JP2011247938A - Imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable an imaging device to accurately detect the focus of an object which no conventional device can do.SOLUTION: An imaging device comprising a variation detecting means that detects whether or not the relative positions of pixels for focus detection and light coming incident on an object have varied, an addition frequency determining means that, if the variation detecting means does not detect the variation, determines an appropriate addition frequency to add a focus detection signal on the basis of the level of the focus detection signal read out by a reading means and, if the variation detecting means has detected the variation, limits the frequency to add the focus detection signal to a frequency less than the appropriate addition frequency, and an adding means that adds the focus detection signals stored in a storage means in a time series as many times retroactively counted from the latest focus detection signal as determined by the addition frequency determining means.

Description

  The present invention relates to an imaging apparatus.

  Conventionally, as this type of imaging apparatus, for example, there is an imaging apparatus disclosed in Patent Document 1. This imaging apparatus photoelectrically converts and accumulates a light beam from an optical system by a plurality of pixels including imaging pixels and focus detection pixels, and reads out signals from each pixel at a predetermined cycle by a reading unit. The focus adjustment state of the optical system is such that the addition of the focus detection pixel signals read out in a predetermined cycle is performed for a predetermined number of additions determined in accordance with the read focus detection pixel signal level and aperture value. It was detected based on the results.

JP 2008-85738 A

  However, in the above conventional imaging device, when the focus detection of the optical system is performed by adding the number of times the signal of the focus detection pixel signal is determined, if the imaging device moves or the subject moves, the subject and focus detection The relative position with respect to the target pixel changes, and accurate focus detection cannot be performed on the subject.

The present invention
Imaging means for photoelectrically converting subject light incident via an optical system by a plurality of imaging pixels and a plurality of focus detection pixels around which the imaging pixels are arranged, and accumulating charges;
Reading means for reading out charges accumulated in the imaging pixels and the focus detection pixels at a predetermined cycle as imaging signals and focus detection signals;
Display means for performing display based on the read imaging signal each time the imaging signal is read by the reading means;
Storage means for storing the focus detection signals read by the reading means in time series;
Change detecting means for detecting whether or not a change has occurred in the relative position between the focus detection pixel and the incident subject light;
When the change is not detected by the change detecting means, an appropriate number of additions for adding the focus detection signal is determined based on the level of the focus detection signal read by the reading means, and the change detection is performed. When the change is detected by the means, an addition number determination means for limiting the number of additions for adding the focus detection signal to a number smaller than the appropriate addition number;
Adding means for adding the number of times determined by the number-of-addition determining means retroactively from the latest focus detection signal to the focus detection signal stored in time series in the storage means;
The imaging apparatus is configured to include a focus detection unit that detects a focus adjustment state of the optical system based on the focus detection signal added by the addition unit.

  ADVANTAGE OF THE INVENTION According to this invention, the imaging device which can perform exact focus detection with respect to a to-be-photographed object can be provided.

(A) is a block diagram which shows the outline of a structure of the digital camera by one Embodiment of this invention, (b) is a front view which shows the structure of the image pick-up element of the digital camera shown to (a). 2 is a flowchart showing an outline of processing for performing focus detection of a subject image and displaying the subject image on an electronic viewfinder in the digital camera shown in FIG. 1. 3 is a detailed flowchart of an addition number determination process for determining the number of additions of focus detection signals in the flowchart shown in FIG. 2.

  An embodiment for carrying out the present invention when an imaging apparatus according to the present invention is applied to a digital camera will be described.

  FIG. 1A is a block diagram showing an outline of the configuration of the digital camera 1 according to this embodiment. FIG. 2B is a front view showing the configuration of the image sensor 12 of the digital camera 1.

  The digital camera 1 includes an interchangeable lens unit 2 and a camera body 3.

  The interchangeable lens unit 2 is configured to be detachably attached to the camera body 3 via a mount portion 4, and includes a lens 5a, a zooming lens 5b, a focusing lens 5c, and a shake correction lens 5d constituting the optical system 5. In addition, a diaphragm 6 is provided. The interchangeable lens unit 2 includes a zoom lens 5b, a focusing lens 5c, and a shake correction lens 5d, and a lens / diaphragm drive motor (not shown) that drives the diaphragm 6, and a zoom lens 5b. An encoder (not shown) for recognizing the position of the focusing lens 5c is provided. The lens / diaphragm drive motor is driven and controlled by the lens drive control circuit 7. Lens information such as the focal length and open F number of the interchangeable lens unit 2 is stored in a storage circuit (not shown).

  A release button (not shown) that is operated at the time of shooting is provided outside the camera body 3, and a CPU (Central Processing Unit) 11 that controls the operation of each circuit is provided inside the camera body 3. . The CPU 11 is connected to a nonvolatile memory (not shown) that stores a control program and the like that is referred to when the CPU 11 performs various controls. The subject light that has entered the camera body 3 through the optical system 5 is incident on an image sensor 12 such as a CCD (Charge Coupled Device) to form a subject image. A part of the subject light is detected by a photometric unit (not shown) configured to include an illuminance sensor, and ambient brightness is measured. The CPU 11 outputs a control signal to the lens drive control circuit 7 through the electrical contact 8 based on the amount of subject light detected by the photometry unit, and drives the lens / diaphragm drive motor by the lens drive control circuit 7. Adjust the opening amount of 6. Thereby, the light quantity of the subject image projected on the image sensor 12 is adjusted. The liquid crystal display drive circuit 13 drives a liquid crystal display element of an electronic view finder (EVF) 14 and causes the electronic view finder 14 to display a subject image formed on the image sensor 12. The photographer can observe the subject image displayed on the electronic viewfinder 14 through the eyepiece 15.

  When the photographer of the digital camera 1 presses the release button while viewing the subject image via the electronic viewfinder 14, the CPU 11 detects this and opens a shutter curtain (not shown). The subject light that has passed through the optical system 5 and the aperture 6 forms a subject image on the image sensor 12 by opening the shutter curtain, and the CPU 11 forms the subject image formed on the image sensor 12 by an image sensor drive circuit (not shown). Take an image. As shown in FIG. 2B, the image pickup device 12 has image pickup pixels arranged in a two-dimensional image pickup device space 12a, and the focus detection pixels are arranged horizontally in a row in the central focus detection area 12b. Has been. The imaging element 12 is an imaging unit that accumulates electric charges by subjecting subject light incident through the optical system 5 to photoelectric conversion by a plurality of imaging pixels and a plurality of focus detection pixels around which the imaging pixels are arranged. Configure. The image sensor driving circuit constitutes a reading means for reading out charges accumulated in the imaging pixels and the focus detection pixels as an imaging signal and a focus detection signal at a predetermined cycle, for example, 60 frames / second. In addition, the electronic viewfinder 14 constitutes a display unit that performs display on the electronic viewfinder 14 based on the read imaging signal each time the imaging signal is read by the reading unit. In addition, a buffer memory (not shown) constitutes storage means for storing the focus detection signals read by the reading means in time series.

  In this embodiment, the subject image is focused by the phase difference detection method. In this phase difference detection method, two images having different phase differences are detected by focus detection pixels arranged in the focus detection area 12b, and the relative positional relationship (image shift amount) between the two images is calculated. A defocus amount including information on the focus adjustment state of the subject light is calculated. The CPU 11 calculates a lens driving amount based on the calculated defocus amount and lens information sent from the storage circuit of the interchangeable lens unit 2 and stored in a lens information circuit (not shown). Based on the calculated lens driving amount, the lens driving control circuit 7 drives the lens / aperture driving motor to drive the focusing lens 5c to the in-focus position, and the object image projected onto the imaging device 12 To focus on.

  The subject image captured by the image sensor driving circuit is output by the CPU 11 to an image processing circuit (not shown) as an imaging signal. The image processing circuit performs predetermined analog signal processing on the input image pickup signal, converts it to a digital signal, and performs predetermined image processing such as white balance processing and gamma correction. The image data processed by the image processing circuit is temporarily recorded in a buffer memory (not shown) under the control of the CPU 11 and compressed by an image compression unit (not shown). The image data compressed by the image compression unit is stored in a memory card 16 composed of a nonvolatile memory under the control of a card interface (not shown).

  An angular velocity sensor 17 is connected to the CPU 11. The angular velocity sensor 17 constitutes a shake detection unit that detects a shake of the digital camera 1 caused by a hand shake or the like. Further, the CPU 11 constitutes a shake correction unit that moves the correction lens 5 d in a direction to cancel the shake of the digital camera 1 detected by the angular velocity sensor 17. Note that the shake of the digital camera 1 may be detected using an acceleration sensor or the like instead of the angular velocity sensor 17.

  The CPU 11 constitutes a change detection unit that detects whether or not a change has occurred in the relative position between the focus detection pixel of the image sensor 12 and the subject light incident on the image sensor 12. In the present embodiment, the number of times of adding the focus detection signal is determined based on a change in the relative position between the focus detection pixel detected by the change detection unit and the incident subject light, and the focus detection is performed by adding the determined number of times. The focus detection of the subject image is performed by the above-described phase difference detection method based on the signal for use. That is, if the change detection unit does not detect the change, the CPU 11 determines the appropriate number of additions for adding the focus detection signal based on the level of the focus detection signal read by the reading unit, and changes the change. When the above-described change is detected by the detection means, an addition number determination means for limiting the number of additions for adding the focus detection signal to a number smaller than the appropriate addition number is configured. The CPU 11 constitutes addition means for adding the focus detection signals stored in time series in the buffer memory by the number of times determined by the addition number determination means retroactively from the latest focus detection signal, and adding by the addition means A focus detection unit that detects the focus adjustment state of the optical system 5 based on the focus detection signal thus formed is configured.

  In the present embodiment, the CPU 11 detects that a change has occurred in the relative position between the focus detection pixel and the incident subject light when the correction lens 5d is moved by the shake correction unit. The CPU 11 constitutes tracking means for tracking a moving object from the subject image, and the amount of movement of the object tracked by the tracking means within a predetermined time, for example, within a predetermined number of frames, is greater than or equal to a predetermined threshold value. In addition, it is detected that the relative position between the focus detection pixel and the incident subject light has changed. The CPU 11 also constitutes a face detection means for detecting the face of a person from the subject image, and when the position of the face detected by the face detection means changes more than a predetermined threshold within a predetermined time, for example, within a predetermined number of frames. Then, it is detected that the relative position between the focus detection pixel and the incident subject light has changed. The CPU 11 also constitutes an inter-frame difference detecting unit that detects a difference between pixel values of each frame image captured by the imaging pixels at a predetermined time interval, for example, an inter-frame interval, and the difference detected by the inter-frame difference detecting unit. Is detected to be a change in the relative position between the focus detection pixel and the incident subject light. The CPU 11 also detects that a change has occurred in the relative position between the focus detection pixel and the incident subject light even when the angular velocity sensor 17 detects a shake of the imaging device that is equal to or greater than a predetermined threshold.

  FIG. 2 is a flowchart showing an outline of processing for detecting the focus of a subject image and displaying the subject image on the electronic viewfinder 14 in the digital camera 1.

  When the power of the digital camera 1 is turned on, the CPU 11 in step (hereinafter referred to as “S”) 1 charges generated by photoelectrically converting subject light stored in the imaging pixels and focus detection pixels of the imaging device 12. Is started at a predetermined period, for example, 60 frames / second (periodic operations from S2 to S12).

  Next, in S <b> 2, the CPU 11 completes the operation of reading out the charges stored in the imaging pixels and the focus detection pixels as imaging signals and focus detection signals. The read focus detection signals are stored in the buffer memory in time series. The liquid crystal display driving circuit 13 is driven based on the imaging signal read from the imaging pixels, and an image for one frame is displayed on the electronic viewfinder 14. Next, in S <b> 3, the CPU 11 determines whether or not the luminance of the focus detection signal read from the focus detection pixel is equal to or higher than a predetermined threshold at which the optical system 5 can be focused by the phase difference detection method.

  When the brightness of the focus detection signal is low and less than the predetermined threshold value and the determination in S3 is “NO”, the CPU 11 performs the addition number determination process described later with reference to FIG. Next, the CPU 11 determines whether or not the number of additions of the focus detection signal read from the focus detection pixel and stored in the buffer memory is within the range of the addition number determined by the addition number determination process. When the number of additions of the focus detection signal exceeds the number of additions determined by the addition number determination process and the determination in S5 is “NO”, the CPU 11 determines the number of additions determined by the addition number determination process in S6. The readout result of the oldest focus detection pixel exceeding the range is discarded. For example, in the process of the periodic operation up to the previous time, the number of additions determined by the addition number determination process, for example, 10 has already been added, and the focus detection signal newly read in the process of S2 is added. In the case of a total of 11 additions, the eleventh, that is, the oldest focus detection signal that exceeds the tenth count from the latest order among the focus detection signals stored in time series in the buffer memory. Are discarded and the tenth focus detection signals counted from the latest order are added. When the number of additions is changed by the addition number determination process in S4, all the focus detection signals stored in the buffer memory in time series may be discarded and added using new data. Alternatively, the focus detection signals stored so far in time in the buffer memory may be continuously used and added.

  If the addition count does not exceed the addition count range determined by the addition count determination process and the determination of S5 is “YES”, or after the process of S6, the CPU 11 newly performs the process of S2 this time in S7. Is added to the read focus detection signal. The added focus detection signal is stored in the buffer memory. On the other hand, when the brightness of the read focus detection signal is sufficiently bright above a predetermined threshold and the determination in S3 is “YES”, it is necessary to add a plurality of focus detection signals as in the process of S7 described above. Instead, one focus detection signal read in the current periodic operation is stored in the buffer memory.

  When the luminance of the read focus detection signal is equal to or higher than a predetermined threshold and the determination in S3 is “YES”, or after the processing of S7, the CPU 11 determines whether or not the release button is fully pressed in S8. Alternatively, it is determined whether or not the power button has been pressed. If the release button is fully pressed or the power button is pressed and the determination in S8 is “YES”, the CPU 11 ends the periodic operation of the image sensor 12 and displays an image on the electronic viewfinder 14 in S9. End the operation. Next, in S10, the CPU 11 performs a photographing operation for recording an image obtained by the image sensor 12 on the memory card 16, or turns off the power and ends the process. On the other hand, when the release button is not fully pressed and the power button is not pressed and the determination in S8 is “NO”, the CPU 11 determines in S11 the focus detection signal added in the process of S7 or S3. Based on one focus detection signal with sufficiently high luminance when the determination is “YES”, an operation for calculating the image shift amount is performed, and the focus detection of the subject image is performed by calculating the defocus amount. . Next, in S12, the CPU 11 starts again the accumulation process for accumulating the charges of the next frame in the imaging pixels and the focus detection pixels. By completing the process of S12, the periodic operation for one frame of S2 to S12 is completed.

  FIG. 3 is a detailed flowchart of the addition number determination process for determining the number of additions of the focus detection signal in S4 in the flowchart of FIG.

  In S <b> 41, the CPU 11 determines whether or not the digital camera 1 is moving based on the detection result of the angular velocity sensor 17. For example, when the digital camera 1 is fixed on a tripod and the digital camera 1 is not moving and the determination in S41 is “NO”, the CPU 11 determines in S42 the face detected by the face detection means. It is determined whether or not the position has changed more than a predetermined threshold between predetermined frames. For example, in the frame cycle operation of S2 to S12 shown in FIG. 2, whether the face position has changed by a predetermined threshold or more by comparing the face position detected last time with the face position detected this time. Is determined. If the subject person is stationary, the position of the face detected by the face detection means has not changed more than a predetermined threshold value, and the determination in S42 is “NO”, the CPU 11 detects the tracking means in S43 by the tracking means. It is determined whether or not the tracking target that has been moved has moved by a predetermined threshold value or more between predetermined frames. For example, in the frame cycle operation of S2 to S12 shown in FIG. 2, by comparing the position of the tracking target detected last time with the position of the tracking target detected this time, whether or not the tracking target has moved by a predetermined threshold or more. Is determined. In the process of S42, it is determined whether or not the position of the face detected by the face detection means has changed by a predetermined threshold value or more. In this process of S43, the face of the subject image is detected using the tracking means. It can also be configured to determine whether or not it has moved beyond a threshold value.

  If the tracking target does not move and the determination in S43 is “NO”, the CPU 11 determines in S44 whether or not the interframe difference detected by the interframe difference detection means is greater than or equal to a predetermined threshold. That is, in the periodic operation of S2 to S12 shown in FIG. 2, an inter-frame difference between an image displayed on the electronic viewfinder 14 detected last time and an image displayed on the electronic viewfinder 14 detected this time is taken. It is determined whether or not the difference between the two is greater than or equal to a predetermined threshold. If the interframe difference is less than the predetermined threshold and the determination in S44 is “NO”, the CPU 11 determines whether or not the optical camera shake correction is being controlled in S45, that is, whether or not the correction lens 5d of the optical system 5 is being driven. Is determined. If the optical camera shake correction is not under control and the determination in S45 is “NO”, the CPU 11 determines in S46 the focus detection signal based on the signal level of the focus detection signal and the aperture amount (aperture value) of the diaphragm 6. Is determined, for example, 10 times. Note that at the beginning of the periodic operation, the initial value of the appropriate number of additions is determined due to system limitations (memory space limitations, or module limitations if there is a dedicated module for addition).

  On the other hand, for example, when the digital camera 1 is hand-held and the determination in S41 is “YES”, or the detected face position has changed by a predetermined threshold or more, and the determination in S42 is “YES”. Or when the tracking target has moved more than a predetermined threshold and the determination in S43 is “YES”, or the difference between frames is greater than or equal to a predetermined threshold and the determination in S44 is “YES”, or If the optical camera shake correction is under control and the determination in S45 is “YES”, the CPU 11 determines in S47 that the number of times of addition of the focus detection signal, which is the readout result of the focus detection pixel, is determined in S46. It is limited to a specific number of times less than the number of times, for example, twice. Note that the number of additions determined in S47 may be different depending on the number of addition number restriction requirements that are “YES” in each determination of S41 to S45. Moreover, the predetermined threshold value used in each process of S41 to S45 is not limited to one and may be plural, and the number of additions may be determined according to the plural thresholds.

  According to the digital camera 1 according to the present embodiment as described above, when the subject or the digital camera 1 moves and the relative position between the subject and the focus detection pixel changes, the addition of the focus detection signal is performed. Since the number of times is reduced by the processing of S47 in FIG. 3, the amount of addition of the focus detection signal that is output when incident light from different subject portions enters the focus detection pixel is reduced, and focus detection is appropriately performed on the subject. Can be done. Further, when there is no change in the relative position between the subject and the focus detection pixel, the focus detection signal read by the reading means is added by the appropriate number of additions in the process of S46, and the focus detection is performed with high accuracy. At the same time, the image pickup pixel signal is read out at a constant predetermined cycle and displayed on the electronic viewfinder 14 in the process of FIG. As a result, the digital camera 1 capable of appropriately performing focus detection while maintaining the quality of the image displayed on the electronic viewfinder 14 is provided.

  According to the digital camera 1 according to the present embodiment, when the shake of the digital camera 1 equal to or greater than a predetermined threshold is detected by the angular velocity sensor 17 in FIG. 3 and S41, the relative relationship between the focus detection pixels and the incident subject light is relative. It is detected by the change detecting means that the position has changed, and the number of addition of the focus detection signal is decreased in S47. For this reason, even when the digital camera 1 moves, focus detection can be appropriately performed on the subject.

  According to the digital camera 1 according to the present embodiment, when the position of the face detected by the face detection unit changes by a predetermined threshold value or more within a predetermined time in S42, the relative relationship between the focus detection pixel and the incident subject light is relative. It is detected by the change detecting means that the position has changed, and the number of addition of the focus detection signal is decreased in S47. For this reason, even when the position of the face of the person detected by the face detection unit moves without moving the digital camera 1 during shooting, focus detection can be appropriately performed on the subject.

  According to the digital camera 1 according to the present embodiment, when the amount of movement of the object tracked by the tracking unit within a predetermined time is greater than or equal to a predetermined threshold in S43, the focus detection pixel and the incident subject light are detected. It is detected by the change detecting means that a change has occurred in the relative position, and in S47, the number of additions of the focus detection signal is reduced. For this reason, even when the digital camera 1 does not move and the target tracked by the tracking unit moves during shooting, focus detection can be appropriately performed on the subject.

  According to the digital camera 1 according to the present embodiment, when the difference detected by the interframe difference detection unit is equal to or greater than a predetermined threshold in S44, the relative position between the focus detection pixel and the incident subject light changes. In step S47, the number of additions of the focus detection signal is reduced. Therefore, even when the digital camera 1 does not move and a part of the subject moves during shooting, focus detection can be appropriately performed on the subject.

  According to the digital camera 1 of the present embodiment, when the optical system 5 is moved by the shake correction unit in S45, it is detected that the relative position between the focus detection pixel and the incident subject light has changed, and S47. Thus, the number of additions of the focus detection signal is reduced. For this reason, even when shake correction is performed, focus detection can be appropriately performed on the subject.

  In S47, when the number of additions is limited by the addition number determination means, an amplification means for amplifying the level of the focus detection signal read by the reading means may be provided. According to this configuration, even when the number of additions is limited by the addition number determination unit, the level of the focus detection signal read by the reading unit is amplified by the amplification unit, so that the electronic viewfinder 14 Although the quality of the displayed image is inferior, the detection accuracy of focus detection can be maintained even if the level of the added focus detection signal is small.

  In this embodiment, the CPU 11 that constitutes the shake correction unit moves the optical system 5 in a direction that cancels the shake of the digital camera 1 detected by the angular velocity sensor 17, but the digital that is detected by the angular velocity sensor 17. A configuration in which the image sensor 12 is moved in a direction to cancel the shake of the camera 1 may be used. In this case, the CPU 11 constituting the change detection unit detects that a change has occurred in the relative position between the focus detection pixel and the incident subject light when the image sensor 12 is moved by the shake correction unit.

  In the above embodiment, the case where the photographing apparatus of the present invention is applied to a digital camera has been described. However, the present invention is also applicable to other photographing apparatuses that perform focus detection, such as a video camera or a camera built in a mobile phone. It is possible. Even when the present invention is applied to such a photographing apparatus, the same effects as the above-described embodiment can be obtained.

DESCRIPTION OF SYMBOLS 1 ... Digital camera 5 ... Optical system 5a ... Lens 5b ... Zooming lens 5c ... Focusing lens 5d ... Correction lens 11 ... CPU
DESCRIPTION OF SYMBOLS 12 ... Image sensor 12a ... Image sensor space 12b ... Focus detection area 14 ... Electronic viewfinder 17 ... Angular velocity sensor

Claims (7)

Imaging means for photoelectrically converting subject light incident via an optical system by a plurality of imaging pixels and a plurality of focus detection pixels around which the imaging pixels are arranged, and accumulating charges;
Reading means for reading out charges accumulated in the imaging pixels and the focus detection pixels at a predetermined cycle as imaging signals and focus detection signals;
Display means for performing display based on the read imaging signal each time the imaging signal is read by the reading means;
Storage means for storing the focus detection signals read by the reading means in time series;
Change detecting means for detecting whether or not a change has occurred in the relative position between the focus detection pixel and the incident subject light;
When the change is not detected by the change detecting means, an appropriate number of additions for adding the focus detection signal is determined based on the level of the focus detection signal read by the reading means, and the change detection is performed. When the change is detected by the means, an addition number determination means for limiting the number of additions for adding the focus detection signal to a number smaller than the appropriate addition number;
Adding means for adding the number of times determined by the number-of-addition determining means retroactively from the latest focus detection signal to the focus detection signal stored in time series in the storage means;
An imaging apparatus comprising: focus detection means for detecting a focus adjustment state of the optical system based on the focus detection signals added by the addition means. The imaging device according to claim 1,
Provided with shake detection means for detecting shake of the imaging device;
The change detection unit detects that the change has occurred in a relative position between the focus detection pixel and the incident subject light when the shake detection unit detects a shake of the imaging apparatus equal to or greater than a predetermined threshold. An imaging device that is characterized. In the imaging device according to claim 1 or 2,
With tracking means for tracking moving objects from within the subject image,
The change detection means causes the change to occur in a relative position between the focus detection pixel and incident subject light when an amount of movement of the object tracked by the tracking means within a predetermined time is a predetermined threshold or more. An imaging device characterized by detecting the occurrence of an error. In the imaging device according to any one of claims 1 to 3,
Equipped with a face detection means for detecting the face of a person from a subject image,
The change detection unit is configured to change the relative position between the focus detection pixel and incident subject light when the position of the face detected by the face detection unit changes by a predetermined threshold value or more within a predetermined time. An imaging apparatus characterized by detecting. In the imaging device according to any one of claims 1 to 4,
An inter-frame difference detection means for detecting a difference between pixel values of each frame image captured at a predetermined time interval by the imaging pixel;
The change detection unit detects that the change has occurred in a relative position between the focus detection pixel and incident subject light when the difference detected by the inter-frame difference detection unit is equal to or greater than a predetermined threshold. An imaging device. In the imaging device according to any one of claims 1 to 5,
Shake detection means for detecting shake of the imaging device;
A shake correction unit that moves the optical system or the imaging unit in a direction that cancels a shake of the imaging device detected by the shake detection unit;
The change detection unit detects that the change has occurred in a relative position between the focus detection pixel and incident subject light when the optical system or the image sensor is moved by the shake correction unit. An imaging device. The imaging apparatus according to any one of claims 1 to 6,
An imaging apparatus comprising: an amplification unit that amplifies the level of the focus detection signal read by the reading unit when the addition number determining unit limits the number of additions.

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