after encountering the aperture, both beams thereafter impinging upon separate photodetector elements. The aperture reduces the light incident on the photodetectors from both reflected beams, and the apparatus is so configured that the powers of the reflected beams incident on the photodetector elements are identical when the original beam is in focus on the recording surface.

Abstract: The present invention concerns copying apparatus which automatically controls the quality of copies. The copying apparatus includes a density detector for detecting the frequency of occurrence of density values along a scanning line of a document to be copied, i.e., the frequency distribution of density values is determined. When the frequency distribution has at least three maxima, a smoothing device smooths the frequency distribution via a predetermined filter function till the frequency distribution has one or two maxima. In the event the frequency distribution has one or two maxima, a density detecting device detects at least one density value according to a maximum or minimum value of the frequency distribution. A control device then controls the copy quality of a reproduced image according to the density value.

Abstract: An automatic focus detecting device for a camera adapted to be miniaturized and provided in the form of an integrated circuit. Two arrays of light receiving elements or sensors are disposed in two planes parallel to the surface of the film in the camera on either side of the image plane. The output signals from the sensors are processed in a disclosed electronic circuit to detect desired focus conditions such as front focus, proper focus and rear focus for automatically moving the photographing lens to the position of proper focus.

Abstract: Every image point of an image of a sample formed by an optical objective, focussed by, for each image point, deriving a representation of the autocorrelation function of the brightness distribution of the image of that image point, deriving a representation of the average of the autocorrelation function of the brightness distribution of a plurality of image points in the region of that image point, deriving a representation constituting a function of the quotient formed by dividing the representation of the autocorrelation function for that image point by the representation of the average of the autocorrelation function, and varying the distance between the objective and the sample while iteratively performing the above steps of deriving for determining the distance at which the function of the quotient has a maximum value.

Abstract: An automatic adjustment system for a camera which time division multiplexes inputs from a scanning system, and an automatic exposure control or a film feeding motor speed control into an evaluation circuit. The same electronic circuitry is thereby used for evaluating the input from any of the mentioned adjusting systems to minimize the complexity and bulk of the camera circuitry necessary for processing. Each aforementioned automatic feature compares a respective pair of signals to determine the respective adjustment. A pair of signals is brought to a common condition indicative of proper adjustment by use of feedback from the actual state of the automatic system for the particular feature.

Abstract: In a flow metering apparatus, a bubble detector for detecting bubble formation in tubing includes a light source and first and second light detectors. The first light detector is positioned on the opposite side of the tubing from the light source such that the light transmitted through the tubing to the detector is dependent on the focusing effect of fluid in the lumen of the tubing. A control circuit responsive to the output of the detector interrupts operation of the metering apparatus when the light transmitted through the tubing falls below a predetermined minimum level. The second light detector is positioned at an angle to the light path between the light source and the first detector so as to receive increased light from the light source in the absence of the focusing effect of fluid in the tubing.

Abstract: A focus detecting system for detecting focusing condition of an image forming optical system to an object. In this system there are produced first and second signals corresponding to imaging conditions of object images at first and second positions on front and rear sides of and at substantially equal distances from a predetermined focal plane of said optical system, respectively, and another signal corresponding to imaging condition of an object image at third position substantially coincident with said predetermined focal plane. In accordance with these first, second and third signals, a decision is given as to the focusing condition, namely, in-focus, near-focus or far-focus condition, as well as, the distinction between correctly focused condition and considerably defocused condition.

Abstract: A focus detecting apparatus comprises first means for forming phase outputs from said first and second photosensor arrays of phases respectively corresponding to the relative positions of said first and second photosensor arrays with respect to the light images thereon; second means for comparing the output corresponding to the amount of light entering said first photosensor array with the output corresponding to the amount of light entering said second photosensor array and forming a correlation output corresponding to said comparison; third means for forming outputs corresponding to the sharpness of light images on said photosensor arrays from the outputs from said arrays; and processing means for generating a synthesized output signal representing the focus state of said objective lens with respect to the object from the aforementioned phase outputs, correlation output and sharpness outputs.

Abstract: A system for determining the range to an object utilizing a plurality of radiation responsive detectors arranged in groupings wherein a first grouping of detectors receives radiation from the object in a first pattern and the second grouping of detectors receives radiation from the object in a second pattern. The patterns move with respect to one another as the distance between the object and the system changes. The range is determined from a determination of the relative position of the patterns by computing where the patterns will coincide if the focusing lens of the system is moved. The output is a signal having a characteristic indicative of the desired direction of motion of the lens and a characteristic indicative of the amount of such motion necessary to produce a proper focus condition.

Abstract: An apparatus for detecting an in-focused condition of optical systems by using two values of indices of performance each derived from the number of differences between illumination signals obtained per picture element, comprising first and second image sensors arranged in front of and in the rear of a focal plane of the optical system, first and second analog data processing circuits, and a comparing means.

Abstract: A focus detecting device which performs focus detection in such a manner that an image of an object formed through an image forming lens is received by an array of many electric charge storing type photo-sensors and, under such a condition, the image is electrically scanned by extracting, in a time serial manner, the output of each photo-sensor, and then the sharpness of the image is detected from a scanning output thus obtained; or that two images of the object which are formed through a range-finding optical system with an apparent parallax corresponding to distance to the object are received by different arrays of such photo-sensors respectively and, under such a condition, the two images are electrically scanned separately from each other by extracting, in a time serial manner, the output of each of the photo-sensors and scanning outputs thus obtained are compared with each other to detect the relative parallax of the two images.

Abstract: A focusing detection device is disclosed wherein an electric output obtained by sequentially driving a group of photoelectric elements disposed adjacent to one another on an imaging surface is sampled and held for part or the entirety of the output of a photoelectric converter, this held output is nonlinearized to be compared with a preceding held and nonlinearized output of part or the entirety of the output of the photoelectric converter, the compared value is sampled and held, and extreme values of the displacement of the focus of an image rendered to the photoelectric elements from this held output are derived.

Abstract: A focus detecting device for a camera utilizing a self-scanning type photoelectric element array composed of a plurality of minute photoelectric elements. The input signal from the photoelectric element array is held by first and second memory circuits at opposite phases from one another with the holding time for the memory circuit corresponding to twice the scanning time for a single minute photoelectric element within the array. Signals representing the difference and sum of the output of the memory circuits are formed and the absolute value of the difference signal is taken. The sum signal is connected as the divisor signal to a divider circuit while the absolute value of the difference is utilized as the dividend. The peak value of the signal thus formed is utilized as a contrast detection signal. This signal is substantially unaffected by vibration of the camera or movement of the object being photographed.

Abstract: In a focus detecting device wherein, from an object light passed through an image forming optical system, a first image and a second image are formed by a pair of re-imaging optical systems and the in-focus condition of the image forming optical system with respect to an object is detected from the variations in position of the first and second images with respect to a pair of photoelectric converters disposed on or near the focal planes of the pair of re-imaging optical systems, there is provided shield means for shielding, substantially symmetrically with respect to the optic axis of the image forming optical system, part of light beams forming the first and second images formed on the pair of photoelectric converters by the image forming optical system and the pair of re-imaging optical systems.

Abstract: In a focus detecting device for a camera in which, from an object light passed through a focus plate removably provided on the image formation plane of a phototaking lens, a first image and a second image are formed by a pair of re-imaging optical systems with the in-focus condition of said phototaking lens with respect to an object is detected from the variations in position of said first and second images with respect to a pair of photoelectric converters disposed on or near the focal planes of said re-imaging optical systems, said focus plate being provided with a field lens, there are provided means for shielding, substantially symmetrically with respect to the optic axis of said phototaking lens, part of light beams forming said first and second images formed on said pair of photoelectric converters by said phototaking lens and said pair of re-imaging optical systems, and means for driving said shield means in response to the mounting of said focus plate onto the camera.

Abstract: In the exemplary embodiments, two line-shaped images of a scene are imaged onto two line sensors. The output signals of these line sensors are digitally further processed, whereby the distance measurement ensues by means of sequential examination of the correlation of the digitalized measuring results of the line sensors. For the correlation examination, the parts of the line sensors respectively lying opposite one another and overlapping are employed. The circuit arrangement for implementing this method is contained on one chip in MOS digital technology.

Abstract: An imaging apparatus comprising an array having a central axis and a predetermined number of light responsive elements positioned in the array, with each light responsive element producing an output in response to light impinging thereon and an optical system including a lens for directing light from an image of a predetermined size onto a first number of said light responsive elements which said first number is less than said predetermined number. The apparatus also includes a selection unit for selecting a said first number of said light responsive elements which are positioned with regard to said central axis, means for receiving the outputs of said selected first number of light responsive members and also for producing a stream of data therefrom; and a switch unit for adjustably selecting the particular said first number of light responsive elements upon which light from said image impinges.

Abstract: Automatic focusing adjustor device provided with a focusing sensor signal corresponding to an object distance by photoelectrically comparing an optical image obtainable through a fixed mirror and another optical image obtainable through a movable mirror wherein when the focusing sensor signal is not obtained, two steps of distance adjustment may be made by an output signal from a brightness sensor circuit for use in sensing a brightness of the object.

Abstract: A focus detection system is provided in which an image of an object is projected onto an array comprising a plurality of light acceptor elements, formed by photoelectric elements, to cause them to produce photoelectric signals in accordance with the distribution of light intensity of the image. The photoelectric signals are converted into digital equivalents, and an absolute magnitude of a difference between digital signals of adjacent elements is calculated. These absolute magnitudes are arranged in the sequence of their magnitude, and a given number of them is accumulated, starting from the largest one. The accumulated value is utilized as the value of an evaluation function which indicates the sharpness of the image.