Additional devices and imaging devices

Abstract

This provides a new technology that allows for improved focusing performance by retrofitting existing imaging devices. [Solution] The additional device comprises a second lens group that forms an optical system by being aligned with the first lens group so that their optical axes coincide, a lens drive unit that moves the second lens group along the optical axis, a distance measuring unit that measures the distance to an object and generates first distance information indicating the measured distance, and a control unit that controls the lens drive unit. The control unit comprises a first acquisition unit that acquires the first distance information, a calculation unit that calculates the focus position, which is the position of the second lens group when the image of the object formed by the optical system is in focus, based on the first distance information, and a drive control unit that controls the lens drive unit so that the second lens group moves to the focus position.

Description

Technical Field

[0001] The present invention relates to an attachment device and an imaging device.

Background Art

[0002] Imaging measures equipped with solid-state imaging devices such as CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor) have been rapidly spreading in a wide range of fields such as single-lens reflex cameras, digital still cameras, video cameras, or surveillance cameras. Along with this, the demand for lenses compatible with solid-state imaging devices is expanding. In recent years, the number of pixels and sensitivity of solid-state imaging devices have been increasing, and high-resolution lenses are required. In addition, the miniaturization and spread of imaging devices have been progressing, and it is desired that the photographing lens be miniaturized, lightweight, and inexpensive. In addition, an imaging device that focuses only during arbitrary close-up shooting other than at an infinite distance is required, and an imaging device that performs ranging to focusing in a short time is required.

[0003] Regarding such an imaging device, there is known an imaging device that improves the speed of the focusing operation by attaching and using an attachment lens device so as to be interposed between a master lens without a wobbling function and a camera body (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] On the other hand, when enhancing focusing performance after the use of an imaging device, there may be limitations imposed by the imaging device being used. For example, in the case of a surveillance camera with a camera built into the casing, the space available for later enhancing focusing performance may be limited. Thus, optical systems that may be added to enhance focusing performance are required to accommodate the limitations of the imaging device, and there is a need for new optical systems that satisfy these requirements.

[0006] One aspect of the present invention aims to provide a novel technology that can improve the focusing performance of an existing imaging device by retrofitting it. [Means for solving the problem]

[0007] To solve the above problems, an additional device according to one aspect of the present invention is an additional device arranged on the image plane side opposite to the object side where the object to be imaged is located in the first lens group, and comprises a second lens group which is arranged so as to coincide with the optical axis of the first lens group to constitute a single optical system; a lens drive unit which moves the second lens group along the optical axis; a distance measuring unit which measures the distance to the object and generates first distance information indicating the measured distance; and a control unit which controls the lens drive unit, wherein the control unit comprises a first acquisition unit which acquires the first distance information; a calculation unit which calculates a focus position which is the position of the second lens group when the image of the object formed by the optical system is in focus, based on the first distance information; and a drive control unit which controls the lens drive unit so that the second lens group moves to the focus position.

[0008] Each aspect of the present invention may be implemented by a computer, in which case a program for implementing the add-on device by a computer, by operating the computer as each part (software element) of the add-on device, and a computer-readable recording medium on which the program is recorded also fall within the scope of the present invention.

[0009] Furthermore, in order to solve the above problems, an imaging device according to one aspect of the present invention comprises the above-mentioned additional device, the first lens group, and an image sensor arranged on the image plane side of the second lens group, which converts the image of the object formed by the optical system into an electrical signal and outputs it. [Effects of the Invention]

[0010] According to one aspect of the present invention, a new technology is available that can improve the focusing performance of an existing imaging device by retrofitting it. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic perspective view showing an example of the external appearance of an imaging device according to an embodiment of the present invention. [Figure 2] This figure schematically shows an example of the configuration of an imaging device according to an embodiment of the present invention. [Figure 3] This block diagram shows an example of the functional configuration of the imaging device according to the same embodiment. [Figure 4] This flowchart shows an example of the processing flow performed by the control unit of the imaging device according to the same embodiment. [Figure 5] This diagram schematically shows the optical configuration of the optical system in Example 1. [Figure 6] This figure shows the longitudinal aberration of the optical system of Example 1 when it is in focus at infinity. [Figure 7] This figure shows the longitudinal aberration of the optical system of Example 1 when the first object is in focus at a distance of 5m. [Figure 8] This figure shows the longitudinal aberration of the optical system in Example 1 when the second object distance is 1m and the system is in focus. [Figure 9] This diagram schematically shows the optical configuration of the optical system in Example 2. [Figure 10] This figure shows the longitudinal aberration of the optical system of Example 2 when it is in focus at infinity. [Figure 11] This figure shows the longitudinal aberration of the optical system in Example 2 when the first object is in focus at a distance of 5m. [Figure 12]This is a diagram showing the longitudinal aberration when focusing at an object distance of 1 m, which is the second object distance of the optical system of Example 2. [Figure 13] This is a diagram schematically showing the optical configuration of the optical system of Example 3. [Figure 14] This is a diagram showing the longitudinal aberration when the optical system of Example 3 is focused at infinity. [Figure 15] This is a diagram showing the longitudinal aberration when focusing at an object distance of 5 m, which is the first object distance of the optical system of Example 3. [Figure 16] This is a diagram showing the longitudinal aberration when focusing at an object distance of 1 m, which is the second object distance of the optical system of Example 3. [Figure 17] This is a diagram schematically showing the optical configuration of the optical system of Example 4. [Figure 18] This is a diagram showing the longitudinal aberration when the optical system of Example 4 is focused at infinity. [Figure 19] This is a diagram showing the longitudinal aberration when focusing at an object distance of 5 m, which is the first object distance of the optical system of Example 4. [Figure 20] This is a diagram showing the longitudinal aberration when focusing at an object distance of 1 m, which is the second object distance of the optical system of Example 4.

Embodiments for Carrying out the Invention

[0012] Hereinafter, an embodiment of the present invention will be described in detail.

[0013] 〔Schematic Configuration of Imaging Device 1〕 The imaging device 1 comprises a first lens group, an auxiliary device, and an image sensor. An example of the external appearance of the imaging device 1 according to this embodiment is shown in Figure 1. An example of the configuration of the imaging device is shown in Figure 2. As shown in Figure 1, the imaging device 1 according to this embodiment has a main body 2, a lens barrel 3, and an auxiliary device 4. As shown in Figure 2, the imaging device 1 according to this embodiment has an image sensor inside the main body 2. The imaging device 1 according to this embodiment has a first lens group GA inside the lens barrel 3. The auxiliary device 4 has a second lens group GB and is arranged between the lens barrel 3 and the main body 2. The second lens group GB, together with the first lens group GA, constitutes a single optical system. The optical system in this embodiment will be described first.

[0014] [Optical system] A "lens group" refers to a set of optical elements, such as lenses, that move along the optical axis. During movement, the spacing between the optical elements constituting the lens group in the optical axis direction remains constant, and the entire set of optical elements constituting the lens group moves. A lens group may consist of a single lens or two or more lenses.

[0015] The lenses constituting a lens group can be appropriately determined within a range that allows for the realization of the required optical properties for each lens group. Examples of such lenses include single lenses, bonded lenses formed by bonding the lens surfaces of multiple single lenses together with an adhesive, and composite lenses formed by integrating a single lens with a resin material without an air gap. Examples of single lenses include convex lenses, concave lenses, meniscus lenses, spherical lenses, and aspherical lenses.

[0016] <First lens group> The first lens group is a group of lenses that, when combined with an image sensor, has optical properties that form an image and are used for imaging. For example, the first lens group may have a zoom function, and may include one or more lens groups in order to achieve the optical properties required for the first lens group. The first lens group is immovable with respect to the image plane. That is, the first lens group does not include any lens groups that move when the optical system is focused. The fact that the first lens group does not have a focusing function is preferable from the viewpoint of simplifying the configuration of the first lens group and from the viewpoint of simplifying the control of imaging using an image sensor.

[0017] <Second lens group> The second lens group moves along the optical axis when focusing between a first object distance and a second object distance that is different from the first object distance. The first object distance may be, for example, the longest shooting distance in the optical system, and the second object distance may be the shortest shooting distance in the optical system. In this embodiment, the movement of the second lens group along the optical axis when focusing between the first object distance and the second object distance reduces the overall weight of the focusing group in the optical system and enables further speedup of focusing by moving the second lens group. Note that "focusing group" is a general term for the lens group that moves when focusing in the optical system, and for example, if only the second lens group moves when focusing in the optical system, it refers to the second lens group.

[0018] Furthermore, the second lens group may consist of a single lens. Having the second lens group consist of a single lens is preferable from the viewpoint of reducing the weight of the optical system in this embodiment.

[0019] Furthermore, the shape of the lens surface closest to the object in the second lens group may be concave relative to the object. Having a concave shape on the lens surface closest to the object in the second lens group is preferable from the viewpoint of correcting field curvature.

[0020] <Opening diaphragm> In the optical system, the aperture diaphragm is preferably positioned closer to the object than the second lens group. For example, the aperture diaphragm may be part of the first lens group, or it may be positioned between the first and second lens groups.

[0021] The aperture diaphragm is a component that defines the diameter of the light beam and defines the F-number of another optical system or optical system. Positioning the aperture diaphragm closer to the object is preferable from the viewpoint of reducing the ray angle of the light of the image in the optical system and reducing the diameter of the lens on the image plane side.

[0022] The optical system of this embodiment may further include other components besides the optical elements described above, to the extent that the effects of the present invention are obtained. Examples of such other components include liquid lenses.

[0023] <Optical properties> The optical system of this embodiment preferably satisfies one or more of the following equations. Each equation will be explained below.

[0024] The optical system of this embodiment preferably satisfies the following equation. 0.001 < Bmin / Bmax (1) however Bmax: Maximum magnification of the optical system Bmin: Minimum magnification of the optical system

[0025] Equation 1 defines the range in which the focusing group can be moved by detecting the shooting distance. It is preferable for βmin / Bmax to be within the above range, as this reduces the overall weight of the focusing group in the optical system and enables faster focusing.

[0026] From the viewpoint of suppressing optical performance, a Bmin / Bmax ratio of 0.050 or higher is more preferable, and a ratio of 0.100 or higher is even more preferable. Furthermore, from the viewpoint of suppressing optical performance, a Bmin / Bmax ratio of 1.000 or lower may be acceptable. The Bmin / Bmax ratio can be adjusted, for example, by changing the imaging range.

[0027] Furthermore, it is preferable that the optical system of this embodiment satisfies the following equation. -15.0 <LT / ra<-0.1 (2) however ra: Radius of curvature of the lens surface closest to the object in the second lens group. LT: Total length of the optical system

[0028] Equation 2 defines the total optical length and the radius of curvature on the object side of the focusing group. It is preferable for LT / ra to be within the above range from the viewpoint of effectively suppressing the optical performance in the imaging range.

[0029] From the viewpoint of suppressing the overall optical length of the optical system, LT / ra is preferably greater than -15.0, more preferably -10.0 or higher, and even more preferably -5.0 or higher. Furthermore, from the viewpoint of effectively suppressing the optical performance of the imaging range, LT / ra is preferably less than -0.1, more preferably -0.5 or lower, and even more preferably -0.7 or lower. LT / ra can be appropriately adjusted, for example, by changing the imaging range.

[0030] Furthermore, it is preferable that the optical system of this embodiment satisfies the following equation. 0.85 < |βA| < 1.25 (3) however βA: Lateral magnification of the second lens group when focused at infinity.

[0031] Equation 3 defines the lateral magnification of the second lens group. It is preferable for |βA| to be within the above range from the viewpoint of effectively suppressing the optical performance in the shooting range.

[0032] From the viewpoint of suppressing optical performance in the shooting range, |βA| is preferably greater than 0.85, more preferably 0.95 or greater, and even more preferably 1.00 or greater. Also, from the viewpoint of suppressing the amount of movement when the focusing group moves within the shooting range, |βA| is preferably less than 1.25, more preferably 1.22 or less, and even more preferably 1.20 or less. |βA| can be appropriately adjusted, for example, by changing the focal length of the optical system.

[0033] Note that βA may be the lateral magnification at the telephoto end when the second lens group is in focus at infinity.

[0034] Furthermore, it is preferable that the optical system of this embodiment satisfies the following equation. 0.01 < |Fa / Fb| < 40.00 (4) however Fa: Focal length of the first lens group Fb: Focal length of the second lens group

[0035] Equation 4 defines the ratio of the focal length of the first lens group to the focal length of the second lens group. It is preferable for |Fa / Fb| to be within the above range from the viewpoint of obtaining good optical performance while suppressing the overall optical length of the optical system.

[0036] From the viewpoint of suppressing optical performance across the entire shooting distance range, it is more preferable that |Fa / Fb| be less than 1.5. Also, from the viewpoint of suppressing the overall optical length, it is more preferable that |Fa / Fb| be greater than 0.04.

[0037] Furthermore, it is preferable that the optical system of this embodiment satisfies the following equation. 0.01 < |M| / f < 100.00 (5) however M: Amount of movement of the second lens group relative to the image plane. f: focal length of the optical system

[0038] Equation 5 defines the ratio of the amount of movement of the second lens group relative to the image plane to the focal length of the optical system. It is preferable for |M| / f to be within the above range from the viewpoint of appropriately setting the optical performance across the entire shooting distance range while appropriately setting the amount of movement of the second lens group.

[0039] From the viewpoint of fully satisfying the optical performance at the minimum focusing distance, it is more preferable that |M| / f is greater than 0.05. Also, from the viewpoint of suppressing the overall optical length of the optical system, it is more preferable that |M| / f is less than 10.0.

[0040] The optical system of this embodiment can be appropriately designed experimentally or by computer simulation, depending on the conditions described above, the optical characteristics of another optical system cooperating with it, and the focusing performance newly required of the other optical system.

[0041] [Telescope Tube 3] The lens barrel 3 is positioned closest to the object and has a first lens group GA (lenses L1 to L12) and an aperture diaphragm S on the optical axis OA. In this embodiment, the first lens group GA does not include a lens group that moves when the optical system is focused. That is, the first lens group GA does not have the function of focusing the optical system on its own. However, the first lens group may include a lens group that moves when the optical system is focused. The aperture diaphragm S is provided on the first lens group or on its image plane side. In this embodiment, the aperture diaphragm is positioned between lens L6 and lens L7. The lens barrel 3 also has the lens mount at its image plane end.

[0042] [Additional device 4] The add-on device 4 is positioned on the image plane side of the first lens group GA, opposite to the object side where the object to be imaged is located. In this embodiment, the add-on device 4 is positioned between the lens barrel 3 and the main body 2. As shown in Figure 3, the add-on device 4 comprises a second lens group GB, a lens drive unit 41, a distance measuring unit 42, and a control unit 43. In this embodiment, the add-on device 4 further comprises a housing 44 and a measurement unit 45. The add-on device 4 has the second lens group GB on the optical axis OA. The second lens group GB and the first lens group GA are aligned so that their optical axes OA coincide, thereby forming a single optical system. In this embodiment, the second lens group GB is composed of a single lens L13. The lens L13 is a concave meniscus lens and is positioned so as to be concave on the object side. The lens L13 is also positioned to be movable along the axial direction of the add-on device 4.

[0043] Furthermore, the add-on device 4 has a lens mount at the image plane end that is detachably connected to the body mount of the main unit 2, and a body mount at the object end. Thus, the main unit 2 and the add-on device 4 are connected by the body mount of the main unit 2 and the lens mount on the image plane side of the add-on device 4. In addition, the add-on device 4 and the lens barrel 3 are connected by the body mount on the object side of the add-on device 4 and the lens mount on the image plane side of the add-on device 4. In this way, the lens barrel 3 can be attached to the main unit 2, and the add-on device 4 is configured to be interposed between the lens barrel 3 and the main unit 2.

[0044] The additional device 4 moves from the object side to the image plane side when focusing occurs. When focusing occurs, the object distance of the optical system becomes longer than before focusing. In this embodiment, for example, the object distance of the optical system when focusing occurs corresponds to the first object distance, and the object distance of the optical system before focusing corresponds to the second object distance.

[0045] <Enclosure 44> The housing 44 houses the second lens group GB. As described above, the add-on device 4 is attached to the image plane side of the lens barrel 3, which has an aperture diaphragm. Therefore, the second lens group GB is positioned even closer to the image plane than the aperture diaphragm.

[0046] <Lens drive unit 41> The lens drive unit 41 moves the second lens group GB along the optical axis OA according to the control of the control unit 43. In this embodiment, the lens drive unit 41 is housed together with the second lens group GB in the housing 44.

[0047] <Distance measurement section 42> The distance measuring unit 42 is externally attached to the object-side end of the lens barrel 3. The distance measuring unit 42 measures the distance to the object and generates first distance information indicating the measured distance. In this embodiment, the distance measuring unit 42 is composed of a TOF sensor. The TOF sensor includes a light-emitting unit, a light-receiving unit, and an information generation unit. The light-emitting unit emits pulsed laser light based on the control of the information generation unit. The light-receiving unit receives the reflected laser light. The information generation unit generates first distance information based on the time the laser light was emitted and the time the reflected laser light was received. The distance measuring unit 42 may also be configured to measure distance using a Lidar, Radar, ultrasonic, stereo camera, etc.

[0048] <Measurement section 45> The measurement unit 45 measures the position of the second lens group GB within the optical system and generates position information indicating the measured position. The measurement unit 45 can be configured, for example, by a position sensor.

[0049] <Control Unit 43> The control unit 43 controls the lens drive unit 41. The control unit 43 comprises a first acquisition unit 431, a calculation unit 432, and a drive control unit 433. In this embodiment, the control unit 43 further comprises a second acquisition unit 434 and a determination unit 435.

[0050] (1st acquisition part 431) The first acquisition unit 431 acquires the first distance information generated by the distance measuring unit 42.

[0051] (Calculation unit 432) The calculation unit 432 calculates the focus position based on the first distance information acquired by the first acquisition unit 431. The focus position is the position of the second lens group GB when the image of the object formed by the optical system is in focus.

[0052] (Drive control unit 433) The drive control unit 433 controls the lens drive unit 41 based on the calculation result of the calculation unit 432. As a result, the second lens group GB moves to the focus position.

[0053] (Second acquisition part 434) The second acquisition unit 434 acquires the location information generated by the measurement unit 45.

[0054] (Judgment unit 435) The determination unit 435 determines whether there is a discrepancy between the position of the second lens group GB after movement, as indicated by the position information acquired by the first acquisition unit 431, and the focus position calculated by the calculation unit 432.

[0055] [Specific example of processing performed by the control unit 43] Figure 4 shows a specific example of the processing performed by the control unit 43 according to this embodiment. The control unit 43 performs the following processing, for example, when the switch of the add-on device 4 is turned on.

[0056] (Step S1) First, in step S1, the first acquisition unit 431 acquires the first distance information generated by the distance measuring unit 42.

[0057] (Step S2) After acquiring the first distance information, the process moves to step S2. In step S2, the control unit 43 determines whether the distance to the object indicated by the first distance information is within a predetermined range. The predetermined range can be, for example, the depth of field of the entire optical system.

[0058] (Step S3) In step S2, if the control unit 43 determines that the distance to the object indicated by the first distance information is not within a predetermined range (step S2: NO), the process proceeds to step S3. In step S3, the control unit 43 notifies the main unit 2 that the distance to the object is outside the predetermined range. As a result, the main unit 2 displays, for example, on the display unit 22, that the object is too far away to focus.

[0059] (Step S1A) After notifying the main unit 2 that the distance to the object is outside the predetermined range, the process moves to step S1A. In step S1A, the first acquisition unit 431 acquires new first distance information.

[0060] (Step S4) After acquiring new first distance information, the process proceeds to step S4. In step S4, the control unit 43 determines whether the distance to the object has changed based on the new object distance. If the control unit 43 determines in step S4 that the distance to the object has changed (step S4: YES), the process returns to step S2. On the other hand, if the control unit 43 determines that the distance to the object has not changed (step S4: NO), the control unit 43 terminates the process.

[0061] (Step S5) If the control unit 43 determines that the distance to the object is within a predetermined range (step S2: YES), the process proceeds to step S5. In step S5, the calculation unit 432 calculates the focus position based on the first distance information acquired in step S1.

[0062] (Step S6) After calculating the focus position, the process moves to step S6. In step S6, the drive control unit 433 controls the lens drive unit 41 based on the focus position calculated in step S5. This causes the second lens group GB to move to the focus position.

[0063] (Step S7) After controlling the lens drive unit 41, the process moves to step S7. In step S7, the second acquisition unit 434 acquires the position information generated by the measurement unit 45.

[0064] (Step S8) After acquiring the position information, the process proceeds to step S8. In step S8, the determination unit 435 determines whether there is a discrepancy between the position of the second lens group GB after movement, as indicated by the position information acquired in step S7, and the focus position calculated in step S5. If it is determined in step S8 that there is no discrepancy (step S8: NO), the control unit 43 terminates the process. Even after the process is completed, the imaging device 1 continues imaging.

[0065] (Step S9) If the determination unit 435 determines in step S8 that there is a discrepancy between the position of the second lens group GB after movement and the focus position (step S8: YES), the process proceeds to step S9. In step S9, the calculation unit 432 corrects the focus position based on first discrepancy information indicating the magnitude of the discrepancy. Specifically, first, in step S91, the calculation unit 432 calculates second distance information. The second distance information is the distance to an object such that the focus position becomes the position of the second lens group GB indicated by the position information.

[0066] Next, in step S92, the calculation unit 432 generates second deviation information. The second deviation information is information indicating the difference between the distance indicated by the first distance information and the distance indicated by the second distance information. Next, in step S93, the calculation unit 432 generates third shift information based on the second shift information. The third shift information is information that indicates the difference between the back focus when the distance to the object is the distance indicated by the first distance information and the back focus when the distance to the object is the distance indicated by the second distance information.

[0067] Next, in step S94, the calculation unit 432 corrects the focus position so that the difference indicated by the third misalignment information becomes smaller.

[0068] After correcting the focus position, the process returns to step S6. This causes the drive control unit 433 to control the lens drive unit so that the second lens group GB moves to the corrected focus position. do.

[0069] [Main body 2] As shown in Figure 2, the main body 2 has an image sensor 21 on the optical axis OA of the optical system. The image sensor is, for example, a CCD or CMOS, and includes an image plane I in the image sensor and has a cover glass CG. The image sensor is positioned on the image plane side of the second lens group GB and converts the image of the object formed by the optical system into an electrical signal for output. The main body 2 has a body mount that can be detachably connected to either the lens barrel 3 or the add-on device 4.

[0070] As shown in Figure 3, the main unit 2 according to this embodiment further comprises a display unit 22, a display control unit 23, an operation unit 24, and a storage unit 25. The display unit 22 displays images. The display unit 22 is composed of a liquid crystal display or the like. The operation unit 24 accepts user operations. The operation unit 24 is composed of, for example, buttons or a touch panel. The display control unit 23 generates image data based on electrical signals output by the image sensor 21. The display control unit 23 also controls the display by the display unit 22. For example, if the distance measuring unit measures the distance to an object, the display control unit 23 displays an image of the object based on the electrical signal output by the image sensor 21 on the display unit 22. On the other hand, if the distance measuring unit does not measure the distance to an object, the display control unit does not display an image of the object on the display unit. The storage unit 25 stores the image data generated by the display control unit 23.

[0071] [Variation] The control unit 43 may be configured to multiply the focusing distance calculated by the calculation unit 432 by a predetermined coefficient, and use the resulting value as the focusing distance when the lens drive unit 41 moves the second lens group GB. The coefficient is a value calculated in advance based on the first misalignment information.

[0072] Furthermore, each process described in the above embodiment may be performed by AI (Artificial Intelligence). Specifically, for example, an AI (e.g., a neural network) is prepared that, upon input of first time-series data including first distance information at multiple points in time within a specific period, and first shift information at each point in time, outputs a focused position that takes the shift into account. Then, by inputting the first time-series data and the first shift information into the AI, the lens drive unit 41 may be controlled based on the focused position output by the AI. In this case, the AI ​​may operate on the additional device 4, or it may operate on another device (e.g., an edge computer or cloud server). In this case, the distance measuring unit 42 may be configured to generate first time-series data including first distance information at multiple points in time within a specific period by repeatedly measuring the distance to an object within a specific period.

[0073] Furthermore, the imaging device 1 may have a function to monitor the user's eyes and generate gaze information indicating the direction of their gaze. For example, an AI (e.g., a neural network) may be prepared that, upon input of second time-series data including the control results of the display control unit 23 at multiple points in time within a specific period, and gaze information at multiple points in time, outputs a focus position that takes the user's gaze into account. The lens drive unit 41 may then be controlled based on the focus position output by the AI ​​by inputting the second time-series data and gaze information. In this case, the display control unit may be configured to generate second time-series data including control results at multiple points in time within a specific period by acquiring control results indicating whether or not the display control unit displayed an image of the object in front on the display unit within a specific period.

[0074] [Effects] The add-on device 4 described above can be retrofitted between the lens barrel 3 and the main body 2. When the imaging device composed of the lens barrel 3 and the main body 2 cannot focus on the subject, the add-on device 4 focuses the optical system by moving the second lens group GB (lens L13) along the optical axis OA. Therefore, with the add-on device 4 (imaging device 1), the above subject can also be brought into focus. In other words, the add-on device 4 (imaging device 1) can be retrofitted to an existing imaging device to improve its focusing performance.

[0075] [Examples of implementation using software] The function of the add-on device 4 (hereinafter referred to as "device") is a program that causes the device to function as a computer, and can be realized by a program that causes each control block of the device (particularly each part included in the control unit 43) to function as a computer.

[0076] In this case, the device includes a computer having at least one control device (e.g., a processor) and at least one storage device (e.g., memory) as hardware for executing the program. By executing the program using this control device and storage device, the functions described in each of the embodiments are realized.

[0077] The above program may be recorded on one or more computer-readable recording media, not temporary ones. These recording media may or may not be provided by the above device. In the latter case, the program may be supplied to the above device via any wired or wireless transmission medium.

[0078] Furthermore, some or all of the functions of each of the above control blocks can also be realized by logic circuits. For example, an integrated circuit in which logic circuits functioning as each of the above control blocks are formed is also included in the scope of the present invention. In addition, it is also possible to realize the functions of each of the above control blocks by, for example, a quantum computer.

[0079] 〔summary〕 An additional device according to embodiment 1 of the present invention is an additional device arranged on the image plane side opposite to the object side where the object to be imaged is located in the first lens group, and comprises a second lens group which is arranged to form a single optical system by aligning with the first lens group so as to coincide with the optical axis; a lens drive unit which moves the second lens group along the optical axis; a distance measuring unit which measures the distance to the object and generates first distance information indicating the measured distance; and a control unit which controls the lens drive unit, wherein the control unit comprises a first acquisition unit which acquires the first distance information; a calculation unit which calculates a focus position which is the position of the second lens group when the image of the object formed by the optical system is in focus, based on the first distance information; and a drive control unit which controls the lens drive unit so that the second lens group moves to the focus position.

[0080] An additional device according to embodiment 2 of the present invention may further include, in embodiment 1 above, a measurement unit that measures the position of the second lens group within the optical system and generates position information indicating the measured position, the control unit further includes a second acquisition unit that acquires the position information, and a determination unit that determines whether or not there is a discrepancy between the position of the second lens group indicated by the position information and the focus position, the calculation unit corrects the focus position based on first discrepancy information indicating the magnitude of the discrepancy when the determination unit determines that there is a discrepancy, and the drive control unit controls the lens drive unit so that the second lens group moves to the corrected focus position. Embodiment 2 is even more effective from the viewpoint of improving the accuracy of focus control.

[0081] The additional device according to embodiment 3 of the present invention may be configured such that, in embodiment 2 described above, the calculation unit calculates second distance information indicating the distance to the object such that the focus position becomes the position of the second lens group indicated by the position information, generates second shift information indicating the difference between the distance indicated by the first distance information and the distance indicated by the second distance information, generates third shift information indicating the difference between the back focus when the distance to the object is the distance indicated by the first distance information and the back focus when the distance to the object is the distance indicated by the second distance information based on the second shift information, and corrects the focus position so that the difference indicated by the third shift information becomes smaller. Embodiment 3 is even more effective from the viewpoint of improving the accuracy of focus control.

[0082] The additional device according to embodiment 4 of the present invention may be configured such that, in any one of embodiments 1 to 3 described above, the distance measuring unit generates first time-series data including the first distance information at multiple points in time within the specified period by repeatedly measuring the distance to the object within the specified period.

[0083] The additional device according to embodiment 5 of the present invention may further include a housing for housing the second lens group, in any one of embodiments 1 to 4 described above, and the lens drive unit may be housed together with the second lens group in the housing. Embodiment 5 is even more effective from the viewpoint of miniaturizing the additional device.

[0084] The additional device according to embodiment 6 of the present invention may be configured such that, in any one of embodiments 1 to 5 above, the second lens group is composed of a single lens. Embodiment 6 is even more effective from the viewpoint of miniaturizing the additional device.

[0085] The imaging device according to embodiment 7 of the present invention may be configured in any one of embodiments 1 to 6 above, comprising the additional device, the first lens group, and an image sensor arranged on the image plane side of the second lens group, which converts the image of the object formed by the optical system into an electrical signal and outputs it.

[0086] In the imaging device according to embodiment 8 of the present invention, the optical system may be configured such that it satisfies the following formula (1) in embodiment 7 described above.

[0087] In the imaging device according to embodiment 9 of the present invention, the first lens group may be configured in such a way that it does not include a lens group that moves when the optical system is in focus, as described in embodiment 7 or 8 above.

[0088] In the imaging device according to embodiment 10 of the present invention, the first lens group may be configured such that, in any one of embodiments 7 to 9 above, the first lens group includes a lens group that moves when the optical system is in focus.

[0089] The imaging device according to embodiment 11 of the present invention may further include the first lens group or an aperture diaphragm provided on the image plane side thereof, and the second lens group may be further positioned on the image plane side than the aperture diaphragm.

[0090] The imaging device according to embodiment 12 of the present invention may be configured such that, in any one of embodiments 7 to 11 above, the lens in the second lens group that is closest to the object is concave with respect to the object, and the optical system satisfies the above formula (2).

[0091] In the imaging device according to embodiment 13 of the present invention, the optical system may be configured such that it satisfies the above formula (3) in any one of embodiments 7 to 12.

[0092] In the imaging device according to aspect 14 of the present invention, the optical system may be configured such that it satisfies the above formula (4) in any one of aspects 7 to 13 described above.

[0093] In the imaging device according to aspect 15 of the present invention, the optical system may be configured such that it satisfies the above formula (5) in any one of aspects 7 to 14 described above.

[0094] An imaging device according to embodiment 16 of the present invention further comprises, in any one of embodiments 7 to 15 above, a display unit for displaying an image and a display control unit for controlling the display by the display unit, wherein the display control unit may be configured to display an image of the object based on the electrical signal output by the image sensor on the display unit when the distance measuring unit measures the distance to the object, and not display an image of the object on the display unit when the distance measuring unit does not measure the distance to the object.

[0095] The imaging device according to embodiment 17 of the present invention may be configured such that, in embodiment 16 described above, the display control unit generates a second time-series data including the control results at multiple points in time within the specified period by acquiring the control result of whether or not the display control unit displayed an image of the object on the display unit within the specified period.

[0096] The optical system according to the present invention, as described above, can improve the focusing performance of imaging devices used in various applications with a simple configuration, thereby further enhancing the versatility of imaging devices. This invention, which achieves such effects, is expected to contribute to the further expansion of technologies using imaging devices, and is anticipated to contribute to achieving, for example, United Nations Sustainable Development Goal (SDG) 9, "Build resilient infrastructure, promote inclusive and sustainable industrialization and foster innovation."

[0097] The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Examples]

[0098] Examples of the present invention are described below.

[0099] In the following embodiments, the optical configuration of the optical system is illustrated. In the diagram of the optical configuration, GA represents the first lens group, GB represents the second lens group, S represents the aperture diaphragm, CG represents the cover glass, I represents the image sensor, and L represents the lens. In each embodiment, lens group GB is configured to be detachably positioned between lens group GA and the image sensor.

[0100] Furthermore, the aberrations of the optical system are illustrated for each embodiment. The longitudinal aberration diagrams shown in each figure represent, from left to right, spherical aberration (mm), astigmatism (mm), and distortion (%), respectively.

[0101] In the diagram showing spherical aberration, the vertical axis represents the ratio to the maximum aperture (F-number), and the horizontal axis represents the amount of defocus (mm). The dotted line shows the spherical aberration of the optical system with light of the g line (wavelength λ=435.84nm), the solid line shows the spherical aberration of the d line (wavelength λ=587.56nm), and the dashed line shows the spherical aberration of light of the C line (wavelength λ=656.27nm).

[0102] In the diagram showing astigmatism, the vertical axis represents image height (mm) and the horizontal axis represents defocus amount (mm). The solid line represents the sagittal image plane (S) relative to the d line, and the dotted line represents the meridional image plane (T) relative to the d line.

[0103] In the diagram showing distortion, the vertical axis represents image height (mm), and the horizontal axis represents percentage.

[0104] Furthermore, the lens data for the optical system in each embodiment is shown in a table. In the table, "r" represents the radius of curvature, and "d" represents the lens thickness or lens spacing. Also, "Nd" represents the refractive index for the d line (wavelength λ = 587.56 nm), and "νd" represents the Abbe number for the d line. The symbol "S" in the table represents the aperture. "INF" means infinity. In the "d" column, indications such as "D(23)" indicate that the spacing of the lens surfaces on the term axis is a variable spacing that changes when in focus.

[0105] Furthermore, various data for the optical system are shown in tables for each embodiment (e.g., Table 2 in Embodiment 1). The values ​​in the tables indicate the values ​​for each item at the lens position when the lens is focused at infinity.

[0106] Furthermore, the object distance data for each embodiment is shown in a table. The values ​​in the table indicate the values ​​for each item at the lens position when the lens is focused at infinity. For example, in Table 3, the INF value for D23 indicates the lens position when the lens is focused at infinity, the value of 5.0 mm indicates the lens position when the lens is focused at infinity, and the value of 1.0 mm indicates the lens position when the lens is focused at infinity. Similarly, in Table 3, the INF value for D25 indicates the lens position when the lens is focused at infinity, the value of 5.0 mm indicates the lens position when the lens is focused at infinity, and the value of 1.0 mm indicates the lens position when the lens is focused at infinity.

[0107] [Example 1] Figure 5 is a schematic diagram showing the optical configuration of the optical system of Example 1 when focused at infinity. Figure 6 is a diagram showing the longitudinal aberration of the optical system of Example 1 when focused at infinity. Figure 7 is a diagram showing the longitudinal aberration of the optical system of Example 1 when focused at a first object distance of 5m. Figure 8 is a diagram showing the longitudinal aberration of the optical system of Example 1 when focused at a second object distance of 1m.

[0108] The optical system of Example 1 has, in order from the object side, a first lens group GA and a second lens group GB.

[0109] The first lens group GA has a positive refractive power and consists of, in order from the object side, a concave meniscus lens L1, a concave meniscus lens L2, a concave meniscus lens L3, a biconvex lens L4, a convex meniscus lens L5, a biconvex lens L6, a cemented lens formed by a biconvex lens L7 and a biconcave lens L8, a cemented lens formed by a biconcave lens L9 and a biconvex lens L10, a biconvex lens L11, and a biconvex lens L12.

[0110] The second lens group GB has negative refractive power and is composed of a concave meniscus lens L13. In the optical system of Example 1, focusing from an object at infinity to an object at close range is achieved by moving the second lens group GB in the direction of the arrow in the figure (towards the image plane).

[0111] Table 1 shows the lens data for the optical system of Example 1. In Table 1, surface numbers 1 to 23 are the surface numbers of the lenses in the first lens group GA, and surface numbers 24 and 25 are the surface numbers of the second lens group GB. Surface number 13 represents the aperture. Surface numbers 26 and 27 represent the cover glass (CG), and surface number 28 represents the image plane.

[0112] [Table 1] Lens data Face number rd Nd νd 1 25.2837 2.5000 1.8467 23.78 2 14.6423 3.3167 3 53.7258 1.2000 1.5182 58.96 4 16.3372 4.6659 5 -35.9517 3.0000 1.6730 38.26 6 -144.0646 0.2000 7 108.6731 5.0000 1.9229 20.88 8 -43.7999 6.5133 9 99.9088 2.2618 1.4875 70.44 10 501.6323 1.5000 11 23.9272 4.9343 1.4970 81.61 12 -31.2471 5.8388 13 S INF 1.5000 14 25.0413 2.3892 1.5503 75.50 15 -12.8261 1.0000 1.6200 36.30 16 14.0547 3.1754 17 -8.4423 1.0000 1.7847 25.68 18 41.4020 3.8930 1.5928 68.62 19 -11.3853 0.2000 20 143.0846 3.3628 1.5928 68.62 21 -22.3510 0.2000 22 80.3428 3.0894 1.9229 20.88 23 -48.8527 D(23) 24 -60.0000 1.0000 1.5350 55.71 25 -100.0000 D(25) 26 INF 0.7500 1.5168 64.20 27 INF 1.0000 28 INF Furthermore, various data for the optical system of Example 1 are shown in Table 2, and the object distance data for the optical system of Example 1 is shown in Table 3.

[0113] [Table 2] Various Data Focal length (mm) 17.0789 FNo 3.03 Half-angle (°): 27.7 Image height (mm) 8.900

[0114] [Table 3] Object distance Object distance INF 5.0m 1.0m D 23 2.2585 2.6575 4.3104 D 25 15.7756 15.3767 13.7237

[0115] [Example 2] Figure 9 is a schematic diagram showing the optical configuration of the optical system of Example 2 when focused at infinity. Figure 10 is a diagram showing the longitudinal aberration of the optical system of Example 2 when focused at infinity. Figure 11 is a diagram showing the longitudinal aberration of the optical system of Example 2 when focused at a first object distance of 5m. Figure 12 is a diagram showing the longitudinal aberration of the optical system of Example 2 when focused at a second object distance of 1m.

[0116] The optical system of Example 2 has, in order from the object side, a first lens group GA and a second lens group GB.

[0117] The first lens group GA has a positive refractive power and consists of, in order from the object side, a concave meniscus lens L1, a concave meniscus lens L2, a concave meniscus lens L3, a biconvex lens L4, a convex meniscus lens L5, a biconvex lens L6, a cemented lens formed by a biconvex lens L7 and a biconcave lens L8, a cemented lens formed by a biconcave lens L9 and a biconvex lens L10, a biconvex lens L11, and a biconvex lens L12.

[0118] The second lens group GB has negative refractive power and is composed of a concave meniscus lens L13. In the optical system of Example 2, focusing from an object at infinity to an object at close range is achieved by moving the second lens group GB in the direction of the arrow in the figure (towards the image plane).

[0119] Table 4 shows the lens data for the optical system of Example 2. In Table 4, surface numbers 1 to 23 are the surface numbers of the lenses in the first lens group GA, and surface numbers 24 and 25 are the surface numbers of the second lens group GB. Surface number 13 represents the aperture. Surface numbers 26 and 27 represent the cover glass (CG), and surface number 28 represents the image plane.

[0120] [Table 4] Lens data Face number rd Nd νd 1 25.2837 2.5000 1.8467 23.78 2 14.6423 3.3167 3 53.7258 1.2000 1.5182 58.96 4 16.3372 4.6659 5 -35.9517 3.0000 1.6730 38.26 6 -144.0646 0.2000 7 108.6731 5.0000 1.9229 20.88 8 -43.7999 4.5830 9 99.9088 2.2618 1.4875 70.44 10 501.6323 1.5000 11 23.9272 4.9343 1.4970 81.61 12 -31.2471 5.8388 13 S INF 1.5000 14 25.0413 2.3892 1.5503 75.50 15 -12.8261 1.0000 1.6200 36.30 16 14.0547 3.1754 17 -8.4423 1.0000 1.7847 25.68 18 41.4020 3.8930 1.5928 68.62 19 -11.3853 0.2000 20 143.0846 3.3628 1.5928 68.62 21 -22.3510 0.2000 22 80.3428 3.0894 1.9229 20.88 23 -48.8527 D(23) 24 -35.8388 1.0000 1.5350 55.71 25 -117.9621 D(25) 26 INF 0.7500 1.5168 64.20 27 INF 1.0000 28 INF

[0121] Furthermore, various data for the optical system of Example 2 are shown in Table 5, and the object distance data for the optical system of Example 2 is shown in Table 6.

[0122] [Table 5] Various Data Focal length (mm) 19.3923 FNo 3.44 Half-angle (°): 24.6 Image height (mm) 8.900

[0123] [Table 6] Object distance Object distance INF 5.0m 1.0m D 23 4.1843 4.3681 5.0968 D 25 15.7802 15.5964 14.8677

[0124] [Example 3] Figure 13 is a schematic diagram showing the optical configuration of the optical system of Example 3 when focused at infinity. Figure 14 is a diagram showing the longitudinal aberration of the optical system of Example 3 when focused at infinity. Figure 15 is a diagram showing the longitudinal aberration of the optical system of Example 3 when focused at a first object distance of 5m. Figure 16 is a diagram showing the longitudinal aberration of the optical system of Example 3 when focused at a second object distance of 1m.

[0125] The optical system of Example 3 has, in order from the object side, a first lens group GA and a second lens group GB.

[0126] The first lens group GA has a positive refractive power and consists of, in order from the object side, a biconvex lens L1, a convex meniscus lens L2, a concave meniscus lens L3, a cemented lens formed by a biconvex lens L4 and a biconcave lens L5, a biconcave lens L6, a convex meniscus lens L7, and a biconvex lens L8.

[0127] The second lens group GB has negative refractive power and consists of a concave meniscus lens L9. In the optical system of Example 3, focusing from an object at infinity to an object at close range is achieved by moving the second lens group GB in the direction of the arrow in the figure (towards the image plane).

[0128] Table 7 shows the lens data for the optical system of Example 3. In Table 7, surface numbers 1 to 16 are the surface numbers of the lenses in the first lens group GA, and surface numbers 17 and 18 are the surface numbers of the second lens group GB. Surface number 7 represents the aperture. Surface numbers 19 and 20 represent the cover glass (CG), and surface number 21 represents the image plane.

[0129] [Table 7] Lens data Face number rd Nd νd 1 62.4373 4.0000 1.5168 64.20 2 2456.5636 0.1500 3 19.8616 5.7939 1.7292 54.67 4 33.1214 0.9105 5 52.4685 1.2000 1.5927 35.45 6 16.8903 11.6463 7 S INF 2.0000 8 22.0300 6.0100 1.8348 42.72 9 -52.8763 1.0000 1.6889 31.16 10 28.8198 3.9494 11 -20.9361 1.0000 1.6477 33.84 12 32.5345 1.5394 13 -61.3684 4.2304 1.7292 54.67 14 -27.5414 0.1500 15 47.1007 3.7500 1.8042 46.50 16 -47.1007 D(16) 17 -35.8224 1.0000 1.5350 55.71 18 -61.6781 D(18) 19 0.0000 1.0000 1.5168 64.20 20 0.0000 1.0000 21 0.0000

[0130] Furthermore, various data for the optical system of Example 3 are shown in Table 8, and the object distance data for the optical system of Example 3 is shown in Table 9.

[0131] [Table 8] Various Data Focal length (mm) 53.4058 FNo 3.28 Half-angle (°): 9.3 Image height (mm) 8.800

[0132] [Table 9] Object distance Object distance INF 5.0m 1.0m D 16 3.2610 5.4061 16.7920 D 18 18.4114 16.2664 4.8805

[0133] [Example 4] Figure 17 is a schematic diagram showing the optical configuration of the optical system of Example 4 when focused at infinity. Figure 18 is a diagram showing the longitudinal aberration of the optical system of Example 4 when focused at infinity. Figure 19 is a diagram showing the longitudinal aberration of the optical system of Example 4 when focused at a first object distance of 5m. Figure 20 is a diagram showing the longitudinal aberration of the optical system of Example 4 when focused at a second object distance of 1m.

[0134] The optical system of Example 4 has, in order from the object side, a first lens group GA and a second lens group GB.

[0135] The first lens group GA has a positive refractive power and consists of, in order from the object side, a biconvex lens L1, a convex meniscus lens L2, a concave meniscus lens L3, a cemented lens formed by a biconvex lens L4 and a biconcave lens L5, a biconcave lens L6, a convex meniscus lens L7, and a biconvex lens L8.

[0136] The second lens group GB has negative refractive power and consists of a concave meniscus lens L9. In the optical system of Example 4, focusing from an object at infinity to an object at close range is achieved by moving the second lens group GB in the direction of the arrow in the figure (towards the image plane).

[0137] Table 10 shows the lens data for the optical system of Example 4. In Table 10, surface numbers 1 to 16 are the surface numbers of the lenses in the first lens group GA, and surface numbers 17 and 18 are the surface numbers of the second lens group GB. Surface number 7 represents the aperture. Surface numbers 19 and 20 represent the cover glass (CG), and surface number 21 represents the image plane.

[0138] [Table 10] Lens data Face number rd Nd νd 1 62.4373 4.0000 1.5168 64.20 2 2456.5636 0.1500 3 19.8616 5.7939 1.7292 54.67 4 33.1214 0.9105 5 52.4685 1.2000 1.5927 35.45 6 16.8903 9.7314 7 S INF 2.0000 8 22.0300 6.0100 1.8348 42.72 9 -52.8763 1.0000 1.6889 31.16 10 28.8198 3.9494 11 -20.9361 1.0000 1.6477 33.84 12 32.5345 1.5394 13 -61.3684 4.2304 1.7292 54.67 14 -27.5414 0.1500 15 47.1007 3.7500 1.8042 46.50 16 -47.1007 D(16) 17 -24.5241 1.0000 1.5350 55.71 18 -143.1114 D(18) 19 INF 1.0000 1.5168 64.20 20 INF 1.0000 21 INF

[0139] Furthermore, various data for the optical system of Example 4 are shown in Table 11, and the object distance data for the optical system of Example 4 is shown in Table 12.

[0140] [Table 11] Various Data Focal length (mm) 61.5751 FNo 3.76 Half-angle (°): 8.0 Image height (mm) 8.800

[0141] [Table 12] Object distance Object distance INF 5.0m 1.0m D 16 8.0445 9.0644 13.4340 D 18 15.9945 14.9746 10.6050

[0142] Table 13 shows the values ​​of each parameter in each embodiment. Table 14 shows the numerical values ​​of each formula in each embodiment. In the notes in the tables below, "INF" indicates the lens position when focused at infinity, and "MOD" indicates the lens position when focused at the shortest focusing distance.

[0143] [Table 13] Example 1 Example 2 Example 3 Example 4 Remarks Bmin 0.0034 0.0039 0.0106 0.0122 Bmax 0.0167 0.0189 0.0501 0.058 LT 81.5247 81.5247 72.0023 72.4539 ra -60 -35.8388 -35.8224 -24.5241 βA 1.0667 1.1869 1.1335 1.3281 INF βA 1.0585 1.1737 1.0350 1.1758 MOD Fa 16.0115 16.3387 47.1175 46.377 Fb -282.82 -96.6262 -161.215 -55.2427 M 2.0519 0.9125 13.531 5.3895 f 17.0789 19.3923 53.4051 61.5944

[0144] [Table 14] Example 1 Example 2 Example 3 Example 4 Remarks Bmin / Bmax 0.2036 0.2063 0.2116 0.2103 LT / ra -1.3587 -2.2748 -2.0100 -2.9544 βA 1.0667 1.1869 1.1335 1.3281 INF βA 1.0585 1.1737 1.0350 1.1758 MOD |Fa / Fb| 0.05661 0.1691 0.2923 0.8395 |M| / f 0.1201 0.0471 0.2534 0.0875 [Explanation of Symbols]

[0145] 1. Imaging device 2 Main unit 3 Telescope tubes 4. Additional devices 42 Ranging section

Claims

1. An additional device in the first lens group, which is positioned on the image plane side opposite to the object side where the object to be imaged is located, The second lens group, which is arranged so as to coincide with the optical axis of the first lens group, constitutes a single optical system. A lens drive unit that moves the second lens group along the optical axis, A distance measuring unit measures the distance to the object and generates first distance information indicating the measured distance, The control and control unit of the lens drive unit, Equipped with, The control unit, A first acquisition unit that acquires the first distance information, A calculation unit calculates the focus position, which is the position of the second lens group when the image of the object formed by the optical system is in focus, based on the first distance information. A drive control unit controls the lens drive unit so that the second lens group moves to the focus position, Equipped with, Additional device.

2. The system further includes a measuring unit that measures the position of the second lens group within the optical system and generates position information indicating the measured position. The control unit, A second acquisition unit that acquires the aforementioned location information, A determination unit that determines whether or not there is a discrepancy between the position of the second lens group indicated by the position information and the focus position, Furthermore, When the calculation unit determines that there is a misalignment, it corrects the focus position based on the first misalignment information indicating the magnitude of the misalignment. The drive control unit controls the lens drive unit so that the second lens group moves to the corrected focus position. The additional device according to claim 1.

3. The calculation unit described above, A second distance information is calculated that indicates the distance to the object such that the focusing position is the position of the second lens group indicated by the position information. A second deviation information is generated that indicates the difference between the distance indicated by the first distance information and the distance indicated by the second distance information. Based on the second displacement information, a third displacement information is generated that shows the difference between the back focus when the distance to the object is the distance indicated by the first distance information and the back focus when the distance to the object is the distance indicated by the second distance information. The focus position is corrected so that the difference indicated by the third misalignment information becomes smaller. The additional device according to claim 2.

4. The distance measuring unit generates first time-series data including the first distance information at multiple points in time within a specified period by repeatedly measuring the distance to the object within a specified period. The additional device according to claim 1.

5. The device further comprises a housing for the second lens group, The lens drive unit is housed in the housing together with the second lens group. The additional device according to claim 1.

6. The second lens group is composed of a single lens. The additional device according to claim 1.

7. An additional device according to any one of claims 1 to 6, The first lens group and, An image sensor is positioned on the image plane side of the second lens group and converts the image of the object formed by the optical system into an electrical signal for output. Equipped with, Imaging device.

8. The optical system satisfies the following equation (1): The imaging apparatus according to claim 7. 0.001<Bmin / Bmax (1) however Bmax: Maximum magnification Bmin: Minimum magnification

9. The first lens group does not include a lens group that moves when the optical system is in focus. The imaging apparatus according to claim 7.

10. The first lens group includes a lens group that moves when the optical system is in focus. The imaging apparatus according to claim 7.

11. The first lens group or an aperture diaphragm provided on the image plane side thereof further comprises The second lens group is positioned further toward the image plane than the aperture diaphragm, The imaging apparatus according to claim 7.

12. The lens in the second lens group that is closest to the object has a concave shape relative to the object. The optical system satisfies the following equation (2): The imaging apparatus according to claim 7. -15.0<LT / ra<-0.1 (2) however ra: Radius of curvature of the lens surface closest to the object in the second lens group. LT: Total length of the optical system

13. The optical system satisfies the following equation (3): The imaging apparatus according to claim 7. 0.85<|βA|<1.25 (3) however, βA: Lateral magnification of the second lens group when focused at infinity.

14. The optical system satisfies the following equation (4): The imaging apparatus according to claim 7. 0.01<|Fa / Fb|<40.00 (4) however Fa: Focal length of the first lens group Fb: Focal length of the second lens group

15. The optical system satisfies the following equation (5): The imaging apparatus according to claim 7. 0.01<|M| / f<100.00 (5) however M: Amount of movement of the second lens group relative to the image plane f: Focal length of the optical system

16. A display unit that displays images, A display control unit that controls the display by the display unit, Furthermore, The display control unit, When the distance measuring unit measures the distance to the object, the display unit displays an image of the object based on the electrical signal output by the image sensor. If the distance measuring unit fails to measure the distance to the object, the image of the object will not be displayed on the display unit. The imaging apparatus according to claim 7.

17. The display control unit generates a second time-series data including the control results at multiple points in time within the specified period by obtaining the control result of whether or not the display control unit displayed an image of the object on the display unit within a specified period. The imaging device according to claim 16.

Images