JP5436149B2 - Imaging device - Google Patents

Description

  The present invention relates to an imaging apparatus that performs contrast-type focus detection.

  2. Description of the Related Art Conventionally, a phase difference detection type is used as an automatic focus detection device for a lens interchangeable digital single-lens reflex camera. This type of automatic focus detection apparatus can obtain the defocus direction and defocus amount with a single focus detection operation, so that the time required for automatic focus detection is small and the release time lag, which is important as a single-lens reflex camera, can be shortened. There is an advantage.

  In addition, a contrast detection type automatic focus detection device is also used, and in this method, focus detection can be performed using a signal from the image sensor itself. Therefore, there is an advantage that focus detection can be performed while performing a so-called live view display in which an optical image received by the imaging element is displayed in real time on a display unit such as a liquid crystal display unit for observing a subject image. In addition, since focus detection can be performed using a signal from the image sensor itself, there is an advantage that focusing accuracy is high. However, since the focus cannot be detected unless the contrast information is acquired a plurality of times while the lens is driven, the defocus direction and the defocus amount cannot be detected at the start of focus detection. Therefore, there is a problem that the focus detection takes longer as the defocus amount at the start of focus detection is larger.

  In a digital single-lens reflex camera, in general, a phase difference detection type focus detection apparatus guides a light beam to the focus detection apparatus by reflecting the light beam transmitted through the photographing optical system with a mirror. This mirror is a movable mirror that is retracted so as not to block the imaging light beam during shooting, and when the mirror is retracted, focus detection by the phase difference detection method is interrupted and light can be taken to the image sensor to perform shooting. I can do it. Therefore, focus detection by the phase difference detection method and imaging by the image sensor cannot be performed simultaneously.

  On the other hand, in a conventional compact digital camera or the like, photographing is performed using a so-called electronic viewfinder that observes a live view display. In a digital single lens reflex camera, observation of a subject image is generally performed using an optical viewfinder, but an image using an electronic viewfinder has also been proposed. For example, an optical finder and an electronic finder can be selected, and when the electronic finder is selected, a light beam that has passed through the photographing optical system is guided to the image sensor, and the obtained subject image is displayed in a live view. (Patent Document 1). In a digital single-lens reflex imaging apparatus capable of such live view display, when performing focus detection, it is necessary to use a contrast detection method as described above.

JP 2007-312063 A

  In photographing using contrast detection type focus detection and live view display, exposure is performed by an image sensor, and live view display is resumed after certain imaging processing is completed. When using the optical viewfinder, the subject image can be observed even during the imaging process, but when using the electronic viewfinder, the subject image is observed and the focus is detected until the live view display is resumed. I can not. For this reason, there is a time lag after the photographing until the observation of the subject image and the focus detection are restarted, and the position and distance of the subject may change during that time. In contrast detection focus detection, the larger the defocus amount of the subject, the more time is required until the end of focus detection.Therefore, when shooting continuously, focus detection is performed due to the time lag after shooting. There were cases where time was required and the next shooting could not be performed quickly.

(Object of invention)
An object of the present invention is to provide an imaging apparatus capable of quickly performing the next shooting at the time of live view.

In order to achieve the above object, an imaging apparatus of the present invention includes an imaging unit that captures a subject image that passes through a photographing lens, a display unit that displays a subject image in live view using image data from the imaging unit, and the object information detection means for detecting the subject information for recognizing a focus state of the photographing lens with respect to the subject, while performing a live view display by the display means, based on the detected subject information by the object information detection means after carry out the focus detection means for performing focus detection by the contrast method, the exposure of the shooting image by using the image data from said image pickup means and determines a range for controlling the drive or focus detection of the photographing lens Te, The subject information by the subject information detection means until the focus detection by the focus detection means is resumed. It is characterized in that a control means for causing the output.

  According to the present invention, the next shooting at the time of live view can be quickly performed.

It is a block diagram which shows the structure of the camera which concerns on Example 1 of this invention. 1 is a block diagram illustrating a configuration of a camera according to Embodiment 1. FIG. 6 is a flowchart illustrating a shooting operation in a live view state according to the first embodiment. 6 is a flowchart illustrating an operation of a second focus detection unit according to the first embodiment. It is a figure which shows the focus detection area and subject information of a 2nd focus detection part. 6 is a flowchart illustrating an operation of a first focus detection unit according to the first embodiment. It is a figure which shows the focus detection area and focus detection parameter of a 1st focus detection part. 12 is a flowchart illustrating an operation of a second focus detection unit according to the second embodiment.

  The mode for carrying out the present invention is as shown in Examples 1 and 2 below.

  1 and 2 are block diagrams showing a configuration of a digital single-lens reflex camera (hereinafter simply referred to as a camera) that can exchange a plurality of photographing lenses according to Embodiment 1 of the present invention. Specifically, FIG. 1 shows a case in the optical finder observation state, and FIG. 2 shows a case in the electronic finder observation state (the image sensor is in the imaging state). This camera is composed of a camera body 100 and a photographing lens 300.

  First, the camera body 100 side will be described in detail. Reference numeral 1 denotes a shutter, 2 denotes an image sensor, and 3 denotes an A / D converter. An image processing unit 4 performs predetermined pixel interpolation processing and color conversion processing on image data from the A / D converter 3 or image data from the memory control unit 5 described later. In addition, the image processing unit 4 extracts the contrast information of the image.

  Reference numeral 20 denotes a camera system control unit that controls AF (autofocus) processing, AE (automatic exposure) processing, and the like through a lens system control unit 301 on the photographic lens 300 side described later based on the obtained calculation result. Further, the quick return mechanism drive control of the mirror 13 and the AF sub mirror 14 is performed, and the optical path of the light beam transmitted through the imaging lens 300 is controlled. The relationship between the arrangement of the mirror 13 and the AF sub mirror 14 and the optical path of the light beam transmitted through the photographing lens 300 will be described later. In addition, a focus detection parameter and subject information obtained by a second focus detection unit, which will be described later, are stored. The camera system control unit 20 corresponds to a second microcomputer (second integrated circuit) that has a function of acquiring subject information by executing a second focus detection unit described later.

  A memory control unit 5 corresponding to the first microcomputer (first integrated circuit) controls the A / D converter 3, the image processing unit 4, the image display memory 6, the D / A converter 7, and the memory 8. The data of the A / D converter 3 is sent to the image display memory 6 or the memory 8 via the image processing unit 4 and the memory control unit 5 or the data of the A / D converter 3 is directly sent to the memory control unit 5. Written.

  Reference numeral 9 denotes a first focus detection unit for performing AF processing by a contrast detection method. From the contrast information of the image calculated by the image processing unit 4, the in-focus state of the photographing lens 300 on the image sensor 2 can be detected. Based on the result of the first focus detection, the camera system control unit 20 performs AF control on the focus control unit 302 only through the lens control unit 301 of the photographing lens 300 using focus detection parameters described later.

  Reference numeral 10 denotes an image display unit composed of a liquid crystal monitor or the like, which displays display image data written in the image display memory 6. An electronic viewfinder function (live view display) can be realized by sequentially displaying image data captured using the image display unit 10. Further, the image display unit 10 can arbitrarily turn on / off the display according to an instruction from the camera system control unit 20, and when the display is turned off, the power consumption of the camera body 100 can be greatly reduced. I can do it.

  Reference numeral 8 denotes a memory for storing captured still images and moving images, which has a sufficient storage capacity to store a predetermined number of still images and a predetermined time of moving images. This makes it possible to write a large amount of images to the memory 8 at high speed even in continuous shooting or panoramic shooting in which a plurality of still images are continuously shot. The memory 8 can also be used as a work area for the camera system control unit 20. Reference numeral 11 denotes a shutter control unit that controls the shutter 1.

  Reference numeral 12 denotes a second focus detection unit including a light receiving element for performing focus detection processing by a phase difference detection method. The light beam that has passed through the photographic lens 300 is incident on the second focus detection unit 12 via a camera mount (not shown), the mirror 13, and the AF sub mirror 14, and light that has passed through an optical system (not shown) is received by the light receiving element. To do. As a result, the in-focus state of the photographic lens 300 on the image sensor 2 can be detected. Based on the result of the second focus detection, the camera system control unit 20 performs AF control on the focus control unit 302 via the lens control unit 301 of the photographing lens 300. Further, the AF control may be performed using both the result of the first focus detection by the first focus detection unit 9 and the result of the second focus detection by the second focus detection unit 12.

  A switch 15 (SW1) is turned on when a shutter button (not shown) is half-pressed, and instructs to start shooting preparation operations such as AF processing, AE processing, and AWB processing. Reference numeral 16 (SW2) denotes a switch, which is turned on when a shutter button (not shown) is fully pressed, and instructs the start of a series of processing related to a captured image. The process related to the photographed image is an exposure process, a development process, a recording process, and the like. In the exposure process, the image data is written in the memory 8 through the A / D converter 3 and the memory control circuit 5 from the signal read from the image sensor 2. In the development process, development is performed using computations in the image processing unit 4 and the memory control unit 5.

  Reference numeral 17 denotes an optical viewfinder, which guides the light beam that has passed through the photographing lens 300 through a camera mount (not shown) and the mirror 13 and can be observed as an optical image. Thereby, it is possible to perform photographing using only the optical viewfinder 17 without using the electronic viewfinder function of the image display unit 10. The optical viewfinder 17 has various information display functions.

  Reference numeral 13 denotes a mirror having a semi-transmissive portion, which reflects the light beam that has passed through the photographing lens 300 to the optical finder 17 and transmits a portion of the light beam near the center, and passes through the AF sub-mirror 14 to provide a second focus detection portion. Lead to twelve.

  FIG. 1 shows a state in which the optical finder can be observed, and the light beam that has passed through the photographing lens 300 is divided and guided to the optical finder 17 and the second focus detection unit 12. In this state, since the light beam that has passed through the photographing lens 300 is not guided to the image pickup device 2, observation and photographing of the electronic viewfinder cannot be performed.

  FIG. 2 shows a state in which the electronic viewfinder can be observed, and the light beam transmitted through the photographing lens 300 is guided to the image sensor 2. In this state, the light beam that has passed through the photographing lens 300 is not guided to the optical finder 17 and the second focus detection unit 12, so observation of the optical finder 17 and second focus detection, that is, focus detection by the phase difference detection method is performed. I can't do that.

  Next, details of the interchangeable lens type photographing lens 300 side will be described. Reference numeral 303 denotes a lens, which includes a focus lens and a diaphragm for adjusting the focus of the subject. A focus control unit 302 controls the focus lens operation of the lens 303. A lens system control unit 301 controls the entire photographing lens 300. The lens system control unit 301 has a memory function for storing lens operation constants, variables, programs, and the like. In addition, it also has a non-volatile memory function for storing identification information such as a number unique to the photographing lens, management information, function information such as an open aperture value, minimum aperture value, and focal length, and current and past set values.

  Next, details of the operation of the camera (imaging device) constituted by the camera body 100 and the photographing lens 300 will be described.

  First, operations related to focus detection and photographing will be described with reference to the flowchart of FIG. 3 is an operation in a state where the image display unit 10 is used as an electronic viewfinder (hereinafter referred to as a live view). During the live view, as shown in FIG. 2, the mirror 13 and the AF sub-mirror 14 are used. Is retracted out of the luminous flux by the quick return mechanism. In addition, the operation to be described is an operation in an auto shooting mode in which functions necessary for shooting are automatically set.

  In the live view shown in FIG. 2, first, in step S1, the live view is started when the power is turned on or the mode is switched. In the next step S2, the camera system control unit 20 determines whether or not a shutter button (not shown) is half pressed and the switch SW1 is turned on. If the ON state of the switch SW1 is not confirmed, the status of the switch SW1 is continuously monitored. Thereafter, when the switch SW1 is turned on, the process proceeds to step S3, where the first focus detection unit 9 performs first focus detection (details will be described later).

  In the next step S4, the image processing unit 4 controls TTL AWB (auto white balance) processing based on AE processing using a photometry unit (not shown) and finally obtained image data. Since operations related to the AE process and the AWB process are well known, they are omitted. The mirror 13 and the AF sub-mirror 14 remain retracted from the photographing light beam. Then, based on the calculation result obtained by calculating the image data of the image sensor 2 by the image processing unit 4, the camera system control unit 20 performs AF control and AE on the focus control unit 302 of the photographing lens 300 and the aperture control unit (not shown). Take control.

  In the next step S5, it is determined whether or not the shutter button is fully pressed within a predetermined time and the switch SW2 is turned on. If the switch SW2 is not turned on within the predetermined time, the process returns to step S2 and waits until the switch SW1 is turned on again.

  Thereafter, when it is detected that the shutter button is fully pressed within a predetermined time and the switch SW2 is turned on, the process proceeds to step S6, and the live view is stopped to perform the photographing process. Then, in the next step S7, the recording image (captured image) is exposed to the image sensor 2. The exposure time is the time from resetting the accumulated charge of the image sensor 2 to closing the shutter 1. When the exposure is completed, the process proceeds to step S8, where the shutter 1 is closed and the image sensor 2 is shielded based on the control of the shutter control unit 11.

  After the shutter 1 is closed in step S8, two processes are performed in parallel.

  In the first process performed in parallel, first, a captured image is formed in step S9. As described above, the electric charge generated by the exposure in the image sensor 2 is converted into a digital signal by the A / D converter 3 based on the control of the memory control unit 5, and image data is created by the image processing unit 4. In the next step S10, the image processing unit 4 performs predetermined pixel interpolation processing and color conversion processing on the image data. Further, the image processing unit 4 extracts contrast information of the image and performs white balance processing, γ processing, color matrix processing, and the like.

  In the next step S11, the image data is transferred to the memory 8 by the memory control unit 5 and recorded. When this step S11 is finished, the image processing unit 4 finishes the process related to the series of captured images, and is in a state where the live view display and imaging can be resumed.

  Since the flow in FIG. 3 describes single shooting instead of continuous shooting, the process returns to step S1 to resume live view. However, there is no problem even if it is configured to return to step S3 during continuous shooting and perform shooting again.

  In the other process performed in parallel, first, in step S101, the camera system control unit 20 controls the quick return mechanism. That is, the mirror 13 and the AF sub-mirror 14 are moved into the light beam that has passed through the photographing lens 300, that is, the mirror is moved down, and the state shown in FIG. In this state, the AF sub-mirror 14 guides the light beam that has passed through the photographing lens 300 to the second focus detection unit 12, so that the second focus detection, that is, the focus detection by the phase difference detection method can be performed. In the next step S102, phase difference type focus detection (details will be described later) is performed by the second focus detection unit 12.

  In the next step S103, the quick return mechanism is controlled by the camera system control unit 20. That is, the mirror 13 and the AF sub-mirror 14 are retracted out of the light flux that has passed through the photographing lens 300, that is, mirrored up, and shifted to the state shown in FIG. Then, in the next step S104, the shutter 1 is opened based on the control of the shutter control unit 11, the light beam transmitted through the photographing lens 300 reaches the image sensor 2, and the live view display and imaging can be resumed. And

  As described above, in the first embodiment, during the image data creation, image processing, image transfer, and recording (image acquisition processing in steps S9 to S11) after the image sensor 2 is exposed. Second focus detection (detection of subject information described later) is performed by the second focus detection unit 12. Therefore, the second focus detection unit 12 can grasp the state of the subject that can change after exposure while minimizing the influence on the time required for a series of photographing operations.

  In addition, the memory control unit 5 that performs the image acquisition processing in steps S9 to S11 and the camera system control unit 20 that performs the processing in steps S101 to S104 are configured as separate circuit units as the first and second microcomputers. . For this reason, the parallel processing as described above can be performed at a higher speed.

  In the first embodiment, the image processing unit 4 generates the image data and controls the memory under the control of the memory control unit 5, but the image processing unit 4 generates the image data and transfers it to the memory. You may comprise so that it may control.

  Next, the details of the second focus detection process performed in step S102 of FIG. 3 will be described using the flowchart of FIG.

  In step S1021, phase difference focus detection is performed. The phase difference type focus detection means that a light beam passing through the exit pupil of the photographic lens 300 is divided, and an object image formed on the light receiving element included in the second focus detection unit 12 by the divided light beam. In this method, the focus of the photographic lens 300 is detected by detecting the phase difference. In general, it is possible to calculate the defocus amount of the subject in the focus detection areas discretely arranged within the imaging range by the image sensor 2.

  When the second focus detection unit 12 has a plurality of focus detection areas, focus detection may be performed in all the areas, or the focus detection area based on the first focus detection result performed in step S3 of FIG. The second focus detection may be performed by narrowing down.

  In the next step S1022, subject information is acquired from the result of the second focus detection obtained in step S1021, and stored in the camera system control unit 20. The subject information is for recognizing the focus state of the photographing lens 300 with respect to the subject. That is, the defocus amount of the subject (focus lens provided in the lens 303) in the focus detection region, the direction in which the image sensor 2 is deviated from the focus position of the photographing lens 300 (defocus direction), and the like. When there are multiple focus detection areas, in addition to these, position information of the focus detection areas where focus detection was possible, maximum defocus amounts and minimum defocus amounts of the plurality of focus detection areas, and the like are also stored as subject information. The

  Here, with reference to FIGS. 5A and 5B, a plurality of focus detection areas of the second focus detection unit 12 and subject information stored for each focus detection area will be exemplified.

  In FIG. 5A, reference numeral 500 indicates a range imaged by the image sensor 2. Reference numerals 501 to 505 denote focus detection areas in which focus detection can be performed by the second focus detection unit 12. In other words, this example is configured such that focus detection is possible at five locations within the imaging range.

  FIG. 5B shows an example of subject information acquired in each of the focus detection areas 501 to 505. One is whether or not the focus detection by the second focus detection unit 12 is possible. In this example, only the focus detection region 501 indicates that focus detection is impossible. In the other focus detection areas 502 to 505, focus detection is possible, and the defocus amount at that time is acquired. A direction (defocus direction) in which the image sensor 2 is deviated with respect to the focal position of the photographic lens 300 is indicated by a sign of the defocus amount. From these defocus amounts, 1.0 mm of the focus detection region 505 showing the largest defocus amount and -0.5 mm of the focus detection region 503 showing the smallest defocus amount are also acquired as subject information. . Further, multiple focus detections are possible for the focus detection areas 502, 503, and 504, and the defocus change amount is calculated from the difference from the previous focus detection result, and these are also stored as subject information. A method of using the acquired subject information will be described later.

  In the first embodiment, the phase difference type focus detection and subject information storage are performed only once. However, if there is time, the focus detection may be repeated a plurality of times to store the subject information. In that case, the moving speed of the subject in the optical axis direction of the photographing lens 300 can be calculated by storing the temporal change of the defocus amount of the subject as subject information.

  After completing the flow of FIG. 3 and returning to step S1 and restarting the live view, the time until the first focus detection in step S3 is longer than a certain time or the power is turned off. For example, the subject information is deleted. This is because the subject information obtained by the second focus detection is not useful when performing the first focus detection.

  Next, the details of the first focus detection process performed in step S3 of FIG. 3 will be described using the flowchart of FIG.

  As described above, the second focus detection has been performed in the past within a certain time, and the subject information is stored when the focus detection is possible. In step S301, the presence / absence of subject information stored in the camera system control unit 20 is determined. As a result, when there is no subject information, the process proceeds to step S303, and when there is subject information, the process proceeds to step S302.

  If the process proceeds to step S302 assuming that there is subject information, the focus detection parameter to be used is reset based on the subject information when performing the first focus detection.

  Here, focus detection parameters will be described with reference to FIGS. 7 (a), (b), and (c).

  FIG. 7A shows the relationship between the focus detection area of the first focus detection unit 9 and the range imaged by the image sensor 2, and the same parts as those in FIG. The description is omitted. In FIG. 7A, reference numerals 701 to 705 denote focus detection areas in which focus detection can be performed by the first focus detection unit 9. That is, in this example, both the first focus detection unit and the second focus detection unit are configured to be able to detect five corresponding focus points.

  FIG. 7B is an example of a focus detection parameter stored as an initial value when there is no subject information stored in the camera system control unit 20.

  First, focus detection areas 701 to 705 in which focus detection may be performed are shown. Next, a lens driving range for adjusting the focus of the photographing lens 300 is set for each focus detection region. In this example, there is no subject condition obtained in advance for the first focus detection, so that the lens can be driven in the “entire range”. In the lens driving direction, the direction at the start of lens driving is determined. The first focus detection unit 9 measures the in-focus state of the photographing lens 300 on the image sensor 2 from the contrast information of the image calculated by the image processing unit 4. Therefore, it cannot be determined whether the subject exists on the short distance side or the long distance side with respect to the in-focus state of the photographing lens 300 on the image sensor 2 at the start of lens driving. Therefore, as the initial value of the focus detection parameter, the lens driving direction is uniformly set to “short distance side”. This is set on the assumption that the subject on the short distance side is more likely to be the subject intended by the photographer, but there is no problem even if it is set to “far side”. Next, as for the driving amount at the time of starting the lens driving, there is no subject condition obtained in advance when performing the first focus detection, so that the lens driving suitable for performing the focus detection by the first focus detection unit 9 is performed. As a quantity, a value of a certain quantity “S” is set.

  FIG. 7C illustrates the focus detection parameters that are reset using the subject information illustrated in FIG.

  First, the focus detection possible range is set to focus detection areas 702 to 705 excluding the focus detection area 701 in response to the fact that the focus detection area 501 cannot be detected in the subject information (FIG. 5A). To do. Next, regarding the lens driving range, it is estimated from the subject information that the subject is in the range of −0.5 mm to 1.0 mm in terms of the defocus amount, so this range is set as the lens driving range. To do. Here, the lens driving range is set in this way on the assumption that the second focus detection is performed immediately before the first focus detection. However, in view of the change in the state of the subject, −0.5 mm to 1.. You may set a little wider with respect to the range of 0 mm. In this way, by limiting the lens driving range, the time required for focus detection by the first focus detection unit 9 is greatly reduced.

  The lens driving direction is set from the defocus amount included in the subject information corresponding to the focus detection areas 502 to 505. For example, for the focus detection area 702, since the defocus amount of the corresponding focus detection area 502 is 0.3 mm, it is estimated that the subject is on the far side (far side), and the lens driving direction is set to the far side. Set to start from Next, the driving amount at the start of lens driving is set using the defocus amount and defocus change obtained from the subject information. For example, for the focus detection region 703, the defocus amount of the focus detection region 503 is −0.5 mm, and the defocus change is 0.4 mm / s. If the time interval from the immediately preceding second focus detection to the first focus detection is 0.1 second, −0.5 mm + 0.4 mm / s × 0.1 s = −0.46 mm at the start of lens driving. Drive. This is set for the position of the subject (−0.5 mm) at the time of detecting the second focus in consideration of the subject moving speed (0.4 mm / s) at that time. After driving the set driving amount at the start of lens driving, the lens driving is performed at an interval of a certain constant value (for example, the driving amount S of the initial value of the focus detection parameter), thereby sequentially acquiring contrast information of the image. One focus detection is performed.

  As described above, in step S302 in FIG. 6, the focus detection parameter is reset.

  Returning to FIG. 6, in the next step S303, the focus detection area is determined. Here, at least one focus detection area is selected from focus detection areas that have a possibility of focus detection based on the focus detection parameter. The focus detection area may be selected by giving priority to the focus detection area when the previous first focus detection is performed, or all focus detection areas where focus detection is possible may be selected. In the subsequent step S304, exposure for acquiring information necessary for the first focus detection unit 9 is started. This exposure is exposure to the image sensor 2.

  In the next step S305, the lens driving direction and driving range are determined. In the exposure performed in the next step S304, if there is no new focus detection area where focus detection is impossible, the lens drive direction and drive range are determined using the parameters of the focus detection area. . That is, when the focus detection parameter is an initial value, the lens driving amount is “S” and the lens driving direction is “short distance side”. If the focus detection parameter has been reset, the focus detection area where the subject is closest to the shortest distance is selected from the focus detection areas selected in step S303, and the lens set in that range is selected. The driving amount and the lens driving direction are used.

  In the next step S306, the focus lens included in the lens 303 is moved via the focus control unit 302 in the photographing lens 300 based on the focus detection parameter. In the next step S307, exposure by the image sensor 2 is performed, and the first focus detection unit 9 determines the in-focus state using the contrast information of the image calculated by the image processing circuit 4. Since this determination method is known as a focus detection method using a contrast detection method, a description thereof will be omitted.

  In the next step S308, it is determined whether or not focus detection by the first focus detection unit 9 has been completed. If not completed, the process returns to step S306 and the same operation is repeated. That is, the lens 303 is driven again to perform exposure. When the focus detection is finished, the first focus detection process is finished.

  In this way, by setting the focus detection parameter at the time of the next first focus detection based on the subject information acquired after the live view shooting, the situation of the subject can be grasped more accurately and focus detection can be performed quickly. . The first focus detection unit 9 cannot determine the defocus direction at the start of focus detection because of focus detection by the contrast detection method. However, according to this method, the defocus direction of the subject can be determined in advance, and thus focus detection is performed. Speeding up can be realized.

  In the first embodiment, the example in which the focus detection parameters are reset using all of the subject information obtained by the second focus detection unit 12 is shown, but not all are used, and only a part is used. You may comprise as follows.

  In addition, although the example in which the focus detection areas of the first focus detection unit 9 and the second focus detection unit 12 correspond one-to-one has been shown, it does not have to correspond. In that case, the focus detection parameter is reset by using subject information in the focus detection area of the second focus detection unit 12 that is close to the focus detection area of the first focus detection unit 9. May be.

  In the first embodiment, the second focus detection unit 12 has been described using a phase difference detection method. However, those that perform focus detection or subject information detection in a time shorter than the time required for focus detection by the first focus detection unit 9, that is, those that are useful for focus detection of the first focus detection unit 9, and those that assist focus detection Can be used. For example, instead of the second focus detection unit 12 described above, an imaging unit that can also acquire subject color information is provided to perform approximate focus detection using a contrast detection method or subject recognition such as subject face detection. You may comprise so that it may go.

  In the above description, an interchangeable lens system capable of exchanging a plurality of photographing lenses has been described as an example. However, the present invention can also be applied to a camera (imaging device) in which the camera body 100 and the photographing lens 300 are integrally formed. .

  Next, Example 2 of the present invention will be described. The configuration of the camera is the same as that shown in FIGS.

  The second embodiment is an example corresponding to the case where the lens is driven based on the second focus detection result by the second focus detection unit 12. In the first embodiment, the second focus detection unit 12 is used only as an auxiliary to the first focus detection unit 9. However, in the second embodiment, the second focus detection unit 12 also adjusts the focus of the photographing lens 300. Has been added.

  The overall operation of the camera in the second embodiment is the same except for the part of the second focus detection process in step S102 in FIG. Therefore, only this part will be described with reference to the flowchart of FIG.

In step S2021 in FIG. 8, phase difference type focus detection is performed. When the second focus detection unit 12 has a plurality of focus detection areas, focus detection may be performed in all the areas, or based on the result of the first focus detection performed in S3 of FIG. Focus detection may be performed by narrowing down. The focus detection result by the second focus detection unit 12 is converted into the driving amount of the photographing lens, and is stored in the camera system control unit 20 in a later step S2024.
In step S2022, the focus lens included in the lens 303 is driven via the focus control unit 302 of the photographing lens 300 based on the focus detection result calculated in step S2021. Then, in the next step S2023, it is determined whether or not the second focus detection should be finished. In the second focus detection, as described above, after the image sensor 2 is exposed, image data creation, image processing, image transfer, and recording (image acquisition processing in steps S9 to S11 in FIG. 3) are performed. To be done. Therefore, the second focus detection must be performed within a limited time. In the second embodiment, it is desirable that the second focus detection is completed within a certain period of time so as not to hinder the photographing operation of the photographer. If it is determined in step S2023 that there is time to perform focus detection again with respect to the time allocated to the second focus detection, the process returns to step S2021 to perform focus detection again.

  If it is determined in step S2023 that the second focus detection should be finished, the process proceeds to step S2024. In step S2024, subject information is stored. The contents stored at this time are the same as the contents of the first embodiment described above. The processing for restarting the live view after finishing the second focus detection and the creation of the captured image is the same as in the first embodiment.

  In this way, after shooting, the second focus detection is performed during the processing of the image data, and the lens is driven, so that the subject can be kept in focus after the live view is resumed. This leads to faster focus detection. In addition, since the photographer maintains the focused state of the subject, it is easy to adjust the focus, adjust the shooting composition, and the like.

  The camera in each of the above embodiments includes the following components. It has an image processing unit 4 and a memory control unit 5 (control unit) that process a captured image from the image sensor 2 (imaging unit) that captures the subject image that has passed through the photographic lens 300 (operations in steps S9 to S11). Furthermore, it has the focus detection part 9 (focus detection means) which performs the focus detection by a contrast system. In addition, it has a second focus detection unit 12 (subject information detection means) for detecting subject information for recognizing the focus state of the photographing lens 300 with respect to the subject. Further, at the time of live view by the image display unit 10 (display means), the mirror 13 and the AF sub mirror 14 (optical member) for guiding the light beam transmitted through the photographing lens to the image sensor 2 are provided. The mirror 13 and the AF sub-mirror 14 (optical member) are transmitted through the photographic lens after the photographic image is exposed until the first focus detector 9 returns to a state where the focus can be detected again. The light beam is guided to the second focus detection unit 12. Then, after the focus detection by the first focus detection unit 9, the second focus detection unit after the exposure of the captured image is performed until the focus detection by the first focus detection unit 9 is restored again. 9 has a camera system control unit 20 (control means) that performs subject information detection. Alternatively, the camera system control unit 20 includes a camera system control unit 20 (control unit) that performs not only subject information detection by the second focus detection unit 12 but also focus adjustment of the photographing lens based on the result.

  Further, the camera system control unit 20 (control unit) stores the result of the subject information detection by the second focus detection unit 12 (subject information in FIG. 5B). Then, the subject information detection result stored when the first focus detection unit 9 is restored to the focus detectable state is reset as the focus detection parameter of the first focus detection unit 9.

  In addition, the first microcomputer for processing the captured image and the second microcomputer for operating the second focus detection unit 12 are separately provided.

  As described above, since the subject information can be detected by the second focus detection unit 12 even during the processing of the captured image, it is necessary for the focus detection of the contrast method at the time of the next capturing after the captured image processing is completed. The time can be shortened and the next shooting can be performed smoothly.

2 Image sensor 4 Image processing unit 5 Memory control unit (first microcomputer)
DESCRIPTION OF SYMBOLS 9 1st focus detection part 10 Image display part 12 2nd focus detection part 13 Mirror 14 AF submirror 20 Camera system control part (2nd microcomputer)

Claims (6)

Imaging means for imaging a subject image that passes through the taking lens;
Display means for displaying a subject image in live view using image data from the imaging means;
Subject information detection means for detecting subject information for recognizing a focus state of the photographing lens with respect to the subject;
While performing live view display by the display means , a range for performing drive control or focus detection of the photographing lens is determined based on subject information detected by the subject information detection means, and image data from the imaging means focus detection means for performing focus detection by a contrast method using,
After to perform the exposure of the shadow image shooting, until it is returned to the state capable of focus detection by said focus detecting means again, that a control means for causing the subject information detected by the object information detection means An imaging device that is characterized.   The control means causes the subject information detection means to perform subject information detection between the time when the captured image is exposed and the time when the focus detection means again returns to a state in which focus detection is possible. The imaging apparatus according to claim 1, wherein focus adjustment of the photographing lens is performed based on a result of information detection.   The control means stores a result of subject information detection by the subject information detection means, and returns the stored subject information detection result of the focus detection means when returning the focus detection means to a focus detectable state again. The imaging apparatus according to claim 1, wherein the imaging apparatus is reset as a focus detection parameter.   At the time of live view by the display means, a light beam that passes through the photographing lens is guided to the imaging means, and after the photographed image is exposed, until the focus detection means returns to a state where focus detection is possible again. The imaging apparatus according to claim 1, further comprising an optical member that guides a light beam transmitted through the photographing lens to the subject information detection unit.   The imaging apparatus according to claim 1, wherein the subject information detection unit performs phase difference type focus detection. A first microcomputer for processing the captured image;
6. The imaging apparatus according to claim 1, further comprising a second microcomputer that operates the subject information detection unit.

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