JP2019053315A - Focus adjustment device and imaging device - Google Patents

Abstract

To provide a focus adjustment device capable of appropriately adjusting the focus state of an optical system.SOLUTION: A focus adjustment device comprises: a first optical receiver 137 having a first spectral characteristic, which receives a light flux from an optical system to output a first output value; a second optical receiver 160d having a second spectral characteristic different from the first spectral characteristic, which receives a light flux from the optical system to output a second output value; a focus adjustment part 170 for adjusting the focus state of the optical system; and a computation unit 170 for calculating a correction amount according to an optical component which is not detected by the first optical receiver 137 but is detected by the second optical receiver 160d, on the basis of the first output value and the second output value. The focus adjustment part 170 adjusts the focus state of the optical state on the basis of the correction amount.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a focus adjustment device and an imaging device.

  Conventionally, there has been known a focus adjusting device that calculates a defocus amount based on an image shift amount by an optical system and adjusts a focus state of the optical system based on the calculated defocus amount. In such a focus adjustment device, in order to prevent out-of-focus due to chromatic aberration, it is determined whether the light source is a fluorescent lamp based on the output difference between two photometric sensors having different spectral characteristics, and the light source is a fluorescent lamp. A technique is known that corrects the defocus amount with a constant correction amount based on chromatic aberration data of a fluorescent lamp when it is determined that there is (see, for example, Patent Document 1).

JP2013-211885A

  However, since the conventional technology corrects the defocus amount with a uniform correction amount based on the chromatic aberration data of the fluorescent lamp when the light source is determined to be a fluorescent lamp, the light environment changes depending on the weather during outdoor shooting. In some cases, the focus state of the optical system cannot be appropriately adjusted according to the wavelength or light amount of the received light, for example, when there are a plurality of light sources.

  The present invention solves the above problems by the following means.

  [1] A focus adjustment apparatus according to the present invention has a first spectral characteristic, receives a light beam from an optical system and outputs a first output value, and the first spectral characteristic. A second light receiving unit having a second spectral characteristic different from that of the optical system, receiving a light beam from the optical system and outputting a second output value, a focus adjusting unit for adjusting a focus state of the optical system, A calculation unit that calculates a correction amount according to a light component that is not detected by the first light receiving unit but is detected by the second light receiving unit, based on the first output value and the second output value; The focus adjustment unit adjusts the focus state of the optical system based on the correction amount.

[2] In the invention related to the focus adjustment device, the calculation unit calculates an image shift amount by the optical system based on the first output value, and the focus adjustment unit calculates the shift amount and the correction. The focus state of the optical system can be adjusted based on the amount.

  [3] In the invention related to the focus adjusting apparatus, the first spectral characteristic and the second spectral characteristic may be configured to have different light receiving sensitivities in at least a near-infrared light region.

  [4] In the invention related to the focus adjustment apparatus, the first spectral characteristic may be configured to be substantially the same as the spectral characteristic of the imaging device.

  [5] In the invention related to the focus adjusting apparatus, the first light receiving unit may be a photometric sensor, and the second light receiving unit may be a focus detecting sensor.

  [6] In the invention related to the focus adjustment device, an illumination device that irradiates near infrared light is built in or detachable, and the focus adjustment unit is irradiated with the near infrared light by the illumination device. In this case, the focus state of the optical system can be adjusted based on the correction amount.

  [7] An imaging apparatus according to the present invention includes the above-described focus adjustment apparatus.

  According to the present invention, it is possible to appropriately adjust the focus state of the optical system.

FIG. 1 is a block diagram showing a camera according to the present embodiment. FIG. 2 is a graph showing the spectral characteristics of the photometric sensor. FIG. 3 is a schematic diagram showing the configuration of the line sensor and its peripheral components. FIG. 4 is a graph showing the spectral characteristics of the line sensor. FIG. 5 is a flowchart showing correction amount calculation processing according to the present embodiment. FIG. 6 is a flowchart showing the focus adjustment processing according to the present embodiment. FIG. 7 is a graph for explaining the near infrared light content. FIG. 8 is a graph for explaining a correction amount calculation method.

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

  FIG. 1 is a block diagram showing a single-lens reflex digital camera 1 according to this embodiment. As shown in FIG. 1, the camera 1 of this embodiment includes a camera body 100, a lens barrel 200, and a strobe device 300. The camera body 100 and the lens barrel 200 are detachably coupled, and the camera body 100 and the strobe device 300 are also detachably coupled.

  The lens barrel 200 incorporates a photographing optical system including lenses 211, 212, 213 and a diaphragm 220.

  The focus lens 212 is provided to be movable along the optical axis L1 of the lens barrel 200. The position of the focus lens 212 is adjusted by the lens driving motor 230 while the position thereof is detected by the encoder 260. In the present embodiment, since the position of the focus lens 212 in the optical axis L1 direction correlates with the rotation angle of the rotary cylinder, the encoder 260 detects the relative rotation angle of the rotary cylinder with respect to the lens barrel 200, thereby focusing. The position of the lens 212 can be obtained.

  Information on the current position of the focus lens 212 detected by the encoder 260 is sent to the camera control unit 170 described later via the lens control unit 250. Then, the drive amount of the focus lens 212 calculated based on this information is sent from the lens drive control unit 165 via the lens control unit 250, and the lens drive motor 230 is driven based on this.

  The aperture 220 has an aperture diameter centered on the optical axis L1 in order to limit the amount of light flux that passes through the imaging optical system and reaches the image sensor 110 provided in the camera body 100 and adjusts the amount of blur. It is configured to be adjustable. Adjustment of the aperture diameter by the aperture 220 is performed, for example, by sending an appropriate aperture diameter calculated in the automatic exposure mode from the camera control unit 170 to the aperture drive unit 240 via the lens control unit 250. Is done. Further, the set aperture diameter is input from the camera control unit 170 to the lens control unit 250 by a manual operation by the operation unit 150 provided in the camera body 100. The aperture diameter of the aperture 220 is detected by an aperture sensor (not shown), and the lens controller 250 recognizes the current aperture diameter.

  As shown in FIG. 1, the camera 1 of the present embodiment includes a strobe device 300. The strobe device 300 is provided with a main light emitting unit 301 and is driven to emit light by a strobe driving unit 302 configured by a light emitting circuit. The light emission amount and the light emission timing of the main light emission unit 301 are controlled by a control signal from the camera control unit 170.

  Further, the strobe device 300 is provided with an AF auxiliary light emitting unit 303, which is driven to emit light by an AF auxiliary light driving unit 304 configured by a light emitting circuit. The emission of the AF auxiliary light is controlled by the camera control unit 170. For example, when the camera control unit 170 determines that the subject has low luminance or the subject has a low contrast, a control signal for emitting AF auxiliary light is sent to the AF auxiliary light driving unit 304. Based on this, the AF auxiliary light driving unit 304 performs the driving of AF auxiliary light.

  In the present embodiment, the AF auxiliary light emitting unit 303 includes a red LED. The AF auxiliary light emitting unit 303 irradiates light having a wavelength in the near infrared region near 650 nm to 740 nm (near infrared light) as AF auxiliary light, for example. Thereby, when the subject is a person, it is possible to effectively prevent the person from feeling that the AF auxiliary light is dazzling.

  On the other hand, the camera body 100 includes a mirror system 120 for guiding the light flux from the subject to the image sensor 110, the finder 135, the photometric sensor 137, and the focus detection unit 160. The mirror system 120 includes a quick return mirror 121 that rotates by a predetermined angle between the observation position and the photographing position of the subject around the rotation axis 123, and the quick return mirror 121 that is pivotally supported by the quick return mirror 121. And a sub mirror 122 that rotates in accordance with the rotation. In FIG. 1, a state where the mirror system 120 is at the observation position of the subject is indicated by a solid line, and a state where the mirror system 120 is at the photographing position of the subject is indicated by a two-dot chain line.

  The mirror system 120 is inserted on the optical path of the optical axis L1 in the state where the subject is in the observation position, while rotating so as to retract from the optical path of the optical axis L1 in the state where the subject is in the photographing position.

  The quick return mirror 121 is a half mirror. In a state where the quick return mirror 121 is at the observation position of the subject, a part of the light flux (optical axis L2, L3) from the subject (optical axis L1) is reflected by the quick return mirror 121 to be used for the finder 135 and photometry. The light is guided to the sensor 137 and a part of the light beam (optical axis L4) is transmitted and guided to the sub mirror 122. On the other hand, the sub mirror 122 is configured by a total reflection mirror, and guides the light beam (optical axis L4) transmitted through the quick return mirror 121 to the focus detection unit 160.

  Therefore, when the mirror system 120 is at the observation position, the light beam (optical axis L1) from the subject is guided to the finder 135, the photometric sensor 137, and the focus detection unit 160, and the subject is observed by the photographer and exposure calculation is performed. And the focus adjustment state of the focus lens 212 is detected. When the photographer fully presses a release button (not shown), the mirror system 120 is rotated to the photographing position, and all the light flux (optical axis L1) from the subject is guided to the image sensor 110, and the photographed image data is illustrated. Do not save to memory.

  The light flux from the subject reflected by the quick return mirror 121 forms an image on a focusing screen 131 disposed on a surface optically equivalent to the image sensor 110 and can be observed through the pentaprism 133 and the eyepiece lens 134. It has become. At this time, the transmissive liquid crystal display 132 superimposes and displays a focus detection area mark on the subject image on the focusing screen 131 and relates to shooting such as the shutter speed, aperture value, and number of shots in an area outside the subject image. Display information. As a result, the photographer can observe the subject, its background, and photographing related information through the finder 135 in the photographing preparation state.

  In addition, a photometric lens 136 and a photometric sensor 137 are provided in the vicinity of the eyepiece lens 134 to receive a part of subject light imaged on the focusing screen 131. The photometric sensor 137 divides the photographing screen into a plurality of regions and outputs a photometric signal corresponding to the luminance of each region in order to calculate the exposure value at the time of photographing. A signal detected by the photometric sensor 137 is output to the camera control unit 170 and used for automatic exposure control and focus adjustment.

  Here, FIG. 2 is a graph showing the spectral characteristics of the photometric sensor 137. In the present embodiment, the photometric sensor 137 is constituted by a two-dimensional color CCD image sensor or the like, and has a plurality of pixels arranged two-dimensionally on the plane of the light receiving surface. The plurality of pixels, like the respective pixels constituting the image sensor 110, include a green pixel G having a color filter that transmits a green wavelength region, a red pixel R having a color filter that transmits a red wavelength region, A blue pixel B having a color filter that transmits a blue wavelength region is a so-called Bayer Arrangement. Therefore, the spectral characteristic of the photometric sensor 137 is the sum of the spectral characteristic of the green pixel G, the spectral characteristic of the red pixel R, and the spectral characteristic of the blue pixel B, as in the image sensor 110. On the other hand, the red pixel R constituting the photometric sensor 137 has high sensitivity to light in the red wavelength region, but has low sensitivity to near-infrared light that cannot be detected by human eyes. Therefore, in the spectral characteristics of the photometric sensor 137, as shown in FIG. 2, the light receiving sensitivity in the wavelength region near 730 nm, which is the center wavelength of AF auxiliary light (near infrared light), is low.

  Returning to FIG. 1, the focus detection unit 160 is an apparatus for executing automatic focusing control by a phase difference detection method using subject light. The focus detection unit 160 has a light receiving surface at a position optically equivalent to the imaging surface of the imaging device 110 of the light beam (optical axis L4) reflected by the sub mirror 122. The focus detection unit 160 acquires a pair of image signals by receiving a pair of light beams passing through a pair of regions having different exit pupils of the focus lens 212 with a pair of line sensors 160d provided on the light receiving surface.

  FIG. 3 is a diagram illustrating a configuration example of the line sensor 160d and its peripheral components. In the present embodiment, as shown in FIG. 3, the focus detection unit 160 includes a condenser lens 160a, a diaphragm mask 160b having a pair of openings, a pair of re-imaging lenses 160c, and a pair of line sensors 160d. Have As described above, the focus detection unit 160 receives a pair of light beams passing through a pair of regions having different exit pupils of the focus lens 212 by the pair of line sensors 160d. The focus detection unit 160 detects the focus state of the optical system by obtaining a phase shift between the pair of image signals acquired by the pair of line sensors 160d by a known correlation calculation.

  For example, as shown in FIG. 2, when the subject P is imaged on the equivalent surface (scheduled imaging surface) 160e of the image sensor 110, the focused state is reached, but the focus lens 212 moves in the direction of the optical axis L1, and the result is reached. If the image point shifts from the equivalent surface 160e toward the subject (referred to as the front pin) or shifts toward the camera body 100 (referred to as the rear pin), the focus is shifted.

  When the imaging point of the subject P is shifted from the equivalent surface 160e toward the subject, the interval W between the pair of image signals detected by the pair of line sensors 160d becomes shorter than the interval W in the focused state. Conversely, when the image formation point of the subject image P is shifted to the camera body 100 side, the interval W between the pair of image signals detected by the pair of line sensors 160d becomes longer than the interval W in the focused state.

  That is, in the in-focus state, the image signals detected by the pair of line sensors 160d overlap with the center of the line sensor, but in the out-of-focus state, the image signals are shifted from the center of the line sensor. That is, since a phase difference occurs in the image signal, focusing is performed by moving the focus lens 212 by an amount corresponding to the phase difference (deviation amount).

  Specifically, the focus detection unit 160 converts the phase difference (shift amount) between the pair of image signals into a defocus amount, and transmits the defocus amount to the camera control unit 170. Accordingly, the camera control unit 170 calculates the lens drive amount according to the defocus amount transmitted from the focus detection unit 160, and transmits the calculated lens drive amount to the lens drive motor 230 via the lens control unit 250. To do. The lens drive motor 230 that has received the lens drive amount adjusts the position of the focus lens 212 by driving the focus lens 212 in accordance with the received lens drive amount.

  FIG. 4 is a graph showing the spectral characteristics of the line sensor 160d. In the present embodiment, when the luminance of the subject is low or the contrast of the subject is low, the AF auxiliary light emitting unit 303 of the strobe device 300 irradiates the subject with AF auxiliary light that is near infrared light. The AF auxiliary light applied to the subject is reflected by the subject and then received by the line sensor 160d. This makes it possible to focus on the subject even when the subject brightness is low or the subject contrast is low. In the present embodiment, when the subject is a person, light with a wavelength in the near-infrared region is emitted as AF auxiliary light so that the person does not feel the AF auxiliary light dazzling. Therefore, the spectral characteristic of the line sensor 160d according to this embodiment is designed so that the detection sensitivity of light having a wavelength in the near infrared region is higher than that of the photometric sensor 137, as shown in FIG. ing.

  Returning to FIG. 1, the image sensor 110 is provided on the camera body 100 on the optical axis L <b> 1 of the luminous flux from the subject and at a position that is a planned focal plane of the photographing optical system including the lenses 211, 212, and 213. A shutter 111 is provided on the front surface. The image sensor 110 is a two-dimensional array of a plurality of photoelectric conversion elements, and can be constituted by a two-dimensional CCD image sensor, a MOS sensor, a CID, or the like. The electrical image signal photoelectrically converted by the image sensor 110 is subjected to image processing by the camera control unit 170 and then stored in a memory (not shown). Note that the memory for storing the photographed image can be constituted by a built-in memory or a card-type memory.

  The operation unit 150 includes a shutter release button and an input switch for a photographer to set various operation modes of the camera 1, and can switch between an autofocus mode and a manual focus mode. The shutter release button switch includes a first switch SW1 that is turned on when the button is half-pressed and a second switch SW2 that is turned on when the button is fully pressed. The shutter release button switches SW1 and SW2 and various modes set by the operation unit 150 are transmitted to the camera control unit 170.

  The camera body 100 is provided with a camera control unit 170. The camera control unit 170 includes a microprocessor and peripheral components such as a memory. The camera control unit 170 is electrically connected to the lens control unit 250, receives lens information such as a focus lens position from the lens control unit 250, and sends a defocus amount, an aperture control signal, and the like to the lens control unit 250. Send information. The camera control unit 170 reads image information from the image sensor 110, performs predetermined information processing as necessary, and outputs the information to a memory (not shown). In addition to these, the camera control unit 170 controls the entire camera 1 such as correction of captured image information and detection of the focus adjustment state and the aperture adjustment state of the lens barrel 200.

  In the present embodiment, the camera control unit 170 adjusts the focus state of the optical system based on the output of the photometric sensor 137 and the output of the line sensor 160d. Conventionally, chromatic aberration may occur due to near-infrared light included in AF auxiliary light or sunlight. Due to the influence of chromatic aberration, the focus lens position focused on the image received by the line sensor 160d having higher near-infrared light detection sensitivity than the image sensor 110 and the lower-infrared light detection sensitivity lower than that of the line sensor 160d. The focus lens position that focuses on the image picked up by the element 110 is different. For this reason, even when the focus state of the optical system is adjusted based on the focus detection result (defocus amount) of the line sensor 160d, the subject may not be in focus when the subject is imaged by the image sensor 110. In order to prevent such a shift in focus due to chromatic aberration, the camera control unit 170 according to the present embodiment, like the image sensor 110, and the output value of the photometric sensor 137 with a low near-infrared light detection sensitivity, and the near-red A correction amount for correcting the defocus amount obtained by the focus detection unit 160 is calculated based on an output value from the line sensor 160d having a high external light detection sensitivity. The camera control unit 170 according to the present embodiment identifies near infrared light that is not detected by the photometric sensor 137 but is detected only by the line sensor 160d, and corrects the defocus amount based on the identified near infrared light. Thus, the focus state of the optical system is adjusted based on the corrected defocus amount. The details of the correction amount calculation method and the defocus amount correction method will be described later.

  Next, an operation example of the camera 1 according to the present embodiment will be described with reference to FIGS. FIG. 5 is a flowchart showing a correction amount calculation process for calculating a correction amount for correcting a focus shift due to chromatic aberration. FIG. 6 is a flowchart showing a focus adjustment process for adjusting the focus state of the optical system using the correction amount calculated by the correction amount calculation process shown in FIG.

  First, the correction amount calculation process shown in FIG. 5 will be described. The correction amount calculation process shown in FIG. 5 is repeatedly executed by the camera control unit 170 at predetermined time intervals. In the present embodiment, the correction amount is calculated based on the difference between the output value of the photometric sensor 137 and the output value of the line sensor 160d, but the present invention is not limited to this. The correction amount may be calculated based on the ratio between the output value of the photometric sensor 137 and the output value of the line sensor 160d.

  In step S101, the camera control unit 170 acquires the outputs of the photometric sensor 137 and the line sensor 160d. In step S102, the camera control unit 170 calculates an output difference D between the output value of the photometric sensor 137 and the output value of the line sensor 160d.

  Here, FIG. 7A is a graph in which the spectral characteristics of the photometric sensor 137 and the spectral characteristics of the line sensor 160d are superimposed. FIG. 7A shows a relative difference in spectral characteristics between the photometric sensor 137 and the line sensor 160d in gray as a difference in light receiving sensitivity between the photometric sensor 137 and the line sensor 160d. The difference in spectral sensitivity between the photometric sensor 137 and the line sensor 160d can be considered to represent the spectral characteristics of a virtual detection sensor that detects light detected by the line sensor 160d but not detected by the photometric sensor 137. In particular, in this embodiment, the photometric sensor 137 has a low near-infrared light detection sensitivity, and the line sensor 160d has a high near-infrared light detection sensitivity. Therefore, the difference in spectral sensitivity between the photometric sensor 137 and the line sensor 160d is It can be regarded as representing the spectral characteristics of a virtual detection sensor that detects near-infrared light. FIG. 7B is a graph showing spectral characteristics of a virtual detection sensor that detects near-infrared light.

Specifically, the camera control unit 170 first calculates an output difference D between the output value of the photometric sensor 137 and the output value of the line sensor 160d based on the following formula (1).

In the above formula (1), L is the output value of the line sensor 160d, R is the output value of the red pixel constituting the photometric sensor 137, G is the output value of the green pixel constituting the photometric sensor 137, and B is the photometric sensor. 137 is an output value of a blue pixel constituting 137. In addition, α, β _R , β _G , and β _B are set so that the output value of the photometric sensor 137 and the output value of the line sensor 160d are substantially equal in the visible light region having a wavelength shorter than that of near-infrared light. This is a coefficient for adjusting the output values of the photometric sensor 137 and the line sensor 160d, and is appropriately determined according to the gain and the light receiving time.

なお、上記式（２）において、ＤはステップＳ１０２で算出された測光センサ１３７の出力値とラインセンサ１６０ｄの出力値との出力差であり、Ｌはラインセンサ１６０ｄの出力値である。 In step S103, the ratio of near infrared light included in the light received by the line sensor 160d based on the output difference D calculated in step S102 by the camera control unit 170 is the near infrared light content rate. Calculated as I. Specifically, the camera control unit 170 calculates the near infrared light content I based on the following formula (2).

In the above equation (2), D is the output difference between the output value of the photometric sensor 137 calculated in step S102 and the output value of the line sensor 160d, and L is the output value of the line sensor 160d.

  In the present embodiment, as described above, the difference in spectral sensitivity between the photometric sensor 137 and the line sensor 160d can be regarded as representing the spectral characteristics of a virtual detection sensor that detects near-infrared light. Therefore, as shown in the above equation (2), the ratio between the output value L of the line sensor 160d and the output difference D between the photometric sensor 137 and the line sensor 160d is the near infrared of the light received by the line sensor 160d. It can be regarded as a ratio including light.

なお、γはフォーカスレンズ位置のずれ量をデフォーカス量に換算するための係数である。 In step S104, the camera control unit 170 calculates a correction amount for correcting the defocus amount based on the near-infrared light content I calculated in step S103. Here, FIG. 8 is a graph showing an example of a focus shift amount due to chromatic aberration. In the example illustrated in FIG. 8, the amount of focus shift due to chromatic aberration is expressed for each wavelength with reference to the wavelength (indicated by G in FIG. 8) received by the green pixel of the image sensor 110. For example, in the example shown in FIG. 8, the focus lens position focused on the near-infrared light image is the wavelength received by the green pixel of the image sensor 110 due to the influence of chromatic aberration (indicated by G in FIG. 8). On the other hand, the shift amount d is shifted closer. In this case, by moving the focus lens 212 to the infinity side by the shift amount d, it is possible to prevent a focus shift due to chromatic aberration. However, since the light received by the line sensor 160d includes light other than near-infrared light, the ratio of near-infrared light included in the light received by the line sensor 160d, that is, the near-infrared light content I Accordingly, the shift amount d is corrected. Thereby, it is possible to prevent a focus shift due to chromatic aberration. In the present embodiment, the drive amount of the focus lens 212 is determined based on the defocus amount. The camera control unit 170 calculates, as a correction amount A for correcting the defocus amount, an amount obtained by converting the shift amount (d × I) corresponding to the near-infrared light content I to the defocus amount. The camera control unit 170 can move the focus lens 212 to the infinity side by a shift amount (d × I) corresponding to the near-infrared light content I, and can prevent a focus shift due to chromatic aberration. Specifically, the camera control unit 170 calculates a correction amount A for correcting the defocus amount based on the following equation (3).

Note that γ is a coefficient for converting the shift amount of the focus lens position into the defocus amount.

  Next, a focus adjustment process for adjusting the focus state of the optical system using the correction amount calculated by the correction amount calculation process shown in FIG. 5 will be described with reference to FIG. FIG. 6 is a flowchart showing the focus adjustment process.

  First, in step S201, the camera control unit 170 determines whether or not the shutter release button has been pressed halfway (the first switch SW1 is turned on). If the shutter release button is pressed halfway, the process proceeds to step S202. If the shutter release button is not pressed halfway, the process waits in step S201.

  In step S202, the defocus amount is calculated. Specifically, charge accumulation is first performed by the line sensor 160d. A pair of image signals accumulated by the pair of line sensors 160 d are read by the focus detection unit 160. Further, the focus detection unit 160 calculates the defocus amount based on the read pair of image signals by calculating the correlation between the pair of image signals. The calculated defocus amount is output to the camera control unit 170.

  In step S203, the camera control unit 170 acquires the correction amount calculated in the correction amount calculation process shown in FIG. In step S204, the camera control unit 170 performs a correction process for correcting the defocus amount calculated in step S202 based on the correction amount acquired in step S203.

  For example, the camera control unit 170 is such that the defocus amount calculated in step S202 drives the focus lens 212 to the close side, and the correction amount acquired in step S203 is as shown in FIG. When correcting the focus shift to the close side due to chromatic aberration, the correction amount is subtracted from the defocus amount so that the focus lens 212 moves to the infinity side by the shift amount due to chromatic aberration. Correct.

  In step S205, driving of the focus lens 212 is started based on the defocus amount corrected in step S204. Specifically, the camera control unit 170 calculates a lens driving amount necessary for driving the focus lens 212 to the in-focus position based on the corrected defocus amount. The camera control unit 170 outputs the calculated lens driving amount to the lens driving motor 230 via the lens control unit 250. Thereby, the lens drive motor 230 drives the focus lens 212 to the in-focus position based on the lens drive amount based on the corrected defocus amount.

  In step S206, the camera control unit 170 determines whether or not the focus state of the optical system is a focused state. In this embodiment, after driving the focus lens 212 in step S205, the process proceeds to step S206 with the focus lens 212 being driven, and a determination is made as to whether or not the focus state of the optical system is in focus. Is called. If it is determined in step S206 that the subject is not in focus, the process returns to step S202. Returning to step 202, the defocus amount is corrected again based on the newly calculated defocus amount and the newly acquired correction amount. Based on the newly corrected defocus amount, the process of driving the focus lens 212 is repeated. Then, for example, when the corrected defocus amount df is equal to or less than a predetermined value, the camera control unit 170 determines that the focus state of the optical system is the in-focus state, stops driving the focus lens 212, The focus adjustment process shown in FIG. 6 ends.

  As described above, in the present embodiment, based on the output difference D between the output value of the photometric sensor 137 and the output value of the line sensor 160d, the ratio of near infrared light included in the light received by the line sensor 160d is reduced. Calculated as the infrared light content I. Then, the correction amount A is calculated based on the calculated near infrared light content I and the focus shift amount d due to chromatic aberration, and the defocus amount is corrected based on the correction amount A. Thereby, in this embodiment, the focus shift amount d due to chromatic aberration can be appropriately corrected according to the amount of near infrared light. Therefore, the camera 1 of the present embodiment can effectively suppress the focus shift due to chromatic aberration even when the light received by the line sensor 160d includes near infrared light such as AF auxiliary light or sunlight. It becomes possible to appropriately adjust the focus state of the optical system.

  The embodiment described above is described for facilitating understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

  For example, the above-described correction amount calculation process illustrated in FIG. 5 and the focus adjustment process illustrated in FIG. 6 may be performed only in a scene where shooting is performed under sunlight or a scene where AF auxiliary light is used. In such a scene, it is highly possible that near-infrared light is included in the light received by the line sensor 160d, so that the influence of chromatic aberration due to near-infrared light can be effectively suppressed. Note that the camera control unit 170 can determine that the scene is for shooting under sunlight when an exposure mode such as “outdoor mode” or “sunny sky mode” is set.

  In the above-described embodiment, the configuration in which the defocus amount is corrected by the correction amount A is exemplified, but the present invention is not limited to this configuration. For example, the lens driving amount calculated based on the defocus amount may be corrected with the driving amount based on the correction amount A without correcting the defocus amount.

  Furthermore, in the above-described embodiment, the configuration including the strobe device 300 that can be attached to and detached from the camera body 100 is illustrated, but the configuration is not limited thereto. For example, the camera body 100 may be configured to include an irradiation device that irradiates near infrared light as AF auxiliary light.

  Further, in the above-described embodiment, a configuration in which a light component in the near infrared region that is not detected by the photometric sensor 137 but detected by the line sensor 160d is extracted based on the output difference between the photometric sensor 137 and the line sensor 160d. Although illustrated, it is not limited to this configuration. For example, instead of the photometric sensor 137 and the line sensor 160d, a light component detected by only one sensor is extracted based on an output difference between two sensors having different spectral characteristics, so that chromatic aberration due to the light component is detected. The correction amount may be obtained.

  The camera 1 according to the present embodiment is not particularly limited. For example, the present invention is applied to other optical devices such as a single lens mirrorless digital camera, a digital compact camera, a digital video camera, and a camera for a mobile phone. Also good.

DESCRIPTION OF SYMBOLS 1 ... Camera 100 ... Camera body 110 ... Image pick-up element 137 ... Photometric sensor 160 ... Focus detection part 160d ... Line sensor 170 ... Camera control part 200 ... Lens barrel 212 ... Focus lens 300 ... Strobe device 303 ... AF auxiliary light emission part

Claims (7)

A first light receiving unit having a first spectral characteristic, receiving a light beam from the optical system and outputting a first output value;
A second light receiving unit having a second spectral characteristic different from the first spectral characteristic, receiving a light beam from the optical system, and outputting a second output value;
A focus adjustment unit for adjusting a focus state of the optical system;
A calculation unit that calculates a correction amount according to a light component that is not detected by the first light receiving unit but is detected by the second light receiving unit, based on the first output value and the second output value; With
The focus adjustment device, wherein the focus adjustment unit adjusts a focus state of the optical system based on the correction amount. The focus adjustment device according to claim 1,
The calculation unit calculates an image shift amount by the optical system based on the first output value,
The focus adjustment device, wherein the focus adjustment unit adjusts a focus state of the optical system based on the shift amount and the correction amount. The focus adjustment device according to claim 1 or 2,
The focus adjusting apparatus, wherein the first spectral characteristic and the second spectral characteristic are different in at least light receiving sensitivity in a near-infrared light region. It is a focus adjustment apparatus in any one of Claims 1-3,
The focus adjusting apparatus, wherein the first spectral characteristic is substantially the same as the spectral characteristic of the image sensor. It is a focus adjustment apparatus in any one of Claims 1-4,
The first light receiving unit is a photometric sensor,
The focus adjustment device, wherein the second light receiving unit is a focus detection sensor. It is a focus adjustment apparatus in any one of Claims 1-5,
Built-in or detachable lighting device that emits near infrared light,
The focus adjustment device adjusts a focus state of the optical system based on the correction amount when the near-infrared light is irradiated by the illumination device.   An imaging device provided with the focus adjustment apparatus in any one of Claims 1-6.

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