JP2000089099A - Optical equipment having focus detector and range- finding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optical equipment having a focus detector and a photometry device constituted so that an accurate focus detecting action and the accurate photometry of a film surface can be executed by installing the focus detector and the photometry device in a narrow space formed at the bottom part of the mirror box of a single-lens reflex camera. SOLUTION: This optical equipment is provided with a main mirror 3, the focus detector and the range-finding device. The mirror 3 is arranged behind a projection lens 101 and provided with a semi-transmission part transmitting one part of luminous flux transmitted through a photographing lens 101. The focus detector is arranged between the mirror 3 and a photosensitive surface so as to detect the focusing state of the lens 101 by utilizing the luminous flux transmitted through the mirror 3. The range-finding device is arranged between the focus detector and the photosensitive surface so as to detect the luminance information of the photosensitive surface by condensing light beams reflected from the respective areas of the photosensitive surface by a condensing lens 23 and receiving them by a light receiving element 25. Besides the range-finding device is provided with a light reduction means reducing the quantity of the light beam made incident on the element 25 among the light beams reflected from the respective areas of the photosensitive surface as the distance between the respective areas of the photosensitive surface and the lens 23 becomes short.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical device having a focus detecting device and a photometric device, and more particularly to an optical device such as a single-lens reflex camera for taking photometric light for performing focus detection and exposure determination on a subject image. This is performed efficiently using the light beam that has passed through the lens.

[0002]

2. Description of the Related Art Conventionally, in an optical apparatus such as a single-lens reflex camera, as a basic configuration for simultaneously performing focus detection and photometry, a main mirror having a semi-transmissive portion behind a photographing lens and a photosensitive surface are provided. A focus detection device and a photometric device are arranged in a mirror box. In the focus detection device, a part of the light beam that has passed through the photographing lens is guided to the focus detection device at the bottom of the mirror box below the camera body.

In a photometric device, when a main mirror is flipped up, reflected light from a photoreceptor (film surface) of a light beam passing through a photographing lens and entering the photoreceptor is condensed by a condensing lens. Then, the light is guided to the light receiving element, and the luminance of the photoreceptor, that is, the luminance information of the subject is detected using the signal from the light receiving element.

[0004]

Generally, in an optical device such as a single-lens reflex camera, if both a photometric device and a focus detection device are to coexist at the bottom of a mirror box, optical and spatial restrictions are greatly restricted. Come up.

In particular, if a photometric device is disposed between a focus detecting device and a photoreceptor (film surface) in order to effectively use the space at the bottom of the mirror box, the photoreceptor of the condensing lens constituting the photometric device is required. There is a large difference in the viewing angle between the far (upper) region and the near (lower) region of the photoconductor.

As a result, there has been a problem that the light receiving element receives more reflected light from a near area of the photoconductor than in a distant area and cannot measure light uniformly on the surface of the photoconductor.

According to the present invention, when both the focus detection and the photometry are performed by contracting both the focus detection device and the photometry device into a narrow space at the bottom of the mirror box of the camera, the configuration of the photometry device is appropriately set. Accordingly, an object of the present invention is to provide a focus detection device capable of uniformly measuring the surface of a photoreceptor even when the photometry device is arranged close to the surface of the photoreceptor, and an optical apparatus having the photometer.

[0008]

According to the present invention, there is provided an optical apparatus having a focus detecting device and a photometric device, comprising: (1-1) a semi-transmissive device which transmits a part of a light beam passing through the photographing lens behind the projection lens. A main mirror having a portion, and a focus detection device that detects a focus state of the photographing lens using a transmitted light beam from the main mirror between the main mirror and the photosensitive surface; and An optical device provided with a distance measuring device for condensing reflected light from each area on the photosensitive surface with a condensing lens, receiving the light with a light receiving element and detecting luminance information on the photosensitive surface between the photosensitive surface and the photosensitive surface In the distance measuring device, the amount of light incident on the light receiving element of the reflected light from each region on the photosensitive surface decreases as the distance between each region on the photosensitive surface and the condenser lens decreases. It is characterized by having various light reducing means.

In particular, (1-1-1) the dimming means comprises an optical filter having a distribution in which the amount of transmitted light decreases as the distance between each area of the photosensitive surface and the condenser lens decreases.

(1-1-2) The optical filter has a structure in which a light transmitting portion and a light shielding portion are provided in area on a transparent glass surface.

(1-1-3) The focus detecting device includes a plurality of light quantity distributions related to the subject image using light beams passing through different areas of the pupil of the objective lens by optical means provided on the image plane side of the objective lens. Is formed, a relative positional relationship between the plurality of light amount distributions is determined by a photoelectric conversion element including a plurality of elements, and the in-focus state of the objective lens is determined by using a signal from the photoelectric conversion element within a field of view of an imaging field. It is characterized in that it is required in one or a plurality of areas.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic view of a main part of a first embodiment when the present invention is applied to an optical device such as a single-lens reflex camera.
2, 3, and 4 are schematic views of a part of FIG. 1.

In FIG. 1, reference numeral 101 denotes an objective lens, 1 denotes an optical axis of the objective lens 101, 2 denotes a film (image pickup surface), 3 denotes a semi-transmissive main mirror arranged on the optical axis 1 of the objective lens 101,
Above the main mirror 3, there is a focusing screen, and an objective lens 101
Is formed via the main mirror 3, and the subject image on the reticle is observed via the pentaprism and the eyepiece.

Reference numeral 4 denotes a first reflecting mirror disposed obliquely on the image plane side of the objective lens 101 with respect to the optical axis 1, and comprises a plane mirror, a condensing concave mirror, an elliptical mirror, or the like. Reference numeral 5 denotes a paraxial image plane conjugate to the film 2 formed by the first reflecting mirror 4, on which a subject image is formed. Reference numeral 6 denotes a second reflecting mirror, 7 denotes an infrared cut filter, 8 denotes a stop having two openings 8-1 and 8-2, and 9 denotes a stop corresponding to the two openings 8-1 and 8-2 of the stop 8. A secondary imaging system having two lenses 9-1 and 9-2 arranged, 10 is a third reflecting mirror, and 11 is a photoelectric conversion element (light receiving means) having two area sensors 11-1 and 11-2. ) Respectively. First reflector 4, second
The reflecting mirror 6, and the secondary imaging system 9 constitute one element of the optical means. Aperture 8, secondary imaging system 9, light receiving means 11
Constitutes one element of the focus detection device.

The first reflecting mirror 4 in this embodiment has a light-converging curvature, and projects the two openings 8-1 and 8-2 of the stop 8 near the exit pupil 101 a of the objective lens 101. ing.

The first reflecting mirror 4 is formed of a metal film such as aluminum or silver so as to reflect light only in a necessary area. I also work. In the other reflecting mirrors 6 and 10 as well, in order to reduce stray light incident on the photoelectric conversion element 11, only a necessary minimum area is deposited for light reflection. Each reflecting mirror is provided with a restricting means such as applying a light-absorbing paint or the like to a region not functioning as a reflecting surface, or providing a light shielding member in proximity.

FIG. 3 is a plan view of the stop 8 shown in FIG. The diaphragm 8 has a configuration in which two horizontally long apertures 8-1 and 8-2 are arranged in a direction in which the aperture width is narrow (up and down direction of the photographing range).
The apertures 8-1 and 8-8 of the stop 8 are indicated by dotted lines in the figure.
The lenses 9-1 and 9-2 of the secondary imaging system 9 disposed behind the lens corresponding to -2.

FIG. 4 is a plan view of the photoelectric conversion element 11.
The two area sensors 11-1 and 11-2 shown in FIG. 1 are two-dimensionally arranged with a plurality of pixels as shown in FIG.
The area sensors 11-1 and 11-2 are arranged.

In the above configuration, the photographing lens 1 shown in FIG.
The two light beams 12-1 and 12-2 from 01 are the main mirror 3
, The light is reflected by the first reflecting mirror 4 in a direction substantially along the inclination of the main mirror 3, and forms an object image on the paraxial image plane 5. At this time, the first reflecting mirror 4 is configured to form a reduced image of the subject image formed on the imaging plane 2 on the paraxial imaging plane 5. The luminous flux from the subject image formed on the paraxial imaging plane 5 is reflected by the second reflecting mirror 6 and changes its direction again, and thereafter, the infrared cut filter 7 and the two apertures 8-1 and 8 of the diaphragm 8. -2, each lens 9-of the secondary imaging system 9
The light is condensed by 1 and 9-2 and reaches the area sensors 11-1 and 11-2 of the photoelectric conversion element 11 via the third reflecting mirror 10, respectively.

The light fluxes 12-1 and 12-2 in the figure indicate the light flux which forms an image at the center of the film 2, but the light flux which forms an image at another position passes through the same path and is subjected to photoelectric conversion. The photoelectric conversion element 1 reaches the element 11 and corresponds to a predetermined two-dimensional area on the film (in the photographing range) 2 as a whole.
Two light quantity distributions relating to the subject image are formed on each of the area sensors 11-1 and 11-2.

With respect to the two light quantity distributions of the subject image obtained in this manner, the separation direction, that is, the two areas shown in FIG. The relative positional relationship between the sensors 11-1 and 11-2 in the vertical direction is determined by the area sensors 11-1 and 11-1.
The focus state of the objective lens 101 is detected two-dimensionally in an arbitrary region in the photographing range by calculating at each position composed of an arbitrary plurality of elements 1-2.

Reference numeral 21 denotes a shutter, and reference numeral 22 denotes a dimming means, which comprises, for example, an optical filter having a configuration as shown in FIG. When the shutter means 21 is opened (the main mirror 3 and the sub-mirror 4 are also retracted from the optical path as shown in FIG. 1), the light-reducing means 22 receives a light beam from the photographing lens 101 and a film surface (photosensitive surface) 2 A large amount of light from a region far from the condenser lens 23 of the light beam reflected by the light transmitting portion is transmitted. That is, as shown in FIG.
The structure is such that a large amount of luminous flux is transmitted therethrough.

In FIG. 2, reference numeral 22a denotes a light-shielding portion, which has a circular shape and has a distribution in which the transmittance decreases as a whole in the direction indicated by the arrow 22b. Reference numeral 23 denotes a condensing lens for dimming, 24 denotes a cover glass, and 25 denotes a photoelectric conversion element for dimming.

In this embodiment, a focus detection device (distance measuring unit) and a photometric device (dimming unit) are arranged in this order between the mount 31 and the shutter 21 at the bottom of the mirror box from the mount 31 side.

For this reason, the photoelectric conversion element 25 and the film surface 2
The difference in the distance between the upper region A and the upper region B increases. Since the area B is closer to the condensing lens 23 than the area A, more light fluxes enter the condensing lens 23 from the area B than the area A. As a result, the film surface 2
When the overall brightness is measured, the area B is mainly measured.

In the present embodiment, in order to prevent this, a dimming means having the structure shown in FIG. 2 is provided in front of the condenser lens 23 so that the light flux from the entire film surface 2 is uniformly distributed through the condenser lens 23. The light is incident on the photoelectric conversion element 25. Thereby, the brightness of the entire film surface 2 can be measured uniformly.

In FIG. 1, reference numeral 32 denotes contact dust on the camera body, and a contact pin 33 for communicating with the lens body is provided in a part thereof. Reference numeral 34 denotes a lens barrel, and a contact pin 35 for communicating with the camera body is provided in a part of the lens barrel. When the lens barrel 34 is mounted on the camera mount 31, the contact pins 35 on the lens and the contact pins 33 on the camera body come into contact with each other.

FIG. 5 is an explanatory view of another embodiment of the light shielding means applicable to the present embodiment. In FIG. 5, the light shielding portion 22a is not a circle but a plurality of rectangles, and the width thereof is increased in the direction indicated by the arrow 22b. Thereby, the transmittance as a whole is sequentially reduced in the direction of the arrow 22b.

FIG. 6 is a block diagram of the release control in this embodiment. The mirror driving device 62 performs retraction of the main mirror and the sub-mirror to the outside of the photographing light beam when photographing, and returns to the photographing light beam during viewfinder observation and distance measurement. The shutter driving device 63 performs a shutter opening / closing operation during photographing. This is performed by the CPU 61 in the camera. ^I / ₀
64 controls the strobe light emitting device 65,
The threshold information corresponding to the film sensitivity is received from U61, and the light emission is stopped according to the amount of light received by the photoelectric conversion element 66 for dimming.

FIG. 7 is a flow chart at the time of flash photography of the release control in this embodiment.

When the photographer presses a release button (not shown), the release Sw is turned on (step 1). The imaging light flux is guided to the photoelectric conversion element for distance measurement, and the CPU calculates the amount of defocus from the image signal information at this time. The lens drive information is sent to the CPU in the lens (step 2). CPU in lens
The lens is driven by the control of (1) to perform focus adjustment (step 3). The main mirror and sub-mirror are retracted out of the photographic light beam under the control of the CPU in the camera (step 4). The shutter is opened under the control of the CPU in the camera (step 5). Instruction strobe light emission start from the camera CPU to ^I / ₀ is issued, ^I / ₀ initiates a strobe emission (step 6). The dimming photoelectric conversion element receives the light reflected on the film surface (step 7). When the amount of received light reaches the threshold
^I / ₀ stops strobe light emission (step 8). The shutter is closed under the control of the CPU in the camera (step 9). Under the control of the CPU in the camera, the main mirror and the sub-mirror return to the luminous flux to enable viewfinder observation and distance measurement (step 10). Thereafter, film feeding and the like are performed as needed.

[0032]

As described above, according to the present invention, when both the focus detection and the photometry are performed by contracting both the focus detection device and the photometry device into the narrow space at the bottom of the mirror box of the camera, the photometry is performed. By properly setting the configuration of the device,
Even if the photometric device is arranged close to the photoconductor surface, an optical instrument having a focus detection device and a photometric device capable of uniformly measuring the photoconductor surface can be achieved.

[Brief description of the drawings]

FIG. 1 is a schematic view of a main part of a first embodiment of the present invention.

FIG. 2 is an enlarged explanatory view of a light shielding unit of FIG. 1;

FIG. 3 is an enlarged explanatory view of the diaphragm shown in FIG. 1;

FIG. 4 is an enlarged explanatory view of the light receiving means of FIG. 1;

FIG. 5 is an enlarged explanatory view of another embodiment of the light shielding means of FIG. 1;

FIG. 6 is a block diagram of release control according to the present invention.

FIG. 7 is a block diagram of flash photography according to the present invention.

[Explanation of symbols]

 Reference Signs List 101 shooting lens 1 optical axis 2 photosensitive surface 3 main mirror 4 sub-mirror (first reflecting mirror) 5 paraxial image surface 6 second reflecting mirror 7 infrared cut filter 8 aperture 9 secondary imaging system 10 third Reflecting mirror 11 Light receiving means 21 Shutter 22 Light reducing means 23 Condensing lens 24 Cover glass 25 Light receiving element

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Keishi Otaka 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term in Canon Inc. (reference) 2H002 CD07 DB11 EB00 GA54 HA04 JA02 2H011 AA01 BA23 BB01 BB02 2H051 AA01 BA06 CB09 CB12 CB22 CB29 DA03

Claims (4)

[Claims] 1. A main mirror having a semi-transmissive portion behind a projection lens for transmitting a part of a light beam passing through the photographing lens, and transmitting a light beam transmitted from the main mirror between the main mirror and a photosensitive surface. A focus detection device is provided for detecting the in-focus state of the taking lens by utilizing the light, and reflected light from each area on the photosensitive surface is condensed by a condenser lens between the focus detection device and the photosensitive surface. And a distance measuring device for detecting luminance information on the photosensitive surface by receiving light with the light receiving element, wherein the distance measuring device is incident on the light receiving element of light reflected from each area on the photosensitive surface. An optical device having a focus detecting device and a photometric device, characterized in that it has a dimming means so that the amount of light to be reduced decreases as the distance between each area on the photosensitive surface and the condenser lens becomes shorter. . 2. A focal point according to claim 1, wherein said dimming means comprises an optical filter having a distribution in which the amount of transmitted light decreases as the distance between each area of the photosensitive surface and the condenser lens decreases. Optical equipment having a detection device and a photometric device. 3. The optical filter according to claim 2, wherein the optical filter is formed by providing a light transmitting portion and a light shielding portion on a transparent glass surface in an area. Optical equipment. 4. The focus detecting device forms a plurality of light amount distributions on a subject image by using optical beams provided through different areas of a pupil of the objective lens by optical means provided on an image plane side of the objective lens. A relative positional relationship between a plurality of light amount distributions is obtained by a photoelectric conversion element including a plurality of elements, and a focus state of the objective lens is determined using a signal from the photoelectric conversion element in one or a plurality of areas in a field of view. 4. An optical apparatus comprising the focus detection device and the photometry device according to claim 1, wherein the focus detection device and the photometry device are determined.