JP2019032370A - Imaging device and control method thereof - Google Patents

Abstract

To provide an imaging device capable of improving distance resolution in a distance zone in which moving image photography is performed by driving a focus lens at a low speed, and accurately extracting a still image focused on a subject.SOLUTION: The imaging device includes: imaging means for photo-electrically converting a subject image formed after passing through a photographic optical system including a focus lens to generate an image signal; setting means (step S202) for setting a movement range of the focus lens when performing moving image photography while causing the focus lens to move on the basis of a range finding result; specification means (step S203) for dividing a photographic viewing angle into a plurality of focus detection regions, and for analyzing a histogram of a distance zone in which a subject exists from a focusing position obtained for each focus detection region, and for specifying the distance zone in which the subject exists with a predetermined frequency or more as a main subject distance zone in a focusing state from an analysis result; and control means (steps S204 to S206) for driving the focus lens in the main subject distance zone at a lower speed than the other distance zone when performing moving image photography.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a focus adjustment technique in an imaging apparatus such as a digital camera or a digital video camera.

  In an imaging device such as a digital camera, when performing autofocus (AF), the position in the optical axis direction of the lens where the high frequency component of the luminance signal obtained from the imaging device such as a CCD (charge coupled device) is maximized is aligned. A method of setting a focal position is used.

  For example, the evaluation value (focus evaluation value) based on the high frequency component of the luminance signal obtained from the image sensor while driving the lens is stored each time, and the lens position corresponding to the maximum value of the stored value is the in-focus position. A scanning method is known. Further, a hill-climbing method (continuous AF) is known in which a lens is driven in a direction in which the focus evaluation value increases, and a position where the focus evaluation value is maximized is set as a focus position.

  Conventionally, continuous AF is performed before a shooting preparation instruction and the focus state is maintained, thereby limiting the moving range of the focus lens in the scanning AF performed after the shooting preparation instruction and shortening the time of the AF operation. Technology has been proposed (Patent Document 1). In this proposal, the focusing operation is made faster by combining the scanning method with the continuous AF.

  However, in Patent Document 1, since the user does not determine the subject on the screen to be focused, there is a problem that the subject to be focused cannot be focused depending on the shooting scene.

  Therefore, a technique has been proposed in which a user designates a plurality of subjects in advance and cuts out a still image focused on the designated subject by shooting a video while moving the focus lens between a plurality of in-focus positions of the designated subject. (Patent Document 2). In this proposal, a still image in focus can be cut out by moving the focus lens at a low speed near the focal length of the designated subject.

Japanese Patent No. 4106485 Japanese Patent Laid-Open No. 2006-59033

  However, in Patent Document 2, when there are three or more subjects designated by the user, there is a problem that the focus accuracy is lowered when extracting a still image focused on another subject not designated. This is because the focus lens moves at a low speed near the focal length of the designated subject, but does not move at a low speed except near the focal length of the designated subject.

  Therefore, the present invention provides an imaging apparatus and a control method therefor that can improve the distance resolution in a distance zone in which a focus lens is driven at a low speed to capture a moving image and can accurately extract a still image focused on a subject. The purpose is to do.

  In order to achieve the above object, an image pickup apparatus according to the present invention includes an image pickup unit that photoelectrically converts a subject image formed through a photographing optical system including a focus lens to generate an image signal, and moves the focus lens. Setting means for setting a moving range of the focus lens when shooting a moving image based on a distance measurement result, and focusing obtained by dividing the shooting angle of view into a plurality of focus detection areas. Analyzing the histogram of the distance zone where the subject is present from the position, and specifying the distance zone where the subject is present as a main subject distance zone in focus at a predetermined frequency or more from the analysis result; And a control means for driving the focus lens at a lower speed than the other distance zones in the main subject distance zone.

  According to the present invention, the distance resolution in the distance zone in which the focus lens is driven at a low speed to capture a moving image is improved, and a still image focused on the subject can be accurately extracted.

1 is a block diagram illustrating an outline of a system configuration of a digital camera that is a first embodiment of an imaging apparatus of the present invention. It is a flowchart explaining the imaging operation of a digital camera. It is a figure explaining the group photo which is a typical imaging | photography scene. FIG. 4 is a diagram showing subject distance information superimposed on the group photo shown in FIG. 3. It is a figure which shows the histogram analysis result of the distance information linked | related for every AF frame. It is the graph which plotted the focus lens position according to photographing distance with the conversion value of the focal depth. It is a figure which shows the control table of the division | segmentation number of the distance zone for every zoom state, and a lens moving speed. It is a time chart explaining the change of a focus lens position from a photography start to an end and a still picture extraction. It is a block diagram which shows the outline of the system configuration | structure of the digital camera which is 2nd Embodiment of the imaging device of this invention. It is a block diagram which shows the outline of the system configuration | structure of the digital camera which is 3rd Embodiment of the imaging device of this invention. It is a flowchart explaining the imaging | photography operation | movement which performs the focusing determination for every AF frame. FIG. 6 is a schematic diagram in which an in-focus determination result for each AF frame is displayed superimposed on a captured image. FIG. 6 is a schematic diagram in which only an AF frame determined to be in focus in focus determination is displayed superimposed on a captured image. 14 is a flowchart illustrating a shooting operation for performing focusing determination for each AF frame in a digital camera that is the fourth embodiment of the imaging apparatus of the present invention. It is a figure which shows typically the position change of the focus lens at the time of face detection being performed.

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

(First embodiment)
FIG. 1 is a block diagram showing an outline of a system configuration of a digital camera which is a first embodiment of an imaging apparatus of the present invention. In the present embodiment, a digital camera that is not a lens interchangeable type is illustrated as an example of the image capturing apparatus, but an image capturing apparatus such as a lens interchangeable digital single-lens reflex camera or a digital video camera may be used.

  In FIG. 1, a control unit 101 includes a CPU, a ROM, a RAM, and the like, and controls each block of a digital camera 100 (hereinafter referred to as camera 100). The operation unit 102 includes various operation members such as a release button and receives an operation from the user. The imaging unit 103 includes an imaging element that photoelectrically converts an object image formed through a photographing optical system including a focus lens and a zoom lens to generate an image signal. The imaging device is an imaging surface phase difference imaging device, and an AF evaluation value related to the subject distance is output via the image processing unit 104. Details of the AF evaluation value will be described later.

  The image processing unit 104 performs various image processing on the output image signal of the imaging unit 103. The image processing unit 104 has a function of adding non-signal information indicating no signal (for example, information indicating black) to an arbitrary pixel of the output image signal of the imaging unit 103. The encoding processing unit 106 encodes an image signal captured by the imaging unit 103 and subjected to predetermined processing by the image processing unit 104. The memory 105 temporarily stores user setting information of the camera 100, captured images, and the like. The display unit 110 is controlled by the display control unit 111 and displays an output image of the imaging unit 103, information indicating the state of the camera 100, and the like.

  The external storage medium 121 is detachably attached to the camera 100 and mainly records captured image data. The recording / playback unit 120 controls recording / reading of image data to / from the external storage medium 121. The image output unit 130 outputs the output image signal of the imaging unit 103, the output image signal of the image processing unit 104, the image signal stored in the memory 105, and the image signal read from the recording medium 121 to an external device. The distance determination unit 132 detects a subject distance for each AF frame (focus detection area) from an AF evaluation value described later.

  The communication unit 131 is for receiving control signals, still image data, moving image data, and the like from an external device, and may be, for example, a wireless LAN, a wired LAN, USB, Bluetooth (registered trademark), The communication method is not particularly limited. For example, if the terminal of the image output unit 130 is an HDMI (registered trademark) terminal, CEC (Consumer Electronic Control) communication may be performed via the terminal. Here, as long as the external device can communicate with the digital camera 100, any device such as a personal computer, a liquid crystal projector, a mobile phone, a smartphone, a hard disk recorder, a game machine, and a remote controller can be used. Good.

  Next, AF evaluation value information will be described with reference to FIGS. FIG. 2 is a flowchart for explaining the photographing operation of the camera 100. Each process in FIG. 2 is executed by a CPU or the like after a program stored in the ROM or the like of the control unit 101 is expanded in the RAM.

  In FIG. 2, in step S201, the control unit 101 proceeds to step S202 when the release button is pressed halfway and the release switch SW1 is turned on. In step S202, the control unit 101 sets a moving range of the focus lens, and proceeds to step S203. Here, the control unit 101 first divides the shooting angle of view into a plurality of AF frames for each predetermined size, and measures the distance from the subject in each AF frame.

  FIG. 3 is a diagram for explaining a group photo that is a typical shooting scene, and is the same video as the video displayed on the display unit 110. 3 captured by the imaging unit 103 is divided into 7 × 7 AF frames by the image processing unit 104, and an AF evaluation value is passed to the distance determination unit 132 for each AF frame. The distance determination unit 132 detects the subject distance for each AF frame from the AF evaluation value.

  When the imaging device of the imaging unit 103 is an imaging plane phase difference method, a prediction value is used as the AF evaluation value. The prediction value is information corresponding to the amount of deviation between two types of imaging pixels of the pupil-divided imaging device. If the prediction value is zero, the subject is present at the in-focus position. As the prediction value, the defocus amount (focus amount) can be calculated as it is, so that it is possible to roughly calculate the distance of the subject that is not in focus in one shooting.

  If the digital camera is equipped with a phase difference AF sensor separately in addition to the image sensor, the subject distance information is detected for each AF frame in one shooting, as in the case of the image sensor with the image plane phase difference method. It is possible to do. Similarly, in the case of TVAF in which the focus lens is moved to detect the in-focus position, it is possible to detect subject distance information for each AF frame.

  As for the subject distance information, the distance determination unit 132 obtains the farthest subject distance and the latest subject distance. The control unit 101 sets a focus lens moving range when moving image shooting is performed while moving the focus lens between the farthest subject distance and the nearest subject distance. In addition, the control unit 101 performs photometry for AE, but the description thereof is omitted.

  Returning to FIG. 2, in step S203, the control unit 101 generates a distance histogram, and proceeds to step S204. Here, distance histogram generation will be described with reference to FIGS. 4 and 5.

  The subject distance information calculated for each AF frame by the distance determination unit 132 is associated with each AF frame. FIG. 4 is a diagram in which subject distance information is superimposed on the group photo shown in FIG. In the group photo, the main subject is gathered at the center, but if the subject in the surrounding AF frame is included, the subject distance information covers a wide range up to an infinite distance.

  When moving the focus lens movement range set in step S202 in FIG. 2 at a constant speed, the lens movement pitch for each frame of the captured moving image is equally spaced in the wide lens movement range. It becomes constant. Conventionally, in order to make the distance resolution fine, the lens is moved at a low speed, and there is a problem that the moving image shooting time becomes long.

  In this embodiment, the distance determination unit 132 performs a histogram analysis of the distance information associated with each AF frame in FIG. 4 in order to solve the conventional problem that the moving image shooting time becomes long. As the analysis result, histogram information shown in FIG. 5 is generated. In the AF frame in which a group photo person is photographed, the distance information from 2.1 m to 3.4 m has a high frequency, and otherwise, the distance information is infinite distance from the surrounding 7 m.

  The distance determination unit 132 divides the subject distance zone based on the zoom magnification state of the imaging unit 103 and the distance measurement information of a predetermined AF frame, for example, the center AF frame, and then calculates the frequency of the calculated distance information. Count every time. Then, the result is passed from the distance determination unit 132 to the control unit 101. A method of dividing the distance zone according to the zoom state will be described later.

  Returning to FIG. 2, in step S204, the control unit 101 drives the low-speed lens in the AF frame number for each received distance zone, that is, a zone where the frequency of the subject is greater than the predetermined count number (distance zone greater than the predetermined frequency). The range is set, and the process proceeds to step S205. At this time, the control unit 101 excludes the farthest subject distance corresponding to the background, that is, the infinite distance zone, from the low speed zone in advance. In step S205, when the release button is fully pressed and the release switch SW2 is turned on, the control unit 101 proceeds to step S206.

  In step S206, the control unit 101 performs moving image shooting while moving the focus lens within the movement range set in step S202, and proceeds to step S207. At that time, the control unit 101 drives the focus lens at a lower speed in the distance zone set in step S204.

  In the low-speed moving distance zone, a moving image with a finely changed focal length can be acquired, so that the shooting distance resolution for each frame becomes fine, and when a still image is extracted, an image focused on the subject is easily obtained. Here, the control unit 101 records the focus lens position on the captured video in the memory 105 in association with each frame of the video shooting. In other words, if the shooting distance is designated, it is possible to select a moving image frame that is in focus at the designated shooting distance.

  In step S207, the control unit 101 displays a video at the end of shooting on the EVF screen of the display unit 110 after shooting the moving image. Then, when the photographer touches and selects a subject to be focused on the screen of the display unit 110, the control unit 101 proceeds to step S208.

  In step S208, the control unit 101 extracts a still image from the moving image based on the focus lens position information associated with each recorded moving image frame and the AF frame information selected by touch, and displays the still image on the display unit 110. The data is saved in the external storage medium 121, and the process ends.

  In this embodiment, in the group photo, a large number of human subjects are photographed, and moving image data obtained by driving the focus lens at a low speed is acquired at that distance. The focused image can be extracted.

  Next, with reference to FIG. 6, a description will be given of the fact that the upper limit value of the focus lens movement amount during distance zone division and moving image shooting varies depending on the zoom state. FIG. 6 is a graph in which the focus lens position corresponding to the shooting distance is plotted with the converted value of the focal depth, taking a 40 × high-power digital camera as an example.

  In FIG. 6, the horizontal axis represents the shooting distance to the subject, which is changed from a distance of 30 cm to an infinite distance, and the vertical axis represents the focus lens position for each shooting distance. When the zoom is in the Tele state (maximum magnification), the vertical axis is on the left side, and when the zoom is in the Wide state (minimum magnification), the vertical axis is on the right side. The zoom state of Wide to Tele is divided into 100, and in the zoom state of Mid70 at 70, the same vertical axis on the left side as Tele is used.

  As can be seen from FIG. 6, in the Wide state, the in-focus range is provided up to a macro distance of less than 30 cm. However, even if the subject distance changes greatly, the movement of the focus lens position is limited to a very narrow range. . In the depth of field, there is only a width of 7 depths in all shooting distance ranges. In general, when the depth of field is shifted by one or more depths, it is known that the captured video is blurred. Therefore, when moving images are shot while moving the focus lens in the wide zoom state, it is theoretically possible to extract still images that are in focus on subjects existing at all subject distances by shooting more than 7 frames. Become.

  However, it is different in Tele zoom state. In FIG. 6, when the value of the Tele depth change is confirmed, the focus range is up to 2.1 m, but the change amount from the infinite distance of the focus lens position corresponds to 284 depths. If the distance is divided in consideration of the focus shift, moving image shooting for 284 frames is required.

  In the case of a shooting rate of 60 frames / second, it is not suitable for a group photo because it requires shooting of less than 4 seconds and the subject must be stationary during that time. Similarly, when the focus lens is moved from 2 m to an infinite distance even in the mid 70 zoom state, photographing for 100 depths, that is, less than 2 seconds is required.

  Next, consider shooting with a fixed video shooting time. In the case of fixed video recording time of 2 seconds (60 frames / second), Wide captures a moving image while moving the focus lens position from a 30 cm subject to an infinite background, and the distance resolution per frame is 0.1. Depth and high resolution. On the other hand, in Tele, when shooting from 2m to infinity, if you move the constant-speed lens, there is only a coarse resolution of 2.4 depths. The probability of not being obtained is 15%. If the shooting time is 1 second, the probability is 58%.

  In the present embodiment, the control unit 101 sets the moving speed of the focus lens from the value of the main subject distance acquired in step S201 in FIG. 2 for both the low speed moving speed and the high speed moving speed. Assuming that there are subjects at all shooting distances, a low-speed moving speed of the focus lens is equivalent to 60 depths per second in order to shoot a moving image in which all the subjects are in focus. The value needs to be smaller than the lens moving speed value. Further, the lens position corresponding to one depth varies depending on the zoom state. That is, even at a high moving speed, the speed needs to be changed depending on the zoom state.

  A specific setting example of the moving speed of the focus lens will be described with reference to FIG. FIG. 7 is a diagram illustrating a control table of the number of divisions of the distance zone and the lens moving speed in accordance with the zoom state. The control unit 101 sets the division width of the distance zone from the zoom state acquired from the imaging unit 103. Since the division width of the distance zone is set to be a width corresponding to 10 depths, in the case of Tele, it is divided into 28. In the case of Wide, the division number is zero, and all distances are the same zone.

  The low speed moving speed set in the distance zone where the main subject is detected is set to a moving speed equivalent to 100 depths per second. If the focus lens is moved at that speed, all the main subjects existing in the distance zone are always in focus in any frame in which the moving image is taken. In a distance zone other than the main subject, it moves at a high speed (the value of the lens movement speed in FIG. 7). For example, in Mid70, 10 distance zones are set.

  According to the subject distance information detected in FIG. 4, two distance zones are selected as main subject distance zones as shown in FIG. In the other distance zones (eight), a high focus lens moving speed is set, so in the case of moving image shooting conditions from 2 m to infinity, the shooting time is about 1.14 seconds. Therefore, in order to guarantee a still image focused on all of the main subjects, when the focus lens is moved at a constant speed, the shooting time is significantly shortened compared with the case where it took 3.8 seconds. it can.

  FIG. 8 is a time chart for explaining the change of the focus lens position from the start to the end of photographing and the extraction of a still image in correspondence with steps S201 to S208 in FIG. In FIG. 8, when the release switch SW1 is turned on (step S201), the focus lens is at the in-focus position in the live view state on the EVF screen of the display unit 110. Next, as described above, the captured image is captured and the distance is measured by the image sensor of the imaging unit 103.

  Then, the lens movement range is set from the distance measurement result (step S202), and the focus lens does not move until the moving image shooting condition setting from the distance histogram generation (step S203) to the low speed movement range setting (step S204). When the release switch SW2 is turned on (step S205), the focus lens starts to move.

  After the focus lens has moved to the farthest distance position, video recording and recording are started, and when the focus lens enters the main subject distance zone, it switches to low speed movement. After that, when the focus lens leaves the main subject distance zone, the speed returns to the high speed, and after the focus lens has moved to the latest subject distance position, shooting and recording are finished.

  Thereafter, the focus lens is stopped until the subject (AF frame) is designated by the photographer (step S207) and the still image extraction (step S208) is completed.

  As described above, in this embodiment, distance histogram analysis is performed using information measured for each AF frame, a distance zone where many subjects are present is identified, and the moving lens is moved while moving the focus lens at a low speed. Take a picture. As a result, the distance resolution in the photographed distance zone is improved, and a still image focused on the designated subject can be accurately extracted.

  In this embodiment, the farthest subject distance corresponding to the background, i.e., the infinite distance zone, is excluded from the low speed zone in advance, but a still image focused on the background according to the photographer's intention is used. There is a scene you want to extract. In this case, it is conceivable that a shooting scene is selected on a menu screen or the like, and main subject distance zone determination is set to valid / invalid for each distance zone.

  In the present embodiment, the distance zones with a large distribution are continuous. However, like a self-portrait scene in a room, it is desirable to extract a still image in which the photographer and the background stationary object are in focus. There is. Therefore, it is conceivable to provide means for switching between low speed / high speed multiple times for each distance zone even if the subject distance is distributed discretely.

  Further, the histogram frequency threshold for determining the main subject distance zone may be configured such that the photographer can freely set the operation menu, or a different threshold may be set according to the distance zone. It may be.

(Second Embodiment)
Next, a digital camera which is a second embodiment of the imaging apparatus of the present invention will be described with reference to FIG. FIG. 9 is a block diagram showing an outline of the system configuration of the digital camera of this embodiment. In the present embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  In the first embodiment, it has been described that even if the distance zone where the main subject exists is set and the focus lens is moved at a low speed, a shooting time of about 1 second is required. In the case of a group photo, the fact that the person who is the main subject is stationary during the shooting time requires concentration, so some assistance is required.

  As shown in FIG. 9, the present embodiment is characterized in that a low speed notification unit 133 is provided for notifying the subject that the focus lens is moving at low speed during the low speed movement time of the focus lens shown in FIG. .

  The low-speed notification unit 133 may be a light-emitting unit or sound as long as it is installed on the front side of the lens on the front side (subject side) of the imaging optical system of the imaging unit 103 and can be easily recognized by the subject side. Further, a light emitting unit for photometry may be used as the low speed notification unit 133. Other configurations and operational effects are the same as those in the first embodiment.

(Third embodiment)
Next, a digital camera that is a third embodiment of the imaging apparatus of the present invention will be described with reference to FIGS. FIG. 10 is a block diagram showing an outline of the system configuration of the digital camera of this embodiment. In the present embodiment, with respect to the same parts as those in the first embodiment, differences will be mainly described with reference to the drawings and symbols.

  As shown in FIG. 10, the present embodiment is characterized in that a focus determination unit 134 that performs focus determination for each AF frame using information of the distance determination unit 132 is provided.

  FIG. 11 is a flowchart for explaining a photographing operation for performing focusing determination for each AF frame. Each process of FIG. 11 is executed by a CPU or the like by developing a program stored in the ROM or the like of the control unit 101 in the RAM.

  In FIG. 11, in step S1101, the control unit 101 proceeds to step S1102 when the release button of the operation unit 102 is half-pressed and the release switch SW1 is turned on. In step S1102, the control unit 101 sets a moving range of the focus lens, and the process proceeds to step S1103. Specifically, first, the photographing field angle is divided into a plurality of AF frames for each predetermined size, and the distance from the subject in each AF frame is measured. As for the subject distance information, the distance determination unit 132 obtains the farthest subject distance and the latest subject distance. Then, the moving range of the focus lens when moving image shooting is performed while moving the focus lens is set between the farthest subject distance and the nearest subject distance.

  In step S1103, the control unit 101 performs focusing determination for each AF frame to determine whether or not the subject distance information calculated by the distance determination unit 132 is within the focusing allowable width, and the process proceeds to step S1104. In step S1104, the control unit 101 displays the focus determination result in step S1103 so as to overlap the video displayed on the display unit 110, and the process proceeds to step S1105. By displaying the focus determination result in step S1103 superimposed on the captured image displayed on the display unit 110, when the subject to be focused is out of focus, the photographer reviews the shooting conditions and composes it. Can be changed.

  In step S1105, when the release button of the operation unit 102 is fully pressed and the release switch SW2 is turned on, the control unit 101 proceeds to step S1106. In step S1106, the control unit 101 performs moving image shooting while moving the focus lens within the movement range of the focus lens set in step S1102, and proceeds to step S1107. At the time of moving image shooting, the focus lens position is recorded in the memory 105 in association with each frame of the moving image shooting. In other words, if the shooting distance is designated, it is possible to select a moving image frame that is in focus at the designated shooting distance.

  In step S1107, after shooting the moving image, the control unit 101 displays the image at the end of shooting on the EVF screen of the display unit 110 and the focus determination result in step S1103 superimposed on the image, and proceeds to step S1108. By displaying the focus determination result, the photographer can select only the image of the focused AF frame, and the useless extraction of the still image is eliminated.

  In step S1108, when the photographer touches and selects the subject to be focused on the screen of the display unit 110, the control unit 101 proceeds to step S1109. In step S1109, the control unit 101 extracts a still image from the moving image based on the focus lens position information associated with each recorded moving image frame and the AF frame information selected by touch, and displays the still image on the display unit 110. Image information is stored in the storage medium 121.

  FIG. 12 is a schematic diagram in which the focus determination result for each AF frame performed in step S1103 in FIG. It is determined for each AF frame whether or not the subject distance information acquired at the time of distance measurement in step S1101 in FIG. 11 is within the focus allowable width, and the result is associated with each AF frame. Based on the associated focus determination result, the focus determination result is displayed on the EVF screen of the display unit 110 when the focus determination result is displayed in steps S1104 and S1107 in FIG.

  Next, a display example of the focus determination result in step S1104 in FIG. 11 will be described with reference to FIG. FIG. 13 is a schematic diagram in which only the AF frame determined to be in focus in the focus determination in step S1103 of FIG. 11 is superimposed on the captured image and displayed on the display unit 110.

  As shown in FIG. 13, since the AF frame without the focus point can be confirmed when the focus determination result before moving image shooting in step S1104 of FIG. 11 is displayed, the photographer can review the shooting conditions or determine whether to change the composition. Becomes easier. In addition, since the in-focus AF frame is not displayed when the focus determination result before extracting the still image in step S1107 in FIG. 11 is displayed, the photographer can easily determine whether to extract the still image.

  As described above, in this embodiment, by displaying only the focused AF frame on the display unit 110, the photographer can easily determine whether to shoot or extract a still image.

(Fourth embodiment)
Next, a digital camera which is a fourth embodiment of the imaging apparatus of the present invention will be described with reference to FIGS. In the present embodiment, with respect to the same parts as those in the first embodiment, differences will be mainly described with reference to the drawings and symbols.

  FIG. 14 is a flowchart for describing a photographing operation for performing focusing determination for each AF frame. Each process in FIG. 14 is executed by a CPU or the like after a program stored in the ROM or the like of the control unit 101 is expanded in the RAM.

  In FIG. 14, in step S1401, the control unit 101 proceeds to step S1402 when the release button of the operation unit 102 is pressed halfway and the release switch SW1 is turned on. In step S1402, the control unit 101 sets the movement range of the focus lens, and proceeds to step S1403. Specifically, first, the photographing field angle is divided into a plurality of AF frames for each predetermined size, and the distance from the subject in each AF frame is measured. As for the subject distance information, the distance determination unit 132 obtains the farthest subject distance and the latest subject distance. Then, the focus lens movement range when moving image shooting is performed while moving the focus lens is set between the farthest subject distance and the nearest subject distance.

  In step S1403, the control unit 101 performs face detection by the face detection unit of the image processing unit 104 within the shooting angle of view, and extracts a human face existing at a distance within the focus lens movement range. If the human face is detected at a distance within the focus lens movement range, the control unit 101 proceeds to step S1404. In step S1404, the control unit 101 sets the distance zone corresponding to the distance at which the face is detected to low speed movement, sets the remaining distance zone to high speed movement, and proceeds to step S1405. The division of the distance zone is the same as that in the first embodiment.

  In step S1405, when the release button of the operation unit 102 is fully pressed and the release switch SW2 is turned on, the control unit 101 proceeds to step S1406. In step S1106, the control unit 101 performs moving image shooting while moving the focus lens within the focus lens movement range set in step S1402, and the process advances to step S1407. At the time of moving image shooting, the focus lens position is recorded in the memory 105 in association with each frame of the moving image shooting. In other words, if the shooting distance is designated, it is possible to select a moving image frame that is in focus at the designated shooting distance.

  In step S1407, after the moving image is shot, the control unit 101 displays a video at the end of shooting on the EVF screen of the display unit 110. When the photographer touches and selects a subject to be focused on the screen of the display unit 110, step S1407 is performed. The process proceeds to S1408. In step S1408, the control unit 101 extracts a still image from the moving image based on the focus lens position information associated with each recorded moving image frame and the AF frame information selected by touching, and displays the still image on the display unit 110. Image information is stored in the storage medium 121.

  FIG. 15 is a diagram schematically showing a focus lens position change when the face detection from step S1401 to step S1408 in FIG. 14 is performed. When the release switch SW1 is turned on (step S1401), the focus lens is at the in-focus position in the live view state (EVF screen display).

  Next, as described above, the captured image is captured and the distance is measured by the imaging surface phase difference type imaging device. A lens movement range is set from the distance measurement result (step S1402). Then, face detection is performed from the photographed image (step S1403), the faces 1501 and 1502 within the lens movement range are detected, and the low speed movement setting is set with respect to the distance zones 1503 and 1504 of the detected distance (step S1404). )I do.

  When the release switch SW2 is turned on (step S1405), the focus lens starts to move, and after moving to the position of the farthest distance focus lens position, moving image shooting and recording are started. When the focus lens enters the position of the face detection distance zone 1503, the focus lens is switched to low speed movement.

  After that, the focus lens returns to the high speed movement when it leaves the face detection distance zone, and when it enters the face detection distance zone 1504 again, it switches to the low speed movement. After the focus lens has recently moved to the subject distance position, shooting and recording are finished (step S1406). Thereafter, the focus lens stops until the photographer specifies the subject (AF frame) (step S1407) and the still image extraction is completed (step S1408).

  As described above, in this embodiment, since moving images are shot by driving the focus at a low speed in the vicinity of the focal length where the face is detected, the distance resolution in the taken distance zone is improved, and the still image focused on the designated subject is captured. Can be extracted with high accuracy. In addition, since the number of images in focus on the same face increases, shooting failures such as blinking can be reduced.

  In addition, this invention is not limited to what was illustrated by said each embodiment, In the range which does not deviate from the summary of this invention, it can change suitably.

  The present invention can also be realized by executing the following processing. That is, the present invention supplies a program that realizes one or more functions of the above-described embodiments to a system or apparatus via a network or a storage medium, and one or more processors in the computer of the system or apparatus read the program. It can also be realized by processing to be executed. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

101 Control Unit 110 Display Unit 132 Distance Determination Unit

Claims (13)

Imaging means for photoelectrically converting a subject image formed through a photographing optical system including a focus lens to generate an image signal;
Setting means for setting a moving range of the focus lens based on a distance measurement result when moving image shooting is performed while moving the focus lens;
Divide the shooting angle of view into a plurality of focus detection areas, analyze the histogram of the distance zone where the subject exists from the focus position obtained for each focus detection area, and the subject exists at a predetermined frequency or more from the analysis result Identifying means for identifying the distance zone to be focused as the main subject distance zone in focus;
An image pickup apparatus comprising: a control unit that drives the focus lens at a lower speed than the other distance zones in the main subject distance zone when performing the moving image shooting.   The image pickup apparatus according to claim 1, further comprising a recording unit configured to record the position of the focus lens in association with each moving image shooting frame with respect to the moving image shot image.   The imaging apparatus according to claim 1, wherein the specifying unit specifies the main subject distance zone by excluding the frequency of the farthest distance zone from the analysis result of the histogram.   4. The imaging apparatus according to claim 1, wherein the specifying unit specifies a plurality of the main subject distance zones. 5.   The imaging apparatus according to claim 4, wherein in the plurality of main subject distance zones, focus positions are set discretely rather than continuously. The photographing optical system includes a zoom lens that changes a focal length,
6. The control unit according to claim 1, wherein the control unit sets a moving speed when the focus lens is driven at a low speed in the main subject distance zone based on the focal length and the in-focus state. An imaging apparatus according to one item.   The imaging apparatus according to any one of claims 1 to 6, further comprising notification means for notifying that the focus lens is driven at low speed by light or sound when the focus lens is driven at low speed.   The image pickup apparatus according to claim 1, wherein the image pickup unit is an image pickup surface phase difference type image pickup device.   The imaging apparatus according to claim 1, further comprising a focus determination unit that determines a focus state for each focus detection region.   The image pickup apparatus according to claim 9, further comprising a display unit configured to display a determination result obtained by the focus determination unit on a display unit so as to be superimposed on an image acquired at the time of moving image shooting. Imaging means for photoelectrically converting a subject image formed through a photographing optical system including a focus lens to generate an image signal;
Setting means for setting a moving range of the focus lens based on a distance measurement result when moving image shooting is performed while moving the focus lens;
Face detection means for detecting the face of the subject within the movement range of the focus lens;
Specifying means for specifying the distance zone in which the face is detected by the face detecting means as the main subject distance zone in focus;
An image pickup apparatus comprising: a control unit that drives the focus lens at a lower speed than the other distance zones in the main subject distance zone when performing the moving image shooting. A method for controlling an imaging apparatus including imaging means for photoelectrically converting a subject image formed through a photographing optical system including a focus lens to generate an image signal,
A setting step for setting a moving range of the focus lens based on a distance measurement result when shooting a movie while moving the focus lens;
Divide the shooting angle of view into a plurality of focus detection areas, analyze the histogram of the distance zone where the subject exists from the focus position obtained for each focus detection area, and the subject exists at a predetermined frequency or more from the analysis result A specific step of identifying the distance zone to be performed as the main subject distance zone in focus;
And a control step of driving the focus lens at a lower speed than the other distance zones in the main subject distance zone when performing the moving image shooting. A method for controlling an imaging apparatus including imaging means for photoelectrically converting a subject image formed through a photographing optical system including a focus lens to generate an image signal,
A setting step for setting a moving range of the focus lens based on a distance measurement result when shooting a movie while moving the focus lens;
A face detection step of detecting the face of the subject within the movement range of the focus lens;
A specifying step of specifying the distance zone in which the face is detected in the face detection step as a main subject distance zone in focus;
And a control step of driving the focus lens at a lower speed than the other distance zones in the main subject distance zone when performing the moving image shooting.