JPH11281885A - Focus position detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To put a lens in focus on an object or a part of the object with multiple range-finding precision according to the full-aperture F value of the lens. SOLUTION: The focus position detecting device is provided with 1st range finding sensors 16a and 16b having short base length corresponding to luminous flux transmitted through the pupil 30 with a 1st full-aperture F value (e.g. F6.7) of an image pickup optical system 201 and 2nd range finding sensors 246a and 246b having long base length corresponding to pieces 50A and 50B transmitted through the pupil 50 with a 2nd full-aperture F value (e.g. F2.8) of the image pickup optical system 201. When an image pickup optical system which has a full-aperture F value smaller than the 2nd full-aperture F value is mounted, the image pickup optical system is put in focus by using the 1st range finding sensors 146a, 146b and 2nd range finding sensors 246a, 246b. When an image pickup optical system which has a full-aperture F value larger than the 2nd full-aperture F value is mounted, the image pickup optical system 201 is put in focus by using the 1st range finding sensors 146a and 146b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a focus position detecting device of an image pickup optical system used for an AF single-lens reflex camera or the like.

[0002]

2. Description of the Related Art A basic configuration of a focus position detecting apparatus conventionally used in an AF single lens reflex camera or the like will be described with reference to FIGS. As shown in FIG. 13, the focus position detection device 20 is provided behind the scheduled focal plane 11 of the imaging optical system 10, and includes a condenser lens 21 for condensing a light beam that has passed through the imaging optical system 10, and an aperture mask. 22
Focus position by detecting the relative positional relationship between the re-imaging lens 23, the photoelectric conversion element array 24 such as a CCD line sensor, and the two subject images formed on the photoelectric conversion element array 24. And an arithmetic circuit 25 for calculating the amount of deviation and the direction of deviation.

When the focus position of the image pickup optical system 10 matches the subject, that is, when the subject is in focus, the distance between the two subject images formed on the photoelectric conversion element array 24 is constant (when the focus is attained). The distance between the two subject images in the case of the so-called front focus is narrower than L0, while the distance between the two subject images in the case of the so-called rear focus is wider than L0. Therefore, by detecting the distance between the two subject images on the photoelectric conversion element array 24, it is possible to know whether the object is in focus or out of focus, and in the out of focus state, it is possible to know the amount and direction of defocus.

An AF single-lens reflex camera is equipped with a lens having an image pickup optical system having various focal lengths and an open F value (an interchangeable lens as a completed product including an image pickup optical system, an aperture mechanism, and an image pickup optical system extension mechanism). can do. FIG.
4, the open F value as shown by the solid line is F2.8 or F
4 and the like, the open F-number as shown by the one-dot chain line is smaller than that in the case of using the small (bright) imaging optical system 10a such as F4.
6, a large (dark) imaging optical system 10 such as F6.7
When b is used, the cross-sectional diameter of the light beam from the subject reaching the position of the aperture mask 22 (the diameter of the pupil of the imaging optical system) is smaller. Therefore, the positions of the pair of openings 22a of the aperture mask 22 correspond to the imaging optical system having the largest open F-number (for example, F6.7) so as to correspond to all the interchangeable lenses usable in this camera. It is provided in.

On the other hand, when the focal length is the same, an imaging optical system having a smaller open F-number has a smaller depth of field and requires higher focusing accuracy. The relationship between the base line length and the distance measurement accuracy of a distance measurement sensor including an aperture mask, a re-imaging lens, a photoelectric conversion element array, and the like will be described with reference to FIG. In FIG. 15, F is the film surface, L is the optical axis, O is the intersection of the optical axis L and the film surface F, P is the position of the image on the optical axis, D is the defocus amount, and d1 and d2 are the defocus amounts, respectively. The amount of movement of the image on the photoelectric conversion element array with respect to D, R1, R
1 ', R2 and R2' are re-imaging lenses, S1 and S1 'are islands constituting a photoelectric conversion element array (distance measuring sensor) having a base length T1, and S2 and S2' are base lengths T.
2 shows islands constituting a photoelectric conversion element array of 2 (T2> T1).

[0006] Assuming that an object on the optical axis is imaged at a point P by an imaging optical system (not shown), the light flux passing through the point P is re-imaged by lenses R1, R1 ', R2, and R2'. Incident on the islands S1, S1 ', S2 and S2'. Next, when the image of the object moves to the point O by moving the imaging optical system, the images move by d1 on the islands S1 and S1 ′ close to the optical axis L, and move to the island S1 away from the optical axis L.
On 2 and S2 ', the image moves by d2 (d2> d1). That is, assuming that the defocus amount D is constant, the further the island of the photoelectric conversion element is from the optical axis, the larger the amount of movement of the image thereon. Further, assuming that the size of the pixel of each island is constant, the focus detection accuracy is higher when using the islands S2 and S2 ′ remote from the optical axis L than when using the islands S1 and S1 ′ closer to the optical axis L. Get higher. That is, the longer the base line length of the distance measuring sensor, the higher the focus detection accuracy.

[0007]

However, the conventional focus position detecting apparatus is compatible with an imaging optical system having the largest open F value (smallest pupil diameter) among the interchangeable lenses that can be used, and an aperture mask. The aperture 22a, the re-imaging lens 23, the photoelectric conversion element array 24, and the like are areas where a light beam transmitted through the pupil of the imaging optical system having the largest open F value can reach (a relatively narrow area near the optical axis). Is located within. Therefore, there is a certain limit in the base line length of the distance measuring sensor including the aperture mask 22, the re-imaging lens 23, the photoelectric conversion element array 24, and the like.

When a lens having an imaging optical system with a small open F value (large pupil diameter) is mounted on an AF single-lens reflex camera or the like using a conventional focus position detecting device, a light beam transmitted through a pupil of the imaging optical system is generated. Although the reachable area is wide and the base line length of the distance measuring sensor can be lengthened, the distance must be measured with a distance measuring sensor having a short base line length. However, there is a problem that it is not possible to obtain a distance measurement accuracy suitable for the measurement.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem of the prior art, and has a focus position detection method capable of focusing on a subject with a distance measurement accuracy corresponding to the open F-number of an imaging optical system of a lens to be used. It is intended to provide a device.

[0010]

In order to achieve the above object, a focus position detecting apparatus according to the present invention is provided at a position where a light beam from a predetermined portion of a subject can reach by a first open F-number imaging optical system. The first distance measuring sensor and the first opening F
A second distance measuring sensor provided at a position where a light beam from a portion substantially the same as a predetermined portion of the subject can reach by an imaging optical system having a second open F value smaller than the value.
When an imaging optical system having an open F value smaller than the open F value is mounted, the focusing operation of the imaging optical system is performed using the first distance measurement sensor and the second distance measurement sensor, and the second operation is performed. When an imaging optical system having an open F value larger than the open F value is mounted, the focusing operation of the imaging optical system is performed using the first distance measuring sensor. Further, it is preferable that the second distance measuring sensor is provided at a position farther from the optical axis than the first distance measuring sensor.

For example, assuming that the first open F value is F6.7 and the second open F value is F2.8, the open F value is F2 or F2.
In the case where an imaging optical system having a shallow depth of field with an aperture value near the open F-number and a shallow depth of field such as 8 is mounted, the distance measurement sensor of both the first distance measurement sensor and the second distance measurement sensor is used. Since the luminous flux from almost the same portion arrives, the focusing operation is performed using all these distance measuring sensors. On the other hand, when the open F value is larger than the second open F value, such as F4 or F5.6,
When the imaging optical system of the value is mounted, since the light beam from the subject does not reach the second distance measuring sensor, the focusing operation of the lens is performed using the first distance measuring sensor. In the latter case, which is the same as the conventional example, in the former case, the imaging optical system can be focused on the subject using a long distance measuring sensor provided at a position further away from the center of the screen. ,
A focusing operation with high ranging accuracy can be performed.

The first distance measuring sensor and the second distance measuring sensor may each include a photoelectric conversion element array, and each photoelectric conversion element array may be formed on the same chip. Further, the first distance measuring sensor and the second distance measuring sensor further include a re-imaging lens, and the re-imaging lens has an optical axis passing through an optical axis of the imaging optical system and an optical axis of the imaging optical system. The lens array may be configured so as to be arranged on the same line orthogonal to. According to these configurations, the first distance measuring sensor and the second distance measuring sensor can be integrated into one chip, and it is possible to reduce the size of the device and reduce assembly errors.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a focus position detecting device according to the present invention will be described in detail with reference to the drawings. First, FIG. 1 shows a configuration example of an AF single-lens reflex camera in which each embodiment of the focus position detection device of the present invention is used.

At the substantially center of the camera body 100, a main mirror 111 is provided at an angle of about 45 degrees with respect to the optical axis L, and is provided on the back of the main mirror 111. A mirror box 110 having a mirror 112 and the like is provided. Mirror box 1
A finder 120 including a reticle 121, a prism 122, an eyepiece 123, a display element 124, and the like is provided on an upper part of the apparatus 10. A light emitting unit 1 for emitting a flash light is provided above the finder 120.
70 are provided.

At the bottom of the mirror box 110 (the side opposite to the finder 120), there are provided a focus position detecting device 140, a light control sensor 150, an AF drive unit 160, and, if necessary, a relay lens 151 and the like. A shutter unit 130 is provided between the rear surface of mirror box 110 (the side opposite to lens 200) and film surface 1. The flexible printed circuit board 300 provided with the AFCPU 301 and the wiring 302 is provided in a gap or the like of the camera body 100.

The lens 200 includes an imaging optical system 201, a lens barrel 202 holding the imaging optical system 201, a lens driving mechanism 203 for driving the lens barrel 202 in a direction A parallel to the optical axis L, a focal length of the lens, and an F-number. (Open F value, open F value for AF, minimum F value, etc.)
A lens CPU 204 for outputting to the PU 301 is provided. In the following description of each embodiment, the lens 2
00 is the first open F-number (for example, F
6.7) has an open F-number equal to or less than
Enable auto focus.

Note that the open F value for AF is an open F value used for automatic focus adjustment, and does not always match the actual open F value of the image pickup optical system. For example, 50mm /
With a lens of F2.8, the open F value for AF is F5.6.
Is used. Therefore, the first open F value and the second open F value of the imaging optical system are broad concepts including both the open F value of the imaging optical system and the open F value for AF.

The main mirror 111 reflects a large part of the light beam from the imaging optical system 201 in the direction of the reticle 121 and transmits the remaining part. The auxiliary mirror 112 guides the light beam transmitted through the main mirror 111 to the focal position detection device 140. The prism 122 reverses the left and right of the image on the focusing screen 121 and guides the image to the photographer's eye via the eyepiece lens 123.

A photometric unit 180 is provided near the exit surface of the prism 122. Photometric unit 180
Includes a condenser lens and a photoelectric conversion element such as a photodiode, and outputs a signal corresponding to the luminance of the subject 2 to the AFCPU 3.
Output to 01. The display element 124 includes a light-emitting element such as a light-emitting diode, a liquid crystal display element, and the like, and displays a state in which the lens is focused on the subject 2 (focused state), a shutter speed, an aperture value of the lens, and the like.

The light emitting unit 170 includes a capacitor (not shown) for storing light emitting energy, a charging circuit (not shown) for charging the capacitor, and discharges electric energy stored in the capacitor to light energy. An arc tube 171 for conversion, a reflector 172 for reflecting flash light from the arc tube 171 forward of the camera, and a Fresnel lens 17 for condensing or diffusing the flash light in a predetermined range.
3 and so on. The light control sensor 150 includes, for example, a photoelectric conversion element such as a condenser lens and a photodiode, detects light reflected from the film 1 during emission of flash light by the light emitting unit 170, and outputs a signal corresponding to the amount of light to the AF CPU 301. Output to When the AF CPU 301 determines that the exposure amount of the film 1 has reached a predetermined value based on a signal from the light control sensor 150, the light emitting unit 17
Light emission of 0 is stopped.

The AF drive unit 160 includes an actuator such as a DC motor, a stepping motor, or an ultrasonic motor, an encoder that detects the rotation direction and the number of rotations of the actuator and outputs the detected signal to the AF CPU 301, and a deceleration for reducing the number of rotations of the actuator. It includes a system (not shown) and is connected to the lens driving mechanism 203 via the output shaft 161. The lens driving mechanism 203 is composed of, for example, a helicoid and a gear (not shown) for rotating the helicoid, and integrally drives the imaging optical system 201 and the lens barrel 202 in the direction of the arrow A by the driving force of the actuator of the AF driving unit 160. Move to The moving direction and the moving amount of the imaging optical system 201 and the lens barrel 202 follow the rotation direction and the rotation speed of the actuator, respectively.

(First Embodiment) A first embodiment of a focus position detecting device according to the present invention will be described with reference to FIGS.

In the focus position detection device 140 shown in FIG. 2, the field mask 141 is provided near a position where the distance from the imaging optical system 201 is relatively equal to that of the film 1. Of the light beams, the light beam incident on the focus position detection device 140 is restricted. The field mask 141 has nine openings 141a to 141i corresponding to the respective distance measurement areas 31 to 40 (see FIG. 3) described later.

Behind the field mask 141, there is provided a condenser lens 142 in which nine condenser lens groups 142a to 142i corresponding to the respective openings 141a to 141i of the field mask 141 are integrated. Further, a mirror 143 is provided behind the condenser lens 142, and the luminous flux transmitted through the field mask 141 and the condenser lens 142 is converted into an aperture mask 144 having a plurality of apertures.
Lens array 145 integrating a plurality of re-imaging lens groups
And a plurality of photoelectric conversion element array groups are made incident on a detection element 146 integrated therewith.

Further, the field mask 141, the condenser lens 142, the mirror 143, the aperture mask 144, the lens array 145, and the detection element 146 are integrally connected to a frame (not shown) and are modularized. The aperture mask, the re-imaging lens, and the photoelectric conversion element array corresponding to each of the distance measurement areas 31 to 40 and 41 constitute a distance measurement sensor. The same applies to the following embodiments.

In the case of the first embodiment, in order to realize the optimum ranging accuracy in accordance with the open F-number of the imaging optical system 201 of the mounted lens 200, for example, the first lens is placed at the center of the screen in FIG. The first F value corresponding to the open F value (eg, F6.7)
Among the distance measurement area groups 31 to 40, a distance measurement area 31 (particularly, a first distance measurement area 31) at the center and parallel to the horizontal direction of the screen and a second open F value (for example, F2.8) ) Are overlapped and set (hatched). In the first embodiment, only one ranging area 41 is set as the second ranging area. However, a plurality of areas 41 and 42 are set as in the following second embodiment. If there is, a second ranging area group is set.

Each of the first ranging area groups 31 to 40 has a range in which a light beam (hereinafter, referred to as a distance measuring light beam) from a subject passing through a pupil of the imaging optical system 201 having the first open F value can reach. Is set within. In the first ranging area group,
The distance measurement areas 33 to 40 are used for focusing on a subject or a part of the subject located at a position away from the center of the screen.

The first ranging sensor group corresponding to the first ranging area groups 31 to 40 is always used regardless of the open F value of the imaging optical system 201 of the lens 200 mounted. Further, the second ranging sensor (group) corresponding to the second ranging area (group) 41 has an open F value equal to or smaller than the second open F value (for example, F1.4, F1.4). F2, F2.8
Etc.) are used only when the lens 200 having the imaging optical system 201 is mounted. As is clear from FIG. 3, the first distance measurement area groups 31 to 40 and the second distance measurement area (group) 41 are formed by moving the screen approximately three times in the vertical and horizontal directions.
It is provided in a central area among nine equally formed areas.

The aperture mask 144 in the first embodiment
FIGS. 4 to 6 show the arrangement of the aperture, the re-imaging lens of the lens array 145, and the photoelectric conversion element array of the detection element 146, respectively. As is clear from FIG. 6, the first distance measuring sensor and the second distance measuring sensor corresponding to the first distance measuring area 31 and the second distance measuring area 41 are respectively on the horizontal axis H passing through the center of the screen. And two photoelectric conversion element arrays 146a and 146b, 246a and 24
6b. Similarly, the other first ranging area groups 32
The first distance measurement sensor group corresponding to .about.40 also includes two photoelectric conversion element arrays 146a and 146b, respectively.
The openings 144a and 144b, 244a and 244 of the aperture mask 144 correspond to the structure of the photoelectric conversion element array.
44b, the re-imaging lenses 145a and 145b, 245a and 245b of the lens array 145 are also arranged symmetrically with respect to a predetermined axis.

FIG. 7 shows how the light beam for distance measurement that has passed through the pupil of the image pickup optical system 201 reaches the photoelectric conversion element array of the detection element 146. In order to simplify the illustration, the field mask 141, the mirror 143, the aperture mask 14
4 and the re-imaging lens (lens array) 145 are omitted. In the drawing, F represents a film surface.

Of the luminous flux emitted from the subject or the portion of the subject in a random direction and incident on the imaging optical system 201 of the lens 200, the luminous flux having passed through the inner region of the pupil 30 of the imaging optical system having the first open F-number. 30A and 30B advance as shown by the dashed line in the figure, and the first distance measurement area 31 in FIG.
Distance measuring sensor (photoelectric conversion element array) 1 corresponding to
46A and 146B are reached, but are cut off by the aperture of the imaging optical system 201, and a second distance measuring sensor (photoelectric conversion element array) 246a corresponding to the second distance measuring area 41
And 246b. Similarly, an area (imaging) that is emitted from the same subject or the same part of the subject and that is outside the pupil 30 of the imaging optical system having the first open F value and within the pupil 50 of the imaging optical system having the second open F value The luminous fluxes 50A and 50B that have passed through the optical system (off-axis portion of the optical system) advance as shown by solid lines in the drawing, and the second distance measuring sensors (photoelectric conversion element arrays) 246a and 246b corresponding to the second distance measuring area 41. To reach. The luminous fluxes 50A and 50B are in the first ranging area 31.
Distance measuring sensor (photoelectric conversion element array) 1 corresponding to
It also reaches 46a and 146b.

Accordingly, the open F value of the imaging optical system 201 of the mounted lens 200 is equal to the second open F value (for example, F2.
If the distance is larger than 8), the distance cannot be measured by the second distance measuring sensor corresponding to the second distance measuring area 41. vice versa,
If the open F value of the imaging optical system 201 of the mounted lens 200 is equal to or smaller than the second open F value, the second
The distance can be measured by the second distance measuring sensor corresponding to the distance measuring area 41 of FIG.

As is apparent from FIGS. 15 and 6, the second
The photoelectric conversion element arrays 246a and 246b constituting the second distance measurement sensor corresponding to the first distance measurement area 41 are the photoelectric conversion element arrays 146a constituting the first distance measurement sensor corresponding to the first distance measurement area 31. And 146b are provided at positions farther from the optical axis L. That is, the second distance measuring sensor corresponding to the second distance measuring area 41 has a longer base line length and higher distance measuring accuracy than the first distance measuring sensor corresponding to the first distance measuring area 31. . Accordingly, the imaging optical system 201 having an open F value equal to or smaller than the second open F value
When the lens is mounted, a second distance measurement sensor having high distance measurement accuracy can be used for at least the subject or the part of the subject located at the center of the screen, and the open F value of the imaging optical system of the lens to be used can be used. It becomes possible to focus on the subject with the corresponding distance measurement accuracy.

Next, the operation of the first embodiment will be described with reference to the flowchart shown in FIG. First,
When the lens 200 is mounted on the camera body 100 and the main switch is turned on (step S100), the AF CPU
Reference numeral 301 denotes an AF open F value stored in the lens CPU 204 (step S105), and the read A
It is determined whether or not the open F value for F is equal to or smaller than the second open F value (step S110). If the AF open F value is equal to or smaller than the second open F value (YES in step S110), the AF CPU 301
Are a first ranging sensor group (particularly, a photoelectric conversion element array) corresponding to the first ranging area groups 31 to 40 and a second ranging sensor (corresponding to the second ranging area (group) 41). (Group) is set (step S115). On the other hand, AF
When the open F value for use is larger than the second open F value (NO in step S110), AFCPU 301 uses only the first distance measurement sensor group corresponding to first distance measurement area groups 31 to 40. Is set (step S120).

When any one of the first distance measuring sensor group, the second distance measuring sensor group, and only the first distance measuring sensor group is set, the AF CPU 301 performs distance measurement using these distance measuring sensor groups. Then, the defocus amount and the lens driving direction are calculated (step S125). Further, the AFCPU 30
1 controls the lens driving mechanism 203 using the calculated defocus amount and the driving direction of the lens, and
1 is moved (step S130).

When the movement of the imaging optical system 201 is completed, A
The FCPU 301 uses the imaging optical system 2
It is determined whether or not 01 is in focus (step S13)
5). If not in focus (N in step S135)
O), the AF CPU 301 calculates the defocus amount and the lens driving direction again (step S125), and moves the imaging optical system 201 (step S130). on the other hand,
If the camera is in focus (YES in step S135), the in-focus operation ends (step S140), and the process waits for the next operation, for example, turning on a shutter release button.

In the case of focus position detection using a plurality of ranging areas, a defocus amount is calculated for each ranging area, and the movement of the imaging optical system 201 is actually controlled from among the plurality of defocus areas. Is determined. As an example, the F value of the imaging optical system 201 is the second open F
If the value is smaller than the value (for example, F2.8), the arithmetic circuit 14
8 calculates a defocus amount for each ranging area using the ranging sensors corresponding to the first ranging area groups 31 to 40 and the second ranging area (group) 41, respectively. The focus amounts are compared and, for example, data closest to the camera is output as the final defocus amount (near-position priority method). Similarly, when the F-number of the imaging optical system 201 is larger than the second open F-number, the arithmetic circuit 148 uses the distance measurement sensor groups respectively corresponding to the first distance measurement area groups 31 to 40. The amount of defocus for each ranging area is calculated, and these defocus amounts are compared. For example, data closest to the camera is output as the final defocus amount.

(Second Embodiment) A second embodiment of the focus position detecting device according to the present invention will be described with reference to FIGS. Note that the description of the parts common to the focus position detection device of the first embodiment will be omitted.

As is apparent from FIG. 9, in the second embodiment, the open F value of the imaging optical system of the mounted lens 200 is equal to or higher than the second open F value (for example, F2.8). Is smaller, the second measurement area (hatched) is formed on the first distance measurement area groups 31 and 32 so as to form a cross sensor on the vertical axis V and the horizontal axis H passing through the center of the screen. Distance area groups 41 and 42 are set to overlap.

Next, the arrangement of the aperture of the aperture mask 144, each re-imaging lens of the lens array 145, and the photoelectric conversion element array of the detection element 146 in the second embodiment are shown in FIGS. As is clear from FIG. 12, the distance measurement sensor groups corresponding to the first distance measurement area groups 31 to 40 each include two photoelectric sensors provided symmetrically with respect to a predetermined axis, similarly to the first embodiment. Conversion element array 146a
And 146b. Further, the photoelectric conversion element arrays 246a and 246b constituting the distance measuring sensor group corresponding to the second distance measuring area groups 41 and 42 are provided on the horizontal axis H and the vertical axis V so as to constitute a cross sensor. Have been. The aperture mask 14 corresponds to the structure of the photoelectric conversion element array.
4 openings 144a and 144b, 244a and 244
b, re-imaging lenses 145a and 1 of lens array 145
45b, 245a, and 245b are also arranged symmetrically with respect to a predetermined axis.

As described above, a lens having an open F value equal to or smaller than the second open F value is attached, and, for example, the contrast of the subject or the subject at the center of the screen is changed in the vertical and horizontal directions of the screen. Even if the directions are different,
The focal position can be detected using a distance measuring sensor in any of the directions having a high contrast, and the possibility that distance measurement cannot be performed is reduced.

Other Embodiments In the above embodiments, the first open F value is F6.7, and the second open F value is F2.8. However, the present invention is not limited to this. Other open F values may be used. Further, although simply referred to as the open F value of the imaging optical system 201 of the lens 200, as described above, the open F value of the imaging optical system does not always match the open F value used in automatic focus adjustment. Accordingly, the first open F value and the second open F value of the imaging optical system 201 are respectively the actual open F value and the AF value of the imaging optical system.
Needless to say, both of the open F-numbers are included. Further, in each of the above embodiments, the AF single-lens reflex camera has been described as an example of the device using the focus position detecting device. However, the present invention is not limited to this. Can be used.

[0043]

As described above, according to the focal position detecting apparatus of the present invention, the first open F-number imaging optical system is provided at the position where the light beam from the predetermined portion of the subject can reach. A second distance measurement sensor and an imaging optical system having a second open F-number smaller than the first open F-number provided at a position where a light beam from a portion substantially equal to a predetermined portion of the subject can reach. When the image pickup optical system having the second open F value and an open F value smaller than the second open F value is mounted, an image is picked up using the first distance sensor and the second distance sensor. Since the focusing operation of the optical system is performed and the focusing operation of the imaging optical system is performed using the first distance measurement sensor when the imaging optical system having an open F value larger than the second open F value is mounted. In the case where an imaging optical system having a shallow depth of field with an aperture value close to the open F-number is attached. Also, the imaging optical system can be focused on the subject using the second distance measuring sensor having a longer base line provided at a position further away from the center of the screen, thereby achieving a focusing operation with high distance measuring accuracy. It is possible to do.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration example of an AF single-lens reflex camera in which each embodiment of a focus position detection device according to the present invention is used.

FIG. 2 is a perspective view showing a configuration of a first embodiment of a focus position detection device of the present invention.

FIG. 3 is a diagram showing an arrangement of distance measurement areas on a screen according to the first embodiment of the present invention.

FIG. 4 is a diagram illustrating an aperture of an aperture mask according to the first embodiment.

FIG. 5 is a diagram illustrating an arrangement of a re-imaging lens according to the first embodiment.

FIG. 6 is a diagram illustrating an arrangement of a photoelectric conversion element array according to the first embodiment.

FIG. 7 is a diagram illustrating a state in which a light beam that has passed through a pupil of an imaging optical system reaches an imaging optical system array of a distance measurement sensor in the first embodiment.

FIG. 8 is a flowchart showing the operation of the first embodiment.

FIG. 9 is a diagram illustrating an arrangement of distance measurement areas on a screen according to a second embodiment of the present invention.

FIG. 10 is a diagram illustrating openings of an aperture mask according to a second embodiment.

FIG. 11 is a diagram illustrating an arrangement of a re-imaging lens according to a second embodiment.

FIG. 12 is a diagram illustrating an arrangement of a photoelectric conversion element array according to a second embodiment.

FIG. 13 is a diagram illustrating a configuration and a detection principle of a conventional focus position detection device.

FIG. 14 is a diagram illustrating a difference in incident light flux between two imaging optical systems having different F-numbers.

FIG. 15 is a diagram for explaining the relationship between the base line length of the distance measurement sensor and the distance measurement accuracy.

[Explanation of symbols]

 31 to 40: First ranging area group 41, 42: Second ranging area group 140: Focus position detecting device 141: Field mask 142: Condenser lens 143: Beam splitter 144: Aperture mask 144a, 144b: Opening 145 : Lens array 145a, 145b: re-imaging lens 146: detecting element 146a, 146b: photoelectric conversion element array 244a, 244b: aperture 245a, 245b: re-imaging lens 246a, 246b: photoelectric conversion element array

Claims (4)

[Claims] 1. A first distance measuring sensor provided at a position where a light beam from a predetermined portion of a subject can reach by an imaging optical system having a first open F value, and a first distance measuring sensor smaller than the first open F value. 2
A second distance measuring sensor provided at a position where a light beam from a portion substantially the same as a predetermined portion of the subject can reach by the imaging optical system having the open F value. Also, when the imaging optical system having a small open F value is mounted, the focusing operation of the image pickup optical system is performed using the first distance measuring sensor and the second distance measuring sensor, and the focusing operation is performed to be larger than the second open F value. A focus position detecting device, wherein a focusing operation of an imaging optical system is performed using a first distance measuring sensor when an imaging optical system having an open F value is mounted. 2. The focus position detecting device according to claim 1, wherein the second distance measuring sensor is provided at a position farther from the optical axis than the first distance measuring sensor. 3. The first distance measuring sensor and the second distance measuring sensor each include a photoelectric conversion element array, and each photoelectric conversion element array is formed on the same chip. Or the focus position detecting device according to 2. 4. The first distance measuring sensor and the second distance measuring sensor further include a re-imaging lens, and the re-imaging lens has an optical axis passing through an optical axis of the imaging optical system and an imaging optical system. 4. The focus position detecting device according to claim 3, wherein a lens array is formed so as to be arranged on the same line orthogonal to the optical axis of the lens.