JP2011002473A - Imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging device excellent in focus detection accuracy even when a subject is a moving body in a distance.SOLUTION: A video camera includes: a focus detecting part 42 of a contrast system; a focus detecting part 60 of a phase difference system; a subject distance prediction part 53 which predicts the subject distance from past history of the phase difference focus-detecting part 60; and a CPU 50 that selects the output of a contrast focus-detecting part for focusing when the subject distance exceeds a distance threshold, and selects the output of the subject distance prediction part for focusing when the subject distance does not exceed the distance threshold.

Description

  The present invention relates to an imaging apparatus.

  In Patent Document 1, the focus lens is moved to the vicinity of the in-focus position of the subject by phase difference AF (auto focus) (phase difference AF), and then focused to the focus position with high accuracy by contrast AF (TVAF). A hybrid AF that moves the lens is disclosed.

  Patent Document 2 discloses an imaging apparatus that performs phase difference AF if the subject is a moving object or the focal length is less than a threshold value, and performs hybrid AF if not.

  Furthermore, based on the result of the past phase difference AF, it is determined whether or not the subject is a moving object. If the subject is a moving object, the subject tracking AF for operating the focus lens by predicting the subject distance at the next shooting timing is also performed. Proposed.

JP 2002-258147 A JP 2006-053545 A

  However, the accuracy of the phase difference AF decreases as the distance from the imaging device to the subject (subject distance) increases because of distance conflict, and in this case, the motion of the subject cannot be accurately predicted, and the accuracy of the moving object tracking AF Also decreases.

  An object of the present invention is to provide an imaging apparatus that is excellent in focus detection accuracy even if a subject is a moving object at a long distance.

  An imaging apparatus according to an aspect of the present invention includes a first detection unit that detects a peak position of contrast of a subject image via a first optical system, and a second optical system that is different from the first optical system. A second detection unit that detects information corresponding to the subject distance from the subject image; a prediction unit that predicts a subject distance after a change in distance from the subject based on a past history of the second detection unit; When the subject distance is the first distance, focus adjustment is performed by following the movement of the subject using the output of the first detection unit, and the predicted subject distance is shorter than the first distance. And a control unit that adjusts the focus by following the movement of the subject using the output of the prediction unit when the distance is the second distance.

  The present invention can provide an imaging apparatus with excellent focus detection accuracy even when a subject is a moving object at a long distance.

It is a block diagram of the video camera (imaging device) of the present embodiment. 3 is a flowchart for explaining an AF operation executed by a CPU of the video camera shown in FIG. 1. It is a graph which shows a moving body tracking operation | movement when a to-be-photographed object moves away from a video camera. It is a graph which shows a moving body tracking operation | movement when a to-be-photographed object approaches a video camera. It is a graph which shows the characteristic of a rear focus zoom optical system. It is a graph which shows the change of the distance threshold when F number changes with the state of the aperture_diaphragm | restriction shown in FIG.

  FIG. 1 is a block diagram showing the configuration of the video camera (imaging device) of this embodiment. The video camera includes a photographing lens, an aperture 14, an image sensor 15, an image processing circuit 16, various drive sources (21 to 23), various encoders (31 to 33), various gates (40 and 41), a contrast focus detection unit 42, A CPU 50, a phase difference focus detection unit 60, and a speed detection unit 62 are included.

  The photographing lens (first optical system) includes four groups in the present embodiment, but is not limited to this. The photographing lens includes a fixed front lens (group) 10, a variator lens (group) 11, and a focusing lens (group) for focusing (hereinafter simply referred to as “focus lens”) 13.

  The variator lens 11 is used to change the focal length, and is configured to be movable in the optical axis direction indicated by a one-dot chain line. The absolute position of the variator lens 11 in the optical axis direction is detected by the variator encoder 31, and is moved in the optical axis direction by the variator driving source 21. The variator drive source 21 is composed of, for example, a step motor or a power transmission member, and is connected to the CPU 50 and controlled by the CPU 50. The variator encoder 31 is connected to the CPU 50, and the output of the variator encoder 31 is supplied to the CPU 50.

  The focus lens 13 is used for focus adjustment and is configured to be movable in the optical axis direction. The absolute position of the focus lens 13 in the optical axis direction is detected by the focus encoder 33 and is moved in the optical axis direction by the focus drive source 23. The focus drive source 23 is composed of, for example, a step motor or a power transmission member, and is connected to the CPU 50 and controlled by the CPU 50. The focus encoder 33 is connected to the CPU 50, and the output of the focus encoder 33 is supplied to the CPU 50.

  The aperture state of the aperture 14 is detected by the aperture encoder 32, and the aperture is adjusted by the aperture drive source 22. The aperture drive source 22 is composed of, for example, a step motor or a power transmission member, and is connected to the CPU 50 and controlled by the CPU 50. The aperture encoder 32 is connected to the CPU 50, and the output of the aperture encoder 32 is supplied to the CPU 50.

  The image sensor 15 is composed of a CCD, a CMOS sensor, and the like, and generates image data by photoelectrically converting light from a subject.

  The image processing circuit 16 is a signal processing circuit that performs amplification and gamma correction on the output of the image sensor 15. The video signal subjected to signal processing is output to a recording system (shown as “REC” in FIG. 1) and a display system (not shown), and is also output to the AE gate 40 and the AF gate 41.

  The AE (automatic exposure) gate is connected to the image processing circuit 16 and receives a video signal subjected to signal processing from the image processing circuit 16 to determine an optimum signal extraction range for exposure determination.

  The AF gate 41 is connected to the image processing circuit 16, receives the video signal subjected to signal processing from the image processing circuit 16, and determines an optimum signal extraction range for focusing.

  The contrast focus detection unit (first detection unit) 42 extracts and integrates high-frequency components included in the signal of the region extracted by the AF gate circuit 41 in the luminance signal of the video, and corresponds to the contrast. It is a signal processing circuit that outputs an AF evaluation value (focus signal) to the CPU 50. The contrast focus detection unit 42 is used to perform TVAF, and detects the focus state by detecting the peak position of the contrast of the subject image via the photographing lens.

  A CPU (control unit, processor) 50 performs various calculations related to AF and controls each unit of the video camera. The CPU 50 includes a focal length detection unit 51, a moving object detection unit 52, a subject distance prediction unit 53, an F number calculation unit 54, a subject distance estimation unit 55, a subject distance comparison unit 56, and an AF switching unit 57. One or more components of the CPU 50 may be formed outside the CPU 50 as a unit (circuit, processor) separate from the CPU 50. The CPU 50 is connected to the memory 58.

  The focal length detection unit 51 obtains the output of the variator encoder 31 and detects the focal length.

Motion detector 52, the object speed v _n obtained from the speed detecting unit 62 detects whether or larger than the threshold value Vth stored in the memory 58. CPU50 is larger than the object speed v _n is the threshold value Vth, it is possible to subject it is determined that the moving object is determined not to be a moving object if less than the threshold value Vth. When the CPU 50 determines that the subject is a moving object from the detection result of the moving object detector 52, the CPU 50 prepares the moving object tracking AF. Since the moving body tracking AF performs AF based on the detection result of the phase difference focus detection unit 60, the accuracy decreases when the subject is at a long distance.

  The subject distance prediction unit (prediction unit) 53 predicts the subject distance after the distance change with the subject from the past history of the phase difference focus detection unit.

  The F number calculation unit 54 calculates the F number value based on the output of the aperture encoder 32.

  The subject distance estimation unit 55 estimates the subject distance based on the position of the focus lens 13 measured by the focus encoder 33 when TVAF is being performed.

  The subject distance comparison unit 56 includes the subject distance estimated by the subject distance estimation unit 55 (or an amount corresponding thereto) or the subject distance input from the phase difference focus detection unit 60 and the distance threshold value (or stored in the memory 58). And the corresponding amount).

  The AF switching unit 57 switches (or is used preferentially) the focus detection unit for focus adjustment between the contrast focus detection unit 42 and the phase difference focus detection unit 60 when the subject is not a moving object. In addition, when the subject is a moving object, the AF switching unit 57 sets the focus detection unit for focus adjustment between the contrast focus detection unit 42 and the subject distance prediction unit 53 based on the comparison result of the subject distance comparison unit 56. Switch between (or use preferentially).

  The memory 58 stores various threshold values and data necessary for the AF operation, and an AF method program executable by the processor shown in FIG.

  The phase difference focus detection unit (second detection unit) 60 detects the focus state of the photographing lens by a phase difference method (a method different from the contrast method). Specifically, the phase difference focus detection unit 60 collects light from the subject, divides it into two light beams by a separator lens (which is a second optical system different from the photographing lens), and makes the two light beams different. An image is formed on two photoelectric conversion element arrays. When the subject distance changes, the distance between the subject images generated from the two light fluxes fluctuates. The photoelectric conversion element array accumulates electric charge for a time determined by the subject luminance, and after the electric charge is accumulated, the output of the photoelectric conversion element array is quantized by the AD converter, and the correlation is detected by the correlation calculation circuit. . By this correlation calculation, a shift amount in pixel units between the two signals is calculated. The phase difference focus detection unit 60 measures the subject distance in the optical axis direction using the principle of triangulation from the deviation amount, the distance between the two photoelectric element arrays, and the focal length of the distance measuring optical system, and outputs this to the CPU 50. To do.

The speed detection unit 62 is connected to the phase difference focus detection unit 60 and the CPU 50, calculates the subject distance change amount per unit time based on the output (subject distance) of the phase difference focus detection unit 60, and the optical axis direction of the subject The movement speed (subject speed) is transmitted to the CPU 50. Speed detecting section 62, the acquisition time _{t 0, t 1, t 2} ... t n of the output of the phase difference focus detection unit 60, (the value of the object _distance) measured distance value _{d 0, d 1, d 2} ... d n calculating an object velocity _{v n} as follows from the supplies it to CPU 50 (moving object detection section 52).

  Hereinafter, the AF operation of the video camera will be described with reference to FIG. Here, FIG. 2 is a flowchart for explaining the AF operation, and “S” is an abbreviation of a step.

  First, the CPU 50 determines whether or not the subject is a moving object based on the detection result of the moving object detection unit 52 (S102). If the CPU 50 determines that the subject is not a moving object (No in S102), it performs normal hybrid AF (S104). In the hybrid AF, the focus lens 13 is moved to the vicinity of the in-focus position of the subject by the phase difference AF (S122), and then the focus lens 13 is moved to the in-focus position with high accuracy by the hill-climbing TVAF (S122).

  On the other hand, when determining that the subject is a moving object (Yes in S102), the CPU 50 determines whether or not the focal length has changed based on the detection result of the focal length detection unit 51 (S106).

  If the CPU 50 determines that the focal length has not changed (No in S106), the CPU 50 determines whether the F number detected by the F number calculation unit 54 has changed (S108).

  When the CPU 50 determines that the F number has not changed (No in S108), the subject distance comparison unit 56 determines whether or not the subject distance is greater than the distance threshold (S110).

Subject distance comparing section 56 determines that subject distance is less distance threshold (second distance) (No in S110), CPU 50 has the moving speed _{v n} of the object speed detector 62 detects within the memory 58 It is determined whether or not it is larger than the stored speed threshold (S112). This speed threshold is set to be larger than the threshold Vth used for moving object determination and smaller than the speed at which TVAF can follow.

CPU50, when the moving speed _{v n} of the object is determined to be greater than the speed threshold stored in the memory 58 (second speed), the moving object tracking AF using the phase difference focus detection unit 60 (S114). In the moving body tracking AF, the subject distance prediction unit 53 calculates an approximate expression from the past distance measurement result using an approximation method such as least square approximation and obtains a predicted value of the subject distance. The predicted value can be obtained from time information when the image is acquired next and an approximate expression.

  When applied to an electronic still camera, the time lag from when the user releases the shutter to when the image is actually acquired is measured and stored in advance, and the image acquisition time is calculated using this time lag.

  When the predicted value of the subject distance is calculated, the CPU 50 calculates the position of the focus lens 13 (focus lens position) corresponding to the predicted value and controls the focus drive source 23 so that the focus lens 13 moves in the vicinity thereof ( S112). Thereby, the focused state can be maintained when the subject is a moving object.

On the other hand, (No of S112) the moving speed _{v n} of the object is determined to be less than the speed threshold stored in the memory 58 (first speed greater than the threshold Vth), AF switching unit 57 the contrast focus detector 42 The CPU 50 performs TVAF (S116). Since the subject speed can be handled by TVAF, the focus adjustment accuracy is improved.

  Similarly, when the subject distance comparison unit 56 determines that the subject distance is greater than the distance threshold (first distance) (Yes in S110), the AF switching unit 57 selects the output of the contrast focus detection unit 42, and the CPU 50 Performs TVAF (S116). The effect of following a moving object can be obtained by TVAF. This will be described in more detail below.

  FIG. 3 is a graph showing the moving object following operation when the subject moves away from the video camera. The horizontal axis indicates the time measured by a timer (not shown), and the vertical axis indicates the subject distance measured by the phase difference focus detection unit 60. Yes.

First, the subject distance prediction unit 53 uses an approximation method such as least square approximation to approximate based on points T1 to L6 corresponding to the time T1 to T6 as the past distance measurement results and the subject distances D1 to D6 at that time. A formula (straight line L) is calculated to obtain a subject distance predicted value _DE . The predicted value D _E can be obtained from the point L _E corresponding to the time information T _E at which the next image is acquired in the approximate expression.

Next, the subject distance comparison unit 56 determines whether or not the predicted value D _E is larger than the distance threshold value D _th stored in the memory 58 (S110). When the subject distance comparison unit 56 determines that the predicted value D _E is greater than the distance threshold value D _th (Yes in S110), the CPU 50 moves the focus lens 13 to the focus lens position corresponding to the predicted value D _E. The AF switching unit 57 switches the AF method to TVAF (S118).

Note that the subject distance comparison unit 56 may switch the AF method when determining that the output of the phase difference focus detection unit 60 has _exceeded the distance threshold _Dth stored in the memory 58. For example, in FIG. 3, L6 since the subject distance D6 the corresponding Datosuruto latest measurement result greater than the distance threshold _{D th,} AF switching section 57 is switched to TVAF the AF mode from the moving body tracking AF. Then, CPU 50 performs a focusing operation by TVAF moves the focus lens 13 near distance threshold _{D th.} Thus, in FIG. 3, the object distance is D5~D6 is whether to TVAF or perform moving object tracking AF in that section to cross the distance threshold D _th is selective.

The CPU 50 determines that the subject distance is equal to or less than the distance threshold value Dth in the subject distances D1 to _D5 (No in S110). For this reason, when the CPU 50 determines that the subject speed (the slope of the straight line L) is larger than the speed threshold (Yes in S112), the CPU 50 performs the moving body tracking AF (S114) and determines that the subject speed is equal to or lower than the speed threshold. (No in S112), TVAF is performed (S116).

Note that the CPU 50 may always perform the moving body tracking AF with an emphasis on the focusing speed when the subject distance is equal to or less than the distance threshold value _{Dth in} FIG. Since the subject distance is equal to or smaller than the distance threshold _Dth , the moving object tracking AF can maintain a certain degree of focus adjustment accuracy.

The operation of the CPU 50 when the subject approaches from a distance when S116 is performed will be described. Although the subject distance is greater than the distance threshold _{D th} TVAF is used, the TVAF, can not directly measure the subject distance. The AF method is switched as follows.

  In TVAF, the peak of the AF evaluation value is searched. When the focus lens 13 is disposed at the peak of the AF evaluation value, the subject distance estimation unit 55 estimates the subject distance from the focus lens position. Further, the F number calculation unit 54 calculates the value of the F number from the output value of the aperture encoder 32.

The CPU 50 determines the focus that generates the diameter of the permissible circle of confusion from the F number calculated by the F number calculation unit 54, the subject distance estimated by the subject distance estimation unit 55, and the optical system design data stored in the memory 58. calculating a moving distance _{d c} of the lens 13.

On the other hand, the memory 58 stores in advance the focus lens position P _th with respect to the distance threshold value D _th . The subject distance comparison unit 56 (or the CPU 50) uses the current focus lens position P _c obtained as a result of TVAF, the moving distance d _c of the focus lens 13 that generates an allowable circle of confusion, and the position P _th for comparison. To do. Specifically, the object distance comparing section 56 determines _{P c is,} whether it is near than a value obtained by subtracting the _d c / 2 from _{P th} to _{(P c <(P th -d} c / 2)) To do. When the subject distance comparison unit 56 determines that P _c is closer than the value obtained by subtracting d _c / 2 from P _th , the AF switching unit 57 switches the AF method from TVAF to moving object tracking AF.

FIG. 4 shows a curve C showing the change of the AF evaluation value with respect to the focus lens position for a specific subject for explaining the above operation. In FIG. 4, it is assumed that the horizontal axis is the focus lens position, the vertical axis is the AF evaluation value of TVAF, and the threshold value of the AF evaluation value that generates the allowable circle of confusion is Th3. The curve C is almost symmetrical on the near side and the infinity side near the peak. Therefore, when the focus lens position P _th corresponding to the distance threshold value D _th is Th3 on the curve C, the AF evaluation value is in the vicinity of the peak when the focus lens position is (P _th −d _c / 2). I can expect that.

  According to the present embodiment, when the subject distance becomes large, the AF switching unit 57 of the CPU 50 switches the AF method from the moving body tracking AF to the TVAF, and the accuracy of the moving body tracking AF is lowered due to distance competition or the like, resulting in blurring. Can be prevented. In addition, a moving object tracking AF can be quickly performed on an object that moves in a short distance area where the depth of focus is relatively shallow.

  On the other hand, when the CPU 50 determines that the focal length has changed based on the detection result of the focal length detection unit 51 (Yes in S106), based on the detection result of the focal length detection unit 51 used by the subject distance comparison unit 56. The distance threshold to be set is calculated (changed) and set (S118). The case where the focal length of the imaging optical system fluctuates is a case where the user performs a zoom operation.

  The optical system of the present embodiment is a rear focus zoom optical system that compensates for the movement of the focal plane with respect to the movement of the variator lens 11 by the movement of the focus lens 13. The rear focus zoom optical system has a characteristic that the in-focus state cannot be maintained unless the focus lens 13 is moved because the focal plane changes when either the focal length or the subject distance of the optical system changes.

FIG. 5 is a graph showing the characteristics of the rear focus zoom optical system. In FIG. 5, the horizontal axis represents the position of the variator lens 11 (referred to as “variator position” in FIG. 5), and the vertical axis represents the position of the focus lens 13. The solid lines L11 to L11 indicate the relationship between the position of the variator lens 11 and the position of the focus lens 13 for focusing when the subject distance is infinity, 6 m, 3 m, 1 m, 0.3 m, 0.2 m, and 0.1 m. This is indicated by L17. Further, in FIG. 5, the position P _th of the focus lens 13 corresponding to the distance threshold D _th with respect to the movement of the variator lens 11 is indicated by a broken line L10.

In the optical system of the present embodiment, the movement sensitivity of the focal plane with respect to the movement of the focus lens 13 is approximately 1.0, so the broken line L10 is at a position that is approximately equidistant from the solid line L11. In the present embodiment, the distance threshold _Dth is about 0.3 m at the wide end and about 6 m at the tele end. Of course, the setting of the focal plane movement sensitivity to the movement of the focus lens 13 and the distance threshold D _th is not limited.

In operation, when the position of the variator lens 11 fluctuates due to the user's zoom operation, the CPU 50 calculates a distance threshold D _th (f) for the position of the variator lens 11 detected by the variator encoder 31. For the calculation of the distance threshold D _th (f), the relationship between the positions of the plurality of main variator lenses 11 and the distance threshold is stored in the memory 58 in advance and linear interpolation is performed to store the positions of the variator lenses 11 not stored. A method of calculating the relationship with the distance threshold may be applied. Further, the calculation of the distance threshold D _{th (f),} and stored in the memory 58 the relationship between the position and the distance threshold D _th variator lens 11 _(f) as an approximate expression, a distance threshold from the detected position of the variator lens 11 A method of obtaining D _th (f) by calculation or other methods may be applied.

When the distance threshold value D _th (f) is calculated, the flow shown in FIG. 2 proceeds to S110. That is, when the subject distance is equal to or smaller than the distance threshold D _th (f) (No in S110) and the subject speed is larger than the speed threshold (Yes in S112), the moving body tracking AF is performed (S114). When the subject speed is equal to or lower than the speed threshold (No in S112) or exceeds the distance threshold D _th (f) (Yes in S110), TVAF is performed (S116). Thereby, even if the focal length fluctuates, it is possible to reduce the influence of erroneous distance measurement due to distance competition on a long-distance subject. In addition, since the distance threshold is adjusted in accordance with the zoom operation, the influence of erroneous distance measurement is effectively reduced by using TVAF in a wide subject distance range on the wide side where the depth of focus is likely to occur because of perspective conflict. be able to.

  FIG. 6 is a graph showing the change in the distance threshold when the F number changes depending on the state of the diaphragm 14. In FIG. 6, the horizontal axis represents the position of the variator lens 11 (referred to as “variator position” in FIG. 6), and the vertical axis represents the position of the focus lens 13.

A solid line L20 indicates a change of the position P _th (f, F) of the focus lens 13 corresponding to the distance threshold value D _th (f, F) with respect to the position of the variator lens 11 when the diaphragm 14 is opened. The solid lines L21 to L23 indicate the position of the variator lens 11 at the position P _th (f, F) of the focus lens 13 corresponding to the distance threshold value D _th (f, F) when the F numbers are ∞, 8, 16 respectively. Shows changes to As described above, the CPU 50 calculates and sets the distance threshold so that the distance threshold decreases as the F number calculated by the F number calculation unit 54 increases (the output of the contrast focus detection unit 42 is easily selected for focus detection). To do.

In operation, when the variator position fluctuates, the CPU 50 determines the distance threshold value D _th (f, F) with respect to the position of the variator lens 11 detected by the variator encoder 31 and the position P _th (f, F) of the corresponding focus lens 13. calculate.

In calculating the distance threshold D _th (f, F), the relationship between a plurality of main variator positions and D _th (f, F), P _th (f, F) is stored in the memory 58 in advance and linear interpolation is performed. You may obtain | require the relationship between the variator position which went and is not memorize | stored, and _Dth (f), _Pth (f, F). For the calculation of the distance threshold value D _th (f, F), the relationship between the variator position and D _th (f, F), P _th (f, F) is stored in the memory 58 as an approximate expression, and from the detected variator position, You may apply the method of calculating | requiring them by calculation, and another method. When the position P _th (f, F) of the focus lens 13 corresponding to the distance threshold value D _th (f, F) is calculated, the flow shown in FIG. 2 proceeds to S110.
That is, when the subject distance is equal to or less than the distance threshold D _th (f, F) (No in S110) and the subject speed is larger than the speed threshold (Yes in S112), the moving body tracking AF is performed (S114). When the subject speed is equal to or lower than the speed threshold (No in S112) or exceeds the distance threshold D _th (f, F) (Yes in S110), TVAF is performed (S116).

  In this embodiment, when the aperture 14 is narrowed down and the F-number is increased, the distance threshold is reduced, so that the range in which TVAF is used becomes wide when the depth of focus is deep, and the influence of erroneous ranging is reduced. be able to.

  When the CPU 50 determines that the focus lens 13 is driven and focused based on the focus detection result (S124), the CPU 50 performs focus display (S126), and shifts to exposure control using the output of the AE gate 40. If it is determined that the subject is not in focus (S124), the flow returns to S102.

  The imaging device can be applied to imaging a subject.

11 Variator lens 13 Focus lens (group)
14 Aperture 15 Image Sensor 21 Variator Drive Source 22 Aperture Drive Source 23 Focus Drive Source 31 Variator Encoder 32 Aperture Encoder 33 Focus Encoder 42 AF Signal Processing Circuit 50 CPU (Control Unit, Processor)
51 Phase Difference Focus Detection Unit 52 Speed Detection Circuit

Claims (3)

A first detector for detecting a contrast peak position of the subject image via the first optical system;
A second detection unit that detects information corresponding to the subject distance from a subject image via a second optical system different from the first optical system;
A prediction unit that predicts a subject distance after a change in distance from the subject from a past history of the second detection unit;
When the predicted subject distance is the first distance, focus adjustment is performed by following the movement of the subject using the output of the first detection unit, and the predicted subject distance is the first distance. A control unit that adjusts the focus following the movement of the subject using the output of the prediction unit when the second distance is shorter than the distance;
An imaging device comprising: The imaging apparatus further includes an F number calculation unit for calculating an F number of the first optical system,
The imaging apparatus according to claim 1, wherein the control unit is more likely to select an output of the first detection unit for focus adjustment as the F number calculated by the F number calculation unit is larger. The imaging apparatus further includes a speed detection unit for detecting the speed of the subject from the output of the second detection unit,
The control unit moves the subject using the output of the first detection unit when the subject moving speed is the first speed even when the subject distance is the second distance. If the subject distance is the second distance and the moving speed of the subject is a second speed higher than the first speed, the output of the prediction unit is adjusted. The imaging apparatus according to claim 1, wherein the focus adjustment is performed by following the movement of the subject using the camera.