Holding device, camera unit, and imaging system

Abstract

An object of the present invention is to provide a holding device, a camera unit, and an imaging system capable of capturing an image of a subject with higher image quality than before in water.SOLUTION: A holding device insertable into a transparent tubular member, the holding device comprising: a camera holding section capable of holding an image pickup apparatus including an image pickup optical system and an image pickup device for photographing an outside of the tubular member; a correction lens having a curvature at least in a cross section orthogonal to an extending direction of the tubular member; and a lens holding section capable of holding the correction lens to be located between the tubular member and the image pickup optical system when the holding device is inserted into the tubular member and the image pickup apparatus is held by the camera holding section.SELECTED DRAWING: Figure 13

Description

[Technical Field]

[0001] The present invention relates to a holding device, a camera unit, and an imaging system. [Background technology]

[0002] The imaging system described in Patent Document 1 is known as a technology that enables remote observation of animals and the like exhibited at zoos, aquariums, etc. In the imaging system described in Patent Document 1, a camera unit having a drive unit that can move inside the tubular member is inserted into a transparent tubular member. The camera unit is positioned so that it can capture images of the scenery outside the tubular member, and a user can observe and capture images of subjects such as animals by remotely moving the camera unit.

[0003] In this way, the camera unit moves inside the tubular member, allowing it to move stably regardless of road conditions. In addition, the drive unit does not come into contact with animals, etc., increasing the safety of both the camera unit and the subject, such as an animal. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2023-168258 Summary of the Invention [Problem to be solved by the invention]

[0005] Patent Document 1 also describes that the imaging system can be installed underwater. In general, it is desirable to be able to observe and photograph subjects such as animals with higher image quality even underwater.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a holding device, a camera unit, and an imaging system that are capable of photographing a subject underwater with higher image quality than conventional ones. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, the holding device of the present invention is a holding device that can be inserted into a transparent tubular member, and is characterized by having: a camera holding portion that can hold an imaging device having an imaging optical system and an imaging element for photographing the outside of the tubular member; a corrective lens that has a curvature at least in a cross section perpendicular to the extension direction of the tubular member; and a lens holding portion that can hold the corrective lens so that it is positioned between the tubular member and the imaging optical system when the holding device is inserted into the tubular member and the imaging device is held in the camera holding portion.

[0008] In addition, in order to achieve the above-mentioned object, the camera unit of the present invention is a camera unit that can be inserted into a transparent tubular member, and is characterized by having an imaging device having an imaging optical system and an imaging element for photographing the outside of the tubular member, a camera holding part that can hold the imaging device, a corrective lens that has a curvature at least in a cross section perpendicular to the extension direction of the tubular member, and a lens holding part that can hold the corrective lens so that it is positioned between the tubular member and the imaging optical system when the holding device is inserted into the tubular member and the imaging device is held in the camera holding part.

[0009] In addition, in order to achieve the above-mentioned object, the imaging system of the present invention is characterized by having a transparent tubular member, a camera unit that can be inserted into the tubular member, an imaging device having an imaging optical system and an imaging element for photographing the outside of the tubular member, a camera holding part that holds the imaging device, a corrective lens that has a curvature at least in a cross section perpendicular to the extension direction of the tubular member, and a lens holding part that can hold the corrective lens so that it is positioned between the tubular member and the imaging optical system when the holding device is inserted into the tubular member and the imaging device is held in the camera holding part. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a holding device, a camera unit, and an imaging system that are capable of capturing images of a subject underwater with higher image quality than conventional ones. [Brief explanation of the drawings]

[0011] [Figure 1] Schematic diagram of the configuration of an imaging system according to a first embodiment [Figure 2] FIG. 1 is a schematic diagram showing a usage scene of the imaging system according to the first embodiment in landscape orientation; [Figure 3] FIG. 1 is a schematic diagram showing a usage scene of the imaging system according to the first embodiment in portrait orientation; [Figure 4] 1 is a perspective view of an appearance of an imaging device according to a first embodiment; [Figure 5] FIG. 1 is an external perspective view of an imaging system according to a first embodiment; [Figure 6] FIG. 1 is an enlarged perspective view of the periphery of an imaging device of an imaging system according to a first embodiment; [Figure 7] 1 is a cross-sectional view of a translational movement unit of an imaging system according to a first embodiment; [Figure 8] FIG. 1 is an enlarged perspective view of a translational movement unit of an imaging system according to a first embodiment; [Figure 9] FIG. 1 is an enlarged perspective view of a rotation unit of an imaging system according to a first embodiment; [Figure 10] FIG. 1 is a front view showing a range of motion of the imaging system according to the first embodiment; [Figure 11] Schematic cross-sectional view of the imaging system according to the first embodiment, assuming that only the imaging device rotates. [Figure 12] 1 is a cross-sectional view showing a support structure of an imaging system according to a first embodiment; [Figure 13] FIG. 1 is an enlarged perspective view of the periphery of an imaging device of an imaging system according to a first embodiment; [Figure 14] Schematic cross-sectional view of the imaging system according to the first embodiment taken along the optical axis. [Figure 15] 1 is a schematic cross-sectional view of an image formed when an attachment lens is not provided in the imaging system according to the first embodiment; [Figure 16]1 is a schematic cross-sectional view of an image formed when an attachment lens of the imaging system according to the first embodiment is installed; [Figure 17] FIG. 10 is a schematic diagram showing a usage scene of the imaging system according to the second embodiment in horizontal orientation; [Figure 18] FIG. 10 is a schematic diagram showing a usage scene of the imaging system according to the second embodiment in portrait orientation; [Figure 19] FIG. 11 is an enlarged perspective view of the periphery of an imaging device of an imaging system according to a second embodiment. [Figure 20] 10 is a cross-sectional view showing the retraction operation of the attachment lens of the imaging system according to the second embodiment; DETAILED DESCRIPTION OF THE INVENTION

[0012] [First embodiment] [Configuration of imaging system 100] First, the configuration of an imaging system 100 according to this embodiment will be described with reference to Fig. 1. Fig. 1 is a diagram schematically illustrating the components of the imaging system 100. The imaging system 100 includes a transparent pipe (tubular member, transparent tubular member) 101 as a housing, and a camera unit 610 is disposed inside the transparent pipe 101. The camera unit 610 is held so that it can translate in the extension direction of the transparent pipe 101 and tilt and rotate about the central axis of the transparent pipe 101. The camera unit 610 is a collective term for an imaging device 50 and a holding device 110, which will be described later.

[0013] The transparent pipe 101 is a watertight container, and is designed so that liquid will not enter the interior even when submerged in water. The level of sealing need only be such that it does not pose a problem in practical use of the imaging system 100. The transmission cable bundle (wiring) 90 is a bundle of multiple cables, each with one terminal connected to the imaging device 50 or a drive unit. The transmission cable bundle 90 is used to transmit instruction signals and video signals for changing the shooting settings of the imaging device 50 in the camera unit 610, and to send and receive power and control signals to the drive unit that operates the camera unit 610.

[0014] The transmission cable bundle 90 passes through a small-diameter bent pipe 102 extending from a transparent pipe 101, and is protected from the surrounding environment near the transparent pipe 101 by the small-diameter bent pipe 102. The transmission cable bundle 90 is connected to a server 10, which is connected to a display 20 and a controller 30. A user can use the controller 30 to remotely move the camera unit 610 and take pictures while viewing the image of the camera unit 610 displayed on the display 20. The server 10 is also connected to the Internet, and a user can operate the imaging system 100 from a remote location via the Internet using a tablet terminal, smartphone, PC, etc.

[0015] [Usage scenarios for the imaging system 100] Next, a usage scenario of the imaging system 100 will be described with reference to FIGS. 2 and 3. FIG. 2 is a schematic diagram showing the imaging system 100 installed in an aquarium tank. The transparent pipe 101 is submerged in water, and the small-diameter bent pipe 102 extends at a substantially right angle to the transparent pipe 101 so that its tip protrudes above the water surface W. The camera unit 610 and the transmission cable bundle 90 are completely covered by the transparent pipe 101 and the small-diameter bent pipe 102, preventing water from entering the interior. The transmission cable bundle 90 extending from the end of the small-diameter bent pipe 102 is connected to the server 10 shown in FIG. 1. A user can track and observe a living organism F, which is a subject, by operating the zooming operation, shooting operation, translational movement, and tilt rotation of the camera unit 610. By operating the imaging system 100 in this manner, it is possible to enjoy observing and photographing living organisms from angles of view that cannot be seen from outside the aquarium or from close up.

[0016] Figure 3 is a schematic diagram showing the imaging system 100 placed vertically in a deep tank in an aquarium. Unlike Figure 2, the camera unit 610 can be moved up and down and rotated horizontally (tilted around the central axis of the transparent pipe 101). The small-diameter straight pipe 103 is replaced with a straight one that extends in the same direction as the transparent pipe 101, and is positioned so that its tip protrudes above the water surface W. By moving up and down, the user can observe multiple living organisms F swimming at different depths.

[0017] In this way, the imaging system 100 can be placed at various angles and positions depending on the object to be observed, and can be placed in environments where observation is normally difficult, such as at an angle or partially buried underground. Alternatively, the imaging system 100 may be placed so that part of the transparent pipe 101 is in the air and the other part is underwater. The entire transparent pipe 101 can also be placed in the air (on the ground).

[0018] The shape and length of the small diameter straight pipe 103 (or small diameter bent pipe 102) can also be changed depending on the situation, and any shape and length may be used as long as it can protect the transmission cable bundle 90 to a safe space.

[0019] [Configuration of imaging device 50] The imaging device 50 will be described with reference to Fig. 4. Fig. 4 is an external perspective view of the imaging device 50. The imaging device 50 is an interchangeable lens camera. It has an imaging element 53 (not shown in Fig. 4) inside, and various photographic lenses 60 can be attached to a lens mount 52. Still images and videos can be taken by forming an image of a subject on the imaging element 53 through the photographic lens 60.

[0020] Terminal section 51 is provided with multiple terminals, and by connecting to server 10 via transmission cable bundle 90, it is possible to transmit video, operate imaging device 50, and supply power. Since imaging device 50 is held by the user to take pictures, it has a grip shape, a viewfinder, and various operating members, but these are not used in imaging system 100 of this embodiment, and since photography is performed by remote control, an imaging device that does not have these may also be used.

[0021] The power source may be either a built-in battery or an external wired power supply via a transmission cable bundle 90. Furthermore, although this embodiment uses an interchangeable lens camera in which the taking lens 60 can be removed, a digital camera in which the taking lens 60 and camera body (camera main body) 54 are integrated may also be used. The camera body 54 may be a mirrorless camera or a single-lens reflex camera. The camera body 54 is equipped with a viewfinder 55. The camera body 54 may also be configured to have a viewfinder attachment section instead of the viewfinder 55.

[0022] [Configuration for holding the imaging device 50] The holding configuration of the imaging device 50 of the imaging system 100 will be described with reference to Figures 5 and 6. Figure 5 is an external perspective view showing the entire imaging system 100. The coordinate axes in Figure 5 and other figures are defined as follows: The X-axis is the extension axis of the transparent pipe 101 (the central axis, an imaginary axis passing through the center of the circular cross-section of the transparent pipe 101). The Y-axis is the normal axis of the installation surface (ground, etc.) of the imaging system 100 or a plane parallel to the imaginary installation surface (ground, bottom of a water tank, etc.). The imaginary plane here refers to a plane passing through the point where the metal frame 106 would come into contact with the ground, the bottom of a water tank, etc. if the imaging system 100 were floating in the air or water. The Z-axis is an axial direction perpendicular to the X-axis and Y-axis.

[0023] The transparent pipe 101 is a transparent resin pipe made of acrylic. Openable and closable resin caps 104 are attached to both ends of the transparent pipe 101. A sealing rubber (not shown in FIG. 5) is provided on the inside of the cap 104, which is attached to the transparent pipe 101 using a screw shape and can be sealed by charging the sealing rubber. A metal frame 106 is provided as a framework at the bottom of the transparent pipe 101, and the transparent pipe 101 is attached to the metal frame 106 with a holding metal plate 105. The metal frame 106 also functions as a weight, and the mass greater than the buoyancy inside the sealed transparent pipe 101 allows the imaging system 100 to be submerged in water.

[0024] The metal frame 106 as a frame is intended to stably install the imaging system 100 on the bottom of an aquarium or the ground in an area where animals are kept, and as long as it can perform this function, a frame other than the metal frame 106, for example a plastic frame, may be used as the frame. When installing such an imaging system 100 in water, a weight can be provided in addition to the frame.

[0025] The small diameter bent pipe 102 is composed of a PVC pipe 1021, a right-angle joint 1022, and a union joint 1023. Each joint is fixed with adhesive and connected in a way that prevents liquid from entering from the outside. The union joint 1023 is fastened to the cap 104 using a screw shape, so it can be removed during transportation or replaced with a different shape from the small diameter bent pipe 102, such as the small diameter straight pipe 103 in Figure 3. A sealing rubber (not shown in Figure 5) is provided at the boundary surface of the union joint 1023, and the sealing rubber is charged after the screws are fastened, making it waterproof.

[0026] FIG. 6 is an enlarged view of region A in FIG. 5. The holding device 110 has a left side plate (first holding member, first holding portion, first holding means) 1101. It also has a right side plate (second holding member, second holding portion, second holding means) 1102 and a front metal plate (third holding member, third holding portion, third holding means, lens holding portion) 1103. It also has a bottom metal plate (fourth holding member, fourth holding portion, fourth holding means) 1104. The holding device 110 covers the imaging device 50 with these metal plates. The imaging device 50 is held by the holding device 110 by being fixed to the bottom metal plate 1104 with screws, and its position relative to the holding device 110 is fixed. Of the various components of the holding device 110, the components involved in holding the imaging device 50 are collectively referred to as the camera holding portion.

[0027] A photographing lens 60 is attached to the imaging device 50, and FIG. 6 shows the state in which its optical axis 61 faces forward (in the Z-axis direction). Highly lubricating bushings 1105 are provided in three locations on each of the left and right plates 1101 and 1102. A first support column (first shaft member, first shaft portion) 111, a second support column (second shaft member, second shaft portion) 112, and a third support column (third shaft member, third shaft portion) 113 are inserted into the respective bushings 1105. This configuration supports the holding unit 110 for smooth translational movement in the X-axis direction, and each support column functions as a guide during movement. An end of a cable carrier (cable protection member, cable protection portion, cable protection means, wiring holding member) 109 is attached to the left plate 1101. The cable carrier 109 is a protective member for a cable 91 (not shown in FIG. 6) for transmitting control signals and video signals for the imaging device 50. The timing belt 121 is a part of a drive mechanism for translating the holding device 110 , and a part of the timing belt 121 is fixed to the bottom metal plate 1104 .

[0028] [Driving mechanism of imaging system 100] The translational movement mechanism of the imaging system 100 will be described with reference to Figures 7 and 8. Figure 7(a) is a top view (view from the Y-axis direction) of the mechanism provided inside the transparent pipe 101 of the imaging system 100. Figure 7(b) is a cross-sectional view taken along the line AA in Figure 7(a), and Figure 7(c) is a cross-sectional view taken along the line BB in Figure 7(a).

[0029] 7(a) is provided at the right end of the drawing. The driving unit 120 is provided with a first motor (first actuator, first driving member, first driving means) 122, which is an actuator that moves the holding device 110 in the X-axis. Similarly, a second motor (second actuator, second driving member, second driving means) 161, which is an actuator that rotates the rotating unit 160 that includes the driving unit 120, the holding device 110, and the passive rotating unit 130, is also provided. A control board 150 for controlling the first motor 122 and the second motor 161 is also provided. A communication cable 151 (not shown in FIG. 7) that transmits control commands and supplies power is connected to the control board 150.

[0030] A passive rotation unit 130 is provided at the left end in Figure 7(a). The passive rotation unit 130 has multiple passive rollers 131 arranged so as to come into contact with the inner wall of the transparent pipe 101. The passive rollers 131 play a role in supporting the end of the rotation structure during the rotation operation described below. In addition, a ball roller 132 is provided at the end of the passive rotation unit 130. The ball roller 132 reduces friction when it comes into contact with the inner surface of the cap 104 (see Figure 5) that seals the transparent pipe 101.

[0031] FIG. 7(b) mainly shows the path of the cable carrier 109. As described above, one end of the cable carrier 109 is fastened to the left side plate 1101, and the cable 91 that transmits control signals and video signals for the imaging device 50 is inserted inside the cable carrier 109. The opposite end is connected to the drive unit 120, which protects and guides the cable 91 when the holding device 110 moves in the X-axis direction. The cable carrier 109 is flexible around the Z-axis. As long as the cable carrier 109 is flexible around the Z-axis, it may or may not be flexible around other axes. The cable carrier 109 is an elastic member made of plastic, but it may also be a metal member made of aluminum or other material as long as it is flexible around the Z-axis.

[0032] The cable carrier 109 extending from the left side plate 1101 is folded back 180 degrees midway and is arranged to pass under the imaging device 50 and the bottom metal plate 1104. When the holding device 110 moves in the X-axis direction, the folded back portion absorbs the excess length, preventing the cable 91 from becoming tangled. The cable 91 guided by the cable carrier 109 to the drive unit 120 merges with the communication cable 151 (not shown in FIG. 7) which is the communication wiring of the control board 150, and is connected to the server 10 as a transmission cable bundle 90 through the small-diameter bent pipe 102 (see FIG. 1).

[0033] FIG. 7(c) mainly shows the configuration of the timing belt 121. The timing belt 121 is an elastic, belt-like component that is looped around and supported by a drive timing pulley 125 and a driven timing pulley 127. A portion of the timing belt 121 is fixed to a bottom metal plate 1104 of the holding device 110. Rotation of the drive timing pulley 125 causes the timing belt 121 to advance and retreat (rotate), thereby allowing the holding device 110 to slide in the X-axis direction. More specifically, a metal member (not shown in FIG. 7) is fixed to a portion of the timing belt 121, and this metal member is fixed to the bottom metal plate 1104 with multiple screws (not shown in FIG. 7). Therefore, when the timing belt 121 advances and retreats, the metal member also advances and retreats, and the bottom metal plate 1104 fixed to the metal member also advances and retreats, resulting in the imaging device 50 advancing and retreating (translational movement). The timing belt 121 has a drive timing pulley 125, a driven timing pulley 127, and teeth (gear portions) on which the metal members are hooked, but these are omitted from the drawings.

[0034] [Translation] 8 is a perspective view showing elements involved in the translational movement of the drive unit 120, with some members indicated by dashed lines to explain the internal elements. A first pinion gear 123 is attached to the drive shaft of a first motor 122 (shown by a dashed line in the figure). A spur gear 124 is rotatably disposed so as to mesh with the first pinion gear 123, and a drive timing pulley 125 is attached coaxially with the spur gear 124. The timing belt 121 is looped around the drive timing pulley 125. An idler pulley 126 is rotatably disposed so as to hold down the timing belt 121, and plays a role in maintaining the tension of the timing belt 121.

[0035] Therefore, as the drive shaft of the first motor 122 rotates, the first pinion gear 123 rotates, which in turn rotates the spur gear 124 and drive timing pulley 125. As a result, the timing belt 121 advances and retreats. The arrows in the figure show examples of the operation of the timing belt 121 until it is unwound by the above rotation. When the first motor 122 is rotated in the reverse direction, all the arrows move in the reverse direction.

[0036] [Tilt rotation] The tilt rotation mechanism of the imaging system 100 will be described with reference to FIG. 9. FIG. 9 is a perspective view showing elements related to tilt rotation of the drive unit 120, with some internal elements indicated by dashed lines for clarity. A second pinion gear 162 is attached to the drive shaft of the second motor 161 (shown by the dashed line in the figure). An internal gear 163 is rotatably disposed so as to mesh with the second pinion gear 162. A fixed block 141 is fastened to the internal gear 163. Four fixed blocks 141 are adhesively fixed to the inner circumferential surface of the transparent pipe 101; that is, the fixed unit 140 including the internal gear 163 is fixed to the transparent pipe 101. When the second motor 161 rotates, the second pinion gear 162 runs on the tooth surface of the internal gear 163, causing the entire rotating unit 160 to rotate relative to the fixed unit 140. As a result, the camera unit 610 rotates, and the imaging device 50 tilts.

[0037] The first motor 122, which is the drive source for translational movement, and the second motor 161, which is the drive source for tilt rotation, are arranged so as to overlap in the extension direction of the transparent pipe 101, i.e., in the X-axis direction. In other words, the first motor 122 and the second motor 161 are arranged so that at least a portion of the first motor 122 and at least a portion of the second motor 161 overlap when viewed in the Z-axis direction. This overlapping arrangement makes it possible to reduce the length of the drive unit 120 in the X-axis direction, which contributes to the miniaturization of the imaging system 100 and the expansion of the range of translational movement.

[0038] [Measures to prevent the diameter of tubular components from increasing] [Reason for not rotating the imaging device alone] The above-described movements (drives) will be explained again with reference to Fig. 10. Fig. 10 is a front view (viewed in the Z-axis direction) of the mechanism provided inside the transparent pipe 101 of the imaging system 100. As explained in Figs. 7 and 8, during translational movement, the holding device 110 that holds the imaging device 50 moves in the X-axis direction. A first motor 122 is provided in the drive unit 120, and moves the timing belt 121 back and forth to move the holding device 110, which is connected to a metal member fixed to the timing belt 121.

[0039] 9, during tilt rotation, the rotating unit 160 rotates relative to the fixed unit 140 fixed to the transparent pipe 101. The second motor 161 is provided in the driving unit 120, and the entire rotating unit 160, which is an area including the driving unit 120, the holding device 110, and the cable carrier 109, rotates. A passive rotating unit 130 is provided at the right end of the rotating unit 160 in the drawing, and passive rollers 131 arranged around it run on the inner surface of the transparent pipe 101, thereby supporting the end of the rotating unit 160. The above-mentioned range of motion realizes translational movement and tilt rotation of the imaging device 50.

[0040] The effect of tilting the entire rotating unit 160, including the translational movement mechanism, in the imaging system 100 will be described with reference to FIG. 11. FIG. 11 is a cross-sectional schematic diagram of a hypothetical imaging system 100 in which only the imaging device 50 is configured to tilt. Detailed components are omitted, and only the camera body 54, the photographic lens 60, the cable carrier 109 that holds the cable 91 essential for video transmission, and the timing belt 121, which is the translational movement mechanism, are shown. The cable carrier 109 may be understood as, for example, a cable such as the cable 91 being directly disposed. Furthermore, the timing belt 121 may be understood as being replaced by other means, such as a rack gear or a configuration in which wheels run on rails.

[0041] 11(a) shows a state in which the optical axis 61 of the taking lens 60 faces forward (as viewed in the X-axis direction). The cable carrier 109 and timing belt 121 pass under the image capture device 50. The underside of the image capture device 50 here is as follows: That is, it is the range on the side where the tripod seat of the image capture device 50 (or the hole corresponding to the tripod seat in the bottom metal plate 1104) is located, as viewed from the optical axis 61 of the taking lens 60, between the image capture device 50 and the inner circumferential surface of the transparent pipe 101. In other words, it is the range on the side opposite the side where the viewfinder unit 55 is located, as viewed from the optical axis 61 of the taking lens 60, between the image capture device 50 and the inner circumferential surface of the transparent pipe 101.

[0042] On the other hand, Figure 11(b) shows a state in which the image capture device 50 is attempting to tilt upward. In the configuration of Figure 11, the corners of the image capture device 50 interfere with the timing belt 121, limiting the range (angle) in which tilt rotation is possible. In Figure 11, as an example, the cable carrier 109 and timing belt 121 are passed under the image capture device 50, but even if they are passed through other gaps, the outer shapes of the image capture device 50 and taking lens 60 may interfere, raising concerns about impeding tilt rotation.

[0043] 11(c) is a schematic cross-sectional view of a configuration that takes into consideration the interference in FIG. 11(b). The cable carrier 109 and timing belt 121 are arranged outside the cylindrical region P that contains the outer shapes of the camera body 54 and the photographic lens 60. By arranging them in this manner, the image capture device 50 can be tilted and rotated without the image capture device 50 or the photographic lens 60 interfering with the cable carrier 109 or the timing belt 121.

[0044] However, in the configuration of FIG. 11( c ), in which the cable carrier 109 and timing belt 121 are arranged so as to completely avoid the cylindrical region P, there are many gaps, resulting in the transparent pipe 101 being larger in diameter relative to the imaging device 50. A larger diameter of the transparent pipe 101 limits the installation location of the imaging system 100, potentially making installation difficult in a narrow space such as a rocky area. Furthermore, a larger diameter of the transparent pipe 101 requires greater strength against water pressure, making it necessary to increase the thickness of the transparent pipe 101. A thicker transparent pipe 101 increases concerns about optical effects on the imaging lens 60. Furthermore, the increased gaps within the transparent pipe 101 increase the buoyancy of the imaging system 100, necessitating the attachment of a heavier weight. The larger size and weight of the imaging system 100 may impair portability and ease of handling during installation. On the other hand, in order to reduce the diameter of the transparent pipe 101, it is necessary to reduce the size of the imaging device 50 and the photographing lens 60, which limits the options for the camera body 54 and the wide variety of photographing lenses 60 that prioritize image quality.

[0045] As described above, in an imaging system 100 capable of performing translational movement and tilt rotation of the imaging device 50, if the imaging device 50 alone is configured to tilt rotate as shown in FIG. 11 , the space inside the transparent pipe 101 cannot be used efficiently, resulting in various problems. A configuration in which wiring such as the cable carrier 109 and timing belt 121 and the translational movement mechanism do not pass around the imaging device 50 is also possible, but this requires them to move forward and backward in accordance with the translational movement, which could lead to a concern that the mechanism would become larger and more complex. Therefore, the imaging system 100 employs a configuration in which the rotating unit 160, including the cable carrier 109 and timing belt 121, tilts and rotates, as described with reference to FIG. 10 . Because the tilt rotation occurs without changing the positional relationship between the imaging device 50, the cable carrier 109, and the timing belt 121, this reduces concerns about interference and prevents the transparent pipe 101 from becoming larger in diameter.

[0046] [Support placement] The arrangement of the pillars that support the components of the imaging system 100 will be described with reference to Fig. 12. Fig. 12(a) is an enlarged front view of the periphery of the imaging device 50 of the imaging system 100, and Fig. 12(b) is a cross-sectional view taken along CC in Fig. 12(a). In addition, in Fig. 12(b), the imaging element 53 is schematically superimposed to illustrate the positional relationship.

[0047] 12(b), a first support column 111, a second support column 112, and a third support column 113 are arranged inside the transparent pipe 101 so as to surround the imaging device 50. Each support column is inserted into a bushing 1105 provided on the left side plate 1101 and the right side plate 1102, respectively, and the holding device 110 is supported so as to be able to translate using the support columns as guides. In other words, the first support column 111, the second support column 112, and the third support column 113 are members (means) that have both the function of holding the holding device 110 and the function of guiding the translational movement of the holding device 110. This makes it possible to realize a simpler configuration than when a member with a holding function and a member with a guiding function are provided separately.

[0048] The center of gravity G represents the center of gravity when the camera body 54 and the photographing lens 60 are viewed as a single unit. In the cross-sectional view of FIG. 12(b), the area of ​​the triangle T formed by the first support column 111, the second support column 112, and the third support column 113 is increased, and the center of gravity G is positioned inside the triangle T, thereby enabling stable support of the holding device 110. However, if the support column is positioned in front of the photographing lens 60 in the Z-axis direction (at the very front of the photographing lens 60), the space becomes narrow unless the diameter of the transparent pipe 101 is increased, limiting the options for the photographing lens 60. Furthermore, there is a concern that the support column may be captured in the image during shooting depending on the angle of view. Therefore, in the imaging system 100, the first support column 111 is located closer to the subject than the image sensor 53 (toward the front of the camera body 54) and above the photographing lens 60, and the second support column 112 is located closer to the subject than the image sensor 53 and below the photographing lens 60. Additionally, the third support column 113 is positioned on the rear side of the camera body 54, approximately coaxial with the optical axis 61 of the photographing lens 60. By positioning the support column in this manner, the rigidity of the support column structure is increased while maximizing the arrangement space for the camera body 54 and photographing lens 60, thereby increasing the options for mounted equipment. Furthermore, by utilizing the gap between the camera body 54, photographing lens 60, and transparent pipe 101 as arrangement space for the support column, the diameter of the transparent pipe 101 can be reduced, and the dense interior reduces air gaps, which also contributes to suppressing buoyancy.

[0049] A sliding member 164 made of a highly self-lubricating resin material is disposed between the timing belt 121, cable carrier 109, and transparent pipe 101. The sliding member 164 is fixed to the fourth support column 114. The fourth support column 114 is not connected to the holding device 110, and unlike the first support column 111 to the third support column 113, it does not function as a guide during translational movement. The sliding member 164 is also disposed with a clearance so as not to come into contact with the holding device 110, and its position does not change during translational movement. However, the fourth support column 114 and the sliding member 164 are included in the rotating section 160, and rotate together with the other supports. As shown in FIGS. 8 and 9, a plurality of sliding members 164 are provided at regular intervals. By arranging the sliding member 164 in this manner, the cable carrier 109 and timing belt 121 are prevented from rubbing against the inner wall of the transparent pipe 101, preventing a decrease in transparency due to scratches and an increase in friction during rotation.

[0050] [Summary] The configuration of the imaging system 100 has been described above. The imaging system 100 includes a transparent pipe 101 as a housing, and the imaging device 50 disposed therein is held so as to be able to translate in the extension direction of the transparent pipe 101 and tilt and rotate about the central axis of the transparent pipe 101. The transparent pipe 101 is sealed and waterproof, so that even if the imaging system 100 is submerged in water, it can take pictures and move without liquid entering the interior. The adoption of a configuration in which the rotating unit 160, including the drive unit 120 for translating the imaging device 50, the timing belt 121, and the cable carrier 109 for protecting and guiding the connected cable 91, all tilt and rotate together prevents the diameter of the transparent pipe 101 from becoming too large.

[0051] For example, by installing the imaging system 100 inside an aquarium tank, users can observe living organisms from angles, viewpoints, and distances that are difficult to observe from outside the tank. By minimizing the size of the imaging system 100, it can be placed in narrow spaces such as rocky areas or fish reefs. Furthermore, the imaging system 100 can be easily moved when aquarium keepers want to change the location or the aquarium tank where it is installed. In other words, the imaging system 100 is a holding device that holds the imaging device 50 movably and rotatably while also being waterproof. Commercially available cameras can be used for the imaging device 50, and various lenses and the latest models can be installed.

[0052] [Usage of imaging system] In this embodiment, the imaging system 100 has been described as being used to capture images of an aquarium, but its use is not limited to this and it can be used in a variety of environments. For example, by installing it inside a carnivorous animal cage at a zoo, it becomes possible to observe the animals from a close distance that is not normally possible. Because it is protected by the transparent pipe 101, the drive unit 120 and imaging device 50 can be operated without malfunction even in bad weather or when mud and the like are attached. Furthermore, because the drive parts are not exposed to the outside, it can be operated safely without accidentally injuring the animals.

[0053] Other possible uses include using it as a portable and waterproof means of photography for monitoring agricultural crops, or as a highly safe and low-angle means of photography for taking commemorative photos of young children at kindergarten events.

[0054] [Correction lenses] Next, the attachment lens (correction lens) 301 according to this embodiment will be described using Figures 13 and 14. Figure 13 is an enlarged perspective view of the periphery of the imaging device 50 of the imaging system 100. The attachment lens 301 is arranged so as to overlap with the optical axis 61 of the taking lens 60. In other words, the attachment lens 301 is arranged so as to include at least the optical axis 61 of the taking lens 60 when viewed in the direction of the optical axis, and so that at least a portion of the attachment lens 301 overlaps with at least a portion of the taking lens 60.

[0055] The attachment lens 301 is a lens whose radius of curvature in the axial cross section (XZ cross section) of the transparent pipe 101 is different from that in the radial cross section (YZ cross section). The attachment lens 301 is positioned so that the radius of curvature in the radial cross section (YZ cross section) of the transparent pipe 101 is smaller than the radius of curvature in the axial cross section (XZ cross section) of the transparent pipe 101. More specifically, the attachment lens 301 is a cylindrical lens that has curvature only in the YZ cross section, as shown in FIG. 16, which will be described later. The attachment lens 301 is held to the front metal sheet 1103 via adjustment springs 302a, 302b, and 302c, which are mechanisms for adjusting the angle and Z-direction position relative to the transparent pipe 101.

[0056] The front metal plate 1103 is fixed to the right side plate 1102 and the left side plate 1101 with four screws, and by removing these four screws, the front metal plate 1103 can be removed together with the attachment lens 301. In other words, the attachment lens 301 and its holder, the front metal plate 1103, are detachable from the camera holder. When the imaging system 100 is installed underwater, the attachment lens 301 is attached, and when it is installed in air, the attachment lens 301 is removed.

[0057] FIG. 14 is a schematic diagram of a radial cross section (YZ cross section) of the imaging system 100. To obtain good focus at the infinity end and the close-up end of the photographing lens 60, the attachment lens 301 preferably has a focal length similar to the focal length of the water and the transparent pipe 101, and is preferably installed close to the transparent pipe 101. The focal length of the attachment lens 301 in a cross section (YZ cross section) with a small radius of curvature is defined as f_zc (not shown), and the focal length of the transparent pipe 101 in the YZ cross section when the transparent pipe 101 is installed underwater is defined as f_zp (not shown). In this case, the desirable range of focal lengths of the cross section (YZ cross section) with a small radius of curvature of the attachment lens 301 can be expressed by Equation 1. A more desirable range of focal lengths is as shown in Equation 1-1. This means that it is desirable to design the convergence effect of the attachment lens 301 as a positive lens so as to cancel out the divergence effect of the transparent pipe 101 as a negative lens. [Formula 1] 0.95≦|f_zc / f_zp|≦1.2 (Equation 1) [Formula 1-1] 0.96≦|f_zc / f_zp|≦1.1 (Equation 1-1) 14, let Ddc be the distance from the image-side surface of the transparent pipe 101 to the object-side surface of the attachment lens 301, and Dcm be the distance from the image-side surface of the attachment lens 301 to the object-side surface of the taking lens 60. In this case, the desirable installation position of the attachment lens 301 to obtain good focus at the infinity end and the close-up end of the taking lens 60 can be expressed by equation 2. A more desirable installation position is as shown in equation 2-1. [Formula 2] 0.19≦|Ddc / Dcm|≦0.50 (Equation 2) [Formula 2-1] 0.20≦|Ddc / Dcm|≦0.45 (Formula 2-1) The attachment lens 301 may be a convex meniscus lens instead of a cylindrical lens. As shown in Figure 14, the radius of curvature on the object side of the YZ cross section of the attachment lens 301 is R1, and the radius of curvature on the image plane side of the YZ cross section of the attachment lens 301 is R2. In this case, the desirable curvature relationship of the YZ cross section of the attachment lens 301 can be expressed by Equation 3. A more desirable curvature relationship is as shown in Equation 3-1.

[0058] If the difference in refractive index between water and air is ignored, then parallel light beams in the XZ cross section will remain parallel when they enter the taking lens 60, as shown in Figures 15(b) and 16(b) described below. However, in reality, due to the influence of the difference in refractive index between water and air, the attachment lens 301 may also have refractive power in the XZ plane. However, as will be described later, it is the YZ plane, not the XZ plane, that needs to have refractive power to cancel out the influence of the curved surface of the transparent pipe 101. Therefore, in the XZ plane, it is sufficient if the refractive power is sufficient to cancel out the influence of the difference in refractive index between water and air, as described above. From the above perspective, the desirable curvature relationship is within the range shown in Equation 3 and Equation 3-1. [Formula 3] 1.00<|(R2+R1) / (R2-R1)|≦2.00 (Equation 3) [Formula 3-1] 1.20≦|(R2+R1) / (R2-R1)|≦1.80 (Formula 3-1) The effect of providing the attachment lens 301 in the imaging system 100 will be described with reference to Figures 15 and 16. Figure 15 is a schematic diagram showing the light beam incident on the imaging system 100 when the attachment lens 301 is not provided, with Figure 15(a) showing a radial cross section (YZ cross section) of the transparent pipe 101 and Figure 15(b) showing an axial cross section (XZ cross section) of the transparent pipe 101.

[0059] As shown in Figure 15(a), the light beam 401a that passes through the transparent pipe 101 in the circumferential direction is shifted by Δd from the light beam 401b that passes through the transparent pipe 101 in the axial direction as shown in Figure 15(b) because the water and the transparent pipe 101 act as concave lenses.

[0060] Figure 16 is a schematic diagram showing the incident light beam on the imaging system 100 when the attachment lens 301 is installed, where Figure 16(a) shows a radial cross section (YZ cross section) of the transparent pipe 101, and Figure 16(b) shows an axial cross section (XZ cross section) of the transparent pipe 101.

[0061] As shown in Figure 16(a), a light beam 401a transmitted in the circumferential direction of the transparent pipe 101 passes through the attachment lens 301, thereby canceling the effect of the concave lens function of the transparent pipe 101. The image plane coincides with that of a light beam 401b transmitted in the axial direction of the transparent pipe 101 shown in Figure 16(b).

[0062] [summary] The above-described configuration makes it possible to provide a holding device, a camera unit, and an imaging system that are capable of capturing images of a subject underwater with higher image quality than ever before.

[0063] [Second embodiment] [Usage scenarios for the Imaging System 1000] A usage scene of the imaging system 1000 according to this embodiment will be described with reference to Figures 17 and 18. Hereinafter, a description of the same configuration as that of the imaging system 1000 according to the first embodiment will be omitted.

[0064] FIG. 17 is a schematic diagram illustrating an imaging system 1000 installed in an aquarium tank. The imaging system 1000 is partially submerged in water, and the small-diameter bent pipe 102 extends substantially perpendicular to the transparent pipe 101, exposing its tip above the water surface W. The camera unit 6100 and the transmission cable bundle 90 are completely covered by the transparent pipe 101 and the small-diameter bent pipe 102, preventing water from entering the interior. The transmission cable bundle 90 extending from the tip of the small-diameter bent pipe 102 is connected to the server 10 shown in FIG. 1. A user can observe the underwater living organism F and the abovewater living organism F′, which are the subjects, by zooming, translating, and tilting the imaging device 50. Using the imaging system 1000 in this way allows users to enjoy observing and photographing organisms that cannot be seen from outside the aquarium, from a wide angle or up close.

[0065] FIG. 18 is a schematic diagram showing a portion of the imaging system 1000 positioned vertically in a deep aquarium tank. Unlike FIG. 17, the camera unit 6100 can move up and down and rotate horizontally. The small straight pipe 103 is replaced with a pipe that extends in the same direction as the transparent pipe 101 and is positioned so that its tip is exposed above the water surface W. By moving it up and down, the user can observe living organisms F swimming at different depths or living organisms F' living on land. In this way, the imaging system 1000 can be positioned at various angles depending on the object of observation. For example, it may be positioned at an angle, and the shape and length of the small straight pipe 103 (or small-diameter bent pipe 102) can be changed to protect the transmission cable bundle 90 depending on the situation.

[0066] [Driving attachment lens 301] FIG. 19 is an enlarged perspective view of a portion of the periphery of the camera unit 6100 (a collective term for the imaging device 50 and the holding device 1100) of the imaging system 1000. For ease of explanation, some components are indicated by dashed lines. A third pinion gear 322 is attached to the drive shaft of a third motor 321. A third spur gear 323 is rotatably attached so as to mesh with the third pinion gear 322. The rotation axis of the third spur gear 323 is positioned so as to coincide with the central axis of the transparent pipe 101. An attachment lens lever 324 is attached so as to rotate integrally with the third spur gear 323. The attachment lens 301 is held by an attachment lens holder 325. The attachment lens holder 325 is drivably attached to the attachment lens lever 324 via a fourth motor 331, a lead screw 332, and guide bars 333a, 333b, and 333c.

[0067] [Advance and retreat drive (first movement means)] By rotating the fourth motor 331, the attachment lens 301 can move (advance and retreat) in the Z direction at a constant rate in accordance with (i.e., in conjunction with) the drive amount of the focus lens unit (not shown) of the photographing lens 60.

[0068] More specifically, fourth motor 331 and guide bars 333a and 333c are fixed to attachment lens lever 324 (on the right side in FIG. 19). Guide bar 333b is fixed to attachment lens lever 324 (on the left side in FIG. 19). Attachment lens holder 325 is provided with a threaded portion (internal thread) that screws into the threaded portion (external thread) of lead screw 332.

[0069] Rotation of the fourth motor 331 rotates the lead screw 332. The rotation of the lead screw 332 causes the attachment lens holder 325 to move in the Z direction. At this time, guide bars 333a, 333b, and 333c guide the movement of the attachment lens holder 325. As a result, the attachment lens 301 can move smoothly in the Z direction.

[0070] The holding device 1100 has a control means (not shown) for moving the attachment lens 301 in conjunction with the focus lens unit.

[0071] [Rotation, retraction drive (second movement means)] 20A and 20B are cross-sectional schematic diagrams illustrating the retraction operation of the attachment lens 301 of the imaging system 1000. FIG. 20A is a cross-sectional schematic diagram of the imaging system 1000 when the optical axis of the attachment lens 301 overlaps with the optical axis 61 of the photographing lens 60. FIG. 20B is a cross-sectional schematic diagram of the imaging system 1000 when the attachment lens 301 has retracted from the optical axis 61. The third motor 321 rotates counterclockwise from the state shown in FIG. 20A, i.e., from a first position in the optical path of the photographing lens 60. This causes the attachment lens 301 to rotate clockwise, enabling it to be retracted to a second position outside the optical path of the photographing lens 60 (outside the photographing lens 60) as shown in FIG. 20B.

[0072] In this embodiment, the attachment lens 301 is configured to retract in the radial direction of the transparent pipe 101 (rotate circumferentially), but the attachment lens 301 may also be configured to retract in the axial direction of the transparent pipe 101 (move axially, translate).

[0073] 17 and 18, in an area where the imaging system 1000 is installed underwater (when at least a part of the taking lens 60 is facing underwater), the attachment lens 301 is set to the state shown in Fig. 20(a). In an area where the imaging system 1000 is installed on the water (in the air) (when at least a part of the taking lens 60 is facing into the air), the attachment lens 301 is set to the state shown in Fig. 20(b) based on the determination result by a determination means (not shown).

[0074] This allows the imaging device 50 to maintain a high level of focus accuracy both underwater and above water (in the air), making it possible to capture high-quality images.

[0075] [Numerical Example] Numerical examples for each embodiment are shown in the following Table 1. In Numerical Example 1, the attachment lens 301 is a cylindrical lens, and in Numerical Example 2 and Numerical Example 3, the attachment lens 301 is a meniscus lens. Therefore, the calculation of Equation 3 is omitted in Numerical Example 1.

[0076] [Table 1]

[0077] Although the 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 the gist of the present invention.

[0078] The disclosure of the present specification includes the following holding device, camera unit, and imaging system.

[0079] [Configuration 1] A holding device insertable into a transparent tubular member, a camera holding portion capable of holding an imaging device having an imaging optical system and an imaging element for photographing the outside of the tubular member; a correcting lens having a curvature at least in a cross section perpendicular to the extension direction of the tubular member; the holding device is inserted into the tubular member, and a lens holding portion is capable of holding the correction lens so as to be positioned between the tubular member and the imaging optical system when the imaging device is held in the camera holding portion, A holding device characterized by:

[0080] [Configuration 2] the correction lens is a cylindrical lens that has a curvature in a first cross section that is the cross section perpendicular to the extension direction of the tubular member, and has no curvature in a second cross section that is perpendicular to the first cross section and parallel to the optical axis of the imaging optical system or the optical axis of the correction lens. 2. The holding device according to claim 1.

[0081] [Configuration 3] the correction lens is a meniscus lens that has a curvature in a first cross section that is the cross section perpendicular to the extension direction of the tubular member, and also has a curvature in a second cross section that is perpendicular to the first cross section and parallel to the optical axis of the imaging optical system or the optical axis of the correction lens. 2. The holding device according to claim 1.

[0082] [Configuration 4] The cross section perpendicular to the extension direction of the tubular member is defined as a first cross section, R1 is the radius of curvature of the object side of the corrector lens at the first cross section, When R2 is the radius of curvature of the image side of the correction lens at the first cross section, 1.00<|(R2+R1) / (R2−R1)|≦2.00 Satisfy the 4. The holding device according to configuration 3.

[0083] [Configuration 5] 1.20≦|(R2+R1) / (R2-R1)|≦1.80 Satisfy the 5. The holding device according to configuration 4.

[0084] [Configuration 6] The cross section perpendicular to the extension direction of the tubular member is defined as a first cross section, a second cross section that is perpendicular to the first cross section and parallel to the optical axis of the imaging optical system or the optical axis of the correction lens; f_zc is the focal length of the correction lens at the first cross section, Let f_zp be the focal length of the tubular member at the first cross section when the tubular member is placed in water. 95≦|f_zc / f_zp|≦1.2 Satisfy the 6. The holding device according to any one of configurations 1 to 5.

[0085] [Configuration 7] 96≦|f_zc / f_zp|≦1.1 Satisfy the 7. The holding device according to configuration 6. [Configuration 8] The cross section perpendicular to the extension direction of the tubular member is defined as a first cross section, Ddc is the distance from the image-side surface of the tubular member on the optical axis of the imaging optical system or the optical axis of the correction lens to the object side of the correction lens in the first cross section, When Dcm is the distance from the optical axis of the imaging optical system or the image side surface of the correction lens on the optical axis of the correction lens to the object side surface of the imaging optical system in the first cross section, 0.19≦|Ddc / Dcm|≦0.50 Satisfy the 8. The holding device according to any one of configurations 1 to 7.

[0086] [Configuration 9] 20≦|Ddc / Dcm|≦0.45 Satisfy the 9. The holding device according to configuration 8.

[0087] [Configuration 10] the lens holder has an adjustment means capable of adjusting at least one of the distance and the angle between the corrective lens and the tubular member. 10. The holding device according to any one of configurations 1 to 9.

[0088] [Configuration 11] The lens holding part is detachable from the camera holding part. 11. The holding device according to any one of configurations 1 to 10.

[0089] [Configuration 12] a first moving means for moving the correction lens in the optical axis direction of the imaging optical system; and a control means for controlling the first moving means so that the correction lens moves in conjunction with a focus lens unit of the imaging optical system when the focus lens unit moves from infinity to a close distance. 12. The holding device according to any one of configurations 1 to 11.

[0090] [Configuration 13] a second moving means capable of moving the correction lens between a first position within the optical path of the imaging optical system and a second position outside the optical path of the imaging optical system; 13. The holding device according to any one of configurations 1 to 12.

[0091] [Configuration 14] The second moving means is A motor; a lever that holds the lens holding portion and is rotated by the motor about a rotation axis parallel to the axial direction of the tubular member, The correction lens is movable between the first position and the second position by rotating the lever in a circumferential direction of the tubular member. 14. The holding device according to claim 13.

[0092] [Configuration 15] the second means is configured to move the correction lens between the first position and the second position by moving the correction lens in the axial direction of the tubular member. 14. The holding device according to claim 13.

[0093] [Configuration 16] A camera unit that can be inserted into a transparent tubular member, an imaging device having an imaging optical system and an imaging element for capturing an image of the outside of the tubular member; a camera holding unit capable of holding the imaging device; a correcting lens having a curvature at least in a cross section perpendicular to the extension direction of the tubular member; the holding device is inserted into the tubular member, and a lens holding portion is capable of holding the correction lens so as to be positioned between the tubular member and the imaging optical system when the imaging device is held in the camera holding portion, A camera unit characterized by:

[0094] [Configuration 17] A transparent tubular member; an imaging device that can be inserted into the tubular member and has an imaging optical system and an imaging element for capturing an image of the outside of the tubular member; and a camera unit that has a camera holding part that can hold the imaging device; a correcting lens having a curvature at least in a cross section perpendicular to the extension direction of the tubular member; the holding device is inserted into the tubular member, and a lens holding portion is capable of holding the correction lens so as to be positioned between the tubular member and the imaging optical system when the imaging device is held in the camera holding portion, An imaging system characterized by: [Explanation of symbols]

[0095] 50 Imaging device 60 Photographic lens (imaging optical system) 101 Transparent pipe (tubular member) 110 Holding device 1101 Left side panel (camera holder) 1102 Right side plate (camera holding part) 1103 Front metal plate (lens holder) 1104 Bottom metal plate (camera holding part) 301 Attachment lens (corrective lens)

Claims

1. A holding device insertable into a transparent tubular member, a camera holding portion capable of holding an imaging device having an imaging optical system and an imaging element for photographing the outside of the tubular member; a correcting lens having a curvature at least in a cross section perpendicular to the extension direction of the tubular member; the holding device is inserted into the tubular member, and a lens holding portion is capable of holding the correction lens so as to be positioned between the tubular member and the imaging optical system when the imaging device is held in the camera holding portion, A holding device characterized by:

2. the correction lens is a cylindrical lens that has a curvature in a first cross section that is the cross section perpendicular to the extension direction of the tubular member, and has no curvature in a second cross section that is perpendicular to the first cross section and parallel to the optical axis of the imaging optical system or the optical axis of the correction lens.

2. The holding device according to claim 1.

3. the correction lens is a meniscus lens that has a curvature in a first cross section that is the cross section perpendicular to the extension direction of the tubular member, and also has a curvature in a second cross section that is perpendicular to the first cross section and is parallel to the optical axis of the imaging optical system or the optical axis of the correction lens.

2. The holding device according to claim 1.

4. the cross section perpendicular to the extension direction of the tubular member is defined as a first cross section; R1 is the radius of curvature of the object side of the correction lens at the first cross section, When R2 is the radius of curvature of the image side of the correction lens in the first cross section, 1.00<|(R2+R1) / (R2-R1)|≦2.00 Satisfy the 4. The holding device according to claim 3.

5. 1.20≦|(R2+R1) / (R2-R1)|≦1.80 Satisfy the 5. The holding device according to claim 4.

6. the cross section perpendicular to the extension direction of the tubular member is defined as a first cross section; a second cross section is a cross section that is perpendicular to the first cross section and parallel to the optical axis of the imaging optical system or the optical axis of the correction lens; Let f_zc be the focal length of the correction lens at the first cross section, Let f_zp be the focal length of the tubular member at the first cross section when the tubular member is placed in water, 95≦|f_zc / f_zp|≦1.2 Satisfy the 2. The holding device according to claim 1.

7. 96≦|f_zc / f_zp|≦1.1 Satisfy the 7. The holding device according to claim 6.

8. the cross section perpendicular to the extension direction of the tubular member is defined as a first cross section; Ddc is the distance from the image-side surface of the tubular member on the optical axis of the imaging optical system or the optical axis of the correction lens to the object side of the correction lens in the first cross section, When Dcm is the distance from the optical axis of the imaging optical system or the image side surface of the correction lens on the optical axis of the correction lens to the object side surface of the imaging optical system in the first cross section, 0.19≦|Ddc / Dcm|≦0.50 Satisfy the 2. The holding device according to claim 1.

9. 20≦|Ddc / Dcm|≦0.45 Satisfy the 9. The holding device according to claim 8.

10. the lens holder has an adjustment means capable of adjusting at least one of the distance and the angle between the corrective lens and the tubular member.

2. The holding device according to claim 1.

11. The lens holding part is detachable from the camera holding part.

2. The holding device according to claim 1.

12. a first moving means for moving the correction lens in the optical axis direction of the imaging optical system; a control unit that controls the first moving unit so that the correction lens moves in conjunction with a focus lens unit that the imaging optical system has when the focus lens unit moves from infinity to a close distance, 2. The holding device according to claim 1.

13. a second moving means capable of moving the correction lens between a first position within the optical path of the imaging optical system and a second position outside the optical path of the imaging optical system; 2. The holding device according to claim 1.

14. The second moving means includes: A motor; a lever that holds the lens holding portion and is rotated by the motor about a rotation axis parallel to the axial direction of the tubular member, The correction lens is movable between the first position and the second position by rotating the lever in a circumferential direction of the tubular member.

14. The holding device according to claim 13.

15. the second means is configured to move the correction lens between the first position and the second position by moving the correction lens in the axial direction of the tubular member.

14. The holding device according to claim 13.

16. A camera unit that can be inserted into a transparent tubular member, an imaging device having an imaging optical system and an imaging element for capturing an image of the outside of the tubular member; a camera holding unit capable of holding the imaging device; a correcting lens having a curvature at least in a cross section perpendicular to the extension direction of the tubular member; the holding device is inserted into the tubular member, and a lens holding portion is capable of holding the correction lens so as to be positioned between the tubular member and the imaging optical system when the imaging device is held in the camera holding portion, A camera unit characterized by:

17. A transparent tubular member; an imaging device that can be inserted into the tubular member and has an imaging optical system and an imaging element for capturing an image of the outside of the tubular member; and a camera unit that has a camera holding part that can hold the imaging device; a correcting lens having a curvature at least in a cross section perpendicular to the extension direction of the tubular member; the holding device is inserted into the tubular member, and a lens holding portion is capable of holding the correction lens so as to be positioned between the tubular member and the imaging optical system when the imaging device is held in the camera holding portion, An imaging system characterized by:

Images