Abstract: A focus detecting optical includes a condenser lens placed in the proximity of a preset imaging plane equivalent to the imaging plane of a photographic lens, a pair of aperture stops dividing the pupil of the photographic lens placed on the exit side of the condenser lens into two areas, and a pair of re-imaging lenses for forming two secondary object images corresponding to the aperture stops, and satisfies the following conditions:

Abstract: A sub-mirror which deflects a focal point detection light flux passing through an area off the optical axis of a photographing optical system toward the optical axis and a second deflection member that deflects the focal point detection light flux deflected by the sub-mirror to allow it to advance roughly parallel to the photographic optical axis are provided. A pair of light fluxes achieved by deflecting the focal point detection light flux twice are guided to an image sensor to form a pair of subject images on the image sensor. The focal adjustment state is detected based upon the extent to which the pair of subject images are offset.

Abstract: A device for determining an amount of focus adjustment for an image-forming optical system which forms an image on a predetermined image plane includes a sensor, an image-re-forming optical system which re-forms the image on the sensor, and a reference member disposed at a position close to the predetermined image plane of the image-forming optical system. The projection image of the reference member is detected by the sensor, and a correction calculation is performed on the basis of the displacement of the projection image of the reference member from a preset position, so that errors in detection results caused by temperature variation, etc., are corrected.

Abstract: An optical element disposed behind a main mirror and inclined relative to the optical axis is arranged at a position to correct aberration in the luminous flux generated by transmission through the main mirror.

Abstract: A focal point detection apparatus that includes a sub-mirror constituted of a concave mirror and performs focal point detection in the phase difference detection method is capable of implementing a focal point detection over a wide range. A light flux for focal point detection having passed through a semi-transmissive reflecting member and a reflecting member constituted of the concave mirror described above enters a focal point detection optical system. A correction optical system provided between the semi-transmissive reflecting member and the reflecting member constituted of the concave mirror corrects an offset of the direction along which the light flux for focal point detection advances caused by the reflecting member constituted of the concave mirror, in conformance to the image height at the focal point detection position. By utilizing this correction optical system, it becomes possible to reduce the size of the focal point detection apparatus while assuring a large focal point detection area.

Abstract: A focus detection device is provided with a pupil dividing system, an intensity distribution pattern forming system, a plurality of light receiving elements arranged in a direction where the pupil is divided, a focus detection area defining system having an focus detection opening, the focus detection area defining system being arranged on or in the vicinity of a plane equivalent to a focal plane of the photographing lens, the light passing through the pair of focus detection areas passing through the focus detection opening, a deflection prism arranged between the focus detection opening and the pupil dividing system, and an optical element provided in the vicinity of the pupil dividing system, the optical element having an anamorphic refractive power. A refractive power in the pupil dividing direction is greater than a refractive power in a direction perpendicular to the pupil dividing direction.

Abstract: A range finder includes an improved module structure, that facilitates injecting a transparent filler uniformly into the entire light guide spaces neither leaving any unfilled region nor impairing the characteristics thereof. A channel of flow (or U-groove) is formed across a partition wall, connecting light guide spaces arranged side by side. This feature allows smooth flow of transparent filler into the range finder module without an unfilled region and consequently no overflow of the transparent filler onto outer wall of the plastic module and onto terminal portion of the lead frame. Another feature of this invention is the presence of shield walls along the channel of flow protruding from the side walls of the channel of flow in an inter-digitated fashion, to prevent the stray light from one light guide space entering the other light guide space through the channel of flow.

Abstract: A device for determining an amount of focus adjustment for an image-forming optical system which forms an image on a predetermined image plane includes a sensor, an image-re-forming optical system which re-forms the image on the sensor, and a reference member disposed at a position close to the predetermined image plane of the image-forming optical system. The projection image of the reference member is detected by the sensor, and a correction calculation is performed on the basis of the displacement of the projection image of the reference member from a preset position, so that errors in detection results caused by temperature variation, etc., are corrected.

Abstract: A camera includes a finder for enabling an image which is shot on a film to be monitor-displayed by branching a portion of a light beam (image) imaged by a picture-taking lens system, by an up/down movable pellicle mirror comprised of a half mirror, to let the image be received on a image pick-up device. In this camera, a pupil-dividing LCD is arranged in front of the image pick-up device to impart a phase difference to the light beam imaged by the picture-taking lens system to obtain corresponding image data. By doing so, phase difference AF control is carried out. The image pick-up device has both the function of monitoring a pick-up image and the function of detecting a just-in-focus state.

Abstract: A focus detecting device for detecting images from different pupil areas on time-shared basis, and detecting the phase difference of the images from the different areas, thereby detecting the defocus amount, is described. The focus detecting device of this type is incapable of exact defocus amount detection, because of the influence of the relative movement between the object and the photographing optical system. The exact defocus amount can be determined by detecting images from a same pupil area on time-shared basis, determining the phase difference between such images and effecting correction corresponding to the phase difference between the images from the same pupil area.

Abstract: A sub-mirror which deflects a focal point detection light flux passing through an area off the optical axis of a photographing optical system toward the optical axis and a second deflection member that deflects the focal point detection light flux deflected by the sub-mirror to allow it to advance roughly parallel to the photographic optical axis are provided. A pair of light fluxes achieved by deflecting the focal point detection light flux twice are guided to an image sensor to form a pair of subject images on the image sensor. The focal adjustment state is detected based upon the extent to which the pair of subject images are offset.

Abstract: A multipoint focus detecting apparatus of a camera includes a plurality of exit-pupil dividing devices, pairs of light distribution forming devices, a plurality of array type photoelectric conversion sensors, a focus detection zone determining device, and at least one condenser lens positioned between the focus detection zone determining device and the plurality of exit-pupil dividing devices. An exit surface of the condenser lens(es) is formed as a curved surface in both a direction of an optical axis of the photographing lens and a first direction, and is further formed as an aspherical surface in cross section in both the direction of the optical axis of the photographing lens and the second direction, so that the exit pupil and the plurality of exit-pupil dividing devices become optically conjugate to each other in the first direction.

Abstract: An optical system of a composite camera including a first image-forming optical system, a second image-forming optical system, and a condenser lens group, which includes two or more lens elements, or includes a single lens element on which at least one aspherical surface is formed; and at any image height on the equivalent image plane, the following condition is satisfied: &Dgr;&thgr;Pmax−&Dgr;&thgr;Pmin<2° . . .

Abstract: A multipoint focus detecting apparatus of a camera includes a plurality of exit-pupil dividing devices for dividing an exit pupil of a photographing lens into a plurality of detection sub-zones which correspond to a plurality of arrays of light receiving elements; a plurality of pairs of light distribution forming devices, each of which receives light bundles which are passed through a corresponding pair of the plurality of detection sub-zones to form a corresponding pair of light distributions; a focus detection zone determining device; and a light intercepting member which is positioned in a vicinity of an intersection between the at least two light bundles so that each of the at least two light bundles is not incident on any of the plurality of arrays of light receiving elements other than a corresponding one of the plurality of arrays of light receiving elements.

Abstract: The present invention provides a low-cost focus detector that can carry out a focus detection over a wide field of view and can secure a sufficient light-receiving quantity to have an improved S/N ratio and an improved focus detection precision. A camera has a condenser lens disposed near a predetermined focusing surface of an image pick-up lens. At the rear of the condenser lens, a brightness diaphragm having a pair of apertures is disposed. Further, at the rear of the brightness diaphragm, a telecentric type image re-forming lenses are disposed. Images formed by beam fluxes passed through the image re-forming lenses are received by an image pick-up device that includes photoelectric conversion elements.

Abstract: A sub-mirror which deflects a focal point detection light flux passing through an area off the optical axis of a photographing optical system toward the optical axis and a second deflection member that deflects the focal point detection light flux deflected by the sub-mirror to allow it to advance roughly parallel to the photographic optical axis are provided. A pair of light fluxes achieved by deflecting the focal point detection light flux twice are guided to an image sensor to form a pair of subject images on the image sensor. The focal adjustment state is detected based upon the extent to which the pair of subject images are offset.

Abstract: A focus detecting device comprising a taking lens for photographing an object, a relay optical system for re-forming an object image via the taking lens, and a detecting means having first and second sensor pairs for detecting the image re-formed by the relay optical system, wherein focus detection is accomplished using one sensor of the first sensor pair and one sensor of the second sensor pair.

Abstract: A focus detection device is provided with a pupil dividing system, an intensity distribution pattern forming system, a plurality of light receiving elements arranged in a direction where the pupil is divided, a focus detection area defining system having an focus detection opening, the focus detection area defining system being arranged on or in the vicinity of a plane equivalent to a focal plane of the photographing lens, the light passing through the pair of focus detection areas passing through the focus detection opening, a deflection prism arranged between the focus detection opening and the pupil dividing system, and an optical element provided in the vicinity of the pupil dividing system, the optical element having an anamorphic refractive power. A refractive power in the pupil dividing direction is greater than a refractive power in a direction perpendicular to the pupil dividing direction.

Abstract: Laser distance-measuring instrument for large measuring ranges having a transmitting channel and a receiving channel arranged parallel to one another, the receiving lens being a modified single lens comprising a primary lens region with a primary optical reception axis which is aligned parallel to the optical transmission axis, as well as a secondary lens region with a secondary optical reception axis which is inclined to the primary optical reception axis at an angle &agr;, with the result that a primary focal point and a secondary focal point are produced.

Abstract: A focus detecting device for detecting a focusing state of an objective lens includes a field lens disposed adjacent to a prescribed image forming plane of the objective lens and having lens surfaces which differ in shape from each other correspondingly with a plurality of focus detecting areas, a reimaging lens disposed behind the field lens and having a pair of lens parts for forming a pair of light distributions for each of different pupils of the objective lens, and a light receiving sensor arranged to receive the pair of light distributions so as to detect the focusing state of the objective lens, wherein a first area of the field lens has a first field lens part having an optical axis which coincides with an optical axis of the objective lens, and a second area of the field lens which differs from the first area has a second field lens part having an optical axis which does not coincide with the optical axis of the first field lens part.

Abstract: A multipoint focus detecting apparatus of a camera includes a plurality of exit-pupil dividing devices; a plurality of pairs of light distribution forming devices; a plurality of arrays of light receiving elements, light receiving surfaces thereof being provided on a common plane; a focus detection zone determining device which includes a plurality of focus detection apertures and is positioned in a plane located substantially at a position optically equivalent with a focal plane of the camera photographing lens; and at least one deflecting device which deflects light bundles which are respectively passed through corresponding focus detection apertures, at least one corresponding exit-pupil dividing device, and corresponding pairs of light distribution forming devices so that a principal ray of each of light bundle is incident on a corresponding array of light receiving elements in a direction normal to a light receiving surface thereof.

Abstract: A focus detecting device for detecting a focusing state of an objective lens includes a field lens disposed adjacent to a prescribed image forming plane of the objective lens and having lens surfaces which differ in shape from each other correspondingly with a plurality of focus detecting areas, a reimaging lens disposed behind the field lens and having a pair of lens parts for forming a pair of light distributions for each of different pupils of the objective lens, and a light receiving sensor arranged to receive the pair of light distributions so as to detect the focusing state of the objective lens, wherein a first area of the field lens has a first field lens part having an optical axis which coincides with an optical axis of the objective lens, and a second area of the field lens which differs from the first area has a second field lens part having an optical axis which does not coincide with the optical axis of the first field lens part.

Abstract: An optical system of a focus detecting device for detecting a focusing condition of a main lens with respect to an image taking plane. The optical system includes a focus detection area arranged on an equivalent image taking plane, a first deflecting element for deflecting the light from the main lens through the focus detection areas in a first direction, a condenser lens for converging the light deflected by the first deflecting element, a second deflecting element for deflecting the light through the condenser lens in a second direction opposite to the first direction, and a light receiving element for receiving the light deflected by the second deflecting element. The condenser lens is arranged such that the light transmits along about the meridional plane of the condenser lens.

Abstract: A multipoint focus detecting apparatus having a plurality of focus detecting zones arranged in a first pattern on a predetermined focal plane, and a corresponding plurality of arrays of light receiving elements which are arranged in a second pattern, wherein a corresponding plurality of light bundles which are passed through the plurality of focus detecting zones are made incident on the plurality of arrays of light receiving elements. The multipdint focus detecting apparatus includes: a plurality of pairs of separator lenses, each pair of which divides an image in a corresponding one of the plurality of focus detecting zones into two separate images; a separator mask positioned in front of the plurality of pairs of separator lenses and including a plurality of pairs of openings to correspond to the plurality of pairs of separator lenses; and a light bundle deflector positioned in the closevicinity of the plurality of pairs of separator lenses.

Abstract: Disclosed is a multipoint focus detecting apparatus having a plurality of focus detecting zones arranged in a first pattern on a predetermined focal plane around the center thereof, and a corresponding plurality of light receiving elements arranged in a second pattern that is different from the first pattern, a corresponding plurality of light beams which are passed through the plurality of focus detecting zones being made incident on the plurality of light receiving elements, respectively. The plurality of focus detecting zones includes a first focus detecting zone and a second focus detecting zone positioned farther from the center of the predetermined focal plane than the first focus detecting zone.

Abstract: A measuring instrument is formed of an image pickup device having a pair of image-forming lenses and photosensor arrays; and an arithmetic device using two images of a measured object photographed by the image pickup device to calculate the distance to the object based on the principle of triangulation. The image-forming lenses, a first holding member for the image-forming lenses and a second holding member for the photosensor arrays are formed of the same plastic material without hygroscopicity. Changes in size of the measuring instrument by ambient temperature and humidity are prevented to increase distant measurement accuracy.

Abstract: To perform accurate focus detection using a wide range of injected luminous flux from a photographic lens, a deflecting plate, which deflects the injected luminous flux of the photographic optical system in the vertical direction with respect to the direction of a pair of entrance pupils of a focus detecting optical system, is provided at, or near, a predetermined image forming plane of the photographic optical system. By this structure, the entrance pupils of the focus detecting optical system can be spread in a direction vertical to the focus detecting direction, and the focus detecting accuracy can be improved by using a wider range of the injected luminous flux of the focus detecting optical system.

Abstract: A focus detecting device which performs a temperature compensating action on the basis of an output of a temperature sensor includes a focus detecting sensor, a reimaging lens which reimages a light flux to be used for focus detection, a support member on which the focus detecting sensor and the reimaging lens are mounted, and the temperature sensor disposed in the vicinity of a mounting surface of the support member on which the reimaging lens is mounted.

Abstract: A distance measuring device by use of a light passive method which is used in a lens shutter camera and the like. The device includes a distance measuring module which comprises a separator lens and photoelectric conversion element chips. Wherein the module, the element chips are arranged in horizontal and vertical direction in cross-pattern, and each optical path of a plural luminous flux from the separator lens to the element chips is restricted only by the distance measuring module itself. In accordance with an electric signal of pairs of the object image formed on the element chips, a distance to an object can be detected. Thereby a probability of distances measuring is improved without a restriction for taking in luminous flux widely for distance measuring.

Abstract: A focus detection device that is capable of performing focus detection in several focus detection areas within a photographic image plane using, for example, a phase difference method and that uses an auxiliary illumination light with at least one of the areas also includes infrared light cut filters that block the transmission of light above predetermined wavelengths. In particular, the maximum wavelength of the light transmitted by the infrared cut filter for one of the focus detection areas is different than the maximum wavelength of the light transmitted by the infrared cut filter for another one of the focus detection areas.

Abstract: There is disclosed a focus detecting apparatus capable of detecting the focus state of an objective lens in a wide viewing field, comprises a view finder optical unit for observing the image formed by the objective lens, an optical unit for forming a pair of optical amount distributions, based on light beams passing through different areas of the pupil of the objective lens, wherein the optical unit being provided, at the light incident side, with a concave face directed to the light incident side, and, at the light exit side, with a convex face directed to the light exit side, a sensor unit for received said pair of the optical amount distributions, a main mirror positioned in the optical path from the objective lens to the optical unit and adapted to reflect the light beams from the objective lens toward the finder optical unit, and a reflecting mirror having a concave curved face directed to the light entrance side and adapted to reflect the light beams, transmitted by the main mirror, in a direction oppos

Abstract: An apparatus which has a finder optical unit for observing therethrough an image formed by an objective lens, an optical unit for forming a pair of distributions of light quantity on the basis of light beams transmitted through the different pupils of the objective lens, a sensor unit for receiving the pair of distributions of light quantity, a main mirror disposed in an optical path leading to the objective lens and the optical unit for reflecting the light beam from the objective lens to the finder optical unit, and a reflecting mirror having a curved surface having its concave surface facing the light incidence side for reflecting the light beam transmitted through the main mirror in the direction of the optical unit which is opposite to the finder optical unit, and which well makes focus detection possible for a wide field area formed by the objective lens.

Abstract: A compact focus state detection device having a plurality of focus state detection areas at the center of and away from the center of the photo field. A first focus state detection optical system has focus state detection areas away from the center of the photo field and in a direction substantially perpendicular to the radial direction from the center point. The optical axis of each re-imaging lens of the first focus state detection optical system is decentered toward the optical axis of the shooting lens from the center of each corresponding aperture stop. Therefore, when focus state detection light rays pass through the re-imaging lens, the exit direction of the light rays deflects toward the optical axis of the shooting lens.

Abstract: A focus detecting apparatus includes an optical unit provided on an image plane side of an objective lens for detecting a focus state of the objective lens, the optical unit forming a plurality of light quantity distributions, a photoelectrical changing unit having a plurality of elements for outputting a relative positional signal between the plurality of light quantity distributions, and a circuit for detecting a focus state of the objective lens. The optical unit includes a reflecting mirror having a light condensing property for reflecting a light beam from the objective lens to form an object image on a predetermined surface, a secondary imaging lens having at least a pair of lenses for causing the object image formed on the predetermined surface to be reimaged on the photoelectrical changing unit and a pair of apertures having aperture portions respectively corresponding to the pair of lenses.

Abstract: An optical unit for detecting a focus state. The optical unit has a focus detection zone restricting plate having a plurality of openings arranged in a first pattern in a vicinity of a predetermined focal plane on which an object image is formed. A sensor unit having a plurality of sensor sections is arranged in a second pattern, different to the first pattern, in a vicinity of an image reforming surface on which the object image is reformed. A plurality of mirrors deflect light transmitted through the plurality of openings arranged in the first pattern toward the plurality of sensor sections so as to have a direction identical to a direction of the second pattern of the plurality of sensor sections. The plurality of openings and the plurality of sensor sections are provided on a body of the optical unit. The plurality of mirrors are provided on members separate from the body of the optical unit.

Abstract: A focus detecting device includes a photographic lens, a condenser lens disposed adjacent to a preset imaging plane of the photographic lens, an aperture stop having a pair of apertures arranged with sufficient space for ensuring focus accuracy, a reimaging lens having a pair of lens elements arranged to correspond to individual apertures, and a photoelectric converter. Two light beams passing through different areas of the photographic lens are received by the photoelectric converter and the phase difference between the two light beams is detected from the intensity distribution of light on the light-receiving surface of the photoelectric converter so that a focusing state of the photographic lens can be recognized. Further, the focus detecting device satisfies the condition:0.67.ltoreq.h.sub.2 /.delta..ltoreq.0.87where h.sub.2 is the distance from the optical axis of the condenser lens to the centroidal position of an aperture of the aperture stop and .delta.

Abstract: A light beam passing a photographing lens is divided into two portions by a mirror in a camera body. One of the two divided light beams is directed to an eyepiece via a screen and pentagonal prism. The other divided light beam is reflected from a mirror and directed to a focus detection optical system constructed by a field view diaphragm, condenser lens, diaphragm mask and re-imaging lens, and an image in position corresponding to the range-finding field view is divided into two images by the optical system. An image sensor is arranged near the re-imaging surface which receives the two images formed by the focus detection optical system to photoelectrically convert a received signal and transfer data to a CPU. The CPU effects the focus detection operation containing the operation of interpolating the value of correlation between the two images by use of the self-correlation value of one of the two images based on detection data and drives the photographing lens to a focused position.

Abstract: A focus detecting device having a light distribution forming device for forming the light intensity distribution whose relative position varies in accordance with the focus adjustment of an object lens from the light flux passing through the object lens, a sensing device for receiving the light intensity distribution and outputting a signal representing the state of focus adjustment of the object lens based on the relative position in the light intensity distribution, and having a plurality of sensing elements, and a light diffusing device disposed in or near a predetermined imaging plane of the object lens, and having the degree of light diffusion determined so that the light intensity distribution can be moved relatively in accordance with the adjustment of the object lens.

Abstract: A focus detecting apparatus includes a plurality focus detecting zones arranged in a first orientation configuration. A plurality of condenser lenses are disposed behind the zones, each of the condenser lenses corresponding to each of the focus detecting zones. The apparatus further includes plural pairs of separator lenses for splitting images seen through the zones. A sensor unit having multiple line sensors is arranged in a second orientation configuration that differs from the first orientation configuration. The multiple line sensors are disposed on a reimaging plane for reimaging the split images, and each of the line sensors corresponds to each of the multiple focus detecting zones. The apparatus also includes a mechanism for deflecting a bundle of rays, passing through at least one of the plurality focus detecting zones, to be close to another bundle of rays passing through another focus detecting zone while the first configuration orientation is maintained.

Abstract: A focus state detection device includes focus state detection optical systems having focus state detection regions off the optical axis of the object lens (in the lateral areas of the field) that extend in a radial direction relative to the optical axis of the shooting lens. In each focus state detection optical system, images from the object lens are composed into secondary images on a pair of rows of photosensitive elements, and the focussing state of the object lens is detected from the positional relationship between these secondary images. The focus state detection optical systems have a first focus state detection region located on the optical axis of the predicted focussing plane of the object lens, and a second focus state detection region located off the optical axis of the predicted focussing plane and along a radial direction relative to the optical axis.

Abstract: In a focusing state or photographed object distance detector, a pair of distance measuring lenses are arranged in positions symmetrical with respect to the reference axis of a photographing lens. A pair of light-receiving element arrays are arranged behind the pair of distance measuring lenses. A pair of image signals are obtained by controlling operations of the light-receiving element arrays by CCD control sections. A conformity degree between these image signals is calculated by an integral part shifting arithmetic circuit in an element unit of each of the light-receiving element arrays. An interpolating calculation of the conformity degree is made by a decimal part arithmetic circuit to provide a precise conformity degree distribution.

Abstract: A focus detection device for a camera capable of detecting focuses at a plurality of areas on a photographing field, comprises two pairs of photo-electric conversion device arrays arranged on one substrate in optical correspondence to two of said plurality of areas; the two areas being arranged on a line extending generally vertically to a horizontal center axis crossing an optical line on the photographing field, on the opposite sides of the center line; and a refocusing optical system for refocusing light beams passing through different points of an exit pupil of a photographing lens, onto the two pairs of photo-electric conversion device arrays; the refocusing optical system including a pair of refocusing lenses for focusing the light beams onto the two pairs of photo-electric conversion device arrays.

Abstract: A focus detection device permits accurate focus detection within a short length of time. The detection is quick even if there is an error between the output signal strings of a pair of image sensors when the photo lens is in the focused condition. A pair of effective signal strings is extracted from a pair of output signal strings of a pair of photoelectric conversion arrays. The extraction of the pair of effective signal strings is based on a numerical value relating to an error amount between the output signal strings when the photo lens is in the focused condition. The focus adjustment condition of the photo lens is calculated based on the pair of effective signal strings.

Abstract: With a focus detection device equipped with focus detecting optical systems with focus detection areas both on and outside the optical axis of the photographic surface, a focus detection device suppresses vignetting of the focus detection light fluxes through incompatibilities with the exit pupil of the installed objective lens and has stable focus detection accuracy.

Abstract: To improve the responsiveness of an automatic focus adjustment camera in which focus adjustment of the photographic lens is performed based on the results of focus detection in multiple regions, defocus amounts of the photographic optical system in multiple focus detection regions are detected asynchronously and independently of one another in multiple focus detection regions that are established on the photographic screen of the photographic optical system. The value of the defocus amounts in the various focus detection regions are compensated at times T3, T5, T8 and T9 when the defocus amounts are detected in the various focus detection regions, or at preset time intervals W, and the final defocus amount is set from among these multiple compensated defocus amounts in order to drive the photographic optical system.

Abstract: In an image pick-up device including an image forming lens, a focal condition of the image forming lens is detected by means of a focus detecting optical system including a condenser lens arranged near a predetermined focal plane of the image forming lens, a plurality of aperture stops which divides a light flux emanating from an object into a plurality of light fluxes, a plurality of image reforming lenses each corresponding to respective aperture stops and a plurality of light receiving element arrays each corresponding to respective image reforming lenses. Output characteristics of the light receiving element arrays are are expressed as three dimensional information, while an image position is expressed on X axis, a pupil position through which a light flux is transmitted is expressed on Y axis, and an intensity of light is expressed on Z axis. The three dimensional image is distorted on X-Z plane in accordance with defocus.

Abstract: A focus detection apparatus adapted to reform images of light fluxes that pass through differing regions of a photographic lens into a pair of images on light receiving element arrays by using, for each pair of images, a field mask, a field lens, a pair of re-imaging lenses and an aperture mask having a pair of aperture openings provided in the vicinity of the pair of re-imaging lenses. The focus detection apparatus has multiple focus detection blocks that detect the focus condition of the photographic lens from positions relative to the pairs of images. The focus detection apparatus is further adapted to detect the focus condition of multiple areas on a focal plane. The focus detection apparatus includes a deflection mirror positioned between the field lens and the pair of re-imaging lenses. The deflection mirror causes the light fluxes to be deflected at nearly right angles for focus detection.

Abstract: A focus detecting device for use in a camera or the like increases the probability of capturing a desired object in a view finder by a light-receiving unit having a small width in a projected image when a focus frame in a view finder is placed on the object. The device includes a phototaking optical system for forming a primary image of the object on the phototaking image frame, a focus detecting optical system for re-imaging the primary image as second images, an image sensor including first and second light-receiving units for receiving the secondary images and a focus detecting calculation unit for detecting the focus state of the phototaking optical system from the output of the image sensor.