JP2012032444A - Single lens reflex camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a single lens reflex camera with a simple configuration, which reduces a change (an error) at a focus detection position due to the color temperature of a subject without reducing a light amount to be led to a finder and a focus detection sensor.SOLUTION: A single lens reflex camera includes: a reflection optical system having multiple reflection surfaces for reflecting toward an eyepiece, a subject light flux which is made incident from a focus plate arranged at a position optically equivalent to the image formation surface of a photographic lens; and an in-finder display device for displaying information to be displayed in a finder visual field by superimposition on a finder image. A semi-transmissive surface is formed on one of the reflection surfaces of the reflection optical system, where a light flux from the in-finder display device is made incident and also a part of the subject light flux from the photographic lens is emitted outward. A color temperature detection photodetector is arranged at a position where the subject light flux emitted outward from the semi-transmissive surface is made incident.

Description

  The present invention relates to a phase difference type focus detection device and a single-lens reflex camera equipped with an in-finder display device capable of displaying information related to photographing on a finder image.

  Conventionally, in a single-lens reflex camera, a pair of focus detection sensors (line sensors) is obtained by using a re-imaging lens system (condenser lens and separator lens) of a focus detection optical system for subject light beams that have passed through different portions of the exit pupil of a photographing lens. A focus detection device is mounted that forms an image above and detects the in-focus state of the photographic lens based on the relationship between the output signals of the pair of focus detection sensors. In such a focus detection device, when the distance between the first and second images on the pair of focus detection sensors is a predetermined length, the focus detection apparatus is in focus, and when the distance is shorter than the predetermined length, before focusing on the object side from the imaging surface. When the pin is longer than the predetermined length, it is determined as a rear pin that focuses on the back side from the imaging surface (phase difference detection method), and the amount of defocus from the in-focus position is output as a defocus amount.

  As the focus detection sensor, a light receiving element having sensitivity to wavelengths other than the visible light region and the visible light region mainly on the long wavelength side may be used. In this case, different focus detection is performed for light of different wavelengths due to chromatic aberration of the photographing lens. Chromatic aberration at wavelengths other than the visible light region is larger than that in the visible light region.For example, when the subject is illuminated with a light source with a low color temperature, such as a tungsten lamp typified by an incandescent lamp, the same subject is exposed to daylight or fluorescent light. Different focus detection is performed depending on the chromatic aberration of the lens when illuminated with a light source having a high color temperature such as a lamp. In particular, this chromatic aberration is large in a photographing lens having a long focal length. Therefore, when an interchangeable lens with a long focal length is attached to a single-lens reflex camera, subject light incident through the long focus lens is photoelectrically converted by the above-described light receiving element, and the focus state of the subject is detected by the photoelectric output, the chromatic aberration causes The focus detection error is significantly increased.

  Normally, in order to reduce such focus detection error, a filter that cuts wavelengths outside the visible light region on the long wavelength side is inserted in the optical path. In some cases, the near-infrared wavelength region is used so that the subject does not feel glare. Therefore, a filter characteristic that transmits the near-infrared wavelength region is required. In Japanese Patent Publication No. 8-3575 (Patent Document 1), in addition to a filter that cuts wavelengths outside the visible region on the long wavelength side, a filter that cuts near-infrared wavelengths and transmits only visible light is further provided. A method has been proposed in which either one is switched and inserted into the optical path.

  Further, as a conventional example for correcting that different focus detection is performed depending on the chromatic aberration of the lens caused by transmitting the near-infrared wavelength region, it is described in JP-B-1-45883 (Patent Document 2). There is. This is because the light receiving means (sensor) that picks up photoelectric signals from visible light out of the light flux from the subject and the light receiving means (sensor) that picks up photoelectric signals from near-infrared light separately are formed on the same substrate, and all incident wavelengths The correction value up to the in-focus position by the light of the desired wavelength with respect to the in-focus position detected by the light of is determined based on the individually extracted photoelectric signals.

  In Japanese Patent No. 2666274 (Patent Document 3), a sensor unit having a predetermined filter means for detecting a color temperature of a subject in the vicinity of a light receiving element surface for focus detection of a focus detection device is referred to as a focus detection sensor. A configuration is shown that realizes high-precision focus detection by using focus correction information for each color temperature stored in the lens in advance by arranging the same on the same substrate and outputting the color temperature information of the subject. ing.

  In Japanese Patent Publication No. 3-73847 (Patent Document 4), a detection error due to a color temperature in a focus detection unit having sensitivity to visible light and light other than visible light is provided separately from the focus detection unit. A configuration for correcting using the output of the color temperature measuring means is shown.

  Further, JP 2009-37139 A (Patent Document 5) includes two types of photoelectric conversion units having different spectral sensitivity characteristics on a photometric sensor, one as a photometric sensor having sensitivity to visible light, and the other as a photometric sensor. A configuration is shown in which each is used as a color temperature measuring means sensitive to light other than visible light, and a detection error due to the color temperature is corrected from the output ratio of the photometric sensor and the color temperature measuring means.

  Some conventional single-lens reflex cameras include an in-finder display device that can superimpose information related to shooting on a finder image. As shown in, for example, Japanese Patent Application Laid-Open No. 2000-194052 (Patent Document 6), an in-finder display device includes a third reflecting surface of a pentaprism as a semi-transmissive surface, and an auxiliary prism bonded to the semi-transmissive surface. The superimpose display light is incident through the light.

Japanese Patent Publication No. 8-3575 Japanese Examined Patent Publication No. 1-45883 Japanese Patent No. 2666274 Japanese Patent Publication No. 3-73847 JP 2009-37139 A JP 2000-194052 A

  However, when mechanical switching means is provided as in Patent Document 1, not only the focus detection device is increased in size, but also the reliability of the drive portion becomes a problem. When the focus detection sensor and the sensor for detecting near infrared light are arranged on the same substrate as in Patent Document 2, the arrangement of the sensor that receives only near infrared light becomes a problem. Since the focus detection sensor and near-infrared light receiving sensor receive light coming from different parts of the subject, respectively, depending on the structure of the subject (near-infrared light reflectivity), completely different light is received, and appropriate corrections are made. May not be possible. In recent years, the number of focus detection points has increased and the area has further increased, and the focus detection sensors have been finely arranged on the substrate, making it difficult to arrange sensors that receive only near-infrared light. When the color temperature measuring means is provided separately from the focus detection section as in Patent Documents 3 and 4, it is necessary to provide an extra branching portion that branches to the color temperature measuring means provided separately on the finder side. There is a problem that the amount of light guided to the focus detection unit side is reduced. Even when a part of the photometric sensor is used as the color temperature measuring means as in Patent Document 5, the light receiving area of the visible light portion is reduced, so that the sensitivity of the photometric sensor is lowered.

  On the other hand, in the configuration in which a part of the third reflecting surface of the pentaprism is used as a semi-transmissive surface for making the superimpose display light incident as in Patent Document 6, conversely, a part of the subject luminous flux incident on the pentaprism. Has been ejected to the outside through the translucent surface.

  The present invention is based on the above problem awareness, and in a single-lens reflex camera equipped with a phase difference type focus detection device and a display device in the viewfinder, focus detection based on the color temperature of the light source without reducing the amount of light guided to the viewfinder or focus detection sensor. An object of the present invention is to obtain a single-lens reflex camera that reduces a change (error) in position with a simple configuration.

  The present invention provides a subject light flux that has leaked outward from a semi-transmissive surface that is provided to allow superimpose display light to enter, that is, a light flux that has not been used so far among the subject light flux guided from the photographing lens to the eyepiece. If the lens is effectively utilized, the focus position change due to the color temperature of the light source can be corrected using the luminous flux without reducing the amount of light guided to the finder or the focus detection sensor.

  That is, the present invention relates to a reflection optical system having a plurality of reflection surfaces for reflecting a subject light beam incident from a focusing plate at a position optically equivalent to an imaging surface of a photographing lens toward an eyepiece, and the reflection optical system. In a single-lens reflex camera provided with an in-finder display device that displays information to be displayed in a finder field superimposed on a finder image formed via the finder image, the finder image is provided on one of the reflecting surfaces of the reflecting optical system. The focus plate is formed on the outer side of the semi-transmission surface of the reflective optical system, and a semi-transmission surface on which a light beam from the inner display device is incident and a part of the light beam incident from the focus plate is emitted. And a color temperature detecting light receiving element on which a light beam from the light enters is provided.

  More specifically, between the in-finder display device and the reflective optical system, the light beam incident from the in-finder display device is superimposed on the subject light beam reflected toward the eyepiece, and the finder optical system It is preferable to provide an auxiliary prism that emits the subject luminous flux that has passed through the semi-transmissive surface to the outside, and to provide the color temperature detection element at a position where the subject luminous flux emitted outward from the auxiliary prism is incident. A condensing lens can be disposed in the optical path from the auxiliary prism to the color temperature detection light receiving element. According to this aspect, the light receiving area of the subject can be narrowed down to the distance measuring area.

  The auxiliary prism is preferably bonded to the semi-transmissive surface of the finder optical system. Alternatively, it is preferable to dispose the reflective optical system so that the surface facing the semi-transmissive surface is parallel to the semi-transmissive surface of the reflective optical system with a predetermined air gap.

  The reflection optical system is preferably a reflection optical system in which a subject light beam that has passed through the focusing plate is a semi-transmission surface that is a reflection surface that first reflects the light beam except the roof reflection surface. Examples of the reflective optical system of this aspect include a pentaprism having a third reflecting surface as a semi-transmissive surface, and a trapezoid prism having a first reflecting surface that first reflects a subject light beam that has passed through the focus plate as a semi-transmissive surface. .

  According to another aspect, the reflecting optical system has a roof reflecting surface, and a pentaprism-type reflecting surface having a reflecting surface that finally reflects the subject light beam transmitted through the focusing plate toward the eyepiece as a semi-transmitting surface. An optical system is preferable. Examples of the reflective optical system of this aspect include a pentaprism and a pentamirror.

  The color temperature detection light-receiving element is preferably composed of a plurality of light-receiving elements that detect the amounts of light in different wavelength ranges. In this case, it is practical to include a visible light sensor and a long wavelength sensor that detects a longer wavelength region than a detected long wave region of the visible light sensor.

  The color temperature detection light-receiving element preferably detects light in a wavelength region different from that of the photometric sensor that receives part of the light beam reflected from the finder optical system toward the eyepiece. The photometric sensor can be used as a light receiving element for detecting color temperature. Therefore, if the photometric sensor is also used as a color temperature detecting light receiving element, the color temperature detecting light receiving element only needs to have one light receiving element that detects light in a wavelength region different from that of the photometric sensor. It can be simplified.

  In the single-lens reflex camera, light beams that have passed through different portions of the exit pupil of the photographic lens are imaged on a pair of focus detection sensors, and the in-focus position is detected based on the relative positional deviation of the paired images. A focus detection device is provided. By correcting the in-focus position detected by the focus detection device in accordance with the color temperature of the subject detected by the color temperature detection element, a change in the focus detection position due to the color temperature can be reduced.

  According to the present invention, since the color temperature detecting element is provided at the position where the subject light flux leaking outward from the semi-transmissive surface provided for the incidence of the superimpose display light is incident, the branching optics to the color temperature measuring means is provided. It is not necessary to provide a new system, and a single-lens reflex camera can be obtained in which the change (error) in the focus detection position due to the color temperature is reduced without reducing the amount of light guided to the finder, photometric sensor, or focus detection unit.

1 is an optical configuration block diagram showing a first embodiment of a single-lens reflex camera according to the present invention. It is an enlarged block diagram which shows the optical structure of the periphery of a finder optical system. It is a block diagram which shows the focus control system of a single-lens reflex camera. It is a figure explaining the wavelength characteristic of a different light source with a graph. It is a figure explaining the relationship between the chromatic aberration of an imaging lens, and the focus detection position by a different light source with a graph. FIG. 3 is an enlarged block diagram showing a second embodiment of a single-lens reflex camera according to the present invention, particularly an optical configuration around a finder optical system. FIG. 6 is an enlarged block diagram showing a third embodiment of a single-lens reflex camera according to the present invention, particularly an optical configuration around a finder optical system. FIG. 6 is an enlarged block diagram showing a fourth embodiment of a single-lens reflex camera according to the present invention, particularly an optical configuration around a finder optical system. It is an optical block diagram which shows 5th Embodiment of the single-lens reflex camera by this invention.

  FIG. 1 is a block diagram showing the main part of a single-lens reflex camera according to the first embodiment of the present invention. The subject luminous flux from the photographic lens 11 is reflected by the main mirror 13 and forms an image on a focus plate 15 that is optically equivalent to the image sensor surface (image forming surface) 17. The pentaprism (reflection optical system) 19 includes a roof reflection surface (first reflection surface, second reflection surface) 19a and a third reflection surface 19b for reflecting the light beam from the focus plate 15, and a third reflection. The light beam reflected by the surface 19b is guided to the eyepiece 21. A part of the light beam reflected by the third reflecting surface 19b is received by a photometric sensor (not shown) provided in the vicinity of the eyepiece 21. As is well known, the roof reflection surface 19a and the third reflection surface 19b of the pentaprism 19 constitute a reflection surface for observing the subject image as an erect image together with the main mirror 13. The central portion of the main mirror 13 is a semi-transmissive surface, and a subject light beam transmitted through the semi-transmissive surface is guided to the multipoint ranging AF module 25 via the sub mirror 23.

  The third reflecting surface 19b of the pentaprism 19 is configured as a semi-transmissive surface that guides superimpose display light (superimposed light flux) into the prism within a certain range centered on the eyepiece optical axis 21x. .

  On the outside of the third reflecting surface 19b of the pentaprism 19, a diopter matching lens 33 and a reflecting mirror 35 that are positioned on the eyepiece optical axis 21x and that constitute the in-finder display device are sequentially arranged. The display plate 37 and the illumination light source 39 are sequentially arranged on the reflected light path (eyepiece optical axis 21x). That is, the eyepiece optical axis 21x and the superimpose optical axis (the optical axis of the diopter alignment lens 33) are coaxial. The positive power diopter adjusting lens 33 sets the position of the display plate 37 to an optically equivalent position to the focus plate 15. The display board 37 is orthogonal to the eyepiece optical axis 21x. In this embodiment, the display board 37 has a plurality of distance measurement area masks (information masks) for multipoint distance measurement. A plurality of LEDs capable of selective light emission are provided corresponding to the number of the LEDs. The distance measuring area mask is a translucent area, and other areas on the display board 37 are formed as non-translucent areas.

  In the optical path from the diopter adjustment lens 33 (display device in the viewfinder) to the third reflecting surface 19b of the pentaprism 19, superimpose display light from the display device in the viewfinder is incident and incident from the photographing lens 11. An auxiliary prism 31 is provided for emitting the light beam that has passed through the semi-transmissive surface of the third reflecting surface 19 b of the pentaprism 19 out of the subject light beam that has been emitted to the outside of the pentaprism (reflection optical system) 19.

  The auxiliary prism 31 is made of the same material as the pentaprism 19 and is bonded to the semi-transmissive surface of the third reflecting surface 19 b of the pentaprism 19. As shown in FIG. 2, the first surface 31 a on the incident side of the auxiliary prism 31 is orthogonal to the eyepiece optical axis 21 x, and the light beam from the illumination light source 39 passes through one of the ranging area masks on the display plate 37. Then, the light beam reaches the reflection mirror 35, is reflected by the reflection mirror 35, enters the pentaprism 19 through the diopter matching lens 33 and the auxiliary prism 31, and is reflected on the subject luminous flux reflected by the third reflection surface 19b of the pentaprism 19. Superimposed. Thereby, a superimposed image is observed together with an image (finder image) on the focus plate 15 through the eyepiece 21.

  The first surface 31 a on the incident side of the auxiliary prism 31 simultaneously functions as a reflecting surface that reflects the subject light flux that has entered from the semi-transmissive surface of the third reflecting surface 19 b of the pentaprism 19. The third surface 31c of the auxiliary prism 31 is an adhesive surface with the third reflection surface 19b of the pentaprism 19 and functions as a transmission surface that transmits the superimpose display light and the finder light beam. Therefore, the subject luminous flux that has passed through the semi-transmissive surface of the third reflecting surface 19b of the pentaprism 19 and the third surface 31c of the auxiliary prism 31 is totally reflected by the first surface 31a of the auxiliary prism 31, and is removed from the second surface 31b. It is injected towards.

  In the vicinity of the second surface (outgoing surface) 31 b of the auxiliary prism 31, a color temperature detecting element 40 on which the subject light beam emitted from the second surface 31 b of the auxiliary prism 31 enters is provided. The color temperature detection element 40 is used to correct the focus position detected by the multipoint ranging AF module 25 according to the color temperature of the subject.

  The color temperature detection element 40 includes a visible light sensor 41 and a long wavelength sensor (infrared light sensor) 42 that detect the light amounts of light in different wavelength ranges. FIG. 3 is a block diagram showing a focus control system of the present single-lens reflex camera. The visible light sensor 41 detects the amount of visible light from the subject luminous flux (the same luminous flux as that used for focus detection), and the long wavelength sensor 42 detects a longer wavelength region (for example, than the visible light from the subject luminous flux). (Near-infrared light) is detected. The color temperature detection circuit 43 detects the color temperature of the subject light (wavelength distribution, light amount ratio between visible light and near infrared light) from the light amounts detected by the visible light sensor 41 and the long wavelength sensor 42. The control circuit 50 inputs the in-focus position detected by the multipoint ranging AF module 25 (the calculated defocus amount in a plurality of ranging areas), and corrects the in-focus position according to the color temperature of the subject light. Then, the AF drive system 26 is driven based on the corrected defocus amount, and the focus adjustment optical system of the photographing lens 11 is moved so as to focus on the subject in the selected distance measurement area.

  The control circuit 50 also functions as a control unit for the illumination light source 39. The color of the illumination light source 39 can be a color that can be seen when superimposed on the subject image on the focus plate 15, for example, red (wavelength; about 600 nm).

An embodiment of a color temperature detection and focus position information correction method will be described with reference to FIGS. FIG. 4 is a spectral distribution graph showing wavelength characteristics of sunlight, an incandescent bulb, and a fluorescent lamp, which are three typical light sources. In FIG. 4, the vertical axis represents specific energy (%), and the horizontal axis represents wavelength. When the sensitivity characteristics depending on the wavelengths of the visible light sensor 41 and the long wavelength sensor 42 are flat, the amounts of light in the visible light region and the long wavelength region (near infrared) of FIG. ) And the two visible light sensors 41 and the long wavelength sensor 42 are used for photometry. At this time, the light amount ratio, the energy in the long wavelength region / the energy in the visible light region in the representative three light sources are approximately the following values.
Fluorescent light: 0%
Sunlight; 40%
Incandescent bulb: 90%
By estimating the light source from these light quantity ratios, calculating the shift amount of the focal position corresponding to the chromatic aberration of the photographing lens, and multiplying by the correction value, it is possible to correct the deviation of the focal position due to the different light sources.

FIG. 5 is an example showing chromatic aberration of the taking lens. In FIG. 5, the vertical axis represents the defocus amount, and the horizontal axis represents the wavelength. Since an image sensor normally has sensitivity only in the visible light region, focus detection is usually based on the in-focus position in the visible light region. In focus detection under a light source having light energy only in the visible light region such as a fluorescent lamp, there is no need for correction because it is not affected by chromatic aberration in the long wavelength region of the photographing lens. On the other hand, in the case of sunlight and incandescent light bulbs, there is light energy up to the long wavelength region, so it is affected by the large positive chromatic aberration of the photographing lens in this region, and the positive direction from the optimal focus position on the image sensor ( Defocused in the direction away from the taking lens). The defocus amount at this time is determined by the chromatic aberration of the photographing lens and the wavelength characteristics of the light source (energy in the long wavelength region / energy in the visible light region). Information on chromatic aberration possessed by the photographing lens can be previously stored in a memory in the photographing lens. For example, a defocus correction amount at the auxiliary projection wavelength can be used. An appropriate correction amount can be calculated by calculating together with the information of the visible light sensor 41 and the long wavelength sensor 42 described above. For example, in the case of the condition of FIG.
It can be calculated by setting the correction amount of sunlight = 0.3 × auxiliary projection correction amount Incandescent light bulb correction amount = 0.6 × auxiliary projection correction amount.

  As described above, in the first embodiment, in order to detect the color temperature of the subject (light quantity ratio between visible light and near infrared light), the color temperature detection element is located near the second surface (outgoing surface) 31b of the auxiliary prism 31. 40 is arranged. The position of the color temperature detection element 40 uses a light beam other than the light beam directed to the eyepiece 21 among the light beams of the subject incident on the pentaprism 19 from the photographing lens 11, that is, a light beam that has not been used conventionally. There is no adverse effect on the finder display device and the focus detection device. Therefore, the color temperature of the subject can be obtained based on the visible light amount and near-infrared light amount detected by the color temperature detection element 40, and the error of the focus detection position due to this color temperature can be reduced.

  FIG. 6 shows a second embodiment of the single-lens reflex camera according to the present invention. In this embodiment, the auxiliary prism 31 is turned upside down with respect to the first embodiment. The auxiliary prism 31 is disposed below the diopter alignment lens 33 (in-finder display device), and is viewed. The light beam from the alignment lens 33 enters from the second surface 31b above the auxiliary prism 31, is totally reflected by the first surface 31a, and goes straight to the third surface 31c side, which is the adhesive surface with the pentaprism 19, The third surface 31 c is configured to enter the third reflecting surface 19 b of the pentaprism 19. That is, the light beam that has entered the pentaprism 19 from the photographic lens 11 is reflected by the roof reflecting surface 19 a, and part of the light enters the auxiliary prism 31 via the third reflecting surface 19 b, and the first surface of the auxiliary prism 31. Passes 31a and injects outward. The color temperature detection element 40 is provided in the vicinity of the first surface 31a of the auxiliary prism 31 at a position where the subject light flux that has passed through the first surface 31a can be received.

  FIG. 7 shows a third embodiment of the single-lens reflex camera according to the present invention. In this embodiment, in the single-lens reflex camera of the second embodiment, a condensing lens 60 that collects the subject luminous flux that has passed through the first surface 31 a on the color temperature detection element 40 in the vicinity of the first surface 31 a of the auxiliary prism 31. Is arranged. By providing the condenser lens 60 between the auxiliary prism 31 and the color temperature detecting element 40, the light receiving area of the subject can be narrowed down to the distance measuring area.

  FIG. 8 shows a fourth embodiment of the single-lens reflex camera according to the present invention. In this embodiment, a pentamirror 20 is provided instead of the pentaprism 19 as a finder optical system. The pentamirror 20 includes a roof mirror 20a that reflects the light beam from the focus plate 15, a part of the light beam reflected by the roof mirror 20a, and a semi-transmissive mirror that transmits the light beam from the diopter matching lens 33 (display device in the viewfinder). 20b. With this configuration, the above-described auxiliary prism is not necessary. Between the diopter matching lens 33 and the semi-transmissive mirror 20b, a reflection mirror 36 for allowing a superimposing light beam to enter the pentamirror 20 is provided. The light beam from the illumination light source 39 passes through one of the distance measuring area masks of the display plate 37, reaches the reflection mirror 35, is reflected by the reflection mirror 35, and is semi-transmissive through the diopter matching lens 33 and the reflection mirror 36. The light is incident on the mirror 20b and transmitted therethrough, so that it is superimposed on the subject luminous flux incident from the photographing lens 11 and reflected by the roof mirror 20a and the semi-transmissive mirror 20b. Most of the subject luminous flux from the photographic lens 11 is reflected by the roof mirror 20a and the semi-transmissive mirror 20b, but the remaining part passes through the semi-transmissive mirror 20b and exits outward. The color temperature detection element 40 is provided in the vicinity of the semi-transparent mirror 20b at a position where the subject light flux that has passed through the semi-transparent mirror 20b can be received.

  FIG. 9 shows a fifth embodiment of the single-lens reflex camera according to the present invention. In this embodiment, a trapezoid prism 70 is provided instead of the pentaprism 19 as a finder optical system. The subject luminous flux from the photographic lens 11 is reflected by the main mirror 13 and forms an image on a focus plate 15 that is optically equivalent to the image sensor surface (image forming surface) 17. The light flux from the focusing plate 15 enters the trapezoid prism 70 via the condenser lens 71, and the light flux reflected by the first reflecting surface 70 a, the second reflecting surface 70 b, and the third reflecting surface 70 c is relay optical system 72. Through the eyepiece 21. In this embodiment, the image is erected by the relay optical system 72. The first reflecting surface 70a of the trapizoid prism 70 has a certain range as a semi-transmissive surface that guides the superimposing light beam into the prism. Most of the light flux from the focusing plate 15 is reflected from the first reflecting surface 70a to the second reflecting surface 70b, reflected from the second reflecting surface 70b to the third reflecting surface 70c, and the third reflecting surface 70c reflects the eyepiece 21. The light is reflected so as to coincide with the optical axis 21x and enters the relay optical system 72, but the remaining part enters the auxiliary prism 31 via the first reflecting surface 70a. The auxiliary prism 31 is bonded to the first reflecting surface 70a of the trapezoid prism 70, and emits a subject light beam incident through the third surface 31c, which is the bonding surface, outward from the first surface 31a. In the vicinity of the first surface 31a, a color temperature detecting element 40 is provided at a position where the light beam transmitted through the first surface 31a can be received. On the other hand, the light beam from the illumination light source 39 is incident on the second surface 31 b of the auxiliary prism 31 through the display plate 37 and the reflection mirror 35. The incident light beam from the illumination light source 39 is reflected by the first surface 31a, enters the trapezoid prism 70 from the semi-transmissive surface of the first reflective surface 70a of the trapizoid prism 70, and is superimposed on the subject light beam.

  In each embodiment except for the fourth embodiment, the auxiliary prism 31 is provided by being bonded to the semi-transmission surface of the pentaprism 19 or the trapizoid prism 70. However, the auxiliary prism 31 is parallel to the semi-transmission surface and the semi-transmission surface. Auxiliary prisms may be arranged in a direction facing each other with a slight air gap therebetween.

  In each embodiment, the visible light sensor 41 and the long wavelength sensor 42 are provided as light receiving elements for color temperature detection. However, a photometric sensor (not shown) provided in the finder is used for light reception for color temperature detection. It is good also as a structure provided with one light receiving element which doubles as an element and detects the light quantity of the light of a wavelength range different from this photometric sensor. In the digital camera, the color temperature detecting element 40 can be used for white balance adjustment.

11 Shooting lens 13 Main mirror 15 Focus plate 17 Film surface (imaging surface)
19 Penta prism 19a Dach reflecting surface (first reflecting surface)
19b Third reflecting surface (second reflecting surface)
20 Penta mirror 20a Dach mirror (first reflective surface)
20b Transmission mirror (second reflecting surface)
21 Eyepiece 21x Eyepiece optical axis 23 Sub mirror 25 Multi-point ranging AF module 26 AF drive system 31 Auxiliary prism 31a First surface 31b Second surface 31c Third surface (adhesion surface)
33 Diopter matching lens 35 Reflective mirror 36 Reflective mirror 37 Display board 39 Illumination light source 40 Color temperature detection element 41 Visible light sensor 42 Long wavelength sensor 43 Color temperature detection circuit 50 Control circuit 60 Condensing lens 70 Trapezoid prism 70a First reflection Surface (first reflective surface)
70b Second reflecting surface 70c Third reflecting surface (second reflecting surface)
71 Condenser lens 72 Relay optical system

Claims (12)

A reflection optical system having a plurality of reflection surfaces for reflecting an object light beam incident from a focusing plate at a position optically equivalent to the imaging surface of the photographing lens toward the eyepiece, and the reflection optical system is formed through the reflection optical system. In a single-lens reflex camera equipped with a display device in the viewfinder that displays information to be displayed in the viewfinder field superimposed on the viewfinder image,
Forming a semi-transparent surface on one of the reflective surfaces of the reflective optical system, on which a light beam from the in-viewfinder display device is incident, and a part of the light beam incident from the focus plate is emitted; and
A color temperature detection light-receiving element on which the light beam from the focusing plate is incident outside the transflective surface of the reflective optical system;
SLR camera featuring The single-lens reflex camera according to claim 1, wherein a light beam incident from the in-finder display device is superimposed on a subject light beam reflected toward the eyepiece between the in-finder display device and the reflective optical system, and A single-lens reflex camera in which an auxiliary prism that emits a subject light beam that has passed through the semi-transmissive surface of the reflective optical system is provided, and the color temperature detection element is provided at a position where the subject light beam emitted from the auxiliary prism is incident. The single-lens reflex camera according to claim 2, wherein a condensing lens is disposed in an optical path from the auxiliary prism to the color temperature detection light-receiving element. 4. The single-lens reflex camera according to claim 2, wherein the auxiliary prism is bonded to a semi-transmissive surface of the reflective optical system. 4. The single-lens reflex camera according to claim 2, wherein the auxiliary prism is disposed so that a surface facing the semi-transmissive surface is parallel to the semi-transmissive surface of the reflective optical system with a predetermined air gap. A single-lens reflex camera. 6. The single-lens reflex camera according to claim 1, wherein the reflective optical system has a semi-transparent surface as a reflection surface that first reflects a subject luminous flux that has passed through the focus plate, excluding a roof reflection surface. A single-lens reflex camera that is a reflective optical system. 7. The single-lens reflex camera according to claim 1, wherein the reflective optical system has a roof reflecting surface, and reflects the subject light beam that has passed through the focus plate toward the eyepiece last. A single-lens reflex camera, which is a pentaprism type reflection optical system with a semitransparent surface. 7. The single-lens reflex camera according to claim 1, wherein the reflective optical system has a first reflecting surface that first reflects a subject light beam that has passed through the focusing plate as a semi-transmitting surface. A SLR camera that is a prism. 9. The single-lens reflex camera according to claim 1, wherein the color temperature detection light-receiving element includes a plurality of light-receiving elements that detect light amounts of light in different wavelength ranges. 10. 9. The single-lens reflex camera according to claim 1, wherein the color temperature detection light-receiving element is different from a photometric sensor that receives a part of a light beam reflected toward the eyepiece from the reflection optical system. A single-lens reflex camera that detects light in the wavelength range. The single-lens reflex camera according to claim 9, wherein the plurality of light receiving elements include a visible light sensor and a long wavelength sensor that detects a longer wavelength range than a detection wavelength range of the visible light sensor. The single-lens reflex camera according to any one of claims 1 to 11, wherein light beams that have passed through different portions of the exit pupil of the photographing lens are imaged on a pair of focus detection sensors, and the relative images of the paired images are relative to each other. A single-lens reflex camera that includes a focus detection device that detects a focus position based on a positional shift, and that corrects the focus position detected by the focus detection device in accordance with the color temperature of the subject detected by the color temperature detection element.

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