JP2018116290A - Focus adjustment device and imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a focus adjustment device capable of appropriately adjusting a focus state of an optical system.SOLUTION: A focus adjustment device includes: a specifying section 170 for specifying an image corresponding to an image being an object as a specific object from a picked-up image picked up through via an optical system including a focus adjustment optical system 212; a focus detection section 160 for detecting a focus state of the optical system in a plurality of focus detection positions set in a pick up screen; and a drive control section 170 for driving the focus adjustment optical system 212 to a first lens position corresponding to focus detection result of the focus detection section. The drive control section 170 drives the focus adjustment optical system 212 to a second lens position different from the first lens position when the specific object is specified by the specifying section 170, and the specific object is not present in any of the focus detection positions.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a focus adjustment device and an imaging device.

  2. Description of the Related Art Conventionally, a focus adjustment device that detects a focus state of an optical system and adjusts the focus state of the optical system based on the detection result is known (for example, Patent Document 1). In such a focus adjustment device, a technique is known in which a focus state of an optical system is detected at a plurality of focus detection positions set in a shooting screen, thereby focusing on a subject corresponding to the focus detection position.

JP 09-101449 A

  Provided are a focus adjustment device and an imaging device capable of appropriately adjusting a focus state of an optical system.

  The present invention solves the above problems by the following means.

[1] A focus adjustment apparatus according to a first aspect of the present invention is a specifying unit that specifies, as a specific subject, an image corresponding to a target image from a captured image captured through an optical system including a focus adjustment optical system. A focus detection unit that detects a focus state of the optical system at a plurality of focus detection positions set in the photographing screen, and the focus adjustment optical system up to a first lens position according to a detection result by the focus detection unit A drive control unit that drives the first control unit, and when the specific subject is specified by the specifying unit and the specific subject does not exist in any of the focus detection positions, the drive control unit The focus adjustment optical system is driven to a second lens position different from the first lens position.
[2] In the invention related to the focus adjustment apparatus, the focus detection unit may be configured to detect a focus state of the optical system by detecting an image shift amount by the optical system.
[3] In the invention relating to the focus adjustment device, when the specific subject is specified by the specifying unit and the specific subject does not exist in any of the focus detection positions, the focus adjustment optical system is changed to the first focus adjustment optical system. And a mode setting unit capable of setting a first focus adjustment mode for driving to the second lens position and a second focus adjustment mode for not driving the focus adjustment optical system to the second lens position. Can do.
[4] In the invention related to the focus adjustment device, the second lens position is a shooting magnification of the optical system, a size of the specific subject in the shooting screen, and a position of the specific subject in the shooting screen. According to at least one, it can constitute so that it may be a lens position shifted from the 1st lens position.
[5] In the invention related to the focus adjustment device, the drive control unit may identify the specific object when the specific object is specified by the specifying unit and the specific object does not exist in any of the focus detection positions. When the subject is a person's face, the posture of the person is detected from the captured image, and when the detected posture of the person is a forward tilt posture, the focus adjustment optical system is moved to the second lens position. It can be configured to drive up to.
[6] The focus adjustment apparatus according to the second aspect of the present invention specifies an image corresponding to a target image as a specific subject from a captured image captured via an optical system including a focus adjustment optical system. A focus detection unit that detects a focus state of the optical system at a plurality of focus detection positions set in the photographing screen, and the focus adjustment optics up to a first lens position according to a focus detection result of the focus detection unit A drive control unit that drives a system, and the drive control unit is configured to change the state when the specific subject is present at any one of the focus detection positions to a state that does not exist at the focus detection position. The focus adjustment optical system is driven to a second lens position different from the first lens position.
[7] An imaging device according to a first aspect of the present invention includes the above-described focus adjustment device.
[8] An imaging apparatus according to a second aspect of the present invention includes an identifying unit that identifies an image corresponding to a target image from a captured image captured via an optical system including a focus adjustment optical system as a specific subject. A focus detection unit for detecting a focus state of the optical system at a plurality of focus detection positions set in the photographing screen; and an aperture control unit for controlling a diaphragm for limiting a light beam that has passed through the optical system. The aperture control unit sets the aperture value of the aperture to a value on the aperture side when the specific subject is specified by the specifying unit and the specific subject does not exist in any of the focus detection positions. It is characterized by changing.
[9] A focus adjusting apparatus according to a third aspect of the present invention includes a specifying unit that specifies a specific subject, a focus detection unit that detects a focus state of a focus detection region, and at least a part of the specific subject is the focus. When in the detection area, control is performed to drive the focus optical system to the first lens position using the detection result by the focus detection unit, and when at least a part of the specific subject is not in the focus detection area, And a control unit that performs control to drive the focus optical system to a second lens position different from the first lens position.
[10] In the invention related to the focus adjustment apparatus, the second lens position can be configured to be a position moved from the first lens position by a predetermined correction amount.
[11] The invention relating to the focus adjustment apparatus may be configured to include a calculation unit that calculates the predetermined correction amount.
[12] In the invention according to the focus adjustment device, the calculation unit may be configured to select at least one of a shooting magnification, a size of the specific subject in the shooting screen, and a position of the specific subject in the shooting screen. A predetermined correction amount can be calculated.

  According to the present invention, it is possible to appropriately adjust the focus state of the optical system.

FIG. 1 is a block diagram showing a camera according to the present embodiment. FIG. 2 is a diagram illustrating an example of a shooting screen. FIG. 3 is a flowchart showing the operation of the camera according to the first embodiment. FIG. 4 is a diagram illustrating an example of a correspondence relationship between the imaging magnification and the shift amount. FIG. 5 is a diagram illustrating how the image plane position changes when the defocus amount is corrected using the shift amount. FIG. 6 is a flowchart showing the operation of the camera according to the second embodiment. FIG. 7 is a diagram illustrating how the depth of field changes when the aperture value is changed using the shift amount.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<< First Embodiment >>
FIG. 1 is a block diagram showing a single-lens reflex digital camera 1 according to the first embodiment. As shown in FIG. 1, the single-lens reflex digital camera 1 (hereinafter simply referred to as camera 1) of the present embodiment includes a camera body 100 and a lens barrel 200, and the camera body 100 and the lens barrel 200 are detachable. Combined as possible.

  The lens barrel 200 incorporates a photographing optical system including lenses 211, 212, 213 and a diaphragm 220.

  The lens 212 is a focus lens, and can adjust the focal length of the photographing optical system by moving in the direction of the optical axis L1. The focus lens 212 is provided so as to be movable along the optical axis L1 of the lens barrel 200, and its position is adjusted by the focus lens drive motor 230 while its position is detected by the encoder 260.

  Information on the current position of the focus lens 212 detected by the encoder 260 is sent to the camera control unit 170 described later via the lens control unit 250. Then, the drive amount of the focus lens 212 calculated based on this information is sent from the camera control unit 170 to the focus lens drive motor 230 via the lens control unit 250, and based on this, the focus lens drive motor 230 is transmitted. To drive.

  The aperture 220 has an aperture diameter centered on the optical axis L1 in order to limit the amount of light flux that passes through the imaging optical system and reaches the image sensor 110 provided in the camera body 100 and adjusts the amount of blur. It is configured to be adjustable. Adjustment of the aperture diameter by the aperture 220 is performed by transmitting an appropriate aperture diameter calculated in the automatic exposure mode from the camera control unit 170 to the aperture drive unit 240 via the lens control unit 250, for example. In addition, the adjustment of the aperture diameter is performed by a manual operation via the operation unit 150 provided in the camera body 100, and the set aperture diameter is transmitted from the camera control unit 170 to the aperture drive unit 240 via the lens control unit 250. Is also done. The aperture diameter of the aperture 220 is detected by an aperture aperture sensor (not shown), and the lens controller 250 recognizes the current aperture diameter.

  On the other hand, the camera body 100 includes a mirror system 120 for guiding the light flux from the subject to the image sensor 110, the finder 135, the photometric sensor 137, and the focus detection unit 160. The mirror system 120 includes a quick return mirror 121 that rotates by a predetermined angle between the observation position and the imaging position of the subject around the rotation axis 123, and the quick return mirror 121 that is pivotally supported by the quick return mirror 121. And a sub mirror 122 that rotates in accordance with the rotation. In FIG. 1, a state where the mirror system 120 is at the observation position of the subject is indicated by a solid line, and a state where the mirror system 120 is at the imaging position of the subject is indicated by a two-dot chain line.

  The mirror system 120 is inserted on the optical path of the optical axis L1 in the state where the subject is at the observation position of the subject, while rotating so as to retract from the optical path of the optical axis L1 in the state where the subject is in the imaging position.

  The quick return mirror 121 is composed of a half mirror, and in a state where the subject is at the observation position, the quick return mirror 121 reflects a part of the light flux (optical axes L2 and L3) from the subject (optical axis L1). Then, the light is guided to the finder 135 and the photometric sensor 137, and a part of the light beam (optical axis L4) is transmitted to the sub mirror 122. On the other hand, the sub mirror 122 is configured by a total reflection mirror, and guides the light beam (optical axis L4) transmitted through the quick return mirror 121 to the focus detection unit 160.

  Therefore, when the mirror system 120 is at the observation position, the light beam (optical axis L1) from the subject is guided to the finder 135, the photometric sensor 137, and the focus detection unit 160, and the subject is observed by the photographer and exposure calculation is performed. And the focus adjustment state of the focus lens 212 is detected. Then, when the photographer fully presses the release button, the mirror system 120 rotates to the photographing position, and all the luminous flux (optical axis L1) from the subject is guided to the image sensor 110, and the photographed image data is stored in a memory (not shown). To do.

  The light flux (optical axis L2) from the subject reflected by the quick return mirror 121 forms an image on a focusing screen 131 disposed on a surface optically equivalent to the image sensor 110, and forms a pentaprism 133 and an eyepiece lens 134. It is possible to observe through. At this time, the transmissive liquid crystal display 132 superimposes and displays a focus detection area mark on the subject image on the focusing screen 131 and relates to shooting such as the shutter speed, aperture value, and number of shots in an area outside the subject image. Display information. As a result, the photographer can observe the subject, its background, and photographing related information through the finder 135 in the photographing preparation state.

  In addition, a photometric lens 136 and a photometric sensor 137 are provided in the vicinity of the eyepiece lens 134 to receive a part of subject light imaged on the focusing screen 131.

  The photometric sensor 137 is composed of a two-dimensional color CCD image sensor or the like, and divides the photographing screen into a plurality of regions and outputs a photometric signal corresponding to the luminance of each region in order to calculate an exposure value at the time of photographing. A signal detected by the photometric sensor 137 is output to the camera control unit 170 and used for automatic exposure control and detection of a specific subject such as a human face.

  The image sensor 110 is provided on the optical axis L1 of the light beam from the subject of the camera body 100, and is provided on a planned focal plane of the imaging optical system including the lenses 211, 212, and 213, and a shutter 111 is provided on the front surface thereof. ing. The image sensor 110 is a device in which a plurality of photoelectric conversion elements are two-dimensionally arranged, and can be composed of a device such as a two-dimensional CCD image sensor, a MOS sensor, or a CID. The image signal photoelectrically converted by the image sensor 110 is subjected to image processing by the camera control unit 170 and then stored in a memory (not shown). Note that the memory for storing the photographed image can be constituted by a built-in memory or a card-type memory.

  The focus detection unit 160 is a device for executing automatic focusing control by a phase difference detection method using subject light. The focus detection unit 160 has a light receiving surface at a position optically equivalent to the imaging surface of the imaging element 110 of the light beam (optical axis L4) reflected by the sub mirror 122, and a pair of different exit pupils of the focus lens 212. A pair of image signals are acquired by receiving a pair of light fluxes passing through the region of light by a pair of line sensors (not shown) provided on the light receiving surface. Then, the focus detection unit 160 calculates the shift amount of the pair of image signals by obtaining the phase shift of the pair of image signals acquired by the pair of line sensors by correlation calculation, and the calculated shift amount is determined as the defocus amount. And transmitted to the camera control unit 170.

  Further, as shown in FIG. 2, a plurality of focus detection areas AFP are set in the photographing screen 10 of the photographing optical system (in the example shown in FIG. 2, nine focus detection areas AFP are provided). ), A pair of line sensors are provided at positions corresponding to these focus detection areas AFP. The focus detection unit 160 calculates a defocus amount for each focus detection area AFP by acquiring a pair of image signals from a pair of line sensors corresponding to each focus detection area AFP. FIG. 2 is a diagram showing an example of the photographing screen 10 of the photographing optical system, and the number and arrangement of the focus detection areas AFP are not limited to the mode shown in FIG.

  The camera control unit 170 includes a microprocessor and peripheral components such as a memory. The camera control unit 170 reads an image signal from the image sensor 110, performs predetermined information processing as necessary, generates image data, and generates the generated image data. And stored in a memory (not shown). In addition, the camera control unit 170 controls the entire camera 1 such as correction of captured image information, detection of the focus adjustment state of the lens barrel 200, and detection of the aperture adjustment state.

  In addition, the camera control unit 170 calculates the lens driving amount of the focus lens 212 according to the defocus amount transmitted from the focus detection unit 160, and the calculated lens driving amount via the lens control unit 250 is a lens driving motor. 230. Thereby, the lens position of the focus lens 212 can be adjusted by driving the lens driving motor 230.

  Furthermore, in this embodiment, the camera control unit 170 performs image recognition processing for detecting a person's face based on the image signal output from the photometric sensor 137. When the person's face exists in any focus detection area AFP, the camera control unit 170 causes the focus detection unit 160 to perform focus detection in the focus detection area AFP where the person's face exists. Thereby, it is possible to focus on the face of the person.

  Further, as shown in FIG. 2, the camera control unit 170 detects a person's face, but if the person's face does not exist in any focus detection area AFP, the person who does not exist in the focus detection area AFP. The defocus amount transmitted from the focus detection unit 160 is corrected so that the subject's face is in focus, and control is performed to drive the focus lens 212 based on the corrected defocus amount. As a result, for example, as shown in FIG. 2, in a scene where the person is sliding in a forward leaning posture, the person's face does not exist in the focus detection area AFP. Even if it cannot be adjusted, the defocus amount is corrected so that the face of the person who does not exist in the focus detection area AFP is in focus, and the lens position of the focus lens 212 is shifted to the closest side, so that the face of the person It is possible to focus on. Details of the defocus amount correction method will be described later.

  The operation unit 150 includes a shutter release button and an input switch for a photographer to set various operation modes of the camera 1, and can switch between an autofocus mode and a manual focus mode. In the present embodiment, the operation unit 150 detects the human face when adjusting the focus state of the optical system, and the human face exists in any focus detection area AFP as described above. If not, the first focus adjustment mode for correcting the defocus amount and driving the focus lens 212 based on the corrected defocus amount, and detecting the focus of the human face and the human face are detected. Even when it does not exist in the area AFP, it is possible to switch to the second focus adjustment mode in which the focus lens 212 is driven based on the defocus amount still detected in the focus detection area AFP. Further, the shutter release button switch includes a first switch SW1 that is turned on when the button is half-pressed and a second switch SW2 that is turned on when the button is fully pressed. The shutter release button switches SW1 and SW2 and various modes set by the operation unit 150 are transmitted to the camera control unit 170.

  Next, an operation example of the camera 1 according to the first embodiment will be described. FIG. 3 is a flowchart illustrating an operation example of the camera 1 according to the first embodiment. The following operation is started when the camera 1 is turned on. In the following, a scene where shooting is performed in the composition shown in FIG. 2 will be described as an example.

  First, in step S101, the focus detection unit 160 starts calculating the defocus amount by the phase difference detection method. More specifically, the line sensor of the focus detection unit 160 accumulates charges according to the light flux, and the accumulated signal information is output as a pair of image signals. Then, the focus detection unit 160 reads a pair of image signals for each focus detection area AFP set in the shooting screen 10, and performs a correlation operation on the read pair of image signals, thereby shifting the pair of image signals. The amount is calculated, and the defocus amount is calculated based on the calculated shift amount. Note that the calculation of the defocus amount is repeated at regular intervals even after step S101.

  In step S102, the camera control unit 170 acquires an image signal for subject recognition from the photometric sensor 137, and starts an image recognition process for detecting a human face based on the acquired image signal. For example, the camera control unit 170 can detect a person's face from the captured image by comparing a template image of the person's face stored in advance with a captured image captured by the photometric sensor 137. it can.

  For example, in the example shown in FIG. 2, the camera control unit 170 detects the face of a person who is skating on the shooting screen 10, and the transmissive liquid crystal display 132 displays a frame in the detected face area of the person. Line 20 is superimposed. Note that the image recognition processing for detecting a person's face is repeatedly performed at regular intervals even after step S102.

  In step S103, the camera control unit 170 determines whether or not the shutter release button is half-pressed (the first switch SW1 is turned on). If it is determined that the first switch SW1 is on, the process proceeds to step S104. If it is determined that the first switch SW1 is not on, the process waits in step S103 until the first switch SW1 is turned on.

  In step S104, the camera control unit 170 determines whether a human face has been detected. If a person's face is detected, the process proceeds to step S105 to focus on the person's face. On the other hand, if a person's face is not detected, the subject located in the focus detection area AFP is focused. In order to match, the process proceeds to step S109.

  In step S105, the camera control unit 170 determines whether or not a person's face is present in any focus detection area AFP. When a person's face exists in any focus detection area AFP, the focus lens 212 is driven based on the defocus amount of the focus detection area AFP in which the person's face is detected, thereby focusing on the person's face. Therefore, the process proceeds to step S109 without performing the processes of steps S106 to S108. On the other hand, if the person's face does not exist in any focus detection area AFP, the process proceeds to step S106 in order to focus on the person's face that does not exist in the focus detection area AFP. Even when a part of the human face exists in the focus detection area AFP, it can be determined that the human face exists in the focus detection area AFP, and the process can proceed to step S109.

  In step S106, the camera control unit 170 determines whether the user has selected the first focus adjustment mode via the operation unit 150. If the first focus adjustment mode is selected, the process proceeds to step S107. On the other hand, if the second focus adjustment mode is selected, in order to focus on the subject located in the focus detection area AFP, The process proceeds to step S109.

  In step S107, the camera control unit 170 calculates a shift amount for correcting the defocus amount. For example, as shown in FIG. 4, the camera control unit 170 stores in advance a table indicating the correspondence between the shooting magnification and the shift amount in the memory of the camera control unit 170, and refers to this table to The shift amount can be calculated from the shooting magnification. FIG. 4 is a diagram illustrating an example of a correspondence relationship between the photographing magnification and the shift amount. The correspondence relationship between the photographing magnification and the shift amount can be appropriately set by experiment or the like. The shift amount is set to be large. This is because the depth of field decreases as the shooting magnification increases, and the focus lens 212 needs to be driven by that much in order to focus on the person's face. Note that the correspondence relationship between the imaging magnification and the shift amount shown in FIG. 4 is an example, and is appropriately determined according to the type of the lens barrel 200.

  In addition, the acquisition method of the present imaging magnification is not specifically limited, The present imaging magnification can be acquired using a well-known method. For example, the camera control unit 170 can calculate the current shooting magnification from the ratio between the focal length and the subject distance. Further, the camera control unit 170 may be configured to calculate the shooting magnification based on the distance from the position of the person's face in the shooting screen 10 to the center of the screen. In this case, the longer the distance from the center of the screen to the person's face, the higher the shooting magnification. Alternatively, the camera control unit 170 may calculate the shooting magnification by determining that the shooting magnification is higher as the position of the person's face in the shooting screen 10 is higher. Further, the camera control unit 170 may be configured to calculate the shooting magnification based on the size (area) of the person's face in the shooting screen 10. In this case, the larger the person's face in the shooting screen 10 is, the higher the shooting magnification can be calculated. Further, the position and size of the person's face in the shooting screen 10 are directly related to the shift amount, not the shooting magnification, and the shift amount is calculated from the position and size of the person's face in the shooting screen 10. Also good.

  In step S108, the camera control unit 170 performs a correction process for correcting the defocus amount using the shift amount calculated in step S107. In the present embodiment, the camera control unit 170 corrects the defocus amount using the shift amount so that the focus lens 212 is driven to a lens position closer to the lens position based on the defocus amount. For example, when the focus lens 212 is driven to the close side when the defocus amount is a positive value, the camera control unit 170 corrects the defocus amount by adding a shift amount to the defocus amount.

  Here, FIG. 5 is a diagram showing how the image plane position changes when the defocus amount is corrected using the shift amount, and shows a state in which the subject (person) shown in FIG. 2 is viewed from the side. ing. When the focus lens 212 is driven based on the defocus amount detected in the focus detection area AFP when a human leg exists in the focus detection area AFP, the image plane position of the optical system is, for example, FIG. (A), the person's leg is in focus and the person's face is not in focus. On the other hand, in the present embodiment, the focus lens 212 is driven based on the corrected defocus amount by correcting the defocus amount detected in the focus detection area AFP with the shift amount calculated in step S107. In this case, for example, the image plane position of the optical system is moved to the closest side by an image plane movement amount corresponding to the shift amount from the image plane position of the optical system before correction shown in FIG. To (b), and as a result, the face of the person can be focused.

  In step S109, the camera control unit 170 performs drive control of the focus lens 212 based on the defocus amount corrected in step S108. As a result, as shown in FIG. 2, since the leg of the person exists in the focus detection area AFP, the leg on the infinity side of the person's face is in focus, and the person's face is in focus. Even in such a situation, the lens position to which the focus lens 212 moves can be shifted closer to the lens position based on the defocus amount, and the person's face can be focused.

  It should be noted that if the human face cannot be detected in step S104 (step S104 = No), if it is determined in step S105 that the human face exists in the focus detection area AFP (step S105 = Yes), and in step S106 If the second focus adjustment mode is set, the process proceeds to step S109, and focus lens drive control is performed based on the defocus amount detected in the focus detection area AFP. In these cases, since the defocus amount is not corrected, the subject in the focus detection area AFP can be focused.

  As described above, in the camera 1 according to the first embodiment, when a human face is detected and the detected human face does not exist in any focus detection area AFP, the camera 1 in the focus detection area AFP. The defocus amount is corrected so that a non-existent person's face is in focus, and the focus lens 212 is driven based on the corrected defocus amount. As a result, as shown in FIG. 2, in the scene where the person is leaning forward, the leg of the person exists in the focus detection area AFP, so the leg at the infinity side of the person's face is in focus. Therefore, it is possible to effectively prevent the person's face from being out of focus.

  In particular, as shown in FIG. 2, when shooting a person performing a sporting event, the entire body of the person is often shot. In such a case, the face of the person is placed at the center of the shooting screen 10. In many cases, the focus detection area AFP deviates. In addition, when performing a sports competition, as shown in FIG. 2, the athlete often takes a forward leaning posture, so the effect of the present invention becomes even more pronounced when shooting a person performing a sports competition. . Further, as shown in FIG. 2, when shooting is performed so that the shooting screen 10 is vertically long, the person's face is easily removed from the focus detection area AFP arranged at the center of the shooting screen 10. The effect of the present invention is also remarkable when shooting with 10 being vertically long.

  Further, in the present embodiment, when a human face is detected and the human face does not exist in any focus detection area AFP, the defocus amount is corrected by the shift amount, and based on the corrected defocus amount. The first focus adjustment mode for driving the focus lens 212 and the person's face is detected and the person's face is not present in any focus detection area AFP. Since the second focus adjustment mode for driving the focus lens 212 can be selected, the photographer focuses on the subject desired by the photographer by selecting the focus adjustment mode desired by the photographer. Is possible.

  Furthermore, the amount of lens driving required to focus on a person's face differs for each lens barrel 200 and each photographing magnification. In the present embodiment, each lens barrel 200 is provided with a table indicating the correspondence between the photographing magnification and the shift amount, and by referring to this table, the shift amount is determined according to the current photographing magnification. It becomes possible to focus on a human face with higher accuracy.

<< Second Embodiment >>
Next, 2nd Embodiment of this invention is described based on drawing. In the second embodiment, the camera 1 shown in FIG. 1 is the same as the first embodiment except that the camera 1 operates as shown in FIG. Hereinafter, the operation of the camera 1 according to the second embodiment will be described with reference to FIG. FIG. 6 is a flowchart showing the operation of the camera 1 according to the second embodiment.

  In steps S201 to S203, similarly to steps S101 to S103 of the first embodiment, the calculation of the defocus amount and the recognition of the human face are started (steps S201 and S202), and the shutter release button is pressed halfway (first It is determined whether or not the switch SW1 is turned on (step S203). If it is determined that the first switch SW1 is on, the process proceeds to step S204. If it is determined that the first switch SW1 is not on, the process waits in step S203 until the first switch SW1 is turned on.

  In step S204, the focus lens 212 is driven based on the defocus amount detected in step S201. In the second embodiment, the focus lens 212 is driven using the defocus amount as it is without correcting the defocus amount with the shift amount.

  In steps S205 to S207, as in steps S104 to S106 of the first embodiment, it is determined whether or not a person's face has been detected (step S205), and the person's face exists in any focus detection area AFP. Whether or not the first focus adjustment mode is selected (step S207). A person's face is detected (step S205 = Yes), no person's face exists in any focus detection area AFP (step S206 = No), and the first focus adjustment mode is selected (step S207 = Yes). ), The process proceeds to step S208; otherwise, the process illustrated in FIG.

  In step S208, the aperture value of the aperture 220 is changed by the camera control unit 170. For example, the camera control unit 170 stores in advance a table (not shown) indicating the correspondence relationship between the photographing magnification and the aperture value shift amount in the memory of the camera control unit 170. With reference to this table, The shift amount of the aperture value corresponding to the shooting magnification is acquired. Then, the camera control unit 170 changes the current aperture value using the shift amount of the aperture value so that the current aperture value becomes a more narrow value (a larger aperture value). The correspondence between the photographing magnification and the aperture value shift amount can be set as appropriate through experiments or the like, and is set such that the larger the photographing magnification, the larger the aperture value shift amount.

  Here, FIG. 7 is a diagram showing a change in the depth of field when the aperture value of the aperture 220 is corrected using the shift amount, and shows a state in which the subject (person) shown in FIG. 2 is viewed from the side. Show. For example, as shown in FIG. 7, when the depth of field at the aperture value before correction when a person's legs are present in the focus detection area AFP is (a), the person's face is covered. It is not included in the range of the depth of field (a), and the person's face cannot be focused. In this embodiment, when a person's face is detected and the detected person's face does not exist in any focus detection area AFP, the aperture value is changed to a value on the narrowing-down side. The depth of field can be expanded from (a) to (b). As a result, the face of the person falls within the range of the subject depth (b), and the face of the person can be focused.

  In subsequent step S209, the camera control unit 170 performs exposure control based on the aperture value changed in step S208. Specifically, the camera control unit 170 controls the exposure so that an exposure suitable for shooting can be obtained by changing the shooting time and shooting sensitivity while fixing the aperture value changed in step S208.

  As described above, in the camera 1 according to the second embodiment, when a person's face is detected and the detected person's face does not exist in any focus detection area AFP, the aperture value is reduced. Change to the value of. As a result, for example, as shown in FIG. 2, in a scene where the person is leaning forward, the leg portion of the person exists in the focus detection area AFP, and the person's face deviates from the depth of field. Even in this case, by changing the aperture value to the value on the aperture side, the depth of field of the optical system becomes wider, so that the face of the person can be within the range of the subject depth. It is possible to focus.

  In addition, since the amount of shift of the aperture value necessary for focusing on the face of a person differs for each lens barrel 200 and for each photographing magnification, in this embodiment, the photographing magnification and the aperture value for each lens barrel 200. A table showing the correspondence with the shift amount of the camera is provided, and by referring to this table and determining the shift amount of the aperture value according to the current shooting magnification, the face of the person can be focused with higher accuracy. Is possible.

  The embodiment described above is described for facilitating the understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

  For example, in the first embodiment described above, the configuration in which the defocus amount or the aperture value is corrected when a human face is detected and the human face does not exist in any focus detection area AFP is exemplified. However, the present invention is not limited to this configuration. For example, when the face of a person is present in any focus detection area AFP and is not present in the focus detection area AFP, the defocus amount or aperture value is changed. It is good also as composition which corrects. That is, instead of determining whether or not a person's face exists in all the focus detection areas AFP, when a person's face is detected in one focus detection area AFP, only the focus detection area AFP is detected. It is possible to determine whether or not a person's face exists and correct the defocus amount or aperture value when the person's face no longer exists in the focus detection area AFP.

  In the above-described embodiment, the configuration in which the defocus amount or the aperture value is corrected when a human face is detected and the human face does not exist in any focus detection area AFP is exemplified. For example, it is determined whether or not a body part other than a person's face exists in the focus detection area AFP, and when a body part other than the person's face exists in the focus detection area AFP, defocusing is performed. It is good also as a structure which correct | amends quantity. For example, the camera control unit 170 can determine whether or not a body part other than a human face exists in the focus detection area AFP based on a change in the color of the subject or the amount of defocus in the focus detection area AFP. .

  Furthermore, in the above-described embodiment, a configuration in which a human face is detected and the defocus amount or the aperture value is corrected when the human face does not exist in any focus detection area AFP is exemplified. The subject is not limited to a person's face. For example, a defocus amount or an aperture value may be corrected when an animal face is detected and the animal face does not exist in any focus detection area AFP.

  In addition, in the first embodiment described above, the configuration in which the shift amount is changed according to the shooting magnification is illustrated, but the configuration is not limited to this configuration, and for example, the shift amount may be a fixed value. For example, when the current aperture value is increased by one step, the camera control unit 170 can set a shift amount corresponding to the amount by which the depth of field spreads to the close side as a fixed shift amount. That is, for example, in FIG. 7, when the depth of field at the current aperture value is (a) and the depth of field when the current aperture value is increased by one step is (b), the current aperture value is When the value is increased by one step, the amount of depth of field spreading to the closest side is (c). Therefore, the amount of shift by which the image plane can be moved by the amount of movement of the image plane corresponding to the amount of spreading (c). Can be set as a fixed shift amount.

  In addition to the above-described embodiment, when the posture of a person is detected by image analysis, it is determined whether or not the posture of the person is a forward leaning posture. The focus amount or the aperture value may be corrected. For example, the camera control unit 170 detects the position of the person's face and the position of the person's arm from the captured image, and when the position of the person's face and the position of the person's arm are approximately the same height, It can be determined that the person is leaning forward. If the person's face can be determined to be on the infinity side of the person's body as a result of detecting the posture of the person, the defocus amount is set so that the focused image plane position shifts to the infinity side. Alternatively, the aperture value may be corrected.

  Furthermore, in the above-described embodiment, the configuration for performing the focus detection of the phase difference detection method for detecting the focus state of the optical system by obtaining the image shift amount by the optical system is exemplified, but the present invention is not limited to this configuration. For example, the contrast detection method for detecting the focus state of the optical system may be performed by calculating the contrast evaluation value based on the image of the optical system.

  The camera 1 of the embodiment described above is not particularly limited, and the present invention may be applied to other optical devices such as a digital video camera, a lens-integrated digital camera, and a camera for a mobile phone.

DESCRIPTION OF SYMBOLS 1 ... Single-lens reflex digital camera 100 ... Camera body 110 ... Imaging device 150 ... Operation part 160 ... Focus detection part 170 ... Camera control part 200 ... Lens barrel 212 ... Focus lens 230 ... Focus lens drive motor 250 ... Lens control part

Claims (12)

A specifying unit that specifies, as a specific subject, an image corresponding to a target image from a captured image captured through an optical system including a focus adjustment optical system;
A focus detection unit for detecting a focus state of the optical system at a plurality of focus detection positions set in the photographing screen;
A drive control unit that drives the focus adjustment optical system to a first lens position according to a detection result by the focus detection unit,
When the specific subject is specified by the specifying unit and the specific subject does not exist at any of the focus detection positions, the drive control unit sets the focus adjustment optical system as the first lens position. Is driven to a different second lens position. The focus adjustment device according to claim 1,
The focus adjustment unit, wherein the focus detection unit detects a focus state of the optical system by detecting a shift amount of an image by the optical system. The focus adjustment device according to claim 1 or 2,
A first focus adjustment mode for driving the focus adjustment optical system to the second lens position when the specific subject is specified by the specifying unit and the specific subject does not exist at any of the focus detection positions. And a mode setting unit capable of setting a second focus adjustment mode in which the focus adjustment optical system is not driven to the second lens position. It is a focus adjustment apparatus in any one of Claims 1-3,
The second lens position depends on at least one of a shooting magnification of the optical system, a size of the specific subject in the shooting screen, and a position of the specific subject in the shooting screen. A focus adjusting device characterized in that the lens position is shifted from the position. It is a focus adjustment apparatus in any one of Claims 1-4,
In the case where the specific subject is specified by the specifying unit and the specific subject is not present at any of the focus detection positions, and the specific subject is a human face, A focus adjustment device that detects the posture of the person from a captured image and drives the focus adjustment optical system to the second lens position when the detected posture of the person is a forward tilt posture. A specifying unit that specifies, as a specific subject, an image corresponding to a target image from a captured image captured through an optical system including a focus adjustment optical system;
A focus detection unit for detecting a focus state of the optical system at a plurality of focus detection positions set in the photographing screen;
A drive control unit that drives the focus adjustment optical system to a first lens position according to a focus detection result of the focus detection unit,
The drive control unit changes the focus adjustment optical system to the first lens position when the specific subject changes from a state where the specific subject exists at any one of the focus detection positions to a state where the specific subject does not exist at the focus detection position. Is driven to a different second lens position.   An imaging device provided with the focus adjustment apparatus in any one of Claims 1-6. A specifying unit that specifies, as a specific subject, an image corresponding to a target image from a captured image captured through an optical system including a focus adjustment optical system;
A focus detection unit for detecting a focus state of the optical system at a plurality of focus detection positions set in the photographing screen;
A diaphragm control unit that controls a diaphragm for limiting the light beam that has passed through the optical system,
The aperture control unit changes the aperture value of the aperture to a value on the aperture side when the specific subject is specified by the specifying unit and the specific subject does not exist in any of the focus detection positions. An imaging apparatus characterized by that. A specific part for identifying a specific subject;
A focus detection unit for detecting the focus state of the focus detection area;
When at least a part of the specific subject is in the focus detection area, control is performed to drive the focus optical system to the first lens position using a detection result by the focus detection unit, and at least a part of the specific subject is And a control unit that performs control to drive the focus optical system to a second lens position different from the first lens position when not in the focus detection region. The focus adjustment device according to claim 9, comprising:
The focus adjustment apparatus, wherein the second lens position is a position moved by a predetermined correction amount from the first lens position. The focus adjustment device according to claim 10, comprising:
A focus adjustment device comprising a calculation unit for calculating the predetermined correction amount. The focus adjustment device according to claim 11, comprising:
The calculation unit calculates the predetermined correction amount according to at least one of a shooting magnification, a size of the specific subject in the shooting screen, and a position of the specific subject in the shooting screen. Focus adjustment device.

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