JP2012133067A - Imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging apparatus that can reduce the time required for auto-focusing, in which a user can control the usability such as the time a battery can last or the easiness of framing.SOLUTION: An imaging apparatus includes: a subject distance calculation part 6 for calculating the subject distance based on two images generated by image signals converted by imaging elements 2; and a focal point detection part 7 for detecting a focal point based on a contrast evaluation value of the subject in the image. The focal point detection part 7 is configured so that a pre-input mode for performing at least rough-focusing drive in a state that the user does not input an imaging operation start instruction in an input part, and a post-input mode for performing rough-focusing drive after the user inputs the imaging operation start instruction in the input part can be switched.

Description

  The present invention relates to an imaging apparatus having at least two imaging optical systems and two imaging elements that respectively convert subject images formed by the imaging optical systems into image signals.

  In a digital camera using an image sensor, autofocus (also referred to as AF, automatic focusing) on a subject is performed based on an image generated from an image signal from the image sensor. For example, while scanning the focus lens provided in the imaging optical system and changing the focus position, the position where the contrast evaluation value of the subject in the image becomes the extreme value is searched for, and the focus position at the extreme value is adjusted. There is a method called contrast AF that detects the focal position.

  Although this method can focus on the subject with good accuracy, it is difficult to reduce the time required for focusing for the following reasons.

  First, it seems that if the scanning speed of the focus lens is increased, the time required to detect the in-focus position can be shortened. However, when the sampling speed is fixed, the contrast evaluation value can be obtained as the scanning speed increases. As the number of focus positions decreases, the possibility of missing an extreme value increases. Therefore, if you try to drive the focus lens at high speed while ensuring that the in-focus position can be detected reliably, the limit value is naturally determined for the scan speed, so the time required for focusing can be increased by increasing the scan speed. It is difficult to shorten.

  Further, it cannot be determined which side the in-focus position is with respect to the focus position at the time when the autofocus is started unless the focus lens is driven for a while and the increase / decrease tendency of the contrast evaluation value is not known. In other words, since it is not known at the start time which direction the focus position should be changed, the focus lens can only be driven in either direction. For this reason, if the focus position is moved in the direction opposite to the direction in which the in-focus position is located, it may be necessary to reverse the movement, which causes a longer time for focusing. ing.

  With respect to such a problem, in a stereoscopic imaging apparatus having two imaging optical systems as shown in Patent Documents 1 and 2, the driving range of the focus lens when performing contrast AF in each imaging optical system is set. There are some that are configured to reduce the time required for focusing by sharing half.

  In addition, in an imaging apparatus having one imaging optical system and an external light passive sensor, a rough subject distance is calculated by the external light passive sensor, and a range of a focus position having a rough focus position from the subject distance There is also an imaging apparatus that performs contrast AF using only the range as a scan range. In the case of an external light passive sensor, there is a problem that the position and the angle of view are not the same because the optical sensor is a separate optical sensor from the optical system for photographing as well as the cost increase and space problems for the separate sensor.

  However, the method of sharing the contrast AF driving range by half in the two imaging optical systems described in Patent Document 1 only halves the driving distance of the focus lens. It is difficult to dramatically reduce the time required for focusing.

  In addition, the distance is regularly detected before the photographer's S1 (shooting start) operation, and the focus is driven in advance in the vicinity of the in-focus, and the focus for final focusing after the S2 (exposure start) operation. If it is configured to drive, the AF time can be shortened, but it may cause unnecessary focus driving such as reacting to framing that the photographer did not intend, and the battery has a short time There is a possibility that a problem such as becoming difficult or a through image displayed on the monitor becomes difficult to see due to wasteful focus driving and framing is difficult to occur. In other words, a configuration that can be adjusted by the user is not shown for the trade-off between high-speed autofocusing and usability as described above, and there is room for further improvement.

JP 2005-70077 A JP 2006-162990 A

  Therefore, the present invention has been made in view of the above-described problems, and it is possible to reduce the time required for autofocus, and the user can adjust the usability such as holding the battery and ease of framing. An object is to provide a possible imaging device.

  That is, the image pickup apparatus of the present invention includes two image pickup optical systems provided in parallel with each optical axis being separated by a predetermined distance, and two object images formed by the image pickup optical systems are converted into image signals, respectively. An imaging device including an imaging device and an input unit for a user to input an imaging operation start command, wherein each image is generated based on two images generated by image signals converted by the imaging devices. A subject distance calculation unit that calculates a subject distance that is a separation distance from the imaging location for the same subject, and a focus position of each imaging optical system is moved along the optical axis, and a plurality of focus positions in the image An in-focus position detecting unit that detects an in-focus position based on a contrast evaluation value of the object, wherein the in-focus position detecting unit calculates the object calculated by the object distance calculating unit. Rough focus drive for moving the focus position to the vicinity of the focus position based on separation, and scan drive for scanning the focus lens from the focus position to the focus position after the rough focus drive is performed. The in-focus mode detection unit performs at least a rough focus drive in a state where an imaging operation start command is not input by the user to the input unit, and the input unit Further, it is possible to switch between a post-input mode in which rough focus driving is performed after an imaging operation start command is input by the user.

  In addition, the imaging method of the present invention includes two imaging optical systems provided in parallel with each optical axis being separated by a predetermined distance, and two subject images formed by the imaging optical systems, each of which is converted into an image signal. An imaging method using an imaging device including an imaging device and an input unit for a user to input an imaging operation start command, wherein two images generated by an image signal converted by each imaging device Based on the subject distance calculating step for calculating a subject distance that is a distance from the imaging location for the same subject in each image, and by moving the focus position of each imaging optical system, An in-focus position detecting step for detecting an in-focus position based on a contrast evaluation value of the object, wherein the in-focus position detecting step includes the object distance calculating step. A rough focus driving step for moving the focus position to the vicinity of the in-focus position based on the subject distance calculated in step (b), and after performing the rough focus driving, the focus position is changed from the vicinity of the in-focus position to the in-focus position. A pre-input mode in which the focus position detecting step performs at least a rough focus driving step in a state where an imaging operation start command is not input to the input unit by the user; And a switching step for switching between a post-input mode in which a rough focus driving step is performed after an imaging operation start command is input by the user to the input unit.

  In such a case, since the user can switch between the pre-input mode and the post-input mode, for example, the subject moves around, and the time required for focusing can be increased rather than the power consumption. If you want to give priority to shortening as much as possible, set the in-focus position detector to the pre-input mode so that the focus lens position is always near the in-focus position to maximize autofocus, If it is not necessary and priority is given to the power consumption and the quality of the through image for framing, the palm position detection unit can be set to the post-input mode. That is, it becomes possible for the user to make adjustments according to the purpose with respect to the speeding up of autofocus and the trade-off problem that appears along with it.

  Further, the subject distance calculation unit can calculate the subject distance from only the image and estimate the in-focus position without performing the lens scan movement using the two imaging optical systems. The detection unit does not make a mistake in the driving direction of the focus position, and can detect an accurate in-focus position only by scanning the focus position for a very small range. Accordingly, it is possible to dramatically reduce the time required for detecting the in-focus position by contrast AF.

  Furthermore, the calculation of the subject distance by the subject distance calculation unit is configured to be performed using two imaging optical systems, so there is no need to separately provide a measurement sensor such as an external light passive sensor. The cost increase due to the increase of In addition, since two image pickup optical systems are used, problems relating to parallax and zooming that occur when an observation optical system such as a sensor is separately provided cannot occur in principle.

  As a specific aspect for the calculation of the subject distance by the subject distance calculation unit, the subject distance calculation unit may measure the distance from each optical axis of the subject image formed on each of the two imaging elements, or There is one configured to calculate the subject distance based on the relative positional relationship between the subjects in the images simultaneously captured by the imaging optical system.

  As a specific mode for the focus position detection unit to determine the direction in which the focus position is driven toward the focus position side without making a mistake, the focus position detection unit may calculate the subject distance. And the driving direction of the focus position is determined based on the subject distance calculated by the unit and the current focus position.

  As a specific method for balancing autofocus speed, power consumption, etc. in the pre-input mode and the post-input mode, the in-focus position detection unit can be used in the pre-input mode and the post-input mode. Examples include those set with different driving speeds for rough focus driving.

  Drive in the pre-input mode to maintain the image quality of the through image displayed on the monitor to some extent and make framing easier and keep the focus position of the imaging optical system near the focus position before shooting. The speed should just be set slower than the drive speed in the post-input mode.

  In order to be able to shoot with almost no waiting time when inputting a shooting operation start command by the input unit, and to prevent an increase in power consumption due to the lens driving unnecessarily before starting shooting, The in-focus position detection unit may be configured to perform only rough focus driving in the pre-input mode.

  As described above, according to the imaging apparatus of the present invention, since the in-focus position detection unit can be operated in two modes, the pre-input mode and the post-input mode, The autofocus speed may be increased to some extent, and the user can appropriately select and adjust the case where priority is given to the elements related to usability such as power consumption and ease of framing.

1 is a schematic front perspective view showing an imaging apparatus according to an embodiment of the present invention. The typical back perspective view showing the imaging device in the embodiment. FIG. 2 is a functional block diagram illustrating an electrical configuration of the entire imaging apparatus according to the embodiment. The functional block diagram of the structure regarding the autofocus in the embodiment. The conceptual diagram for demonstrating the principle which measures the to-be-photographed object distance in the embodiment. The schematic diagram which shows an example of the evaluation value detection area | region in the embodiment. The schematic diagram explaining another method for measuring a to-be-photographed object distance. The conceptual diagram which shows operation | movement of the focus lens in contrast AF in the embodiment. The flowchart which shows the operation | movement in the after-input mode in the embodiment. The flowchart which shows the operation | movement in the mode before input in the same embodiment.

  An embodiment of the present invention will be described with reference to the drawings.

  The imaging apparatus 100 according to the present embodiment is for capturing a stereoscopic image. As shown in the front perspective view of FIG. 1, two lens barrels that hold the imaging optical system 1 are provided on the front surface when the power is turned on. In addition to being provided so as to protrude side by side, a strobe device 38 and the like are provided. These lens barrels are housed inside when the power is off. Further, as shown in the rear perspective view of FIG. 2, a monitor 35 for stereoscopically viewing the captured image and operation keys 53 used for various operations are provided on the back surface. The monitor 35 is, for example, a parallax barrier type 3D monitor. On the upper surface, a shutter button 51 used for performing a shutter release operation and a mode dial 52 for switching a photographing mode are provided.

  That is, the imaging apparatus 100 converts two imaging optical systems 1 in which the optical axes 14 are spaced apart from each other by a predetermined distance and the subject image formed by the imaging optical systems 1 to image signals. Two imaging elements 2 are provided, and two images with parallax can be generated by simultaneously capturing images with the two imaging optical systems 1. A stereoscopic image that is stereoscopically displayed on the monitor 35 is generated based on these two images having parallax.

  FIG. 3 shows an electrical configuration of the imaging apparatus 100 of the present embodiment as a functional block. As shown in FIG. 3, two image pickup optical systems 1, two image pickup devices 2, an image signal processing circuit 31, a VRAM 32, an evaluation value calculation circuit 33, a display image processing circuit 34, a monitor 35, a compression processing circuit 36, and a recording medium 37, the CPU 41, the memories 42, 43, and the like cooperate to exhibit a function as a so-called digital camera. Each part will be described below.

  A configuration common to the two imaging optical systems 1 will be described. When it is necessary to distinguish between the two image pickup optical systems 1 and the image pickup device 2, the image pickup optical system 1 for generating the left image forming the stereoscopic image generates the first right image forming the stereoscopic image. The imaging optical system 1 for doing so is distinguished by attaching a second. The respective imaging optical systems 1 are provided in parallel so as to be separated from each other by a distance substantially the same as the parallax of human eyes so that the respective optical axes 14 are parallel to each other. The imaging optical system 1 is configured by arranging the zoom lens 11, the diaphragm 12, and the focus lens 13 in this order from the outside along the optical axis 14, and the imaging element 2 is behind the focus lens 13. It is provided. As the imaging device 2, for example, a CCD type or CMOS type image sensor is used.

  An iris motor is connected to the diaphragm 12 and is used to control the exposure amount by limiting the luminous flux by changing the value of the diaphragm 12 during the AE (Auto Exposure) operation. In addition, a lens motor is connected to the focus lens 13, and the focus lens 13 is moved along the optical axis 14 of the imaging optical system 1 during an AF (Auto Focus) operation, so that the focus position of the imaging optical system 1 is reached. Is adjusted to adjust the focus.

  The image pickup device 2 changes the subject image formed by the image pickup optical system 1 into an image signal. A timing generator 21 (TG) is connected to the image sensor 2, and photocharge accumulation and transfer operations of the image sensor 2 are controlled by the TG 21. The diaphragm 12 and the focus lens 13 are controlled by a CPU 41 via drivers 15 and 16, and the image sensor 2 is controlled by a CPU 41 via a timing generator 21 (TG).

  The image signal output from the imaging device 2 is input in the order of a correlated double sampling circuit (CDS), an amplifier (AMP) 22, and an A / D converter (ADC) 23, and converted from analog data to digital data. Is done. The image controller 24 controls input / output of the image signal converted into digital data. The image signal is input to the image signal processing circuit 31 and subjected to gradation conversion, white balance correction, γ correction processing, etc., and the first image picked up by the first image pickup optical system 1 and the second image pickup optical system As a second image picked up by 1, they are temporarily stored separately in predetermined areas A and B of the VRAM 32, respectively. Each image stored in the VRAM 32 is updated at predetermined intervals. More specifically, the timing generator 21 updates the image pickup device 2 as exposure and image signal output are repeated every 1/30 seconds (one frame).

  The evaluation value calculation circuit 33 calculates an AF evaluation value, an AE evaluation value, and the like from each of the first and second images stored in the VRAM 32. In the present embodiment, the AF evaluation value corresponds to a phase difference evaluation value of two images and a contrast evaluation value. The phase difference evaluation value is used in the calculation of the subject distance described later. The contrast evaluation value is calculated by accumulating high-frequency components of luminance values for a predetermined region (for example, a plurality of regions surrounded by a line shown in FIG. 6) of each image. That is, the contrast (brightness difference) between adjacent pixels is added in a predetermined area. The AE evaluation value is calculated by integrating the luminance value for a predetermined area of each image data, and represents the brightness of the image. The contrast evaluation value and the AE evaluation value are respectively used in an AF operation and an AE operation which will be described later.

  The display image processing circuit 34 synthesizes a stereoscopic image for stereoscopic display on the LCD monitor 35 based on the first and second images stored in the VRAM 32. When the photographing mode is selected by the mode dial 52 and the LCD monitor 35 is used as a viewfinder, a stereoscopic image synthesized by the display image processing circuit 34 is displayed via the LCD driver 351 on the LCD monitor 35. Displayed as a through image. Further, depending on the mode, the image stored in the VRAM 32 may be displayed as it is on the LCD monitor 35 without using the stereoscopic composite image.

  The compression processing circuit 36 performs compression processing on the first and second images stored in the VRAM 32 using a compression format such as the JPEG method. The media controller 371 stores each image compressed by the compression processing circuit 36 in a recording medium 37 such as a memory 42 or 43 card. Further, when the view mode is selected by the mode dial 52, the stereoscopic image generated by the display image processing circuit 34 based on the first and second images stored in the recording medium 37 is Displayed on the monitor 35.

  The monitor 35 is an LCD monitor and has a parallax barrier display layer on its surface, although its detailed structure is not shown. When performing the stereoscopic display, the monitor 35 generates a parallax barrier having a pattern in which light transmitting portions and light shielding portions are alternately arranged at a predetermined pitch on the parallax barrier display layer. Stereoscopic viewing is possible by alternately arranging strip-shaped image fragments showing left and right images on the surface.

  The CPU 41 controls the overall operation of the imaging apparatus 100 in an integrated manner. In addition to the shutter button 51, mode dial 52, and various operation keys 53, the CPU 41 is connected to a nonvolatile memory 43.

  The shutter button 51 corresponds to an input unit in claims, and has a two-stage push switch structure. When the shutter button 51 is lightly pressed (half pressed) by the user, an imaging preparation operation is started. In the present embodiment, as will be described later, a post-input mode in which all AF operations are started when the shutter button 51 is half-pressed, and a part of the AF operation is performed before the shutter button 51 is half-pressed. There is a pre-input mode that has already started. For example, the mode is switched on the mode dial 52 or the setting screen. When the shutter button 51 is strongly pressed (fully pressed), shooting processing is performed, and the first and second images for one screen are transferred from the VRAM 32 to the recording medium 37 and stored.

  The nonvolatile memory 43 stores various control programs and setting information. Thus, the CPU 41, the SDRAM 42, the nonvolatile memory 43, various circuits, and the like cooperate to configure at least the functions of the subject distance calculation unit 6 and the focus position detection unit 7 based on the program and setting information. It is. Each of these units controls an operation related to autofocus, and a functional block diagram illustrating a configuration related to autofocus by simplifying the imaging apparatus 100 is as shown in FIG.

  The subject distance calculation unit 6 calculates a subject distance, which is a distance from the imaging location, for the same subject in each image, based on the two images generated from the image signals converted by each imaging element 2. It is constituted as follows.

  The subject distance is measured on the basis of the principle of triangular side distance as follows, and when there are two imaging optical systems 1 as shown in FIG. 5, each imaging optical system 1 has parallax. In accordance with the distance from the imaging optical system 1 to the subject, a shift occurs in the position where the image is formed on the imaging element 2. Here, the distance between the optical axes 14 of each imaging optical system 1 that is the magnitude of parallax is B, the distance from the principal point of the imaging optical system 1 to the imaging element 2 is f, and a certain subject is relative to the first imaging element 2. The amount of the image formation position where the image is formed is deviated from the optical axis 14 of the first image pickup optical system 1, and the image of the second image pickup optical system 1 is imaged on the second image pickup device 2. When the amount of deviation from the axis 14 is D2 and the distance from the principal point of the imaging optical system 1 to the subject is L, the subject distance is calculated from L = Bf / (D1 + D2) from the similarity condition of the triangle. Can do. Here, since f and B are known values from the setting information of the imaging apparatus 100, D1 + D2 may be obtained. This D1 + D2 is imaged by each imaging optical system 1 and imaging element 2, and the evaluation value calculation circuit 33 compares the first and second images stored in the VRAM 32 to detect the imaging position of the subject. Thus, D1 + D2 is calculated. Based on this information, the evaluation value calculation circuit 33 outputs the subject distance. Specifically, the evaluation value calculation circuit 33 calculates D1 + D2 for a subject in an area surrounded by three square frames in each image of FIG. 7, and based on this, calculates the subject distance of the subject in each area. calculate. For example, the subject distance of the background in the square frame area on the right side of FIG. 6 is 15 m, the subject distance of the face of the person who is the subject in the center area is 3.0 m, and the object distance in the left area is The subject distance for each region is output such that the subject distance of the trunk is 3.3 m.

  Note that the method for calculating the subject distance is not limited to that described above. For example, the first image and the second image shown in FIG. 7A are simply superimposed as shown on the right side of FIG. 7B. Instead, as shown on the right side of FIG. 7B, the imaging position on the image sensor 2 is determined from the amount of shift of each subject in the image, which is generated by superimposing the first image and the second image at the in-focus position. The deviation amount D1 + D2 can also be calculated, and the evaluation value calculation circuit 33 may be configured as such.

  The focus position detection unit 7 moves the focus position of each imaging optical system 1 and detects the focus position based on the contrast evaluation value of the subject in the image at a plurality of focus positions. Specifically, when the focus lens 13 is scanned, a point at which the contrast evaluation value obtained from the evaluation value calculation circuit 33 becomes an extreme value is detected as a position focused on the subject, and each focus lens is moved to that position. 13 is moved so that the focus position matches the in-focus position.

  Further, the focus position detection unit 7 performs rough focus driving for moving the focus position to the vicinity of the focus position at high speed based on the subject distance calculated by the subject distance calculation unit 6 and after performing the rough focus drive. And the scan driving for moving the focus position at a low speed from the focus position to the focus position. Specifically, first, a subject to be focused is determined based on a multipoint algorithm for determining a subject to be focused from the subject distances of the three regions calculated by the subject distance calculation unit 6. In the multi-point algorithm of the present embodiment, it is determined to focus on the closest subject, but the focused subject may be determined based on other criteria. For example, other conditions such as whether or not the subject is a person may be considered. When the subject to be focused is determined, the focus position is calculated from the subject distance of the subject, and rough focus driving is performed to drive the focus lens 13 at high speed so that the focus position moves in the vicinity of the focus position. It is. Thereafter, from the vicinity of the in-focus position to the in-focus position, low-speed scan driving is performed in order to detect the in-focus position by contrast AF. Since it is necessary to detect the position where the contrast evaluation value becomes an extreme value (peak) in order to detect the in-focus position, the focus lens 13 is detected after moving the focus lens 13 until the extreme value is exceeded once in scan driving. The focus lens 13 is moved to the in-focus position by high-speed movement to the in-focus position.

  In this way, the subject distance of the subject to be focused is calculated by the subject distance calculation unit 6, and the focus position can be almost specified in advance. Therefore, when the focus position is searched by contrast AF, the focus lens 13 is driven in the correct direction. Further, the focus lens 13 can be driven at a higher speed than the contrast AF scan drive up to the vicinity of the in-focus position, and the focus lens 13 can be scan-driven at a low speed only in a very limited region. Therefore, the time required for autofocus can be dramatically shortened.

  The in-focus position detection unit 7 is at least in a state in which the shutter button 51 as an input unit is not half-pressed by the user and the imaging operation start command is not input by the mode setting of the mode dial 52. It is possible to switch between a pre-input mode in which rough focus driving is performed and a post-input mode in which rough focus driving is performed after the shutter button 51 is half-pressed by the user and an imaging operation start command is input to the input unit. It is. In addition, in the pre-input mode and the post-input mode, the moving speed of the focus lens 13 in the rough focus drive is different. Specifically, the drive speed in the pre-input mode is set slower than the drive speed in the post-input mode.

  The operation of the imaging apparatus 100 configured as described above will be described with reference to the flowchart of FIG. First, an operation in a state where the mode of the in-focus position detection unit 7 is selected as the post-input mode by the mode dial 52 will be described with reference to a flow from power activation to the end of imaging.

  First, when the power is turned on (step S1), exposure to each image sensor 2 is started, and each image generated thereby is stored in the VRAM 32. The evaluation value calculation circuit 33 reads these images (step S2) and calculates an AE evaluation value (step S3). A proper exposure control value for the AE evaluation value to be a proper value is calculated (step S4), and a set value is set in the driver of the iris motor so that the exposure amount for the stop 12 is set (step S4). S5). Thereafter, a stereoscopic image generated by the display image processing circuit 34 based on the image in the state of proper exposure is displayed on the monitor 35 (step S6). Here, since the post-input mode is selected by the mode dial 52, the subject distance calculation unit 6 and the focus position detection unit 7 are on standby until the shutter switch is half-pressed by the user.

  Next, when the shutter button 51 is half-pressed by the user (step S7), the subject distance calculation unit 6 is newly exposed to the image sensor 2, and the generated image is read from the VRAM 32 (step S8). The subject distance is calculated from the two images by phase difference calculation (step S9). Thereafter, the focus position detection unit 7 determines which subject is to be a focused subject based on the subject distances of a plurality of subjects output from the subject distance calculation unit 6 based on a multipoint algorithm ( Step S10). The focus position detection unit 7 determines a direction in which the focus lens 13 should be driven based on the subject distance of the focused subject, and then determines a predetermined position near the focus position where the focused subject is focused. The focus lens 13 is moved at a high speed by rough focus driving to a position at a distance away (step S11).

  When the focus lens 13 is moved to a position before the in-focus position, the operation of the in-focus position detection unit 7 is switched to an operation for contrast AF. First, the focus position is changed by scan driving, and a new image that is newly exposed to the image sensor 2 and stored in the VRAM 32 is read (step S12). Thereafter, the contrast evaluation value calculated by the evaluation value calculation circuit 33 is continuously acquired (step S13), and the peak value is determined depending on whether or not the increasing tendency is completed by comparing the currently acquired contrast evaluation value with the previously acquired contrast evaluation value. A determination is made (step 14). If it is determined that the peak continues to increase and is not a peak (step S15), the focus lens 13 continues to move, the contrast evaluation value starts to decrease, and the position of the focus lens 13 exceeds the in-focus position. This determination is repeated until it is determined. If there is a peak in the contrast evaluation value, a focus position is calculated from the position where the peak is present (step S16). Thereafter, the focus position detection unit 7 reverses the moving direction of the focus lens 13. Then, the focus lens 13 is moved to the in-focus position at high speed (step S17).

  If the half-press of the shutter switch is released by the user, the process returns to step S2 (step S18). If the shutter switch is fully pressed (step S19), shooting is performed at the in-focus position. It is executed (step S20).

  Next, the case where the pre-input mode is selected will be described with reference to the flowchart of FIG. When the pre-input mode is selected by the mode dial 52, the operation in the post-input mode and the pre-input mode are the same except that the operations of the subject distance calculation unit 6 and the focus position detection unit 7 are partially different. The operation is substantially the same. Therefore, only the different parts will be described in detail.

  When the pre-input mode is selected, steps SS1 to SS6 in the pre-input mode are the same from steps S1 to S6 in the post-input mode. In the pre-input mode, the difference is that steps S8 to S11 in the post-input mode are performed until the shutter switch is half-pressed by the user.

  That is, as shown in FIG. 10, the subject distance calculation unit 6 newly exposes the image sensor 2, reads the generated image from the VRAM 32 (step SS7), and calculates the subject distance from the two images by phase difference calculation. (Step SS8). Thereafter, the focus position detection unit 7 determines which subject is to be a focused subject based on the subject distances of a plurality of subjects output from the subject distance calculation unit 6 based on a multipoint algorithm ( Step SS9). The focus position detection unit 7 determines a direction in which the focus lens 13 should be driven based on the subject distance of the focused subject, and then determines a predetermined position near the focus position where the focused subject is focused. The focus lens 13 is moved at a high speed by rough focus driving to a position at a distance away (step SS10). Since the operation up to Step SS10 is repeated until the shutter switch is half-pressed by the user, the focus lens 13 is always kept in the vicinity of the in-focus position where the subject is focused. . At this time, if the moving speed of the focus lens 13 is too fast, the quality of the image displayed on the monitor 35 is reduced, and the power consumption due to the continuous driving of the focus lens 13 is reduced. Therefore, compared with the post-input mode, the driving speed of rough focus driving is set slower in this pre-input mode.

  Next, when the shutter switch is half-pressed by the user (step SS11), the in-focus position detector 7 immediately starts the in-focus operation by contrast AF. Note that Steps SS12 to SS20 in the pre-input mode are the same as Steps S2 to S20 in the post-input mode, and thus description thereof is omitted.

  Here, since the position of the focus lens 13 is maintained in the vicinity of the in-focus position before the shutter switch is pressed, the range to be scanned is narrow and the focus lens 13 is instantaneously moved to the in-focus position. Can be made. In other words, if the pre-input mode is set, the user is in focus before half-pressing the shutter switch, and can be focused immediately after half-pressing. Can focus on. On the contrary, if the post-input mode is set, although it is not the fastest focus speed, it is power saving and the quality of the through image displayed on the monitor 35 can be improved, and framing is performed slowly. This is suitable for a case where the operating time of the imaging apparatus 100 is to be extended.

  As described above, since the in-focus position detection unit 7 is configured to be able to switch between the post-input mode and the pre-input mode, the user can appropriately balance the focus speed and the usability.

  Other embodiments will be described.

  In the embodiment, the speed of rough focus driving is different in the post-input mode and the pre-input mode, but other parameters may be different. For example, the period in which the subject distance calculation unit calculates the subject distance may be longer in the pre-input mode than in the post-input mode, and the frequency with which the focus lens is driven near the in-focus position may be reduced. In this way, even if the driving speed is the same, it is possible to prevent an increase in power consumption due to fine driving of the focus lens.

  In the above-described embodiment, only the rough focus drive is performed in the pre-input mode. However, if priority is given to the focus speed, the scan drive is configured so that the subject is always focused. It doesn't matter if you do.

  The subject distance calculation method and the contrast evaluation value calculation method described in the above embodiment are merely examples, and other methods may be used. In the above-described embodiment, the imaging apparatus is used to perform stereoscopic imaging. However, for example, there may be a mode in which a normal planar image can be captured using only one imaging optical system.

  In the above embodiment, only the focus lens is driven to focus on the subject, but the zoom lens may be driven to focus. In the above embodiment, the movement of the focus lens and the movement of the focus position correspond one-to-one. However, any drive system can be used as long as it moves the focused position as the imaging optical system. I do not care.

  In addition, various modifications and combinations of embodiments may be performed without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 100 ... Imaging device 1 ... Imaging optical system 2 ... Imaging element 6 ... Subject distance calculation part 7 ... Focus position detection part 51 ... Input part (shutter switch)

Claims (12)

Two image pickup optical systems provided in parallel with each optical axis being separated by a predetermined distance, two image pickup elements for converting subject images formed by each image pickup optical system into image signals, and a user starts an image pickup operation An input device for inputting a command, and an imaging device comprising:
A subject distance calculation unit that calculates a subject distance that is a separation distance from the imaging location for the same subject in each image based on two images generated by the image signal converted by each imaging element;
A focus position detection unit that moves the focus position of each imaging optical system and detects the focus position based on the contrast evaluation value of the subject in the image at a plurality of focus positions; and
The focus position detection unit moves the focus position to the vicinity of the focus position based on the subject distance calculated by the subject distance calculation unit, and the focus position after performing the rough focus drive. And a scan drive that scans and moves from the vicinity of the in-focus position to the in-focus position, and
The in-focus position detection unit inputs at least a rough focus drive in a state where an imaging operation start command is not input by the user to the input unit, and an imaging operation start command is input by the user to the input unit An image pickup apparatus configured to be able to switch between a post-input mode in which rough focus driving is performed after being performed.   The subject distance calculation unit is based on the distance from each optical axis of the subject image formed on each of the two imaging elements or the relative positional relationship of the subject in each image simultaneously captured by each imaging optical system. The imaging apparatus according to claim 1, wherein the imaging apparatus is configured to calculate the subject distance.   The focus position detection unit is configured to determine a drive direction of the focus position based on the subject distance calculated by the subject distance calculation unit and a current focus position. Imaging device.   The imaging apparatus according to claim 1, wherein the in-focus position detection unit is set with different driving speeds of rough focus driving in the pre-input mode and the post-input mode.   The imaging apparatus according to claim 1, wherein the driving speed in the pre-input mode is set slower than the driving speed in the post-input mode.   The imaging apparatus according to claim 1, wherein the focus position detection unit is configured to perform only rough focus driving in the pre-input mode. Two image pickup optical systems provided in parallel with each optical axis being separated by a predetermined distance, two image pickup elements for converting subject images formed by each image pickup optical system into image signals, and a user starts an image pickup operation An imaging method using an imaging device including an input unit for inputting a command,
A subject distance calculating step for calculating a subject distance, which is a distance from the imaging location, for the same subject in each image, based on two images generated by the image signal converted by each imaging element;
A focus position detecting step of moving a focus position of each imaging optical system and detecting a focus position based on a contrast evaluation value of a subject in the image at a plurality of focus positions;
The focus position detecting step moves the focus position to the vicinity of the focus position based on the subject distance calculated in the subject distance calculating step, and the focus after the rough focus drive is performed. A scan driving step of moving the position from the vicinity of the in-focus position to the in-focus position, and
The in-focus position detection step includes a pre-input mode in which at least a rough focus driving step is performed in a state where an imaging operation start command is not input by the user to the input unit, and an imaging operation start command is input by the user to the input unit. An imaging method comprising: a switching step for switching between a post-input mode in which a rough focus driving step is performed after input.   In the subject distance calculation step, based on the distance from each optical axis of the subject image formed on each of the two imaging elements, or the relative positional relationship of the subject in each image simultaneously captured by each imaging optical system. The imaging method according to claim 7, wherein the subject distance is calculated.   The imaging method according to claim 7 or 8, wherein, in the focus position detecting step, a driving direction of the focus position is determined based on the subject distance calculated in the subject distance calculating step and a current focus position.   10. The imaging method according to claim 7, 8 or 9, wherein the in-focus position detecting step is set with different driving speeds of a rough focus driving step in the pre-input mode and the post-input mode.   11. The imaging method according to claim 7, wherein the driving speed in the pre-input mode is set slower than the driving speed in the post-input mode.   The imaging apparatus according to claim 7, 8, 9, 10 or 11, wherein, in the in-focus position detecting step, only a rough focus driving step is performed in the pre-input mode.