Imaging apparatus, control method of imaging apparatus, and program

Abstract

To provide an imaging apparatus capable of focusing in the case of out-of-focus when using an optical filter.SOLUTION: The imaging apparatus includes: an image sensor (121); an optical filter (160): and a control unit (130) that performs exposure adjustment. The optical filter (160) is capable of moving between a first position where the same is inserted in the imaging range (190) and a second position where the same is retreated from the imaging range (190). The control unit (130) is configured so as to, when the optical filter (160) is in the first position but the focus is not obtained, perform the exposure adjustment.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present invention relates to an imaging device, a method for controlling the imaging device, and a program.

Background Art

[0002] Conventionally, an imaging device provided with an optical filter such as a dimming filter (ND filter) is known. However, in a camera incorporating an ND filter, when focus adjustment is performed so that the image is in focus on the imaging surface when the ND filter is not in use, the optical path length changes when the ND filter is in use, so that the image may not be in focus at the closest distance. Patent Document 1 discloses an imaging device having warning means for issuing a warning when an optical filter is used or when an optical filter is not used.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the imaging device disclosed in Patent Document 1, the image may not be in focus at the closest distance when the optical filter is in use.

[0005] Therefore, an object of the present invention is to provide an imaging device capable of focusing when the image is out of focus while using an optical filter.

Means for Solving the Problems

[0006] An imaging device as one aspect of the present invention comprises an image sensor, an optical filter, and a control unit for adjusting exposure. The optical filter is movable between a first position inserted into the imaging range and a second position retracted from the imaging range. The control unit performs the exposure adjustment when the optical filter is in the first position and cannot focus.

[0007] Other objects and features of the present invention are described in the following examples. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide an imaging device that can focus when the image is not in focus while using an optical filter. [Brief explanation of the drawing]

[0009] [Figure 1] This is an external perspective view of the imaging device in this embodiment. [Figure 2] This is a block diagram of the imaging device in this embodiment. [Figure 3] This is an exploded perspective view of the imaging device in this embodiment. [Figure 4] This is an explanatory diagram illustrating the operation of the optical filter in this embodiment. [Figure 5] This is a cross-sectional view of the imaging device in this embodiment. [Figure 6] This is an explanatory diagram of the optical path of light incident on the image sensor in this embodiment. [Figure 7] This figure shows the relationship between depth of field and image formation position in this embodiment. [Figure 8] This is an explanatory diagram of the defocus map in this embodiment. [Figure 9] This is a flowchart of the autofocus process in the fully automatic shooting mode in this embodiment. [Figure 10] This is a flowchart of the autofocus process in aperture-priority shooting mode in this embodiment. [Figure 11]This is a flowchart of the autofocus process in shutter-priority shooting mode in this embodiment. [Figure 12] This is a flowchart of the autofocus process in this embodiment, where the optical filter remains selected by the user. [Modes for carrying out the invention]

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In these embodiments, common elements are denoted by the same reference numerals. Furthermore, these embodiments are merely examples for realizing the present invention, and should be modified or changed as appropriate depending on the configuration of the apparatus to which the present invention is applied and various conditions. The present invention is not limited to the following embodiments. In addition, some of the embodiments described later may be combined as appropriate.

[0011] First, the imaging device in this embodiment will be described with reference to Figures 1(a) and 1(b). Figures 1(a) and 1(b) are external perspective views of the imaging device (camera body) 100 in this embodiment. Figure 1(a) is an external perspective view of the imaging device 100 as seen from the front, showing the state with the lens device (interchangeable lens) 104 (see Figure 2), which can be attached to the imaging device 100, removed. Figure 1(b) is an external perspective view of the imaging device 100 as seen from the rear. Although this embodiment describes an imaging system in which the lens device 104 can be attached to and detached from the imaging device (camera body) 100, it is not limited to this and can also be applied to imaging devices in which the camera body and lens device are integrally configured.

[0012] The imaging device 100 has a grip portion (holding portion) 101 that is held by the user to stably hold the imaging device 100. On the upper part of the grip portion 101, a shutter button 102, which is a switch for starting imaging, is provided. On the front of the imaging device 100, a mount portion (lens mount) 103 is provided, and the lens device 104 is configured to be detachable from the imaging device 100 via the mount portion 103. The mount contacts 105 make an electrical connection between the imaging device 100 and the lens device 104, and perform power supply to the lens device 104, lens control by electrical signals, and communication regarding lens data. When replacing the lens device 104, the locking can be released by pressing the lens release button 106, and the lens device 104 can be removed.

[0013] The power switch 107 is used when turning on or off the power of the imaging device 100. The main electronic dial 108 and the sub - electronic dial 119 are rotatable operation members that can be rotated clockwise and counterclockwise, and by rotating and operating them, various setting values such as aperture and shutter speed can be changed. The mode - switching dial 109 is an operation part for switching the shooting mode, and is used to switch to various modes such as the shutter - speed - priority shooting mode, the aperture - value - priority shooting mode, and the video - shooting mode. The SET button 110 is a push button and is mainly used for determining selected items and the like.

[0014] The liquid - crystal monitor 111 displays various setting screens of the imaging device 100, the captured images, and the live - view images. The electronic viewfinder 112 is an eyepiece - type finder and displays various setting screens of the imaging device 100, the captured images, and the live - view images. The multi - function button 113 is a push button, and the user can arbitrarily assign and use it to switch various settings related to shooting. The display panel 114 displays various setting states of the imaging device 100 such as the shooting mode and the ISO sensitivity. Also, the display panel 114 is displayed even when the power of the imaging device 100 is OFF.

[0015] The accessory socket 115 has accessory contacts 116 and can attach various accessories such as an external flash or microphone. The media slot cover 173 is openable and closable, and when it is open, an external recording medium (recording medium) 148 such as an SD card (see FIG. 2) can be inserted into and removed from an internal media slot (not shown).

[0016] Next, referring to FIG. 2, the electrical configuration and operation of the imaging device 100 will be described. FIG. 2 is a block diagram of the imaging device 100 and shows a state in which the lens device 104 is attached. Note that the common parts with FIG. 1 are denoted by the same reference numerals.

[0017] The MPU 130 is a small central processing unit (control unit) built into the imaging device 100. Connected to the MPU 130 are a time measurement circuit 131, a shutter drive circuit 132, a switch sense circuit 133, a power supply circuit 134, a battery check circuit 135, a video signal processing circuit 136, an optical filter drive circuit 137, and a piezoelectric element drive circuit 145. The MPU 130 is responsible for the operation control of the imaging device 100, processes input information, and gives instructions and control to each element. The MPU 130 has an EEPROM and can store time information by the time measurement circuit 131, various setting information, and the like.

[0018] Also, the MPU 130 communicates with a lens control circuit 138 built into the lens device 104 via the mount contacts 105. Thereby, the MPU 130 can control the operations of the focus lens 141 and the electromagnetic drive aperture (lens aperture, diaphragm aperture) 142 via the AF drive circuit 139 or the aperture drive circuit 140. In FIG. 2, only one focus lens 141 is schematically shown as the imaging optical system of the lens device 104, but actually the imaging optical system is composed of a number of lens groups.

[0019] The AF drive circuit 139 is connected to, for example, a stepping motor (not shown) and drives the focus lens 141. The MPU 130 calculates the amount of focus lens drive according to the amount of defocus detected using the focus signal read from the image sensor 121 and transmits a focus command including the amount of focus lens drive to the lens control circuit 138. Upon receiving the focus command, the lens control circuit 138 controls the drive of the focus lens 141 through the AF drive circuit 139. This enables autofocus (AF).

[0020] The aperture drive circuit 140 is connected to an aperture actuator such as a stepping motor (not shown) and drives multiple aperture blades (not shown) that form the aperture opening in the electromagnetically driven aperture 142. By driving the multiple aperture blades, the size (diameter) of the aperture opening changes, and the amount of light is adjusted.

[0021] The MPU 130 calculates the aperture drive amount of the electromagnetically driven aperture 142 from the brightness signal read from the image sensor 121 and transmits an aperture command including the aperture drive amount to the lens control circuit 138. In other words, the MPU 130 communicates with the lens control circuit 138 to control the electromagnetically driven aperture 142. Upon receiving the aperture command, the lens control circuit 138 controls the drive of the electromagnetically driven aperture 142 through the aperture drive circuit 140. This automatically sets an appropriate aperture value (F number).

[0022] The mechanical focal-plane shutter 150 is driven by the shutter drive circuit 132. When taking an image, from the moment the user presses the shutter button 102, the front curtain shutter (not shown) is moved to open the shutter, and according to the desired exposure time, the rear curtain shutter (not shown) is moved to close the shutter, thereby controlling the exposure time to the image sensor 121.

[0023] The optical filter 160 is an optical element that gives a special effect to an image by diffusing incident light or attenuating a specific wavelength range. The optical filter 160 is not limited to, but includes ND filters that attenuate the amount of incident light at a constant rate, Polarized Light (PL) filters that suppress reflected light using a polarizing film, and soft filters that create a soft expression by diffusing light. The optical filter 160 is driven by the optical filter drive circuit 137, which allows the position of the optical filter 160 to be moved. The detailed configuration of the optical filter 160 will be described later.

[0024] The imaging unit 120 is mainly composed of an optical low-pass filter 122, an optical low-pass filter holding member 123, a piezoelectric element (piezoelectric member) 124, and an image sensor 121, all integrated into a single unit. The image sensor 121 converts the subject image (optical image) formed via the lens device 104 into photoelectric power. In this embodiment, the image sensor 121 is a Complementary Metal-Oxide-Semiconductor (CMOS) sensor, but is not limited to this. A Charge-Coupled Device (CCD) sensor or a Charge Injection Device (CID) sensor may also be used as the image sensor 121. The optical low-pass filter 122, positioned in front of the image sensor 121, is a single birefringent plate made of quartz, and its shape is rectangular. The piezoelectric element 124 is a single-plate piezoelectric element (piezo element) that is excited by a piezoelectric element driving circuit 145 instructed by the MPU 130, and is configured to transmit its vibrations to the optical low-pass filter 122. This vibration can shake off fine dust particles that have adhered to the optical low-pass filter 122.

[0025] The video signal processing circuit 136 is responsible for all aspects of image processing, including filtering and data compression, of the electrical signals obtained from the image sensor 121. Image data for monitor display from the video signal processing circuit 136 is displayed on the liquid crystal monitor 111 and the electronic viewfinder 112 via the liquid crystal drive circuit 144. The video signal processing circuit 136 can also save image data to the buffer memory 147 via the memory controller 146, according to instructions from the MPU 130. The video signal processing circuit 136 can also perform image data compression processing such as JPEG. When continuous shooting is performed, such as in burst shooting, the image data can be temporarily stored in the buffer memory 147, and the unprocessed image data can be sequentially read out via the memory controller 146. This allows the video signal processing circuit 136 to sequentially perform image processing and compression processing regardless of the speed of the incoming image data.

[0026] The memory controller 146 has the function of storing image data in an external recording medium 148 and the function of reading image data stored in the external recording medium 148. The external recording medium 148 is an SD card or CF card that can be attached to or removed from the imaging device 100, but is not limited to these.

[0027] The switch sense circuit 133 transmits input signals to the MPU 130 according to the operating state of each switch. Switch SW1 (102a) is turned ON by the first stroke (half-press) of the shutter button 102. Switch SW2 (102b) is turned ON by the second stroke (full-press) of the shutter button 102. When switch SW2 (102b) is turned ON, an instruction to start shooting is sent to the MPU 130. The switch sense circuit 133 is also connected to the main electronic dial 108, mode selection dial 109, power switch 107, SET button 110, and multifunction button 113, among others.

[0028] The MPU 130 communicates information via the accessory contact 116 through the accessory communication control circuit 118 to utilize the functions of an accessory unit (not shown). The power supply circuit 134 distributes and supplies power from the battery 143 to each element of the imaging device 100. A battery check circuit 135 is also connected to the battery 143, which transmits information such as the remaining charge of the battery 143 to the MPU 130.

[0029] Next, the internal configuration of the imaging device 100 will be described with reference to Figure 3. Figure 3 is an exploded perspective view of the imaging device 100. The imaging device 100 has a structure mainly covered by an exterior consisting of a front cover 10, a top cover 11, and a rear cover 12, and operating members and display members are attached to each exterior. On the optical axis 1000 of the imaging optical system, in order from closest to the subject, a holding member 200, an imaging unit 120, and a main board (control board) 180 are arranged, and an optical filter 160 is mounted on the holding member 200. Any optical component such as an ND filter, a PL filter, or a soft filter (low-pass filter) may be used for the optical filter 160. Furthermore, the imaging device 100 can operate normally even when the optical filter 160 is not inserted.

[0030] Next, the configuration of the optical filter 160 and its operation during switching will be explained with reference to Figures 4(a) to 4(c). Figures 4(a) to 4(c) are explanatory diagrams of the operation of the optical filter 160, showing the components related to the optical filter 160 and the retaining member 200 as viewed from the rear side of the imaging device 100.

[0031] The optical filter 160 is inserted into and held by a retaining member 200. The retaining member 200 has a gear shape 200a and is mounted on the front cover 10 so as to be rotatable around the gear shape 200a. A motor (actuator, drive unit) 201 for driving the optical filter 160 is also mounted on the front cover 10, and a worm gear 201a is attached to the drive shaft of the motor 201. The worm gear 201a transmits rotational force to the gear shape 200a of the retaining member 200 via an intermediate gear 202, thereby allowing the retaining member 200 to rotate. A battery storage compartment 170 for housing a battery 143 is provided on the right side of the front cover 10.

[0032] In this embodiment, the multifunction button 113 is assigned the function of switching the insertion / retraction of the optical filter 160. Next, the operation when the optical filter 160 is driven by user operation will be described. Note that other buttons, dials, switches, setting screens, etc., may also be used for switching the optical filter 160.

[0033] Figure 4(a) shows the state in which the optical filter 160 is inserted into and superimposed on an opening 190 provided inside the mount portion 103 of the imaging device 100 (inserted state). The opening 190 defines the imaging range. As a result, light incident on the image sensor 121 passes through the optical filter 160, and various photographic expressions become possible due to the effect of the optical filter 160. For example, if an ND filter is inserted as the optical filter 160, the incident light is reduced, making it possible to take long-exposure photographs and suppress overexposure even in bright environments.

[0034] When the multifunction button 113 is pressed from the inserted state shown in Figure 4(a), the press is detected by the switch sense circuit 133. At this time, a drive command for the motor 201 is sent from the MPU 130, and the motor 201 starts rotating via the optical filter drive circuit 137. The rotation of the motor 201 is transmitted from the worm gear 201a to the gear shape 200a via the gear shape 200a, and the retaining member 200 equipped with the gear shape 200a starts to rotate. Figure 4(b) shows the state during rotation (intermediate state).

[0035] The holding member 200 moves to the retracted state shown in Figure 4(c) after passing through the intermediate state shown in Figure 4(b). The pivot axis of the gear shape 200a is located on the bottom side of the imaging device 100, relative to the optical axis 1000 and the aperture 190, and between the optical axis 1000 and the short side of the grip portion 101 of the aperture 190. This allows the holding member 200 to rotate without interfering with internal components such as the top cover 11, as shown in Figure 4(b). Similarly, by positioning the motor 201 on the bottom side of the optical axis 1000 and the aperture 190, the power transmission distance to the gear shape 200a is shortened, and the driving efficiency is improved.

[0036] When the holding member 200 moves to the retracted position (second position) shown in Figure 4(c), the optical filter drive circuit 137 stops the motor 201 in response to a detection signal from a position sensor (not shown). The position sensor refers to a position detection means such as a photoreflector, but the timing of stopping the drive can be determined by any means, such as detecting the rotation angle of the motor 201 or detection by a mechanical switch.

[0037] Figure 4(c) shows the state in which the retaining member 200 has rotated approximately 90 degrees on a plane parallel to the imaging unit 120 relative to the insertion state in Figure 4(a), and has been retracted from the opening 190 (retracted state). With the retaining member 200 retracted, the light focused by the lens device 104 enters the image sensor 121 without passing through the optical filter 160.

[0038] Figure 5 is a cross-sectional view of the imaging device 100, showing a cross-section along line AA in Figure 4(c). As shown in Figure 5, the holding member 200 retracts between the opening 190 and the battery storage section 170, that is, between the opening 190 and the grip section 101. By rotating the holding member 200 by approximately 90 degrees from its inserted state, the short side of the optical filter 160 becomes approximately parallel to the X direction (the lateral direction of the imaging device 100), allowing it to be accommodated between the opening 190 and the battery storage section 170.

[0039] If the user wishes to reinsert the optical filter 160 into the opening 190, pressing the multifunction button 113 in the retracted state shown in Figure 4(c) causes the motor 201 to rotate in the opposite direction to the operation described above. This moves the optical filter 160 through the intermediate state shown in Figure 4(b) to the inserted state shown in Figure 4(a). When the optical filter 160 moves to the inserted state position (first position) shown in Figure 4(a), the optical filter drive circuit 137 stops the motor 201 based on a detection signal from a position sensor (not shown), similar to the retracted state.

[0040] With the above configuration, the optical filter 160 can be inserted into and retracted relative to the optical axis 1000 without interfering with the internal components or units of the imaging device 100. Therefore, the optical filter 160 can be incorporated into the imaging device 100 without increasing its size, and the inserted and retracted states of the optical filter 160 can be easily switched. In this embodiment, the configuration for switching between the inserted and retracted states is not limited to the above configuration. For example, the inserted and retracted states may be switched using a mechanism that slides the optical filter 160 laterally relative to the imaging device 100.

[0041] Next, the control method of the imaging device 100 will be explained with reference to Figures 6(a) to 6(c). Figures 6(a) to 6(c) are explanatory diagrams of the optical path of light incident on the image sensor 121. Figure 6(a) shows the imaging device 100 in the inserted state, Figure 6(b) shows the imaging device 100 in the retracted state, and Figure 6(c) shows the optical path in the cross-section along line BB in both the inserted and retracted states. Note that in the retracted state, the optical filter 160 does not exist in the cross-section along line BB, but in Figure 6(c), the optical filter 160 is shown for comparison of the optical paths in the inserted and retracted states.

[0042] In the inserted state shown in Figure 6(a), light incident on the image sensor 121 passes through the optical filter 160, and therefore travels through the optical path 862 shown by the dashed line in Figure 6(c), forming an image at the imaging point 863. In the retracted state shown in Figure 6(b), light incident on the image sensor 121 does not pass through the optical filter 160, but travels through the optical path 860 shown by the solid line in Figure 6(c), forming an image at the imaging point 861. Thus, the optical path length of the light incident on the image sensor 121 differs between the inserted and retracted states.

[0043] In this embodiment, the flange back is set so that when the lens is retracted, the incident light is imaged onto the surface (image plane) of the image sensor 121. When the lens is inserted, the optical path length changes, and the focal position (focus position) of the lens shifts to the back relative to the direction of incident light, resulting in a so-called back-focus state. Therefore, when the lens is inserted and focusing to the shortest shooting distance, the drive limit of the focus lens 141 may be reached, and the lens may become out of focus.

[0044] Next, with reference to Figure 7, the relationship between depth of field and image formation position will be explained. Figure 7 is a diagram showing the relationship between the change in depth of field due to the driving of the electromagnetically driven aperture 142 and the image formation point in the inserted and retracted states. Similar to Figure 6(c), it shows how light incident from the left side in Figure 7 forms an image, with the solid line being the optical path 860 in the retracted state and the dashed line being the optical path 862 in the inserted state. Depth of field is the range in which an image appears to be in focus. The depth of field changes depending on the setting of the electromagnetically driven aperture 142. When the electromagnetically driven aperture 142 is stopped down, the depth of field changes from the first depth of field 864 to the second depth of field 865.

[0045] In this case, if the image cannot be focused at close range while the lens is inserted, the depth of field is set to the first depth of field 864, and the image is formed at the image-forming point 863 in the inserted state, which is outside the range of the first depth of field 864. Therefore, by setting the depth of field to the second depth of field 865, the image-forming point 863 in the inserted state comes within the range of the second depth of field 865, and the image becomes focused. In this way, by stopping down the electromagnetically driven aperture 142 to increase the depth of field, it is possible to focus even at close range. Also, as can be seen from the explanation in Figure 6(c), it is possible to focus at close range by transitioning from the inserted state to the retracted state.

[0046] When the lens is inserted and the subject cannot be focused at close range, these techniques are applied depending on the shooting scene. For example, in a scene with a bright, moving subject within the shooting angle of view, the shutter speed is kept unchanged, and the electromagnetically driven aperture 142 is stopped down (the aperture opening is reduced), and the ISO sensitivity is increased. By stopping down the electromagnetically driven aperture 142, focus can be achieved, and by increasing the ISO sensitivity, the change in brightness caused by the aperture change is adjusted.

[0047] Furthermore, in bright scenes with no moving subjects within the shooting angle, the electromagnetically driven aperture 142 is stopped down to lower the shutter speed. By stopping down the electromagnetically driven aperture 142, focus can be achieved, and by lowering the shutter speed, the change in brightness caused by the change in the electromagnetically driven aperture 142 is adjusted.

[0048] Furthermore, in scenes with dark, moving subjects within the shooting angle, the shutter speed is kept unchanged, the optical filter 160 is retracted, and the ISO sensitivity is lowered. Retracting the optical filter 160 allows for focusing, and lowering the ISO sensitivity adjusts for the change in the subject's brightness that occurs when transitioning to the retracted state.

[0049] Furthermore, in dark scenes with no moving subjects within the shooting angle, the optical filter 160 is retracted and the shutter speed is increased. Retracting the optical filter 160 allows for focusing, and increasing the shutter speed adjusts for changes in brightness caused by aperture changes.

[0050] The brightness of a subject can be determined by the luminance signal read from the image sensor 121. Furthermore, whether or not there is a moving subject can be determined by known subject detection and image recognition techniques. For example, a configuration that determines the movement of a subject based on changes in the motion vector between consecutive images is acceptable. A moving subject is, for example, an animal, a vehicle, or a flowing waterfall, and a moving subject is detected when the subject is moving at a certain speed or higher. In this embodiment, autofocus (AF) is performed by image-plane phase-detection AF, but other AF methods may also be used.

[0051] Next, referring to Figure 8, we will explain how to determine whether the image is in an inserted state and whether or not it is not in focus at close range. Figure 8 is an explanatory diagram of the defocus map (defocus map information). When autofocusing to focus on the first subject 871 during shooting at a shooting angle of view 870, the amount of defocus corresponding to the distance information to the first subject 871 and the background second subject 872 within the shooting angle of view 870 is acquired. The defocus map is the amount of defocus information within the shooting angle of view 870. During autofocusing, the defocus map is created by the MPU 130 based on the amount of defocus detected using the focus signal read from the image sensor 121.

[0052] The thickness and refractive index information of the optical filter 160 are pre-set in the camera's memory. The MPU 130 acquires the thickness and refractive index information of the optical filter 160 and calculates the optical path length for both the inserted and retracted states. From the defocus map and optical path length information, it is possible to determine that the first subject 871, which is being focused on, is in focus in the retracted state but not in the inserted state. Therefore, it is possible to determine whether the current shooting situation is such that the subject is not in focus at close range. Note that the calculation of the optical path length with and without optical elements in the direction along the optical axis 1000 is well known, so a detailed explanation is omitted.

[0053] Next, with reference to Figure 9, the control method of the imaging device 100 in fully automatic shooting mode (auto mode) will be explained. Figure 9 is a flowchart of the autofocus process in fully automatic shooting mode. As mentioned above, the user can set various shooting modes of the imaging device 100 by operating the mode switching dial 109. Fully automatic shooting mode (auto mode) is a shooting mode in which the aperture value, shutter speed, and ISO sensitivity are automatically set according to the brightness of the subject.

[0054] When the user starts shooting and the autofocus process begins, in step S800, the MPU 130 first acquires a defocus map. Next, in step S801, the MPU 130 determines whether the optical filter 160 is inserted or not. If the optical filter 160 is not inserted (i.e., retracted), the process proceeds to step S812. In step S812, the MPU 130 drives the focus lens 141, and this flow ends. On the other hand, if the optical filter 160 is inserted, the process proceeds to step S802. In step S802, the MPU 130 acquires optical filter information. Optical filter information refers to information regarding the thickness and refractive index of the optical filter 160 mentioned above.

[0055] Next, in step S803, the MPU130 determines whether the subject is in focus when retracted but not when inserted. The determination of whether or not it is in focus can be made, for example, by calculating the amount of defocus of the image based on a known method and determining whether or not the calculated amount of defocus falls within a predetermined range. If the subject is in focus in both the retracted and inserted states, the process proceeds to step S812. In step S812, the MPU 130 drives the focus lens 141, and this flow ends. On the other hand, if the subject is in focus in the retracted state but not in the inserted state, the process proceeds to step S804. In step S804, the MPU 130 displays a warning. This warning is displayed, for example, by showing a warning icon on a display unit such as the LCD monitor 111 or the electronic viewfinder 112. A textual warning may also be displayed. This warning is intended to inform the user of changes to the shooting parameters.

[0056] Next, in step S805, the MPU130 determines whether the brightness at the time of shooting exceeds a threshold (brightness > threshold). Note that the unit of brightness is defined as 1 BV in the so-called APEX (ADDITIVE SYSTEM OF PHOTOGRAPHIC EXPOSURE) system, which is equivalent to one stop of brightness (photometric value). If the brightness exceeds the threshold, the process proceeds to step S806. On the other hand, if the brightness does not exceed the threshold, the process proceeds to step S807. Then, in either step S806 or step S807, the MPU130 determines whether there is a moving subject. If it is determined in step S806 that there is a moving subject, the process proceeds to step S808. On the other hand, if it is determined in step S806 that there is no moving subject, the process proceeds to step S809. Also, if it is determined in step S807 that there is a moving subject, the process proceeds to step S810. On the other hand, if it is determined in step S807 that there is no moving subject, the process proceeds to step S811.

[0057] In step S808, the MPU130 stops down the electromagnetically driven aperture (lens aperture) 142 and increases the ISO sensitivity. In step S809, the MPU130 stops down the electromagnetically driven aperture (lens aperture) 142 and decreases the shutter speed. In step S810, the MPU130 retracts the optical filter 160 and decreases the ISO sensitivity. In step S811, the MPU130 retracts the optical filter 160 and increases the shutter speed. After any of steps S808, S809, S810, or S811, the process proceeds to step S812, where the MPU130 drives the focus lens 141, and this flow ends. Through the above control, it is possible to focus on the subject at close range depending on the shooting scene.

[0058] Next, referring to Figure 10, we will explain the control method when the inserted and retracted states are changed by control in aperture-priority shooting mode. Figure 10 is a flowchart of autofocus in aperture-priority shooting mode. In aperture-priority shooting mode, the aperture value is set by the user. Therefore, a control flow is adopted that prevents the aperture value from being changed against the user's intention.

[0059] When the user starts shooting and autofocus begins, in step S820, the MPU 130 first acquires a defocus map. Next, in step S821, the MPU 130 determines whether the optical filter 160 is inserted or not. If the optical filter 160 is not inserted (i.e., retracted), the process proceeds to step S828. In step S828, the MPU 130 drives the focus lens 141, and this flow ends. On the other hand, if the optical filter 160 is inserted, the process proceeds to step S822. In step S822, the MPU 130 acquires optical filter information. Optical filter information refers to information regarding the thickness and refractive index of the optical filter 160 mentioned above.

[0060] Next, in step S823, the MPU 130 determines whether the subject is in focus when retracted but not when inserted. If the subject is in focus when retracted and also in focus when inserted, the process proceeds to step S828. In step S828, the MPU 130 drives the focus lens 141, and this flow ends. On the other hand, if the subject is in focus when retracted but not when inserted, the process proceeds to step S824. In step S824, the MPU 130 displays a warning. This warning is displayed, for example, by showing a warning icon on a display unit such as the LCD monitor 111 or the electronic viewfinder 112. A textual warning may also be displayed. This warning is to inform the user of a change in the shooting parameters.

[0061] Next, in step S825, the MPU130 determines whether or not there is a moving subject. If it is determined in step S825 that there is a moving subject, the process proceeds to step S826. On the other hand, if it is determined in step S825 that there is no moving subject, the process proceeds to step S827.

[0062] In step S826, the MPU130 retracts the optical filter 160 and lowers the ISO sensitivity. In step S827, the MPU130 retracts the optical filter 160 and increases the shutter speed. After step S826 or step S827, the process proceeds to step S828, where the MPU130 drives the focus lens 141, and this flow ends. Through the above control, it is possible to focus on close objects depending on the shooting scene.

[0063] Next, referring to Figure 11, we will explain the control method when the inserted and retracted states are changed by control in shutter-priority shooting mode. Figure 11 is a flowchart of autofocus in shutter-priority shooting mode. In shutter-priority shooting mode, the shutter speed is set by the user. Therefore, a control flow is adopted that prevents the shutter speed from being changed against the user's intention.

[0064] When the user starts shooting and autofocus begins, in step S830, the MPU130 first acquires a defocus map. Next, in step S831, the MPU130 determines whether the optical filter 160 is inserted or not. If the optical filter 160 is not inserted (i.e., retracted), the process proceeds to step S838. In step S838, the MPU130 drives the focus lens 141, and this flow ends. On the other hand, if the optical filter 160 is inserted, the process proceeds to step S832. In step S832, the MPU130 acquires optical filter information. Optical filter information refers to information regarding the thickness and refractive index of the optical filter 160 mentioned above.

[0065] Next, in step S833, the MPU 130 determines whether the subject is in focus when retracted but not when inserted. If the subject is in focus when retracted and also in focus when inserted, the process proceeds to step S838. In step S838, the MPU 130 drives the focus lens 141, and this flow ends. On the other hand, if the subject is in focus when retracted but not when inserted, the process proceeds to step S834. In step S834, the MPU 130 displays a warning. This warning is displayed, for example, by showing a warning icon on a display unit such as the LCD monitor 111 or the electronic viewfinder 112. A textual warning may also be displayed. This warning is to inform the user of a change in the shooting parameters.

[0066] Next, in step S835, the MPU130 determines whether the brightness at the time of shooting exceeds a threshold (brightness > threshold). If the brightness exceeds the threshold, the process proceeds to step S836. On the other hand, if the brightness does not exceed the threshold, the process proceeds to step S837.

[0067] In step S836, the MPU 130 stops down the electromagnetically driven aperture (lens aperture) 142 and increases the ISO sensitivity. In step S837, the MPU 130 is retracted and the ISO sensitivity is decreased. After step S836 or step S837, in step S838, the MPU 130 drives the focus lens 141, and this flow ends. Through the above control, it is possible to focus on close objects depending on the shooting scene.

[0068] Next, referring to Figure 12, a control method will be described for the case where the inserted and retracted states of the optical filter 160 are not automatically changed, but rather maintained in a state selected by the user. Figure 12 is an autofocus flowchart for the case where the optical filter 160 maintains a state selected by the user. In this embodiment, the inserted and retracted states of the optical filter 160 can be set to be changed only by user selection. In that case, since the focus is on close objects, the method of transitioning from the inserted state to the retracted state cannot be applied. Therefore, a method is used to focus even on close objects by stopping down the electromagnetically driven aperture 142 to increase the depth of field.

[0069] When the user starts shooting and autofocus begins, in step S840, the MPU 130 first acquires a defocus map. Next, in step S841, the MPU 130 determines whether the optical filter 160 is inserted or not. If the optical filter 160 is not inserted (i.e., retracted), the process proceeds to step S848. In step S848, the MPU 130 drives the focus lens 141, and this flow ends. On the other hand, if the optical filter 160 is inserted, the process proceeds to step S842. In step S842, the MPU 130 acquires optical filter information. Optical filter information refers to information regarding the thickness and refractive index of the optical filter 160 mentioned above.

[0070] Next, in step S843, the MPU 130 determines whether the subject is in focus when retracted but not when inserted. If the subject is in focus when retracted and also in focus when inserted, the process proceeds to step S848. In step S848, the MPU 130 drives the focus lens 141, and this flow ends. On the other hand, if the subject is in focus when retracted but not when inserted, the process proceeds to step S844. In step S844, the MPU 130 displays a warning. This warning is displayed, for example, by showing a warning icon on a display unit such as the LCD monitor 111 or the electronic viewfinder 112. A textual warning may also be displayed. This warning is to inform the user of a change in the shooting parameters.

[0071] Next, in step S845, the MPU130 determines whether or not there is a moving subject. If it is determined in step S845 that there is a moving subject, the process proceeds to step S846. On the other hand, if it is determined in step S845 that there is no moving subject, the process proceeds to step S847.

[0072] In step S846, the MPU130 stops down the electromagnetically driven aperture (lens aperture) 142 and increases the ISO sensitivity. In step S847, the MPU130 stops down the electromagnetically driven aperture (lens aperture) 142 and decreases the shutter speed. After step S846 or step S847, the process proceeds to step S848, where the MPU130 drives the focus lens 141, and this flow ends. Through the above control, it is possible to focus on close objects depending on the shooting scene.

[0073] As described above, the imaging device 100 includes an optical filter 160 and a control unit (MPU 130) that performs exposure adjustment. The optical filter 160 is movable between a first position in which it is inserted into the imaging range (aperture 190) and a second position in which it is retracted from the imaging range. The first position is where the optical filter 160 covers the imaging range (imaging area including the optical axis 1000), and the second position is where the optical filter 160 does not overlap the imaging range. If the optical filter is in the first position and focusing is not possible, the control unit performs exposure adjustment.

[0074] Preferably, the control unit adjusts the exposure if, with the optical filter 160 in the first position, the focus lens 141 is at its drive limit position and cannot focus at close range. Also preferably, the control unit adjusts the exposure by changing the setting of the lens aperture (electromagnetic drive aperture 142). Also preferably, the control unit adjusts the exposure by moving the optical filter 160 from the first position to the second position. Also preferably, the control unit adjusts the exposure if, based on the defocus map information and the optical filter information, it determines that the optical filter can focus when it is in the second position but cannot focus when it is in the first position.

[0075] (Other examples) The present invention can also be realized by supplying a program that implements one or more of the functions of the above-described embodiments to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. It can also be realized by a circuit (e.g., an ASIC) that implements one or more functions.

[0076] According to each embodiment, it is possible to provide an imaging device, a control method for the imaging device, and a program that can focus when the image is not in focus while using an optical filter.

[0077] Although preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of its gist. For example, in the embodiments described above, a configuration was described in which the insertion and removal of the optical filter 160 is controlled in response to the user pressing the multifunction button 113, but the invention is not limited to this. For example, if the presence or absence of insertion or removal of the optical filter 160 can be adjusted as one of the parameters for exposure control, the imaging device 100 may be configured to automatically insert or remove the optical filter 160 according to the brightness of the subject. [Explanation of symbols]

[0078] 100 Imaging device 121 Image sensor 130 MPU (Control Unit) 160 Optical Filters

Claims

1. An imaging element; An optical filter; A control unit that adjusts exposure, the optical filter is movable between a first position where the optical filter is inserted into an imaging range and a second position where the optical filter is retracted from the imaging range; the control unit performs the exposure adjustment when the optical filter is in the first position and the focusing is not possible, An imaging device characterized in that the control unit performs the exposure adjustment when it determines, based on defocus map information and optical filter information, that the optical filter is in focus when it is in the second position but not in focus when it is in the first position.

2. the first position is a position where the optical filter covers the imaging range, 2 . The imaging device according to claim 1 , wherein the second position is a position where the optical filter does not overlap the imaging range.

3. 3. The imaging device according to claim 1, wherein the control unit performs the exposure adjustment when the optical filter is in the first position, the focus lens is in a drive limit position, and focus cannot be achieved at close range.

4. 4. The imaging apparatus according to claim 1, wherein the control unit performs the exposure adjustment by changing a lens aperture setting.

5. 5. The imaging apparatus according to claim 1, wherein the control unit performs the exposure adjustment by moving the optical filter from the first position to the second position.

6. 6. The imaging apparatus according to claim 1, wherein the control unit displays a warning on a display unit when focusing is not possible with the optical filter in the first position.

7. 7. The imaging apparatus according to claim 1, wherein the control unit changes the method of the exposure adjustment based on the luminance of a subject.

8. 8. The imaging apparatus according to claim 1, wherein the control unit changes the method of the exposure adjustment based on a movement of a subject.

9. An imaging element; An optical filter; A control unit that adjusts exposure, the optical filter is movable between a first position where the optical filter is inserted into an imaging range and a second position where the optical filter is retracted from the imaging range; the control unit performs the exposure adjustment when the optical filter is in the first position and the focusing is not possible, The control unit changes a method of the exposure adjustment based on a shooting mode, The control unit, when the shooting mode is an aperture value priority shooting mode, performs the exposure adjustment by moving the optical filter from the first position to the second position and lowering the ISO sensitivity.

10. 10. The imaging apparatus according to claim 9, wherein the control unit changes the method of exposure adjustment based on the brightness and movement of a subject when the shooting mode is a fully automatic shooting mode.

11. The imaging device according to claim 9 or 10, characterized in that, when the shooting mode is an aperture value priority shooting mode, the control unit performs the exposure adjustment by moving the optical filter from the first position to the second position and increasing the shutter speed.

12. 12. The imaging device according to claim 9, wherein when the shooting mode is a shutter speed priority shooting mode, the control unit performs the exposure adjustment by changing a lens aperture setting and increasing an ISO sensitivity.

13. 13. The imaging device according to claim 9, wherein when the shooting mode is a shutter speed priority shooting mode, the control unit performs the exposure adjustment by moving the optical filter from the first position to the second position and lowering the ISO sensitivity.

14. 14. The imaging device according to claim 1, wherein the control unit performs the exposure adjustment by changing a lens aperture setting and increasing an ISO sensitivity when the optical filter is set to maintain a state selected by a user.

15. 15. The imaging device according to claim 1, wherein the control unit performs the exposure adjustment by changing a lens aperture setting and lowering a shutter speed when the optical filter is set to maintain a state selected by a user.

16. 15. The imaging device according to claim 1, wherein the optical filter is an ND filter, a PL filter, or a soft filter.

17. A method for controlling an imaging device having an imaging element and an optical filter, comprising the steps of: a first determination step of determining whether the optical filter is located at a first position inserted into an imaging range or at a second position retracted from the imaging range; a second determination step of determining whether or not focusing is possible with the optical filter in the first position; an exposure adjustment step of performing exposure adjustment when it is determined in the second determination step that focusing is not possible, A control method for an imaging device, characterized in that in the second judgment step, if it is determined based on defocus map information and optical filter information that the optical filter is in focus when it is in the second position but is not in focus when it is in the first position, the exposure adjustment step performs the exposure adjustment.

18. A method for controlling an imaging device having an imaging element and an optical filter, comprising: a first determination step of determining whether the optical filter is located at a first position inserted into an imaging range or at a second position retracted from the imaging range; a second determination step of determining whether or not focusing is possible with the optical filter in the first position; an exposure adjustment step of performing exposure adjustment when it is determined in the second determination step that focusing is not possible; and a changing step of changing the method of the exposure adjustment based on a shooting mode, a second position for moving the optical filter from the first position to the second position and a second position for lowering the ISO sensitivity when the shooting mode is an aperture value priority shooting mode in the change step, the exposure adjustment is performed by lowering the ISO sensitivity.

19. A program causing a computer to execute the control method according to claim 17 or 18.

Images