Abstract: A distance measuring device, or a focus detector, including a plurality of sensors provided in association with a plurality of different areas, and a respective plurality of processing circuits provided in association with the plurality of sensors, to process signals output from the plurality of sensors, where power selectively is supplied only to a sensor(s) and a processing circuit(s) associated with the sensor(s) that correspond to a predetermined area from among the plurality of different areas. The predetermined area may be determined on the basis of the state of a power source (e.g., detected voltage level), the focal length of a shooting optical system, the state of an auxiliary light for irradiating an object, and the like.

Abstract: The distance measuring apparatus of the present invention comprises distance measurement value selecting means for detecting the shortest distance measurement value corresponding to the shortest distance among the plurality of distance measurement values, and selecting the distance measurement values which differ from the shortest distance measurement value by a value less than a predetermined threshold value; first computing means for calculating a first correction value, which is the mean value of the difference values between the shortest distance measurement value and the selected distance measurement values; second computing means for detecting the farthest distance measurement value corresponding to the farthest distance among the selected distance measurement values, and calculating a second correction value, which is ½ the difference between the shortest distance measurement value and the farthest distance measurement value; and third computing means for calculating the autofocus data by correc

Abstract: In a camera including a light measuring device having a plurality of light measuring areas into which a light measuring field is divided, and a focus detecting device having a plurality of focus detecting areas which are set at a plurality of places including a place on a boundary between the plurality of light measuring areas, the focus detecting device is arranged to select a particular focus detecting area from among the plurality of focus detecting areas, and a deciding circuit decides a light measuring area which is to be subjected to a specific weighting, from among the plurality off light measuring areas by using a focus detecting state of each of the particular focus detecting area and focus detecting areas adjacent thereto if the particular focus detecting area lies on the boundary between the plurality of light measuring areas.

Abstract: An automatic focusing camera is provided with a determining device that determines a plurality of positions of a lens group or an imaging surface of a CCD for focusing on a plurality of subjects in a subject image, an AF motor that sequentially moves the lens group or the imaging surface of the CCD to the determined positions, and a shooting device that performs shootings when the lens group or the imaging surface of the CCD is at the positions.

Abstract: This invention provides an automatic framing camera that identifies a still subject, frames it, and photographs it. The ranging direction of a ranging unit (light emitting element and light receiving element) that can range in one direction is changed by a pan motor and a tilt motor, and a still person is searched for by changes in the signal from the ranging unit. Then, the photography direction of the imaging element is turned by the tilt motor toward the center of the face of the person that was found, this is framed with the center of the person's face in the center of the angle of view, and the person's face is photographed by the imagining component.

Abstract: In multi-point distance measurement, the distance of a distance measurement object is three-way divided into a very short distance range, a short distance range and a moderate to long distance range, and if the distance of an object located at a very short distance is measured in any one of the endmost distance measurement areas of a plurality of distance measurement areas, and all the distances measured in other distance measurement areas belong to the moderate to long distance, the distance belonging to the very short distance range is not employed, and the shortest distance of distances belonging to the moderate to long distance range is employed as a measured distance. On the other hand, if any of the distances measured in other distance measurement areas belongs to the short distance range which is closer than the moderate to long distance range, the distance belonging to the very short distance range is employed, thereby reducing the frequency of erroneous distance measurement.

Abstract: A correlation value calculation is performed by using AF data arranged at predetermined intervals in the AF data in a pair of window ranges, so that a frequency of calculation can be reduced. On the other hand, a correlation value calculation is performed by using all the AF data in the pair of window ranges only in predetermined ranges before and after the shift amount of the pair of window ranges when the highest correlation value in the correlation values is obtained, thereby suppressing a reduction in measurement precision. For example, in a pair of the AF data obtained from a pair of window ranges, the correlation value calculation is performed by using every third piece of the AF data.

Abstract: In the distance measuring apparatus which uses a passive AF sensor and determines the subject distance by carrying out correlation value calculation according to AF data obtained from a pair of line sensors of the AF sensor to detect the smallest minimum value of the correlation value, if the difference between the smallest minimum value and the second smallest minimum value of the correlation values is smaller than a predetermined value, it is determined that distance measurement is impossible, and the predetermined value is changed in accordance with the magnitude of the smallest minimum value, thus making it possible to appropriately determine whether distance measurement is possible or impossible according to the aspect of AF data. Therefore, problems such that it is determined that distance measurement is impossible more than necessary, or erroneous distance measurement occurs can be prevented.

Abstract: In an apparatus comprising a zoom lens and an electric flash, a range finder that determines, on the basis of an output result obtained by means of one method out of an active AF and a passive AF, whether or not to operate the other method, is utilized.

Abstract: There is disclosed a distance measurement apparatus of a camera which obtains subject distance information (phase difference of a subject luminance signal) of each distance measurement area by a photoelectric conversion element with a plurality of distance measurement areas including a peripheral region outside a region to be photographed arranged therein, divides the distance measurement areas having numeric values in a predetermined range and being adjacent to one another into groups from the obtained subject distance information, excludes the group extending into the region to be photographed, performs distance measurement operation processing of a major subject by a distance measurement result of the group existing only in the region to be photographed, selects a result indicating a closest distance from distance measurement results, and obtains a final distance measurement output.

Abstract: A rangefinder device and a camera are provided, which, in measuring a distance by the active method, are capable of properly measuring the distance even if the object to be measured is located at a short distance, while in measuring a distance by the passive method, are capable of measuring the distance without causing the conflict between far and near objects. A projecting section projects spot-shaped light on a range-finding object. A light receiving section comprises a plurality of photoelectric converting elements. A first calculating section calculates distance measurement information based on an output from the light receiving section receiving reflected light from the range-finding object, by driving the projecting section to project the light, and a second calculating section calculates distance measurement information based on an output from the light receiving section receiving extraneous light reflected from the range-finding object, without driving the projecting section.

Abstract: Provided is a distance measuring apparatus that can cope with the problem of wrong distance measuring attributable to the presence of miscellaneous subjects and minimize the possibility of defocused photographing. In this distance measuring apparatus, passive-type distance measuring is carried out in accordance with a subject image signal for the central portion of a view field. Signal light for distance measuring from an infrared-emitting diode is projected on a subject in the central portion of the view field, and active-type distance measuring is carried out by means of a sensor array in accordance with reflected signal light reflected by the subject. According to the output result of the passive-type central distance measuring, a CPU determines whether or not to effect distance measuring for the peripheral portion of the view field based on an image signal for the peripheral portion.

Abstract: This invention is an inexpensive distance measuring device having short lag time, configured so as to have a pair of light receiving regions at positions of focal points of a pair of image forming optical systems, comprising functions for dividing the light receiving regions and for monitoring the integration control for each divided light receiving region, also comprising an AF area sensor capable of performing pre-integration operations while causing strobe light to be emitted, and a microcomputer that, according to object field luminance distributions obtained from pre-integration results of the AF area sensor and to the focal length value of the photographic lens, divides the light receiving regions of the AF area sensor into respective pluralities, causes final integration operations to be performed while monitoring the integration control in each of the divided light receiving regions, and performs ranging computations based on data obtained for each light receiving region, capable of performing appropr

Abstract: A multi-point autofocus system includes a focus detection device which can calculate a defocus amount for each of a plurality of focus detection zones in a picture plane; a selecting device for manually selecting a focus detection zone from the plurality of focus detection zones for which the defocus amount is to be calculated by the focus detection device; and a determining device for determining a valid focus detection zone by which a valid defocus amount can be calculated out of at least one of the plurality of focus detection zones other than the manually-selected focus detection zone, in such a manner that a higher priority is given to a focus detection zone than another focus detection zone of the plurality of focus detection zones in the case where the result of a calculation of the defocus amount of the manually-selected focus detection zone is invalid.

Abstract: An optical apparatus and a camera are provided, which have line-of-sight detecting means, and are capable of selecting a proper AF point selected even if the actually detected line of sight deviates significantly from the observer's intention and capable of reducing the time required for selecting the AF point. A plurality of focus detecting areas are provided on an observing screen, from which focus information on a subject is detected. A line-of-sight detecting device picks up an image of an eyeball of the user to detect the location of a gazing point of the user, A grouping circuit groups the focus detecting areas into a plurality of groups with priorities based on the detected location of the gazing point. A selecting circuit selects one of the groups according to the priorities and selects at least one focus detecting area from the selected group.

Abstract: A pair of integration-type light-receiving sensors receive the light from subjects via a taking optical system and produce a subject image signal. A light projecting section projects light onto the subjects. A steady-state light removing section obtains an image signal by removing the steady-state light component from the subject image signal the pair of integration-type light-receiving sensors produces, while the light projecting section is projecting light onto the subjects. A first distance-measuring section measures a subject distance on the basis of the image signal obtained by causing the steady-state light removing section to remove the steady-state light component from the subject image signal. A subject select section causes the first distance-measuring section to make distance measurements for a specific time, performs operation on the resulting image signal using a specific correction function, and thereby selects a subject whose distance is to be measured.

Abstract: The present invention comprises a first distance-measuring mode in which a subject distance is measured on the basis of a subject image signal produced by at least a pair of light-receiving elements receiving the light from subjects, a second distance-measuring mode in which the subject distance is measured on the basis of an image signal from which a steady-state light removing section has removed the steady-state light component from the subject image signal, while a projecting source is projecting light onto the subjects, and a CPU which causes the second distance-measuring mode to operate for a specific time and, according to the image signal obtained, selects a subject whose distance is to be measured.

Abstract: A distance measuring apparatus has a sensor, a monitor region selection portion, a distance measuring portion, and a detection portion. The sensor photoelectrically converts the subject image to output a subject image signal corresponding to the luminance distribution. The monitor region setting portion sets the monitor region at the time of integration of the above sensor. The distance measuring calculation portion calculates the distance measurement with respect to the region including the monitor region set with the monitor region setting portion. The detection portion detects a region low in luminance and low in contrast based on the above subject image signal. The monitor region setting portion sets as the second monitor region the low luminance and low contrast region detected with the detection portion out of the first monitor region set at the first time.

Abstract: This invention constitutes a measuring distance device including a sensor array which detects image signals of an object in a finder screen, a projection unit which projects a signal light on the object, a selection unit which selects a detection area for the image signal of the sensor array, a change unit (control unit) which makes detection areas selected by the selection unit different from each other when the signal light is projected or is not projected by the projection unit, and a focus adjustment unit which performs focus adjustment by an image signal output in the detection area of the sensor array selected by the selection unit. A reduction in time lag is achieved without increasing a read area, and an influence of harmful light is reduced. This device which can perform an accurate and high-speed process can be applied to a hybrid AF camera.

Abstract: A pair of integration-type light-receiving sensors receive the light from subjects and produce a subject image signal. A light projecting section projects light onto the subjects. A steady-state light removing section obtains an image signal by removing the steady-state light component from the subject image signal the pair of integration-type light-receiving sensors produces, while the light projecting section is projecting light onto the subjects. A first distance-measuring section measures a subject distance on the basis of the subject image signal from the pair of integration-type sensors. A subject position estimating section causes the first distance-measuring section to make distance measurements for a specific time and, on the basis of the resulting reflected light image signal, estimates the position of the main subject.

Abstract: A multi-point distance measuring apparatus has a plurality of distance measuring points for performing a multi-point distance measurement. Sensor arrays detect an image pattern at each distance measuring point in the picture. A control circuit determines a distance measuring mode for each distance measuring point, based upon the output signal of the sensor arrays.

Abstract: A focus detecting device includes a defocus amount detecting circuit for detecting an amount of defocus obtained at each of a plurality of focus areas disposed within an image plane, a selecting circuit for, on the basis of amounts of defocus detected respectively at the plurality of focus areas, dividing the plurality of focus areas into a plurality of groups and selecting a focus area capturing a target object from among the plurality of groups, a posture sensor for detecting a posture of an apparatus, a weighting circuit for, on the basis of positions of the plurality of focus areas within the image plane, dividing the plurality of focus areas into a plurality of groups and respectively weighting the plurality of groups, the weighting circuit making grouping of the plurality of focus areas differently according to the posture of the apparatus, and a deciding circuit for deciding at least one focus area from among the plurality of focus areas by adding a result of weighting made by the weighting circuit to

Abstract: Provided is a distance measuring apparatus that can cope with the problem of wrong distance measuring attributable to the presence of miscellaneous subjects and minimize the possibility of defocused photographing. In this distance measuring apparatus, passive-type distance measuring is carried out in accordance with a subject image signal for the central portion of a view field. Signal light for distance measuring from an infrared-emitting diode is projected on a subject in the central portion of the view field, and active-type distance measuring is carried out by means of a sensor array in accordance with reflected signal light reflected by the subject. According to the output result of the passive-type central distance measuring, a CPU determines whether or not to effect distance measuring for the peripheral portion of the view field based on an image signal for the peripheral portion.

Abstract: Amulti-point autofocus system includes a focus detection device which can calculate a defocus amount for each of a plurality of focus detection zones in a picture plane; a selecting device for manually selecting a focus detection zone from the plurality of focus detection zones for which the defocus amount is to be calculated by the focus detection device; and a determining device for determining a valid focus detection zone by which a valid defocus amount can be calculated out of at least one of the plurality of focus detection zones other than the manually-selected focus detection zone, in such a manner that a higher priority is given to a focus detection zone than another focus detection zone of the plurality of focus detection zones in the case where the result of a calculation of the defocus amount of the manually-selected focus detection zone is invalid.

Abstract: A camera having a device for detecting a zoom position of a zoom lens, a finder zoomable by being linked to zooming of the zoom lens, a device for detecting a position of a user's gaze in the finder, a range finding device having a plurality of predetermined range finding regions and having a function of forming range finding information on each range finding region, and a selection circuit for selecting at least one of the range finding regions according to the gaze position detected by the gaze position detecting device and the zoom position detected by the zoom position detecting device.

Abstract: An automatic focus adjusting apparatus includes an image move-amount detecting section, an image position predicting section and a control section. The image move-amount detecting section detects, for each of a pair of images of a subject divided in a predetermined direction, image positions of the subject in an image-divided direction and in a direction approximately orthogonal with this image-divided direction respectively on photoelectric conversion elements at mutually different first and second times respectively, and obtains move amounts of the images of the subject in the image-divided direction based on a result of this detection. The image position predicting section predicts an image position of the subject in an image-divided direction at a third time different from the first and second times, based on an output from the image move-amount detecting section.

Abstract: A camera is provided with an SPD and a PSD suitable for implementing a camera capable of enhancing an accuracy of focusing and/or reducing a cost with a small scale of circuit. In the event that a photography is performed at a relatively short distance, a switch is switched by an MPU to offer a low impedance state. An AF-dedicated photo detector circuit determines a distance I1 and I2 obtained through a pair of signal electrodes of the PSD. On the other hand, in case of a relatively long distance, the MPU switches the switch to offer a high impedance state in accordance with distance data representative of the determined distance, so that an AF-dedicated photo detector circuit determines a distance up to the camera subject in accordance with photo-current I3 obtained from one of the signal electrodes of the PSD.

Abstract: A multi-zone autofocus system for a still camera having at least three autofocus distance zone focus settings in which a two-zone autoranging circuit is operated sequentially at different threshold settings corresponding to different distances from the camera under control of a microprocessor to enable discrimination among at least three focus zone settings.

Abstract: There is provided a distance measuring apparatus in a lens-shutter type camera provided with a photographic lens, a focal length of the photographic lens being variable.

Abstract: An automatic-focusing camera is provided with a multiple-point distance-measurement device having a plurality of distance-measurement areas, a multiple-division photometry device having a plurality of photometry areas, and a multiple-division light-amount-control device having a plurality of light-amount-control areas. Part of the photometry areas and part of the light-amount-control areas correspond to the distance-measurement areas. When a taking lens is focused on a subject, its focus is locked. Out of the information obtained from the multiple-point distance-measurement device, a set of information obtained when the focus of the taking lens is locked is compared with a set of information obtained immediately before a shot is taken, and thereby a change in picture composition after the locking of the taking lens focus is detected. This makes it possible to achieve exposure control in ambient-light shooting and light amount control in flash shooting in accordance with a change in picture composition.

Abstract: A camera is provided with a distance measurement device having a plurality of distance measurement regions and outputting distance measurement information of each distance measurement region, a light adjustment device having a plurality of light adjustment regions including regions substantially coinciding with the distance measurement regions, and an auxiliary light emitting device for emitting auxiliary light in distance measurement. The auxiliary light emitting device emits auxiliary light when low contrast is detected in at least one of the plurality of distance measurement regions. When auxiliary light is emitted, the flash light emission quantity is controlled based on the distance measurement information in auxiliary light emission and an output from the light adjustment device.

Abstract: A camera with a distance measuring apparatus has distance measuring functions by means of an active system and a passive system to allow good distance measurement with respect to an object in a wide variety of conditions. The camera includes a first signal forming unit, a second signal forming unit, a release detecting unit, an object condition detecting unit and a selective control unit. The first signal forming unit projects light distance measurement light from a light projecting unit, receives a reflection signal of the distance measurement light from the object at a light receiving unit and forms a focusing signal for the object. The second signal forming unit monitors the luminance distribution state of the object using an image signal detecting unit and forms a focusing signal for the object. The release detecting unit detects whether or not a release operating member is operated.

Abstract: A camera capable of print format selection includes a connecting unit for responding to at least one of a unit for forming information for focus adjustment on the basis of one of distance measurement information of a plurality of portions in a scene and defocus information, and a unit for different print formats, thereby affecting an operation related to at least the other unit, or includes a connecting unit for responding to at least one of a unit for a predetermined distance range and a unit for different print formats, thereby affecting an operation related to at least the other unit.

Abstract: A sensor unit of the present invention is provided with a plurality of line sensors disposed in parallel. Each of the line sensors has a light receiving element array comprising a plurality of light receiving elements arranged in an array, and a processing unit array disposed along the light receiving element array and for processing to output photocharges generated by the plurality of light receiving elements. At least two of the plurality of line sensors are disposed in such a manner that processing unit arrays thereof are opposed to each other.

Abstract: A focus detecting device capable of focus detection in a plurality of focus-detecting areas, includes a setter for setting a first group including at least two focus-detecting areas, and a second group including a plurality of focus-detecting areas, which are not included in the first group, and a focus detector means for executing focus detection in the order from the focus-detecting areas included in the first group. The focus detecter ends focus detection without executing focus detection in the focus-detecting areas included in the second group, when the focus-detecting area included in the first group satisfies a predetermined condition.

Abstract: An optical apparatus having a focus adjusting function, including: a focus detection unit for executing a focus detection operation for each of a plurality of focus areas set in an image plane; a grouping unit for grouping the image plane in accordance with a distribution of defocus amounts or distances obtained from focus detection results of the plurality of focus areas; a focus area selecting unit for selecting at least one focus area from the plurality of focus areas in accordance with a grouping result; a defocus amount comparing unit for comparing a defocus amount of the selected focus area selected with a predetermined defocus amount; a lens driving unit for driving a lens until the selected focus area is made in-focus, if a comparison result by the defocus amount comparing unit shows that the defocus amount of the selected focus area is smaller than the predetermined defocus amount; and a focus area re-selecting unit for re-selecting a focus area by driving the lens in accordance with the defocus amou

Abstract: The area in which focus detection is performed is selected from among a plurality of focus detection areas provided on a photography screen. In the pair of photoelectric converters corresponding to the selected focus detection area, charge accumulation is repeatedly performed based on at least one of the image signals from the pair of image signals output from this pair of photoelectric converters. The focus adjustment condition of the photograph optical system is computed based on this pair of image signals. In the pair of photoelectric converters corresponding to the non-selected focus detection areas, charge accumulation is repeatedly performed over a period longer than the period of charge accumulation in the pair of photoelectric converters corresponding to the selected focus detection area based on at least one of the image signals from the pair of image signals output from this pair of photoelectric converters.

Abstract: There is provided a distance measuring apparatus in a lens-shutter type camera provided with a photographic lens, a focal length of the photographic lens being variable.

Abstract: A focus detector amplifies a plurality of sets of output signals from a plurality of photoelectric transfer element arrays by the most preferable amplifying mode and focuses a focus of an optical lens system on a desired object among a plurality of objects corresponding to the photoelectric transfer element arrays by selecting a method for deciding a defocus among a nearest position priority method, a lateral direction priority method and a reliability priority method responding to a condition of the objects.

Abstract: A camera includes an objective lens, a detection device for detecting defocus associated with each of at least three portions in a view field, a setting device for manually setting whether the each of at least three portions is used for focusing or not and a selecting device for automatically selecting a portion from among a plurality of the manually set portions to have been used for focusing, and for performing focusing for the selected portion by the objective lens.

Abstract: A camera which uses exchangeable photographing lenses, and is capable of focus detection using a plurality of focus areas, includes a memory for storing information pertaining to the number of focus areas that can be used in focus detection in units of mountable photographing lenses, and a microprocessor for controlling focus detection on the basis of information corresponding to the photographing lens mounted, of the information stored in the memory.

Abstract: An optical apparatus having a focus adjusting function, includes: a focus detecting unit for executing a focus detection operation for each of a plurality of focus areas set in an image plane; a grouping unit for grouping the image plane in accordance with a distribution of defocus amounts or distances obtained from focus detection results of the plurality of focus areas; a focus area selecting unit for selecting at least one focus area from the plurality of focus areas in accordance with a grouping result; a defocus amount comparing unit for comparing a defocus amount of the selected focus area selected with a predetermined defocus amount; a lens driving unit for driving a lens until the selected focus area is made in-focus, if a comparison result by the defocus amount comparing unit shows that the defocus amount of the selected focus area is smaller than the predetermined defocus amount; and a focus area re-selecting unit for re-selecting a focus area by driving the lens in accordance with the defocus amoun

Abstract: A camera is designed to select at least any one of a plurality of focus areas and adjust the focus relative to an object located in the selected focus area. The camera comprises panning detection means for detecting a panning operation and focus area selecting means for selecting a specific focus area among the plurality of focus areas based on the detection result of the panning detection means.

Abstract: A focus detector used in an AF-SLR camera has a plurality of focusing sensors disposed not only in the center but also in a region distant from the center of the frame. A first focusing sensor group of the focusing sensors which are disposed in a first region where light flux passing through a pupil of a lens having an F-number larger than a predetermined F-number such as F2.8 is always used without reference to the F-number of the lens. A second focusing sensor group of focusing sensors which are disposed in a second region where light flux passing through a pupil of a lens having an F-number equal to or smaller than the predetermined F-number and having a higher accuracy for focus detection is used only when the F-number of the lens is equal to or smaller than the predetermined F-number.

Abstract: In a module which consists of optical systems and sensors, a pair of first line sensors are arranged vertically to a pair of second line sensors, and each of the line sensors is provided with a lens which projects an object image thereon. One of the first line sensors and one of the second line sensors intersect each other at right angles, and share an object lens which projects an object image onto them. In such a construction, the number of lenses, and the space for the line sensors are reduced, so that the module can be downsized.

Abstract: There is provided a distance measuring apparatus in a lens-shutter type camera provided with a photographic lens, a focal length of the photographic lens being variable.

Abstract: A distance measurement device has a taking lens, a viewfinder, distance measurement elements for performing distance measurement in a plurality of areas on an object, a memory for storing the positional relationship between the field of view of the viewfinder and the distance measurement areas of the distance measurement elements, a selector for selecting one of the distances measured in the plurality of areas in accordance with the positional relationship stored in the memory, and a controller for adjusting the focus of the taking lens in accordance with the distance selected by the selector.

Abstract: In automatic focus controlling of a camera, a method for controlling focusing areas of the camera is performed by setting a supervisory area in the center of a subject area picked up by an optical system; setting plural variable areas into an outer periphery of the supervisory area; and detecting the subject to perform the auto focusing while performing area variation to the variable areas, unless the subject is detected while constantly observing the supervisory area. An apparatus for executing the method is also provided, enhancing precision of the auto focusing to the main subject in the case of multiple subjects, continuously tracking the auto focusing of the subject that moves to the outer peripheral side of the center of the picture, and improving the tracking property of the center area when varying the picture areas.

Abstract: An image pickup apparatus has an AF function which determines a focus state of an object using an image signal obtained from a signal output of an image pickup device and detects the lens position in an in-focus state. The apparatus includes an image-region setting circuit for selectively extracting an image region for detecting the lens position in an in-focus state, an optimum-exposure-amount calculation circuit for calculating an optimum amount of exposure for the image region using an image signal within the image region set by the image-region setting circuit, and a focus detection circuit for calculating the lens position in an in-focus state using an image signal within the image region exposed with the optimum amount of exposure calculated by the optimum-exposure-amount calculation circuit.

Abstract: A distance measuring system of the active type wherein a distance ranging from a short distance to a great distance can be measured with a high degree of accuracy in accordance with a ratio between outputs of two light receiving elements. The system comprises light emitting means which emits light twice to an object, three or more light receiving elements, and selecting means which selects output signals of different pairs of the light receiving elements when the light emitting means emits light for the first and second times for measurement of distances within short and long distance ranges, respectively. The selected output signals in each pair are compared with each other to take a ratio between them, and distances are calculated based on the ratios thus obtained. Finally, a distance to the object is determined based on the calculated two distances.