JP7377063B2 - Imaging device, its control method, program, storage medium - Google Patents

Description

The present invention relates to focus detection technology in an imaging device.

When photographing a subject approaching from a distance with a camera, a user often starts autofocus (hereinafter referred to as AF) before the subject reaches a size on the finder to actually be photographed as an image. In this case, if it is possible to recognize a subject such as a face, AF can be used to focus on the recognized position, but in scenes where it is difficult to recognize a subject, AF is performed based on the detected defocus amount. However, for a distant subject, the difference in depth from the background is small, and the background or other subjects may be in focus instead of the main subject. Therefore, it is necessary to perform transition determination to determine whether there is an object that the user is aiming for other than the position where AF is started, while performing AF.

In Patent Document 1, a moving object is determined based on the amount of image plane movement of the entire screen, and by making it easier to determine the center of the screen as a moving object and making it harder to determine the surroundings as a moving object, it is possible to select a subject that matches the user's intention. A transfer determination method that increases the probability of selection has been disclosed.

Japanese Patent Application Publication No. 2001-194578

However, in Patent Document 1, based on the amount of image plane movement of the entire screen, the extent to which it is likely to be determined as a moving object is switched between the center and the periphery, but in Patent Document 1, the degree to which it is likely to be determined as a moving object is switched between the center and the periphery. There is a problem in that changes in the amount of surface movement are difficult to detect.

The present invention has been made in view of the above-mentioned problems, and its purpose is to provide an imaging device that can appropriately select a subject to focus on even when the subject approaches from a distance. It is.

An imaging device according to the present invention includes an imaging device that captures an image of a subject, a subject detection device that detects a subject based on a signal from the imaging device, and a focus detection device that performs focus detection in a plurality of focus detection areas within a screen. a focus detection means capable of adjusting the focus of the photographing optical system based on the detection result of the focus detection means; and a focus adjustment means capable of adjusting the focus of the photographing optical system based on the detection result of the focus detection means; When a predetermined condition indicating that a subject in focus is a distant subject, a focus detection area used for focus detection is set to a focus detection area near the center of the plurality of focus detection areas. A setting means is provided.

According to the present invention, even when the subject approaches from a distance, it is possible to appropriately select the subject to focus on.

FIG. 1 is a block diagram showing the functional configuration of a digital camera that is a first embodiment of an imaging device of the present invention. FIG. 1 is a side sectional view of a digital camera according to a first embodiment. FIG. 3 is a diagram showing a pixel structure of an image sensor. FIG. 3 is a diagram illustrating a pupil division function of an image sensor. 2 is an overall flowchart during AF in the first embodiment. 5 is a flowchart of focus detection processing in the first embodiment. 7 is a flowchart of recapture determination processing in the first embodiment. 5 is a flowchart of main tracking frame selection processing in the first embodiment. FIG. 7 is an explanatory diagram of an area where focus can be detected during continuous shooting in the second embodiment. FIG. 7 is an explanatory diagram of division of the photographing screen area in the second embodiment. 7 is a flowchart of main tracking frame position control in continuous shooting in the second embodiment. 7 is a flowchart of center movement control of the main tracking frame position in the second embodiment. 7 is a flowchart of moving object determination at the main tracking frame position in the second embodiment. 7 is a flowchart of center movement control of the main tracking frame position in a modification of the second embodiment. 7 is a flowchart of center movement control of the main tracking frame position in a modification of the second embodiment.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the claimed invention. Although a plurality of features are described in the embodiments, not all of these features are essential to the invention, and the plurality of features may be arbitrarily combined. Furthermore, in the accompanying drawings, the same or similar components are designated by the same reference numerals, and redundant description will be omitted.

(First embodiment)
FIG. 1 is a block diagram showing the functional configuration of a digital camera, which is a first embodiment of the imaging apparatus of the present invention. FIG. 2 is a side sectional view of the digital camera shown in FIG.

The digital camera of this embodiment has an autofocus (AF) mode (one-shot AF mode) that focuses on the position of the subject at a certain time, and an autofocus mode that periodically drives the lens to keep the subject in focus. There are two types: (servo AF mode). In the first embodiment, a case will be described in which the digital camera is set to the servo AF mode among these modes.

1 and 2, a digital camera 150 is a digital still camera with interchangeable lenses that uses a combination of a camera body 100 having an image sensor 103 and a photographing lens 120 having a photographing optical system.

The camera body 100 includes an image sensor 103, a display 105, a CPU 110, an image sensor control circuit 102, a memory circuit 101, an interface circuit 106, an image processing circuit 107, and electrical contacts 108.

The image sensor 103 is composed of a CMOS (Complementary Metal Oxide Semiconductor) image sensor, a CCD (Charge Coupled Device) image sensor, etc., and is arranged on the intended imaging plane of the photographing lens 120 of the camera body 100. Details of the image sensor 103 will be described later.

The display 105 is constituted by an LCD (Liquid Crystal Display) panel or the like, and displays photographed images, photographic information, and the like. Furthermore, in the live view mode, the display device 105 displays a moving image of the area to be photographed in real time. Here, the live view mode is a mode in which a subject image from the photographing lens 120 is captured by the image sensor 103 and a low-pixel moving image for preview is displayed on the display 105 in real time. In this live view mode, phase difference AF on the imaging plane, which will be described later, can be performed. Furthermore, during continuous shooting, low-pixel still images from each continuous shooting are displayed on the display 105.

The CPU 110 centrally controls the entire camera. The CPU 110 also includes a subject detection section 111, a phase difference detection section 112, a defocus amount conversion section 112, a subject re-capture determination section 114, a main tracking frame selection section 115, and a focus adjustment section 116, and controls the focal state of the photographic lens 120. Performs calculation and drive control.

The subject detection unit 111 detects a characteristic subject based on the characteristics of the image output from the image sensor 103. The phase difference detection unit 112 detects the phase difference between a pair of image signals output from the image sensor 103. The defocus amount conversion unit 113 converts the image shift amount detected by the phase difference detection unit 112 into a defocus amount using a conversion coefficient. Details of the subject re-capture determination unit 116 will be described later. The main tracking frame selection unit 115 determines the position on the imaging plane for adjusting the focus by the focus adjustment unit 116. The focus adjustment unit 116 sends an instruction to the lens CPU 122 to move the focal position based on the converted defocus amount.

The image sensor control circuit 102 drives and controls the image sensor 103 according to instructions from the CPU 110. The memory circuit 101 stores images captured by the image sensor 103. The interface circuit 106 outputs the image processed by the image processing circuit 107 to the outside of the camera. The image processing circuit 107 performs image processing on the image signal captured by the image sensor 103. The electrical contact 108 contacts the electrical contact 124 of the photographic lens 120 and is used for communication of electric power and various signals.

The photographing lens 120 is an interchangeable lens that can be attached to and detached from the camera body 100. The photographic lens 120 includes a photographic optical system, a lens CPU 122, a photographic lens drive mechanism 121, an aperture drive mechanism 123, an aperture 125, and an electrical contact 124.

The photographing optical system forms an optical image of the subject to be photographed on the image sensor 103. The photographing optical system includes a plurality of lens groups, and is driven by a photographing lens drive mechanism 121 to move a focal point near the imaging surface of the image sensor 103 along the Z direction (along the optical axis).

The lens CPU 122 receives focus adjustment information sent from the CPU 110 of the camera body 100 via the electric contact 124, and drives the photographing lens drive mechanism 121 based on the focus adjustment information. The aperture drive mechanism 123 has a mechanism and an actuator for driving the aperture 125, and drives the aperture 125 according to instructions from the lens CPU 110.

<Structure of image sensor>
Next, with reference to FIG. 3, the pixel structure of the image sensor 103 in this embodiment will be described. FIG. 3 is a diagram showing a pixel structure of the image sensor 103. FIG. 3(A) is an explanatory diagram of the pixel arrangement of the image sensor 103, and FIG. 3(B) is a cross-sectional view of the pixel 210G along the ZX plane.

FIG. 3A shows a pixel array of the image sensor 103 (two-dimensional CMOS sensor) in a pixel range of 4 rows by 4 columns. The color filter arrangement of the pixel 210 employs a Bayer arrangement. A pixel 210G having a spectral sensitivity of G (green) is arranged as two pixels in the diagonal direction. Further, as the other two pixels, a pixel 210R having a spectral sensitivity of R (red) and a pixel 210B having a spectral sensitivity of B (blue) are arranged. Pixels 210R, 210G, and 210B each have two subpixels 201a and 201b for pupil division. Further, the sub-pixel 201a is a first pixel that receives the light flux that has passed through the first pupil region of the imaging optical system. Further, the sub-pixel 201b is a second pixel that receives the light flux that has passed through the second pupil region of the imaging optical system. Each pixel functions as an imaging pixel and a focus detection pixel.

Regarding the coordinate axes indicated by X, Y, and Z in FIG. 3(A), the XY plane is located within the paper plane of FIG. 3(A), and the Z axis is an axis perpendicular to the paper plane. Sub-pixels 201a and 201b are arranged along a direction parallel to the X-axis.

Regarding the coordinate axes indicated by X, Y, and Z in FIG. 3(B), the XZ plane is located within the paper plane of FIG. 3(B), and the Y axis is an axis perpendicular to the paper plane. The detection section has a photodiode made up of a p-type layer 200 and an n-type layer. The microlens 202 is placed a predetermined distance away from the light receiving surface in the Z-axis direction. Microlens 202 is formed on color filter 203.

In this embodiment, all pixels 210R, 210G, and 210B of the image sensor 103 are provided with subpixels 201a and 201b for pupil division. The sub-pixels 201a and 201b are used as focus detection pixels. However, the present embodiment is not limited to this, and a configuration may be adopted in which focus detection pixels capable of pupil division are provided only in some of all pixels.

<Concept of pupil division function using image sensor>
Next, with reference to FIG. 4, the pupil division function of the image sensor 103 will be explained. FIG. 4 is an explanatory diagram of the pupil division function of the image sensor 103, and shows the state of pupil division in one pixel portion.

Regarding the coordinate axes (X, Y, Z) of the pixel portion shown in the lower part of FIG. 4, the XZ plane is located within the plane of the paper of FIG. 4, and the Y axis is an axis perpendicular to the plane of the paper. The pixel includes a p-type layer 200 and n-type layers 301a and 301b (corresponding to subpixels 201a and 201b). The p-type layer 200 and the n-type layer 301a constitute the sub-pixel 201a in FIG. 3, and the p-type layer 200 and the n-type layer 301b constitute the sub-pixel 201b. Microlens 304 is arranged on the Z-axis.

Further, in the upper part of FIG. 4, an exit pupil 302 and a frame 303 (for example, an aperture frame or a lens frame) of the photographic lens 120 are shown. Regarding the coordinate axes (X, Y, Z) shown at the top of FIG. 4, the XY plane is located within the plane of the paper of FIG. 4, and the Z axis is an axis perpendicular to the plane of the paper.

One pixel is provided with n-type layers 301a and 301b embedded in the p-type layer 200, thereby forming two sub-pixels. The two subpixels are regularly arranged along the X direction. Further, since the two sub-pixels are eccentric in the +X direction and the -X direction, it is possible to perform pupil division using one microlens 202. In FIG. 4, a pupil 302a of image signal A and a pupil 302b of image signal B are shown as exit pupils 302. The image signal A is the first image signal acquired by the subpixel 201a corresponding to the n-type layer 301a eccentric in the -X direction. Further, the image signal B is a second image signal acquired by the subpixel 201b corresponding to the n-type layer 301b eccentric in the +X direction.

In this embodiment, the image signal A (first signal) is a signal obtained from a plurality of sub-pixels 201a regularly arranged in the X direction, as shown in FIG. 3(A). be. That is, the image signal A is one of the image signals obtained from a pair of light beams that pass through different exit pupil regions of the imaging optical system and have different baseline lengths depending on the aperture value. Further, the image signal B (second signal) is a signal obtained from a plurality of sub-pixels 201b regularly arranged in the X direction, as shown in FIG. 3(A). That is, the image signal B is the other image signal obtained from a pair of light beams that pass through different exit pupil regions of the imaging optical system and have different base line lengths depending on the aperture value.

The CPU 110 uses the phase difference detection section 112 to calculate the relative image shift amount between the image signal A and the image signal B, and uses the defocus amount conversion section 113 to calculate the defocus amount. Note that in this embodiment, a configuration corresponding to a subject having a luminance distribution in the X direction has been described. However, in this embodiment, by extending the same configuration to the Y direction, it is also possible to adopt a configuration that can also accommodate a subject having a brightness distribution in the Y direction.

Next, the overall control method during photographing according to this embodiment will be explained using the flowchart of FIG.

In step S101, the CPU 110 detects that the photography preparation switch is turned on. In this embodiment, the photographing preparation switch (SW1) is turned on by pressing the release button halfway.

In the next step S102, the CPU 110 performs focus detection processing. Details of the focus detection process will be described later using FIG. 6.

In step S103, the CPU 110 uses the subject detection unit 111 to perform subject detection processing. This is a process of detecting objects that can be photographed, such as people, animals, and vehicles, based on data obtained from the image sensor 103.

In step S104, the CPU 110 performs reacquisition determination processing. Details of the reacquisition determination process will be described later using FIG. 7.

In step S105, the CPU 110 performs main tracking frame selection processing. Details of the main tracking frame selection process will be described later using FIG. 8.

In step S106, the CPU 110 calculates the lens drive amount necessary to focus on the image plane at the screen position selected in step S105, and transmits it to the lens CPU 122.

In step S107, the CPU 110 determines whether or not the photographing preparation switch (SW1) is turned off. If the switch is off, this flow ends, and if it is on, the process returns to step S102.

Next, an example of the operation of the focus detection process in step S102 will be explained based on the flowchart of FIG.

In step S201, the CPU 110 obtains the image signal A and the image signal B output from the image sensor 103.

In step S202, the CPU 110 calculates the amount of image shift of the image signal A and the image signal B acquired in step S201.

In step S203, the CPU 110 converts the image shift amount calculated in step S202 into a defocus amount.

In step S204, the CPU 110 stores the focus detection information in the memory circuit 101. In step S204, the subject image plane position and its detection time are stored.

Next, an example of the operation of the re-capture determination process by the re-capture determination unit in step S104 will be described based on the flowchart of FIG. 7.

In step S301, the CPU 110 determines whether the subject has been captured once. Whether or not the image is captured is determined by performing autofocus once and adjusting the focus to a predetermined depth at a specific position. At this time, if the focus has not been adjusted to the predetermined depth even once, this flow is ended without performing the re-capturing determination process. Once the focus has been adjusted to a predetermined depth, the process advances to S302.

In step S302, the CPU 110 determines whether the subject is a distant subject. The method of determining a distant subject is based on the imaging magnification. The imaging magnification is calculated using equation (1).

Shooting magnification = distance to subject/focal length...Formula (1)
In this embodiment, when the photographing magnification is equal to or higher than the threshold value Th1, the object is determined to be a distant object. In this embodiment, the threshold Th1 is set to 200. If the subject is a distant subject, the process advances to S303, and if the subject is not a distant subject, this flow ends.

In step S303, the CPU 110 determines whether the focal length is equal to or greater than the threshold Th2. If the focal length is equal to or greater than the threshold Th2, the process proceeds to S304; otherwise, the flow ends. In this embodiment, the threshold Th2 is set to 100 mm.

In step S304, the CPU 110 determines whether defocus on the close side has been detected in the central range. In this embodiment, the central range is divided into 3×3 focus detection areas (focus detection frames), and the determination is made based on whether defocus on the close side is detected in even one of the focus detection areas. However, this division method may also be used to divide by numbers other than 3×3. Further, instead of determining whether there is at least one focus detection area in which defocus on the close side is detected, the determination may be made based on whether or not the area is averaged to indicate the close side. In addition, in this embodiment, the result of one focus detection unit is used, but the image surface history of the center is held separately from the image surface history of the currently captured position, and the image surface history of the center position is If the object is moving in that direction, it may be determined that re-acquisition is to be performed. Furthermore, the history of the camera's gyro sensor may be retained, and a determination may be made that re-capturing is not performed when the camera is shaken significantly. If the determination in S304 is YES, the process advances to S305, and if the determination is NO, this flow ends.

In step S305, the CPU 110 determines whether the subject is a moving object. A method for determining that an object is a moving object is to maintain a history of the image plane position of the object, and if the image plane position is monotonically changing in one direction, it is determined that the object is a moving object. If the already captured subject is moving and the user continues to press the shooting preparation switch (SW1), the user wants to take a picture of that subject, so this flow ends without changing the subject. do. If the main subject is not a moving object, the process advances to S306.

In step S306, the CPU 110 determines to transfer to the subject in the center range. This determined process is used in the determination in step S403, which will be described later.

Next, an example of the operation of the main tracking frame selection process in step S105 will be described based on the flowchart of FIG.

In step S401, the CPU 110 determines whether or not the subject was detected in the subject detection process in step S103. If the subject has been detected, the process advances to S407; if the subject has not been detected, the process advances to S402.

In step S402, the CPU 110 determines whether a subject is captured. This is the same determination process as step S301. If the subject has been captured, the process advances to S403; if the subject has not been captured, the process advances to S404.

In step S403, the CPU 110 determines whether or not it has been determined in step S306 to transfer to the subject in the center range. If the decision has been made, the process advances to S406; otherwise, the process advances to S405.

In step S404, the CPU 110 selects a frame for focus adjustment, giving priority to the frame in which defocus is detected in the closest direction, and ends this flow.

In step S405, the CPU 110 selects a frame for focus adjustment, giving priority to a frame whose image plane position is continuous with the previous main tracking frame position, and ends this flow.

In step S406, the CPU 110 selects the frame in the center range as the frame for focus adjustment, and ends this flow.

In step S407, the CPU 110 selects the frame at the position where the subject is detected as the frame for focus adjustment, and ends this flow.

As described above, according to the present embodiment, even if it is not possible to start AF at a location that matches the user's intention for a distant subject whose main subject cannot be detected, the determination of re-acquisition is subsequently made. By doing this, it is possible to refocus the AF on a subject that matches the user's intention.

(Second embodiment)
In the first embodiment, control regarding the position of the main tracking frame has been described in a case where focus detection results have been obtained for the main tracking frame and the central region of the imaging device. However, during actual continuous shooting operation (hereinafter referred to as continuous shooting), in order to maintain the frame speed, focus detection results may only be obtained in the peripheral range of the current main tracking frame. There is.

FIG. 9 is a diagram showing an image of a focus detectable area during continuous shooting. Frame A in FIG. 9 is the main tracking frame, which is currently located at the upper left side of the entire photographic screen C. During continuous shooting in this state, focus detection results can only be obtained within the range of frame B in FIG.

Hereinafter, as a second embodiment, control regarding the position of the main tracking frame when it is determined that the main tracking frame A does not capture the desired subject in such a situation will be described.

FIG. 10A is a diagram in which the entire photographic screen C in FIG. 9 is divided into three regions D, E, and F. Frame D in FIG. 10 is a central region, which is literally the center of the entire photographic screen, and the size of the region is the same as the main tracking frame described above. That is, FIG. 10A shows a state in which the main tracking frame is set at the center of the entire screen, which is the initial setting state of the imaging device. E in FIG. 10 is the central region, which is "approximately near the center" of the entire photographic screen C, and is a region where there is a high probability that the main subject will be present at the time of photographing.

Here, considering the relationship between the main tracking frame in FIG. 9 and B in FIG. 9, where focus can be detected even during continuous shooting, if there is no main tracking frame in the central area E of FIG. 10(A), The focus detection result for frame D, which is the central area, cannot be obtained. Therefore, when the main tracking frame is offset from the center as shown in Fig. 9 and is not in the central area of the entire shooting screen C (E in Fig. 10(A)), how should the control regarding the position of the main tracking frame be performed? How to do this will be explained below.

FIG. 11 is a flowchart showing the main tracking frame position control process during continuous shooting.

First, in step S501, the CPU 110 determines whether the mode is continuous shooting mode. If the mode is continuous shooting mode, the process advances to step S502. Since the target here is control under constraint conditions during continuous shooting, if the continuous shooting mode is not set, this flow is immediately ended.

On the other hand, in step S502, the CPU 110 determines whether continuous shooting is already in progress. If continuous shooting is in progress, the process advances to step S505, and if continuous shooting is not yet in progress and a continuous shooting operation is to be performed, the process advances to step S503.

In steps S503 and S504, the determination flag "HANTEI-Flag" used in "main tracking frame position center movement control" to be executed thereafter is initialized to 0, and the determination timer "HANTEI-Timer" is initialized. At this stage, only both are initialized and the timer operation does not start.

In step S505, the CPU 110 executes "main tracking frame position center movement control".

FIG. 12 is a flowchart showing center movement control of the main tracking frame position.

First, in step S601, the CPU 110 determines whether the main tracking frame position is outside the central area E in FIG. 10(A). If it is outside, the process advances to step S602, and if it is not outside, the process advances to step S611.

In step S602, the CPU 110 determines whether the current focal length f is "100 mm or more" (a predetermined value or more), or in the subsequent step S603, the subject distance d is "200 x f or more" (the subject distance is a predetermined focal length). ). Through this two-step determination, it is determined whether or not a sufficiently distant subject is being photographed based on the current shooting situation during continuous shooting.

If all three stages of determination in steps S601 to S603 are applicable, in the subsequent step S604, the CPU 110 performs "main tracking frame moving object determination." Although the details will be described later, it is determined whether the subject captured by the main tracking frame is a non-moving object.

Using this result as a determination material, a fourth stage determination is performed in step S605, and if all the conditions are met, the determination flag "HANTEI-Flag" initialized at the start of continuous shooting is checked in the subsequent step S606. If the determination flag "HANTEI-Flag" is "0", that is, immediately after initialization, the CPU 110 sets the determination flag "HANTEI-Flag" to "1" in the subsequent step S607, and similarly sets the initialized determination at the start of continuous shooting. Start timing with the timer "HANTEI-Timer".

On the other hand, if the determination flag "HANTEI-Flag" is "1" in step S606, the determination timer "HANTEI-Timer" is measuring, so in step S609, the determination timer exceeds "threshold: 1 second". Determine whether If "1 second" has elapsed (if the predetermined time has continued), it is assumed that all conditions have been met, and the main tracking frame position is moved to the center area D in FIG. 10(A). If "1 second" has not elapsed, timekeeping continues.

Furthermore, if any one of the four stages of determination performed in steps S601 to S605 is not applicable, it is determined that the conditions for moving the main tracking frame position to the center area are not met or are no longer met. Then, similarly to the start of continuous shooting, the determination flag "HANTEI-Flag" and the determination timer "HANTEI-Timer" are initialized in steps S611 and S612.

FIG. 13 is a flowchart showing the "main tracking frame moving object determination" performed in step S604 of FIG.

First, in step S701, the CPU 110 checks from the tracking results of the subject whether there is movement at the main tracking frame position within the photographic screen. If movement within the photographic screen is not recognized, in the subsequent step S702, the CPU 110 checks the continued stability of the focus detection result at the main tracking frame position. Only when both of these two steps of confirmation are met, it is determined that the subject captured by the main tracking frame is a non-moving object.

The above describes how to move the main tracking frame position to the center area when the entire shooting screen C is divided into three areas, center, center, and periphery of D, E, and F, as shown in FIG. 10(A). This is an explanation of the operation of whether or not.

Note that the range B in which focus can be detected during continuous shooting shown in FIG. 9 varies depending on the performance of the image sensor, the continuous shooting speed, etc., and there are various ways of thinking about the concept of "center and periphery of the shooting screen". Therefore, as shown in FIG. 10(B), it is also possible to expand the range treated as the central region, as shown in G in FIG. 10(B), from the range shown in E in FIG. 10(A).

Next, as shown in FIG. 10(C), the main tracking frame position is set to the center area when the peripheral area is divided into two stages with respect to the central area D and the central area E shown in FIG. 10(A). The control to move to is explained. As shown in FIG. 10(C), the peripheral regions of the two stages are designated as G and F.

FIG. 14 is a flowchart showing main tracking frame position control during continuous shooting when the above-mentioned two-stage peripheral area is provided. In the following, steps that are the same as those in FIG. 12 are given the same step numbers, and only portions that are different from FIG. 12 will be described.

In step S601 of FIG. 12, only a determination is made as to whether the main tracking frame position is "outside the central area," but in FIG. It is being carried out in Here, the peripheral region 1 is the peripheral region G in FIG. 10(C). That is, it is determined in which of the two-stage peripheral regions G and F as shown in FIG. 10(C) the main tracking frame position is located. Based on the results, the time threshold N (only "1 second" in FIG. 12) of the judgment timer "HANTEI-Timer" is set at steps S803 and S804, inside (G) and outside (F) of the two-stage peripheral area. Switch between "1 second" and "0.5 second". Therefore, in step S812 of FIG. 14, which corresponds to step S609 of FIG. 12, it is determined whether "threshold value: N seconds" has elapsed.

In the two-step threshold determination here, if the main tracking frame position is in the peripheral area, the main tracking frame position is moved to the central area earlier. As mentioned above, there are various ways of thinking about the concept of "the center and the periphery of the shooting screen," so for example, the surrounding area may be set more precisely and the time may be changed more precisely depending on the position within the screen.

Next, another example of the determination of "whether a sufficiently distant subject is being photographed" performed in steps S602 and S603 in FIG. 12 will be described.

FIG. 15 is a flowchart of main tracking frame position control during continuous shooting in which, in contrast to FIG. 12, "the main tracking frame position is moved to the center area as soon as possible if it is sufficiently far away but closer." In the explanation here, only the parts different from those in FIG. 12 will be explained.

As mentioned above, in contrast to the determination made in steps S602 and S603 in FIG. 12 as to whether the object is sufficiently far away, in step S904 in FIG. Added distance judgment. Specifically, in contrast to the two-stage determination shown in Figure 12, which is ``Is the focal length 100 mm or more?'' and ``Is the shooting distance 200 f or more?'', ``Is the shooting distance 40m or more?'' is added. ing. Based on this result, the time threshold N (only "1 second" in FIG. 12) of the determination timer "HANTEI-Timer" is set in two stages, "1 second" and "0.5 seconds", in steps S905 and S906 of FIG. ”. Therefore, in step S912 of FIG. 15, which corresponds to step S609 of FIG. 12, it is determined whether "threshold value: N seconds" has elapsed.

This effectively results in a two-step judgment for shooting distances of 200f and 40m, and if the shooting distance is 200f or more but less than 40m, it will be faster (0.5 seconds), and if it is 40m or more, it will be judged as shown in Figure 12. The main tracking frame position is moved to the center area in the same time (1 second). In other words, the control is performed such that ``the main tracking frame position is quickly moved to the center area if it is far enough away but closer.''

(Other embodiments)
The present invention also provides a system or device with a program that implements one or more functions of the above-described embodiments via a network or a storage medium, and one or more processors in a computer of the system or device reads the program. This can also be achieved by executing a process. It can also be implemented by a circuit (eg, ASIC) that implements one or more functions.

The invention is not limited to the embodiments described above, and various changes and modifications can be made without departing from the spirit and scope of the invention. Therefore, the following claims are hereby appended to disclose the scope of the invention.

100: Camera body, 101 Memory circuit, 102: Image sensor control circuit, 103: Image sensor, 105: Display, 110 CPU, 121: Photographic lens drive mechanism, 122: Lens CPU, 123: Aperture drive mechanism, 125: Aperture

Claims (16)

an imaging means for imaging a subject image;
a subject detection means for detecting a subject based on a signal from the imaging means;
a focus detection means capable of performing focus detection in a plurality of focus detection areas within a screen;
a focus adjustment means for adjusting the focus of the photographing optical system based on the detection result of the focus detection means;
When the object cannot be detected by the object detection means and a predetermined condition indicating that the object that is in focus by adjustment of the focus adjustment means is a distant object, the focus detection area used for focus detection is , setting means for setting a focus detection area near the center of the plurality of focus detection areas;
An imaging device comprising: The imaging apparatus according to claim 1, wherein when the subject does not satisfy the predetermined condition, the focus detection means performs focus detection so as to continue focusing on the in-focus subject. 2. The predetermined condition is that the distance to the subject is a predetermined multiple or more of the focal length of the photographic optical system, and the focal length of the photographic optical system is a predetermined value or more. 2. The imaging device according to 2. The setting means is configured to set a focus detection area to be used for focus detection when the focus detection means detects defocus on a side closer than the in-focus subject in a focus detection area near the center of the screen. 4. The imaging apparatus according to claim 1, wherein the focus detection area is set to a focus detection area close to the center of the plurality of focus detection areas. The setting means further includes determining means for determining whether or not the in-focus subject is a moving object, and the setting means is configured to: when the determining means determines that the in-focus subject is not a moving object; The imaging device according to any one of claims 1 to 4, wherein a focus detection area used for focus detection is set to a focus detection area near the center of the plurality of focus detection areas. The setting means holds a history of the image plane position of the focus detection area near the center, and if the history of the image plane position indicates that the subject is moving monotonically in the close direction, The imaging device according to any one of claims 1 to 5, wherein a focus detection area used for focus detection is set to a focus detection area near the center of the plurality of focus detection areas. The setting means is configured not to set a focus detection area used for focus detection to a focus detection area close to the center of the plurality of focus detection areas when it is detected that a large movement of the imaging device is detected. The imaging device according to any one of claims 1 to 6. The imaging device according to claim 7, further comprising a gyro sensor that detects movement of the imaging device. If the determining means determines that the in-focus subject is outside the central area of the screen and the determining means continues to determine that the subject is not a moving object for a predetermined period of time, the setting means determines whether the subject is in focus or not. 6. The imaging device according to claim 5, wherein the focus detection area to be used is set to a focus detection area close to the center of the plurality of focus detection areas. 10. The setting means sets the focus detection area used for focus detection to a focus detection area close to the center of the plurality of focus detection areas during continuous shooting. Imaging device. The setting means sets a focus detection area used for focus detection to a focus detection area close to the center of the plurality of focus detection areas when a close-up defocus amount is detected in a focus detection area near the center. The imaging device according to claim 9, characterized in that: 12. The predetermined time period is set according to a position within the screen of a focus detection frame that detects the in-focus subject. imaging device. The imaging device according to any one of claims 9 to 11, wherein the predetermined time is set according to a focal length of the photographing optical system and a subject distance. an imaging device that captures an image of a subject; a subject detection device that detects a subject based on a signal from the imaging device; and a focus detection device that can perform focus detection in a plurality of focus detection areas within a screen; A method for controlling an imaging device, comprising: a focus adjustment means for adjusting a focus of a photographing optical system based on a detection result of the focus detection means,
When the object cannot be detected by the object detection means and a predetermined condition indicating that the object that is in focus by adjustment of the focus adjustment means is a distant object, the focus detection area used for focus detection is . A method of controlling an imaging device, comprising the step of setting a focus detection area close to the center of the plurality of focus detection areas. A program for causing a computer to execute each step of the control method according to claim 14. A computer-readable storage medium storing a program for causing a computer to execute each step of the control method according to claim 14.

Images