Fish-eye lens and imaging device

Abstract

A fish-eye lens of the present disclosure is composed of, in order from an object side to an image surface side: a first lens group having a refractive power and including a first lens and a second lens in order from the object side to the image surface side; an intermediate group having a refractive power and including at least a second lens group; and a rear group having a refractive power. On the occasion of an object distance changing from infinity to near distance, the first lens group and the rear group are fixed, at least the second lens group in the intermediate group moves in the optical axis direction to perform focusing, and a predetermined conditional expression is satisfied.

Description

Technical Field

[0001] The present disclosure relates to a fish-eye lens having a focusing function and an imaging device including such a fish-eye lens.

Background Art

[0002] Similar to the imaging elements of imaging devices mounted on portable terminals such as smartphones and tablets, the imaging elements used in lens-exchange digital camera systems are also increasing in the number of pixels due to the miniaturization of pixel pitch. Along with this, high performance is also required for the imaging lenses used in these imaging devices. In addition, as in the case of use in portable terminals, etc., in lens-exchange digital camera systems, the use cases for shooting videos as well as still images are also increasing. Therefore, elements corresponding to video shooting, such as being small-sized, high-speed focusing, and suppression of the change in the angle of view due to wobbling, etc. are also strongly required. Patent Document 1 proposes an inner focusing type fish-eye lens whose overall length does not change.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] In the fish-eye lens described in Patent Document 1, since the focus group is arranged near the aperture stop where the deflection angle of the light rays is large in the optical system, the change in the angle of view during wobbling is large.

[0005] It is desirable to provide a fish-eye lens that is small-sized, lightweight, has little change in the angle of view during wobbling by the inner focusing method, and is suitable for video shooting, and an imaging device equipped with such a fish-eye lens.

[0006] The fish-eye lens according to an embodiment of the present disclosure includes, in order from the object side toward the image plane side,Positive A first lens group having refractive power and including a first lens and a second lens in order from the object side toward the image plane side, an intermediate group having refractive power and including at least the second lens group, and a rear group having refractive power. When the object distance changes from infinity to a short distance, the first lens group and the rear group are fixed, The distance between the first lens group and the intermediate group, and the distance between the intermediate group and the rear group change, At least the second lens group in the intermediate group is moved in the optical axis direction to perform focusing, and the following conditional expressions are satisfied. -1.06 < (fL1 / f) / (TTL / Y) < -0.44 ……(1) 0.19 < (R21 - R22) / (R21 + R22) < 1.05 ……(2) 0.16 < BF / TTL < 0.24 ……(3) 0.85 < Y / Y’ < 1.18 ……(4) However, fL1: Focal length of the first lens f: Focal length of the entire system TTL: Distance on the optical axis from the vertex of the object-side surface of the first lens to the image plane Y: Maximum Half Image height at the angle of view R21: Curvature radius of the object-side lens surface of the second lens R22: Curvature radius of the image-plane-side lens surface of the second lens BF: Distance on the optical axis from the most image-plane-side lens surface to the image plane Y’: Maximum calculated by the equal solid angle projection method Half Image height at the maximum angle of view θmax (Y’ = 2fsin(θmax / 2)) Let it be.

[0007] An imaging device according to an embodiment of the present disclosure includes a fish-eye lens and an imaging element that outputs an imaging signal corresponding to an optical image formed by the fish-eye lens, and the fish-eye lens is configured by the fish-eye lens according to an embodiment of the present disclosure.

[0008] In a fish-eye lens or an imaging device according to an embodiment of the present disclosure, in a configuration including a first lens group, an intermediate group, and a rear group, the configuration of each group is optimized so as to be small and lightweight, have little change in the angle of view during wobbling by an inner focusing method, and obtain performance suitable for video shooting.

Brief Description of the Drawings

[0009]

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Mode for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The description will be made in the following order. 1. Basic configuration of the lens 2. Action and effect 3. Application examples to imaging devices 4. Numerical examples of the lens 5. Application examples 6. Other embodiments

[0011] <1. Basic configuration of the lens> The present disclosure relates to a fisheye lens and an imaging device having an internal focus type focusing function. The present disclosure is particularly suitable for a small and high-performance imaging lens using a focusing method capable of performing good aberration correction, and an imaging device equipped with such an imaging lens. The fisheye lens according to an embodiment of the present disclosure is optimal, for example, as a single-focus imaging lens applied to a digital still camera, a digital mirrorless camera, or the like.

[0012] FIG. 1 shows a first configuration example of a fish-eye lens according to an embodiment of the present disclosure, which corresponds to the configuration of Example 1 described later. FIG. 4 shows a second configuration example of a fish-eye lens according to an embodiment, which corresponds to the configuration of Example 2 described later. FIG. 7 shows a third configuration example of a fish-eye lens according to an embodiment, which corresponds to the configuration of Example 3 described later. FIG. 10 shows a fourth configuration example of a fish-eye lens according to an embodiment, which corresponds to the configuration of Example 4 described later. FIG. 13 shows a fifth configuration example of a fish-eye lens according to an embodiment, which corresponds to the configuration of Example 5 described later. FIG. 16 shows a sixth configuration example of a fish-eye lens according to an embodiment, which corresponds to the configuration of Example 6 described later. FIG. 19 shows a seventh configuration example of a fish-eye lens according to an embodiment, which corresponds to the configuration of Example 7 described later. FIG. 22 shows an eighth configuration example of a fish-eye lens according to an embodiment, which corresponds to the configuration of Example 8 described later. FIG. 25 shows a ninth configuration example of a fish-eye lens according to an embodiment, which corresponds to the configuration of Example 9 described later.

[0013] In FIG. 1 etc., Z1 indicates the optical axis. An optical member FL such as a cover glass for protecting the imaging element may be disposed between the fish-eye lenses 1 to 9 according to the first to ninth configuration examples and the image plane IMG. In addition to the cover glass, various optical filters such as a low-pass filter and an infrared cut filter may be disposed as the optical member FL.

[0014] Hereinafter, the configuration of the fish-eye lens according to an embodiment of the present disclosure will be described in association with the fish-eye lenses 1 to 9 according to the respective configuration examples shown in FIG. 1 etc. as appropriate. However, the technology according to the present disclosure is not limited to the illustrated configuration examples.

[0015] The fish-eye lens according to an embodiment includes, in order from the object side toward the image plane side along the optical axis Z1, a first lens group G1 having a refractive power, an intermediate group having a refractive power, and a rear group having a refractive power.

[0016] The first lens group G1 includes, in order from the object side toward the image plane side, a first lens L1 and a second lens L2.

[0017] The intermediate group includes at least the second lens group G2. As will be described later, in the first configuration example (Example 1) to the fourth configuration example (Example 4), and the sixth configuration example (Example 6) to the ninth configuration example (Example 9), the intermediate group consists of only the second lens group G2. In the fifth configuration example (Example 5), the intermediate group consists of the second lens group G2, the third lens group G3, and the fourth lens group G4.

[0018] As will be described later, in the first configuration example (Example 1) to the fourth configuration example (Example 4), and the sixth configuration example (Example 6) to the ninth configuration example (Example 9), the rear group consists of only the third lens group G3. In the fifth configuration example (Example 5), the rear group consists of only the fifth lens group G5.

[0019] In the fisheye lens according to one embodiment, when the subject distance changes from infinity to a short distance, the first lens group G1 and the rear group are fixed, and at least the second lens group G2 in the intermediate group moves in the optical axis direction to perform focusing. As will be described later, in the first configuration example (Example 1) to the fourth configuration example (Example 4), and the sixth configuration example (Example 6) to the ninth configuration example (Example 9), the second lens group G2 is the focus group. In the fifth configuration example (Example 5), the second lens group G2 and the fourth lens group G4 are the focus groups. In FIG. 1 and the like, the lens arrangement at infinity focus is shown. In FIG. 1 and the like, the moving direction of the focus group when focusing from infinity to a short distance is indicated by an arrow.

[0020] In addition, it is desirable that the fisheye lens according to one embodiment further satisfies a predetermined conditional expression and the like described later.

[0021] <2. Operation and Effect> Next, the operation and effect of the fisheye lens according to one embodiment of the present disclosure will be described. At the same time, a more desirable configuration in the fisheye lens according to one embodiment of the present disclosure will be described. Note that the effects described in this specification are merely examples and are not limited, and there may be other effects.

[0022] According to the fish-eye lens according to one embodiment, in a configuration including a first lens group G1, an intermediate group, and a rear group, the configuration of each group is optimized, so that it is possible to realize a fish-eye lens that is small, lightweight, has little change in the angle of view during wobbling by an inner focusing method, is suitable for video shooting, and an imaging device.

[0023] The fish-eye lens according to one embodiment desirably satisfies the following conditional expressions (1) to (4). -1.06 < (fL1 / f) / (TTL / Y) < -0.44 ……(1) 0.19 < (R21 - R22) / (R21 + R22) < 1.05 ……(2) 0.16 < BF / TTL < 0.24 ……(3) 0.85 < Y / Y’ < 1.18 ……(4) However, fL1: Focal length of the first lens L1 f: Focal length of the entire system TTL: Distance on the optical axis from the vertex of the object-side surface of the first lens L1 to the image plane IMG Y: Maximum Half Image height at the angle of view R21: Curvature radius of the object-side lens surface of the second lens L2 R22: Curvature radius of the image-side lens surface of the second lens L2 BF: Distance on the optical axis from the lens surface closest to the image plane to the image plane IMG Y’: Maximum calculated by the equal solid angle projection method Half Image height at the angle of view θmax (Y’ = 2fsin(θmax / 2)) Let it be.

[0024] By satisfying the conditional expressions (1) to (4), various aberrations can be corrected, and good performance can be ensured while being small.

[0025] The above conditional expression (1) defines the ratio between the focal length of the first lens L1 and the focal length of the entire system, and the ratio between the distance on the optical axis from the vertex of the object-side surface of the first lens L1 to the image plane IMG and the image height at the maximum angle of view. By satisfying the conditional expression (1), various aberrations can be corrected, and good performance can be ensured while maintaining a small size. If the upper limit of the conditional expression (1) is exceeded, the ratio between the focal length of the first lens L1 and the focal length of the entire system becomes large, the sag amount of the lens surface on the image plane side of the first lens L1 becomes tight (large), and furthermore, the refraction angle with respect to the light ray incident from the most object-side lens surface becomes large, making it difficult to correct off-axis aberrations. Also, since the focal length of the first lens L1 becomes strong, it becomes difficult to shorten the overall lens length. On the other hand, if the lower limit of the conditional expression (1) is exceeded, the ratio between the focal length of the first lens L1 and the focal length of the entire system becomes small, the sag amount of the lens surface on the image plane side of the first lens L1 becomes loose (small), and furthermore, since the refraction angle with respect to the incident light ray becomes small, it becomes difficult to ensure the angle of view.

[0026] In order to better realize the effects of the above-mentioned conditional expression (1), it is more desirable to set the numerical range of the conditional expression (1) as in the following conditional expression (1A). -1.01 < (fL1 / f) / (TTL / Y) < -0.47 ……(1A)

[0027] The above conditional expression (2) defines the shape of the second lens L2. By keeping the conditional expression (2) within the specified range, off-axis astigmatism and field curvature can be corrected well. In particular, it is desirable for the second lens L2 to be a meniscus lens with a convex object-side lens surface.

[0028] In order to better realize the effects of the above-mentioned conditional expression (2), it is more desirable to set the numerical range of the conditional expression (2) as in the following conditional expression (2A). 0.20 < (R21 - R22) / (R21 + R22) < 1.00 ……(2A)

[0029] The above conditional expression (3) defines the ratio of the distance on the optical axis from the lens surface closest to the image plane to the image plane IMG to the distance on the optical axis from the vertex of the object-side surface of the first lens L1 to the image plane IMG. By satisfying the conditional expression (3), it is possible to ensure good performance while being compact. If the upper limit of the conditional expression (3) is exceeded, the ratio of the distance on the optical axis from the lens surface closest to the image plane to the image plane IMG to the distance on the optical axis from the vertex of the object-side surface of the first lens L1 to the image plane IMG becomes large, and a large back focus must be ensured. For this purpose, it is necessary to shorten the focal length of the first lens L1 and increase the power. As a result, it becomes difficult to shorten the overall length of the lens. If the lower limit of the conditional expression (3) is exceeded, the ratio of the distance on the optical axis from the lens surface closest to the image plane to the image plane IMG to the distance on the optical axis from the vertex of the object-side surface of the first lens L1 to the image plane IMG becomes small, and the necessary back focus cannot be ensured.

[0030] In order to better realize the effect of the above conditional expression (3), it is more desirable to set the numerical range of the conditional expression (3) as in the following conditional expression (3A). 0.17 < BF / TTL < 0.22 ……(3A)

[0031] The above conditional expression (4) Half defines the ratio of the image height at the maximum Half field angle to the image height (Y’ = 2fsin(θmax / 2)) calculated by the equal solid angle projection method at the maximum

[0032] field angle θmax. By satisfying the conditional expression (4), it is possible to provide a single-focus fisheye lens with the equal solid angle projection method that ensures good performance. 0.90 < Y / Y’ < 1.13 ……(4A)

[0033] Also, it is desirable that the fisheye lens according to an embodiment satisfies the following conditional expression (5). 0.34 < (R11 - R12) / (R11 + R12) < 0.63……(5) However, R11: Curvature radius of the lens surface on the object side of the first lens L1 R12: Curvature radius of the lens surface on the image side of the first lens L1 shall be as follows.

[0034] By satisfying the above conditional expression (5), various aberrations can be corrected, and good performance can be ensured while maintaining a small size. The above conditional expression (5) defines the shape of the first lens L1. By satisfying the conditional expression (5), various aberrations can be corrected while ensuring a predetermined angle of view, and good performance can be ensured while maintaining a small size. If the upper limit of the conditional expression (5) is exceeded, the power on the image side of the first lens L1 becomes too strong (large), making it difficult to correct off-axis astigmatism and field curvature. If the lower limit of the conditional expression (5) is exceeded, the power of the first lens L1 becomes too weak (small), and the refraction angle with respect to the incident light ray becomes small, making it difficult to ensure the angle of view.

[0035] In addition, in order to better realize the effects of the above conditional expression (5), it is more desirable to set the numerical range of the conditional expression (5) as in the following conditional expression (5A). 0.36 < (R11 - R12) / (R11 + R12) < 0.60 ……(5A)

[0036] Also, it is desirable that the fisheye lens according to an embodiment satisfies the following conditional expression (6). 1.64 < nL1 < 1.93 ……(6) However, nL1: Refractive index of the first lens L1 shall be as follows.

[0037] By satisfying conditional expression (6), various aberrations can be corrected, and good performance can be ensured while the size is small. The above conditional expression (6) defines the refractive index of the first lens L1. If the upper limit of conditional expression (6) is exceeded, the refractive index of the first lens L1 becomes high and the specific gravity of the lens becomes heavy, which is not suitable for weight reduction. If the lower limit of conditional expression (6) is exceeded, the refractive index of the first lens L1 becomes low and the specific gravity of the lens becomes light, but since a necessary and sufficient refractive index cannot be ensured, it is necessary to increase the focal length of the first lens L1. For this reason, it is difficult to shorten the overall length.

[0038] Also, it is desirable that the fisheye lens according to an embodiment satisfies the following conditional expression (7). 3.0 < |f2| / f < 19.0 ……(7) However, f: Focal length of the entire system f2: Focal length of the second lens group G2 shall be.

[0039] By satisfying conditional expression (7), various aberrations can be corrected, and good performance can be ensured while the size is small. The above conditional expression (7) defines the ratio of the focal length of the second lens group G2 to the focal length of the entire system. If the upper limit of conditional expression (7) is exceeded, the ratio of the focal length of the second lens group G2 to the focal length of the entire system becomes large and the focal length of the second lens group G2 becomes weak (long), so the aberration variation is small, but the movement amount becomes large and it becomes difficult to shorten the overall length. If the lower limit of conditional expression (7) is exceeded, the ratio of the focal length of the second lens group G2 to the focal length of the entire system becomes small and the focal length of the second lens group G2 becomes strong (short), so the movement amount is small and it is advantageous for shortening the overall length, but the aberration variation becomes large. In particular, it becomes difficult to correct off-axis aberrations.

[0040] In addition, in order to more favorably realize the effects of the above conditional expression (7), it is more desirable to set the numerical range of conditional expression (7) as in the following conditional expression (7A). 3.14 < |f2| / f < 18.03 ……(7A)

[0041] Also, it is desirable that the fisheye lens according to one embodiment has an aperture stop St within the first lens group G1. For example, as in the first configuration example (Example 1) described later, by arranging the aperture stop St in front of the fixed group (lenses L6, L7, L8) having positive refractive power within the first lens group G1, light rays with a small deflection angle can be incident on the focus group, and an optical system with small angular field variation can be achieved.

[0042] Also, the fisheye lens according to one embodiment may have an aperture stop St within the intermediate group. For example, as in the fifth configuration example (Example 5) described later, by arranging the aperture stop St in front of the fixed group (lenses L7, L8, L9) having positive refractive power within the third lens group G3, which is one of the intermediate groups, light rays with a small deflection angle can be incident on the focus group, and an optical system with small angular field variation can be achieved.

[0043] <3. Application Example to Imaging Device> Next, a specific application example of the fisheye lens according to one embodiment of the present disclosure to an imaging device will be described.

[0044] FIG. 28 shows a configuration example of an imaging device 100 to which a fisheye lens according to one embodiment is applied. This imaging device 100 is, for example, a digital still camera, and includes a camera block 10, a camera signal processing unit 20, an image processing unit 30, an LCD (Liquid Crystal Display) 40, an R / W (reader / writer) 50, a CPU (Central Processing Unit) 60, an input unit 70, and a lens drive control unit 80.

[0045] The camera block 10 is responsible for the imaging function and has an imaging lens 11 and an imaging device 12 such as a CCD (Charge Coupled Devices) or a CMOS (Complementary Metal Oxide Semiconductor). The imaging device 12 is configured to output an imaging signal (image signal) corresponding to the optical image by converting the optical image formed by the imaging lens 11 into an electrical signal. As the imaging lens 11, the fisheye lenses 1 to 9 according to each configuration example shown in FIG. 1 and the like can be applied.

[0046] The camera signal processing unit 20 performs various signal processes such as analog-digital conversion, noise removal, image quality correction, and conversion to luminance / chrominance signals on the image signal output from the imaging device 12.

[0047] The image processing unit 30 performs recording and playback processing of the image signal, and performs compression encoding / expansion decoding processing of the image signal based on a predetermined image data format and conversion processing of data specifications such as resolution.

[0048] The LCD 40 has a function of displaying various data such as the operation state with respect to the user input unit 70 and the captured images. The R / W 50 writes the image data encoded by the image processing unit 30 to the memory card 1000 and reads out the image data recorded on the memory card 1000. The memory card 1000 is, for example, a semiconductor memory that is detachable from a slot connected to the R / W 50.

[0049] The CPU 60 functions as a control processing unit that controls each circuit block provided in the imaging device 100, and is configured to control each circuit block based on an instruction input signal or the like from the input unit 70. The input unit 70 consists of various switches and the like on which the user performs required operations. For example, the input unit 70 is composed of a shutter release button for performing a shutter operation, a selection switch for selecting an operation mode, etc., and is configured to output an instruction input signal corresponding to the user's operation to the CPU 60. The lens drive control unit 80 controls the drive of the lens disposed in the camera block 10, and is configured to control a motor (not shown) or the like that drives each lens of the imaging lens 11 based on a control signal from the CPU 60.

[0050] The operation of the imaging device 100 will be described below. In the standby state for shooting, under the control of the CPU 60, the image signal captured in the camera block 10 is output to the LCD 40 via the camera signal processing unit 20 and is displayed as a camera through image. Also, for example, when an instruction input signal for zooming or focusing is input from the input unit 70, the CPU 60 outputs a control signal to the lens drive control unit 80, and a predetermined lens of the imaging lens 11 moves based on the control of the lens drive control unit 80.

[0051] When a shutter (not shown) in the camera block 10 is operated by an instruction input signal from the input unit 70, the captured image signal is output from the camera signal processing unit 20 to the image processing unit 30, subjected to compression encoding processing, and converted into digital data in a predetermined data format. The converted data is output to the R / W 50 and written to the memory card 1000.

[0052] Note that focusing is performed, for example, when the shutter release button of the input unit 70 is half-pressed or fully pressed for recording (shooting), by the lens drive control unit 80 moving a predetermined lens of the imaging lens 11 based on a control signal from the CPU 60.

[0053] When reproducing the image data recorded on the memory card 1000, in response to an operation on the input unit 70, predetermined image data is read from the memory card 1000 by the R / W 50. After the decompression and decoding process is performed by the image processing unit 30, the reproduced image signal is output to the LCD 40 and the reproduced image is displayed.

[0054] In the above-described embodiment, an example in which the imaging device is applied to a digital still camera or the like has been shown. However, the application range of the imaging device is not limited to digital still cameras, and it can be applied to various other imaging devices. For example, it can be applied to digital single-lens reflex cameras, digital non-reflex cameras, digital video cameras, surveillance cameras, and the like. Further, it can be widely applied as a camera unit of digital input / output devices such as mobile phones incorporating cameras and information terminals incorporating cameras. It can also be applied to interchangeable-lens cameras.

Example

[0055] <4. Numerical Examples of Lenses> Next, specific numerical examples of the fish-eye lens according to an embodiment of the present disclosure will be described. Here, examples in which specific numerical values are applied to the fish-eye lenses 1 to 9 according to each configuration example shown in FIG. 1 and the like will be described.

[0056] In addition, regarding the meanings of the symbols shown in the following tables and descriptions, they are as follows. "Si" indicates the number of the i-th surface numbered in order from the object side. "ri" indicates the value (mm) of the paraxial curvature radius of the i-th surface. "di" indicates the value (mm) of the distance on the optical axis between the i-th surface and the (i + 1)-th surface. "ndi" indicates the value of the refractive index with respect to the d-line (wavelength 587.6 nm) of the material of the optical element having the i-th surface. "νdi" indicates the value of the Abbe number of the material of the optical element having the i-th surface at the d-line. The part where the value of "ri" is "∞" indicates a plane, a stop surface, etc. "ASP" in the column of the surface number (Si) indicates that the surface is configured in an aspherical shape. "STO" in the column of the surface number indicates that the aperture stop St is arranged at the corresponding position. "OBJ" in the column of the surface number indicates that the surface is an object surface (the subject surface). "IMG" in the column of the surface number indicates that the surface is an image surface. "f" indicates the focal length of the entire system (unit: mm). "Fno" indicates the open F-number (F-number). "ω" indicates the semi-field angle (unit: °). "Y" indicates the image height (unit: mm). "L" indicates the overall optical length (the distance on the optical axis from the most object-side surface to the image surface IMG) (unit: mm).

[0057] In addition, among the lenses used in each embodiment, there are those whose lens surfaces are configured by aspherical surfaces. The aspherical shape is defined by the following formula. In each table showing the aspherical coefficients described later, "E-i" is an exponential expression with base 10, that is, " -i ", for example, "0.12345E-05" represents " -5 ".

[0058] (Formula of aspherical surface) x = cy 2 / (1 + (1 - (1 + k)y 2 c 2 )) + A·y 1 / 2 + B·y 4 + C·y 6 + D·y 8 + D·y 10 Here, let the distance in the optical axis direction from the vertex of the lens surface (sag amount) be "x", the height in the direction perpendicular to the optical axis be "y", the paraxial curvature (reciprocal of the radius of curvature) at the vertex of the lens surface be "c", and the conic constant be "k". A, B, C, and D are the aspherical coefficients of the fourth, sixth, eighth, and tenth orders, respectively.

[0059] [Example 1] [Table 1] shows the basic lens data of the fisheye lens 1 according to Example 1 shown in FIG. 1. [Table 2] shows the values of the coefficients representing the aspherical shape in the fisheye lens 1 according to Example 1. [Table 3] shows the values of the overall focal length f, F-number, total field angle 2ω, image height Y, and optical overall length L in the fisheye lens 1 according to Example 1. [Table 4] shows the data of the surface interval that becomes variable during focusing in the fisheye lens 1 according to Example 1. [Table 5] shows the starting surface and focal length (unit: mm) of each group of the fisheye lens 1 according to Example 1.

[0060] The fisheye lens 1 according to Example 1 includes a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a third lens group G3 having a positive refractive power, which are arranged in order from the object side to the image side. In the fisheye lens 1 according to Example 1, the second lens group G2 corresponds to the intermediate group, and the third lens group G3 corresponds to the rear group.

[0061] The first lens group G1 is formed by arranging the first lens L1 to the eighth lens L8 in order from the object side to the image side. The first lens L1 is a meniscus-shaped negative lens with a convex surface facing the object side. The second lens L2 is a meniscus-shaped negative lens with a convex surface facing the object side. The third lens L3 is a meniscus-shaped negative lens with a convex surface facing the object side. The fourth lens L4 is a meniscus-shaped negative lens with a concave surface facing the object side. The fifth lens L5 is a biconvex positive lens. The sixth lens L6 and the seventh lens L7 constitute a cemented lens cemented to each other. The sixth lens L6 is a biconvex positive lens. The seventh lens L7 is a meniscus-shaped negative lens with a concave surface facing the object side. The eighth lens L8 is a biconvex positive lens.

[0062] The second lens group G2 is formed by arranging the ninth lens L9 and the tenth lens L10 in order from the object side to the image plane side. The ninth lens L9 is a biconvex positive lens. The tenth lens L10 is a biconcave negative lens.

[0063] The third lens group G3 is formed by arranging the eleventh lens L11 and the twelfth lens L12 in order from the object side to the image plane side. The eleventh lens L11 is a meniscus-shaped positive lens with a concave surface facing the object side. The twelfth lens L12 is a meniscus-shaped negative lens with a concave surface facing the object side. The eleventh lens L11 and the twelfth lens L12 constitute a cemented lens that is cemented to each other.

[0064] An optical member FL such as a filter FL is disposed between the third lens group G3 and the image plane IMG. The aperture stop St is disposed within the first lens group G and is fixed with respect to the image plane IMG.

[0065] In the fisheye lens 1 according to the first embodiment, when focusing from infinity to a short distance, the second lens group G2 moves in the optical axis direction toward the image plane side as the focus group. Thereby, in the fisheye lens 1 according to the first embodiment, during focusing, the surface interval d16 between the first lens group G1 and the second lens group G2, and the surface interval d20 between the second lens group G2 and the third lens group G3 change. [Table 4] shows the values of the surface intervals at infinity and at the closest distance, which are variable.

[0066]

Table 1

[0067]

Table 2

[0068]

Table 3

[0069]

Table 4

[0070]

Table 5

[0071] FIG. 2 shows the longitudinal aberration of the fisheye lens 1 according to Example 1 at infinity focus. FIG. 3 shows the lateral aberration of the fisheye lens 1 according to Example 1 at infinity focus.

[0072] FIG. 2 shows spherical aberration, astigmatism (field curvature), and distortion as longitudinal aberrations. In the spherical aberration diagram of FIG. 2 and the lateral aberration diagram of FIG. 3, the solid line indicates the value at the d line (587.56 nm), the one-dot chain line indicates the value at the g line (435.84 nm), and the broken line indicates the value at the C line (656.27 nm). In the astigmatism diagram, S indicates the value at the sagittal image plane and M indicates the value at the meridional image plane. The distortion diagram shows the value at the d line. Also, in each aberration diagram, ω indicates the half field angle. The same applies to the aberration diagrams in the other subsequent examples.

[0073] As can be seen from each aberration diagram, the fisheye lens 1 according to Example 1 has good correction of various aberrations and excellent imaging performance.

[0074] [Example 2] [Table 6] shows the basic lens data of the fisheye lens 2 according to Example 2 shown in FIG. 4. [Table 7] shows the values of the coefficients representing the aspherical shape in the fisheye lens 2 according to Example 2. [Table 8] shows the values of the overall focal length f, F number, total field angle 2ω, image height Y, and optical overall length L in the fisheye lens 2 according to Example 2. [Table 9] shows the data of the surface intervals that become variable during focusing in the fisheye lens 2 according to Example 2. [Table 10] shows the starting surface and the focal length (unit: mm) of each group of the fisheye lens 2 according to Example 2.

[0075] The fish-eye lens 2 according to Embodiment 2 includes a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a third lens group G3 having a positive refractive power, which are arranged in order from the object side to the image plane side. In the fish-eye lens 2 according to Embodiment 2, the second lens group G2 corresponds to an intermediate group, and the third lens group G3 corresponds to a rear group.

[0076] The first lens group G1 includes first lens L1 to eighth lens L8 arranged in order from the object side to the image plane side. The first lens L1 is a meniscus-shaped negative lens with a convex surface facing the object side. The second lens L2 is a meniscus-shaped negative lens with a convex surface facing the object side. The third lens L3 is a meniscus-shaped negative lens with a convex surface facing the object side. The fourth lens L4 is a meniscus-shaped negative lens with a concave surface facing the object side. The fifth lens L5 is a biconvex positive lens. The sixth lens L6 and the seventh lens L7 constitute a cemented lens cemented to each other. The sixth lens L6 is a biconvex positive lens. The seventh lens L7 is a meniscus-shaped negative lens with a concave surface facing the object side. The eighth lens L8 is a meniscus-shaped positive lens with a concave surface facing the object side.

[0077] The second lens group G2 includes a ninth lens L9 and a tenth lens L10 arranged in order from the object side to the image plane side. The ninth lens L9 is a biconvex positive lens. The tenth lens L10 is a biconcave negative lens.

[0078] The third lens group G3 includes an eleventh lens L11 and a twelfth lens L12 arranged in order from the object side to the image plane side. The eleventh lens L11 is a meniscus-shaped positive lens with a concave surface facing the object side. The twelfth lens L12 is a meniscus-shaped negative lens with a concave surface facing the object side. The eleventh lens L11 and the twelfth lens L12 constitute a cemented lens cemented to each other.

[0080] An optical member FL such as a filter FL is arranged between the third lens group G3 and the image plane IMG. The aperture stop St is arranged within the first lens group G and is fixed with respect to the image plane IMG.

[0081] In the fish-eye lens 2 according to Example 2, when focusing from infinity to a short distance, the second lens group G2 moves in the optical axis direction toward the image plane side as the focus group. As a result, in the fish-eye lens 2 according to Example 2, during focusing, the surface interval d16 between the first lens group G1 and the second lens group G2, and the surface interval d20 between the second lens group G2 and the third lens group G3 change. [Table 9] shows the values of the surface intervals at infinity and at the closest distance where these are variable.

[0082]

Table 6

[0083]

Table 7

[0084]

Table 8

[0085]

Table 9

[0086]

Table 10

[0087] FIG. 5 shows the longitudinal aberration of the fish-eye lens 2 according to Example 2 at infinity focus. FIG. 6 shows the lateral aberration of the fish-eye lens 2 according to Example 2 at infinity focus.

[0088] As can be seen from each aberration diagram, the fish-eye lens 2 according to Example 2 has various aberrations well corrected and has excellent imaging performance.

[0089] [Example 3] Table 11 shows the basic lens data of the fisheye lens 3 according to Example 3 shown in FIG. 7. Table 12 shows the values of the coefficients representing the aspherical shape in the fisheye lens 3 according to Example 3. Table 13 shows the values of the overall focal length f, F-number, total field angle 2ω, image height Y, and overall optical length L in the fisheye lens 3 according to Example 3. Table 14 shows the data of the surface intervals that vary during focusing in the fisheye lens 3 according to Example 3. Table 16 shows the starting surfaces and focal lengths (unit: mm) of each group of the fisheye lens 3 according to Example 3.

[0090] The fisheye lens 3 according to Example 3 includes a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a third lens group G3 having a positive refractive power, which are arranged in order from the object side to the image side. In the fisheye lens 3 according to Example 3, the second lens group G2 corresponds to the intermediate group, and the third lens group G3 corresponds to the rear group.

[0091] The first lens group G1 is composed of a first lens L1 to an eighth lens L8 arranged in order from the object side to the image side. The first lens L1 is a meniscus-shaped negative lens with a convex surface facing the object side. The second lens L2 is a meniscus-shaped negative lens with a convex surface facing the object side. The third lens L3 is a meniscus-shaped negative lens with a convex surface facing the object side. The fourth lens L4 is a meniscus-shaped negative lens with a concave surface facing the object side. The fifth lens L5 is a biconvex positive lens. The sixth lens L6 and the seventh lens L7 constitute a cemented lens cemented to each other. The sixth lens L6 is a biconvex positive lens. The seventh lens L7 is a meniscus-shaped negative lens with a concave surface facing the object side. The eighth lens L8 is a meniscus-shaped positive lens with a concave surface facing the object side.

[0092] The second lens group G2 is composed of a ninth lens L9 and a tenth lens L10 arranged in order from the object side to the image side. The ninth lens L9 is a biconvex positive lens. The tenth lens L10 is a biconcave negative lens.

[0093] The third lens group G3 is formed by arranging an eleventh lens L11 and a twelfth lens L12 in order from the object side to the image plane side. The eleventh lens L11 is a positive lens with a biconvex shape. The twelfth lens L12 is a meniscus-shaped negative lens with its concave surface facing the object side. The eleventh lens L11 and the twelfth lens L12 constitute a cemented lens that is cemented to each other.

[0094] An optical member FL such as a filter FL is disposed between the third lens group G3 and the image plane IMG. The aperture stop St is disposed within the first lens group G and is fixed with respect to the image plane IMG.

[0095] In the fisheye lens 3 according to the third embodiment, when focusing from infinity to a short distance, the second lens group G2 moves in the optical axis direction toward the image plane side as a focus group. As a result, in the fisheye lens 3 according to the third embodiment, during focusing, the surface interval d16 between the first lens group G1 and the second lens group G2, and the surface interval d20 between the second lens group G2 and the third lens group G3 change. [Table 14] shows the values of these variable surface intervals at infinity and at the closest distance.

[0096]

Table 11

[0097]

Table 12

[0098]

Table 13

[0099]

Table 14

[0100]

Table 15

[0101] FIG. 8 shows the longitudinal aberration of the fish-eye lens 3 according to Example 3 at infinity focus. FIG. 9 shows the lateral aberration of the fish-eye lens 3 according to Example 3 at infinity focus.

[0102] As can be seen from each aberration diagram, the fish-eye lens 3 according to Example 3 has various aberrations well corrected and has excellent imaging performance.

[0103] [Example 4] [Table 16] shows the basic lens data of the fish-eye lens 4 according to Example 4 shown in FIG. 10. [Table 17] shows the values of the coefficients representing the aspherical shape in the fish-eye lens 4 according to Example 4. [Table 18] shows the values of the focal length f, F-number, total field angle 2ω, image height Y, and optical total length L of the entire system in the fish-eye lens 4 according to Example 4. [Table 19] shows the data of the surface intervals that become variable during focusing in the fish-eye lens 4 according to Example 4. [Table 20] shows the starting surface and focal length (unit: mm) of each group of the fish-eye lens 4 according to Example 4.

[0104] The fish-eye lens 4 according to Example 4 includes a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a third lens group G3 having a positive refractive power, which are arranged in order from the object side to the image side. In the fish-eye lens 4 according to Example 4, the second lens group G2 corresponds to the intermediate group, and the third lens group G3 corresponds to the rear group.

[0105] The first lens group G1 is composed of the first lens L1 to the eighth lens L8 arranged in order from the object side to the image plane side. The first lens L1 is a meniscus-shaped negative lens with a convex surface facing the object side. The second lens L2 is a meniscus-shaped negative lens with a convex surface facing the object side. The third lens L3 is a biconcave negative lens. The fourth lens L4 is a meniscus-shaped negative lens with a concave surface facing the object side. The fifth lens L5 is a biconvex positive lens. The sixth lens L6 and the seventh lens L7 constitute a cemented lens that are cemented to each other. The sixth lens L6 is a biconvex positive lens. The seventh lens L7 is a meniscus-shaped negative lens with a concave surface facing the object side. The eighth lens L8 is a meniscus-shaped positive lens with a concave surface facing the object side.

[0106] The second lens group G2 is composed of the ninth lens L9 and the tenth lens L10 arranged in order from the object side to the image plane side. The ninth lens L9 is a biconvex positive lens. The tenth lens L10 is a biconcave negative lens.

[0107] The third lens group G3 is composed of the eleventh lens L11 and the twelfth lens L12 arranged in order from the object side to the image plane side. The eleventh lens L11 is a biconvex positive lens. The twelfth lens L12 is a meniscus-shaped negative lens with a concave surface facing the object side. The eleventh lens L11 and the twelfth lens L12 constitute a cemented lens that are cemented to each other.

[0108] An optical member FL such as a filter FL is arranged between the third lens group G3 and the image plane IMG. The aperture stop St is arranged within the first lens group G and is fixed with respect to the image plane IMG.

[0109] In the fish-eye lens 4 according to Embodiment 4, when focusing from infinity to a short distance, the second lens group G2 moves in the optical axis direction toward the image plane side as a focus group. As a result, in the fish-eye lens 4 according to Embodiment 4, during focusing, the surface interval d16 between the first lens group G1 and the second lens group G2, and the surface interval d20 between the second lens group G2 and the third lens group G3 change. [Table 19] shows the values of the surface intervals at infinity and at the closest distance, which are variable.

[0110]

Table 16

[0111]

Table 17

[0112]

Table 18

[0113]

Table 19

[0114]

Table 20

[0115] FIG. 11 shows the longitudinal aberration of the fish-eye lens 4 according to Embodiment 4 at infinity focus. FIG. 12 shows the lateral aberration of the fish-eye lens 4 according to Embodiment 4 at infinity focus.

[0116] As can be seen from each aberration diagram, the fish-eye lens 4 according to Embodiment 4 has well-corrected various aberrations and excellent imaging performance.

[0117] [Embodiment 5] Table 21 shows the basic lens data of the fisheye lens 5 according to Example 5 shown in FIG. 13. Table 22 shows the values of the coefficients representing the aspherical shape in the fisheye lens 5 according to Example 5. Table 23 shows the values of the overall focal length f, F-number, total angle of view 2ω, image height Y, and overall optical length L in the fisheye lens 5 according to Example 5. Table 24 shows the data of the surface intervals that vary during focusing in the fisheye lens 5 according to Example 5. Table 25 shows the starting surfaces and focal lengths (unit: mm) of each group of the fisheye lens 5 according to Example 5.

[0118] The fisheye lens 5 according to Example 5 includes a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, a third lens group G3 having a positive refractive power, a fourth lens group G4 having a positive refractive power, and a fifth lens group G5 having a negative refractive power, which are arranged in order from the object side to the image side. In the fisheye lens 5 according to Example 5, the second lens group G2, the third lens group G3, and the fourth lens group G4 correspond to intermediate groups, and the fifth lens group G5 corresponds to a rear group.

[0119] The first lens group G1 is composed of a first lens L1 to a fourth lens L4 arranged in order from the object side to the image side. The first lens L1 is a meniscus-shaped negative lens with a convex surface facing the object side. The second lens L2 is a meniscus-shaped negative lens with a convex surface facing the object side. The third lens L3 is a biconcave negative lens. The fourth lens L4 is a biconvex positive lens.

[0120] The second lens group G2 consists of a fifth lens L5 which is a biconvex positive lens.

[0121] The third lens group G3 is composed of a sixth lens L6 to a ninth lens L9 arranged in order from the object side to the image side. The sixth lens L6 is a meniscus-shaped positive lens with a concave surface facing the object side. The seventh lens L7 is a biconvex positive lens. The eighth lens L8 is a biconcave negative lens. The seventh lens L7 and the eighth lens L8 constitute a cemented lens cemented to each other. The ninth lens L9 is a biconvex positive lens.

[0122] The fourth lens group G4 consists of a 10th lens L10 which is a biconvex positive lens.

[0123] The fifth lens group G5 is composed of an 11th lens L11 to a 13th lens L13 which are arranged in order from the object side to the image plane side. The 11th lens L11 is a biconcave negative lens. The 12th lens L12 is a biconvex positive lens. The 13th lens L13 is a biconvex positive lens.

[0124] An optical member FL such as a filter FL is arranged between the fifth lens group G5 and the image plane IMG. The aperture stop St is arranged within the third lens group G3 and is fixed with respect to the image plane IMG.

[0125] In the fisheye lens 5 according to Example 5, when focusing from infinity to a short distance, the second lens group G2 and the fourth lens group G4 move in the optical axis direction toward the object side as the focus groups. As a result, in the fisheye lens 5 according to Example 5, during focusing, the surface interval d8 between the first lens group G1 and the second lens group G2, the surface interval d10 between the second lens group G2 and the third lens group G3, the surface interval d18 between the third lens group G2 and the fourth lens group G4, and the surface interval d20 between the fourth lens group G4 and the fifth lens group G5 change. [Table 24] shows the values of the surface intervals at infinity and at the closest distance when these are variable.

[0126]

Table 21

[0127]

Table 22

[0128]

Table 23

[0129]

Table 24

[0130]

Table 25

[0131] FIG. 14 shows the longitudinal aberration of the fish-eye lens 5 according to Example 5 at infinity focus. FIG. 15 shows the lateral aberration of the fish-eye lens 5 according to Example 5 at infinity focus.

[0132] As can be seen from each aberration diagram, the fish-eye lens 5 according to Example 5 has good correction of various aberrations and excellent imaging performance.

[0133] [Example 6] [Table 26] shows the basic lens data of the fish-eye lens 6 according to Example 6 shown in FIG. 16. [Table 27] shows the values of the coefficients representing the aspherical shape in the fish-eye lens 6 according to Example 6. [Table 28] shows the values of the focal length f, F-number, total angle of view 2ω, image height Y, and overall optical length L of the entire system in the fish-eye lens 6 according to Example 6. [Table 29] shows the data of the surface intervals that vary during focusing in the fish-eye lens 6 according to Example 6. [Table 20] shows the starting surfaces and focal lengths (unit: mm) of each group of the fish-eye lens 6 according to Example 6.

[0134] The fish-eye lens 6 according to Example 6 includes a first lens group G1 having a positive refractive power, a second lens group G2 having a positive refractive power, and a third lens group G3 having a positive refractive power, which are arranged in order from the object side to the image side. In the fish-eye lens 6 according to Example 6, the second lens group G2 corresponds to the intermediate group, and the third lens group G3 corresponds to the rear group.

[0135] The first lens group G1 is composed of the first lens L1 to the eighth lens L8 arranged in order from the object side to the image plane side. The first lens L1 is a meniscus-shaped negative lens with a convex surface facing the object side. The second lens L2 is a biconcave negative lens. The third lens L3 is a meniscus-shaped negative lens with a convex surface facing the object side. The fourth lens L4 is a biconvex positive lens. The third lens L3 and the fourth lens L4 constitute a cemented lens joined to each other. The fifth lens L5 is a biconcave negative lens. The sixth lens L6 is a biconvex positive lens. The seventh lens L7 is a meniscus-shaped negative lens with a concave surface facing the object side. The sixth lens L6 and the seventh lens L7 constitute a cemented lens joined to each other. The eighth lens L8 is a meniscus-shaped positive lens with a concave surface facing the object side.

[0136] The second lens group G2 consists of the ninth lens L9, which is a meniscus-shaped positive lens with a concave surface facing the object side.

[0137] The third lens group G3 is composed of the tenth lens L10 to the twelfth lens L12 arranged in order from the object side to the image plane side. The tenth lens L10 is a meniscus-shaped negative lens with a concave surface facing the object side. The eleventh lens L11 is a biconvex positive lens. The twelfth lens L12 is a meniscus-shaped negative lens with a concave surface facing the object side. The eleventh lens L11 and the twelfth lens L12 constitute a cemented lens joined to each other.

[0138] An optical member FL such as a filter FL is arranged between the third lens group G3 and the image plane IMG. The aperture stop St is arranged within the first lens group G and is fixed with respect to the image plane IMG.

[0139] In the fish-eye lens 4 according to Embodiment 4, when focusing from infinity to a short distance, the second lens group G2 moves in the object side in the optical axis direction as a focus group. As a result, in the fish-eye lens 4 according to Embodiment 4, during focusing, the surface interval d15 between the first lens group G1 and the second lens group G2, and the surface interval d17 between the second lens group G2 and the third lens group G3 change. [Table 29] shows the values of the surface intervals at infinity and at the closest distance, which are variable.

[0140]

Table 26

[0141]

Table 27

[0142]

Table 28

[0143]

Table 29

[0144]

Table 30

[0145] FIG. 17 shows the longitudinal aberration of the fish-eye lens 6 according to Embodiment 6 at infinity focus. FIG. 18 shows the lateral aberration of the fish-eye lens 6 according to Embodiment 6 at infinity focus.

[0146] As can be seen from each aberration diagram, the fish-eye lens 6 according to Embodiment 6 has various aberrations well corrected and has excellent imaging performance.

[0147] [Embodiment 7] Table 31 shows the basic lens data of the fisheye lens 7 according to Example 7 shown in FIG. 19. Table 32 shows the values of the coefficients representing the aspherical shape in the fisheye lens 7 according to Example 7. Table 33 shows the values of the overall focal length f, F-number, total angle of view 2ω, image height Y, and overall optical length L in the fisheye lens 7 according to Example 7. Table 34 shows the data of the surface intervals that vary during focusing in the fisheye lens 7 according to Example 7. Table 35 shows the starting surfaces and focal lengths (unit: mm) of each group of the fisheye lens 7 according to Example 7.

[0148] In the fisheye lens 7 according to Example 7, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a third lens group G3 having a positive refractive power are arranged in order from the object side to the image side. In the fisheye lens 7 according to Example 7, the second lens group G2 corresponds to the intermediate group, and the third lens group G3 corresponds to the rear group.

[0149] The first lens group G1 is composed of a first lens L1 to an eighth lens L8 arranged in order from the object side to the image side. The first lens L1 is a meniscus-shaped negative lens with a convex surface facing the object side. The second lens L2 is a meniscus-shaped negative lens with a convex surface facing the object side. The third lens L3 is a meniscus-shaped negative lens with a convex surface facing the object side. The fourth lens L4 is a biconcave negative lens. The fifth lens L5 is a biconvex positive lens. The sixth lens L6 and the seventh lens L7 constitute a cemented lens cemented to each other. The sixth lens L6 is a biconvex positive lens. The seventh lens L7 is a meniscus-shaped negative lens with a concave surface facing the object side. The eighth lens L8 is a meniscus-shaped positive lens with a concave surface facing the object side.

[0150] The second lens group G2 is composed of a ninth lens L9 and a tenth lens L10 arranged in order from the object side to the image side. The ninth lens L9 is a biconvex positive lens. The tenth lens L10 is a biconcave negative lens.

[0151] The third lens group G3 is composed of an eleventh lens L11 and a twelfth lens L12 arranged in order from the object side to the image plane side. The eleventh lens L11 is a positive lens with a biconvex shape. The twelfth lens L12 is a meniscus-shaped negative lens with its concave surface facing the object side. The eleventh lens L11 and the twelfth lens L12 constitute a cemented lens that is cemented to each other.

[0152] An optical member FL such as a filter FL is arranged between the third lens group G3 and the image plane IMG. The aperture stop St is arranged within the first lens group G and is fixed with respect to the image plane IMG.

[0153] In the fisheye lens 7 according to Example 7, when focusing from infinity to a short distance, the second lens group G2 moves in the optical axis direction toward the image plane side as a focus group. As a result, in the fisheye lens 7 according to Example 7, during focusing, the surface interval d16 between the first lens group G1 and the second lens group G2, and the surface interval d20 between the second lens group G2 and the third lens group G3 change. [Table 34] shows the values of the surface intervals at infinity and at the closest distance when these are variable.

[0154]

Table 31

[0155]

Table 32

[0156]

Table 33

[0157]

Table 34

[0158]

Table 35

[0159] FIG. 20 shows the longitudinal aberration of the fish-eye lens 7 according to Example 7 at infinity focus. FIG. 21 shows the lateral aberration of the fish-eye lens 7 according to Example 7 at infinity focus.

[0160] As can be seen from each aberration diagram, the fish-eye lens 7 according to Example 7 has various aberrations well corrected and has excellent imaging performance.

[0161] [Example 8] [Table 36] shows the basic lens data of the fish-eye lens 8 according to Example 8 shown in FIG. 22. [Table 37] shows the values of the coefficients representing the aspherical shape in the fish-eye lens 8 according to Example 8. [Table 38] shows the values of the overall focal length f, F-number, overall angle of view 2ω, image height Y, and overall optical length L in the fish-eye lens 8 according to Example 8. [Table 39] shows the data of the surface intervals that become variable during focusing in the fish-eye lens 8 according to Example 8. [Table 40] shows the starting surfaces and focal lengths (unit: mm) of each group of the fish-eye lens 8 according to Example 8.

[0162] The fish-eye lens 8 according to Example 8 includes a first lens group G1 having a positive refractive power, a second lens group G2 having a positive refractive power, and a third lens group G3 having a negative refractive power, which are arranged in order from the object side to the image side. In the fish-eye lens 8 according to Example 8, the second lens group G2 corresponds to an intermediate group, and the third lens group G3 corresponds to a rear group.

[0163] The first lens group G1 is composed of the first lens L1 to the eighth lens L8 arranged in order from the object side to the image plane side. The first lens L1 is a meniscus-shaped negative lens with a convex surface facing the object side. The second lens L2 is a meniscus-shaped negative lens with a convex surface facing the object side. The third lens L3 is a meniscus-shaped negative lens with a concave surface facing the object side. The fourth lens L4 is a meniscus-shaped positive lens with a concave surface facing the object side. The fifth lens L5 is a meniscus-shaped positive lens with a convex surface facing the object side. The sixth lens L6 is a meniscus-shaped positive lens with a concave surface facing the object side. The seventh lens L7 is a meniscus-shaped positive lens with a concave surface facing the object side. The eighth lens L8 is a meniscus-shaped negative lens with a concave surface facing the object side. The seventh lens L7 and the eighth lens L8 constitute a cemented lens that is cemented to each other.

[0164] The second lens group G2 is composed of the ninth lens L9 and the tenth lens L10 arranged in order from the object side to the image plane side. The ninth lens L9 is a meniscus-shaped negative lens with a concave surface facing the object side. The tenth lens L10 is a biconvex positive lens.

[0165] The third lens group G3 is composed of the eleventh lens L11 to the thirteenth lens L13 arranged in order from the object side to the image plane side. The eleventh lens L11 is a biconcave negative lens. The twelfth lens L12 is a biconvex positive lens. The eleventh lens L11 and the twelfth lens L12 constitute a cemented lens that is cemented to each other. The thirteenth lens L13 is a meniscus-shaped positive lens with a convex surface facing the object side.

[0166] An optical member FL such as a filter FL is arranged between the third lens group G3 and the image plane IMG. The aperture stop St is arranged within the first lens group G and is fixed with respect to the image plane IMG.

[0167] In the fisheye lens 8 according to Example 8, when focusing from infinity to a short distance, the second lens group G2 moves in the optical axis direction toward the object side as a focus group. As a result, in the fisheye lens 8 according to Example 8, during focusing, the surface interval d16 between the first lens group G1 and the second lens group G2, and the surface interval d20 between the second lens group G2 and the third lens group G3 change. [Table 39] shows the values of the surface intervals at infinity and at the closest distance, which are variable.

[0168]

Table 36

[0169]

Table 37

[0170]

Table 38

[0171]

Table 39

[0172]

Table 40

[0173] FIG. 23 shows the longitudinal aberration of the fisheye lens 8 according to Example 8 at infinity focus. FIG. 24 shows the lateral aberration of the fisheye lens 8 according to Example 8 at infinity focus.

[0174] As can be seen from each aberration diagram, the fisheye lens 8 according to Example 8 has good correction of various aberrations and excellent imaging performance.

[0175] [Example 9] Table 41 shows the basic lens data of the fisheye lens 9 according to Example 9 shown in FIG. 25. Table 42 shows the values of the coefficients representing the aspherical shape in the fisheye lens 9 according to Example 9. Table 43 shows the values of the overall focal length f, F-number, overall angle of view 2ω, image height Y, and overall optical length L in the fisheye lens 9 according to Example 9. Table 44 shows the data of the surface intervals that vary during focusing in the fisheye lens 9 according to Example 9. Table 45 shows the starting surface and the focal length (unit: mm) of each group of the fisheye lens 9 according to Example 9.

[0176] The fisheye lens 9 according to Example 9 includes a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a third lens group G3 having a positive refractive power, which are arranged in order from the object side to the image side. In the fisheye lens 9 according to Example 9, the second lens group G2 corresponds to the intermediate group, and the third lens group G3 corresponds to the rear group.

[0177] The first lens group G1 includes a first lens L1 to an eighth lens L8 arranged in order from the object side to the image side. The first lens L1 is a meniscus-shaped negative lens with a convex surface facing the object side. The second lens L2 is a meniscus-shaped negative lens with a convex surface facing the object side. The third lens L3 is a meniscus-shaped negative lens with a convex surface facing the object side. The fourth lens L4 is a biconcave negative lens. The fifth lens L5 is a biconvex positive lens. The sixth lens L6 is a biconvex positive lens. The seventh lens L7 is a meniscus-shaped negative lens with a concave surface facing the object side. The sixth lens L6 and the seventh lens L7 form a cemented lens that is cemented to each other. The eighth lens L8 is a meniscus-shaped positive lens with a concave surface facing the object side.

[0178] The second lens group G2 includes a ninth lens L9 and a tenth lens L10 arranged in order from the object side to the image side. The ninth lens L9 is a biconvex positive lens. The tenth lens L10 is a biconcave negative lens.

[0179] The third lens group G3 is formed by arranging the eleventh lens L11 and the twelfth lens L12 in order from the object side to the image plane side. The eleventh lens L11 is a biconvex positive lens. The twelfth lens L12 is a meniscus negative lens with a concave surface facing the object side. The eleventh lens L11 and the twelfth lens L12 constitute a cemented lens that is cemented to each other.

[0180] An optical member FL such as a filter FL is disposed between the third lens group G3 and the image plane IMG. The aperture stop St is disposed within the first lens group G and is fixed with respect to the image plane IMG.

[0181] In the fisheye lens 9 according to Example 9, when focusing from infinity to a short distance, the second lens group G2 moves in the optical axis direction toward the image plane side as a focus group. As a result, in the fisheye lens 9 according to Example 9, during focusing, the surface interval d16 between the first lens group G1 and the second lens group G2, and the surface interval d20 between the second lens group G2 and the third lens group G3 change. [Table 44] shows the values of the surface intervals at infinity and at the closest distance, which are variable.

[0182]

Table 41

[0183]

Table 42

[0184]

Table 43

[0185]

Table 44

[0186]

Table 45

[0187] FIG. 26 shows the longitudinal aberration of the fisheye lens 9 according to Example 9 at infinity focus. FIG. 27 shows the lateral aberration of the fisheye lens 9 according to Example 9 at infinity focus.

[0188] As can be seen from each aberration diagram, the fisheye lens 9 according to Example 9 has good correction of various aberrations and excellent imaging performance.

[0189] [Other numerical data of each example] [Table 46] shows the values for each of the above conditional expressions summarized for each example. As can be seen from [Table 46], for each conditional expression, the values of each example are within their numerical ranges. Note that for the conditional expressions (1) and (3), the calculated values are shown in a state where the optical member FL such as a filter is excluded.

[0190]

Table 46

[0191] <5. Application examples> [5.1 First application example] The technology according to the present disclosure can be applied to various products. For example, the technology according to the present disclosure may be realized as a device mounted on any type of moving body such as an automobile, an electric vehicle, a hybrid electric vehicle, a motorcycle, a bicycle, a personal mobility device, an airplane, a drone, a ship, a robot, a construction machine, an agricultural machine (tractor).

[0192] FIG. 29 is a block diagram showing a schematic configuration example of a vehicle control system 7000 which is an example of a movement control system to which the technology according to the present disclosure can be applied. The vehicle control system 7000 includes a plurality of electronic control units connected via a communication network 7010. In the example shown in FIG. 29, the vehicle control system 7000 includes a drive system control unit 7100, a body system control unit 7200, a battery control unit 7300, an outside vehicle information detection unit 7400, an inside vehicle information detection unit 7500, and an integrated control unit 7600. The communication network 7010 connecting these plurality of control units may be an in-vehicle communication network compliant with any standard such as CAN (Controller Area Network), LIN (Local Interconnect Network), LAN (Local Area Network), or FlexRay (registered trademark).

[0193] Each control unit includes a microcomputer that performs arithmetic processing according to various programs, a storage unit that stores programs executed by the microcomputer or parameters used for various arithmetic operations, and a drive circuit that drives devices of various control targets. Each control unit includes a network I / F for communicating with other control units via the communication network 7010, and a communication I / F for communicating with devices or sensors inside and outside the vehicle by wired communication or wireless communication. In FIG. 29, as the functional configuration of the integrated control unit 7600, a microcomputer 7610, a general-purpose communication I / F 7620, a dedicated communication I / F 7630, a positioning unit 7640, a beacon reception unit 7650, an in-vehicle device I / F 7660, an audio / video output unit 7670, an in-vehicle network I / F 7680, and a storage unit 7690 are shown. Similarly, other control units also include a microcomputer, a communication I / F, a storage unit, etc.

[0194] The drive system control unit 7100 controls the operations of devices related to the vehicle's drive system according to various programs. For example, the drive system control unit 7100 functions as a control device for a driving force generation device for generating the driving force of the vehicle such as an internal combustion engine or a driving motor, a driving force transmission mechanism for transmitting the driving force to the wheels, a steering mechanism for adjusting the steering angle of the vehicle, and a braking device for generating the braking force of the vehicle. The drive system control unit 7100 may have functions as control devices such as an ABS (Antilock Brake System) or an ESC (Electronic Stability Control).

[0195] A vehicle state detection unit 7110 is connected to the drive system control unit 7100. The vehicle state detection unit 7110 includes, for example, at least one of a gyro sensor for detecting the angular velocity of the axial rotational movement of the vehicle body, an acceleration sensor for detecting the acceleration of the vehicle, or a sensor for detecting the operation amount of the accelerator pedal, the operation amount of the brake pedal, the steering angle of the steering wheel, the engine speed, or the rotational speed of the wheels. The drive system control unit 7100 performs arithmetic processing using the signals input from the vehicle state detection unit 7110 and controls an internal combustion engine, a driving motor, an electric power steering device, or a braking device.

[0196] The body system control unit 7200 controls the operations of various devices installed in the vehicle body according to various programs. For example, the body system control unit 7200 functions as a control device for a keyless entry system, a smart key system, a power window device, or various lamps such as a headlamp, a backlamp, a brake lamp, a turn signal, or a fog lamp. In this case, radio waves transmitted from a portable device that replaces the key or signals of various switches may be input to the body system control unit 7200. The body system control unit 7200 receives these inputs of radio waves or signals and controls the vehicle's door lock device, power window device, lamps, etc.

[0197] The battery control unit 7300 controls the secondary battery 7310, which is the power supply for the drive motor, according to various programs. For example, information such as the battery temperature, battery output voltage, or remaining battery capacity is input to the battery control unit 7300 from a battery device equipped with the secondary battery 7310. The battery control unit 7300 performs arithmetic processing using these signals and controls the temperature adjustment of the secondary battery 7310 or controls a cooling device or the like provided in the battery device.

[0198] The vehicle external information detection unit 7400 detects information outside the vehicle equipped with the vehicle control system 7000. For example, at least one of the imaging unit 7410 and the vehicle external information detection unit 7420 is connected to the vehicle external information detection unit 7400. The imaging unit 7410 includes at least one of a ToF (Time Of Flight) camera, a stereo camera, a monocular camera, an infrared camera, and other cameras. The vehicle external information detection unit 7420 includes, for example, at least one of an environmental sensor for detecting the current weather or meteorology, or a surrounding information detection sensor for detecting other vehicles, obstacles, or pedestrians around the vehicle equipped with the vehicle control system 7000.

[0199] The environmental sensor may be, for example, at least one of a raindrop sensor for detecting rain, a fog sensor for detecting fog, a sunshine sensor for detecting the degree of sunshine, and a snow sensor for detecting snowfall. The surrounding information detection sensor may be at least one of an ultrasonic sensor, a radar device, and a LIDAR (Light Detection and Ranging, Laser Imaging Detection and Ranging) device. These imaging unit 7410 and vehicle external information detection unit 7420 may be provided as independent sensors or devices, or may be provided as a device in which a plurality of sensors or devices are integrated.

[0200] Here, FIG. 30 shows an example of the installation positions of the imaging unit 7410 and the vehicle exterior information detection unit 7420. The imaging units 7910, 7912, 7914, 7916, 7918 are provided, for example, at at least one position among the front nose, side mirrors, rear bumper, back door of the vehicle 7900, and the upper part of the front windshield inside the vehicle cabin. The imaging unit 7910 provided at the front nose and the imaging unit 7918 provided at the upper part of the front windshield inside the vehicle cabin mainly acquire images in front of the vehicle 7900. The imaging units 7912, 7914 provided at the side mirrors mainly acquire images on the sides of the vehicle 7900. The imaging unit 7916 provided at the rear bumper or the back door mainly acquires images behind the vehicle 7900. The imaging unit 7918 provided at the upper part of the front windshield inside the vehicle cabin is mainly used for detecting a preceding vehicle or pedestrians, obstacles, traffic lights, traffic signs, lanes, etc.

[0201] Note that FIG. 30 shows an example of the imaging ranges of the respective imaging units 7910, 7912, 7914, 7916. The imaging range a indicates the imaging range of the imaging unit 7910 provided at the front nose, and the imaging ranges b and c indicate the imaging ranges of the imaging units 7912 and 7914 provided at the side mirrors, respectively. The imaging range d indicates the imaging range of the imaging unit 7916 provided at the rear bumper or the back door. For example, by superimposing the image data captured by the imaging units 7910, 7912, 7914, 7916, an overhead image of the vehicle 7900 viewed from above can be obtained.

[0202] The vehicle exterior information detection units 7920, 7922, 7924, 7926, 7928, 7930 provided at the front, rear, sides, corners of the vehicle 7900, and the upper part of the front windshield inside the vehicle cabin may be, for example, ultrasonic sensors or radar devices. The vehicle exterior information detection units 7920, 7926, 7930 provided at the front nose, rear bumper, back door of the vehicle 7900, and the upper part of the front windshield inside the vehicle cabin may be, for example, LIDAR devices. These vehicle exterior information detection units 7920 to 7930 are mainly used for detecting a preceding vehicle, pedestrians, or obstacles, etc.

[0203] Returning to FIG. 29, the description will be continued. The vehicle exterior information detection unit 7400 causes the imaging unit 7410 to capture an image of the exterior of the vehicle and receives the captured image data. Further, the vehicle exterior information detection unit 7400 receives detection information from the connected vehicle exterior information detection unit 7420. When the vehicle exterior information detection unit 7420 is an ultrasonic sensor, a radar device, or a LIDAR device, the vehicle exterior information detection unit 7400 transmits ultrasonic waves, electromagnetic waves, etc. and receives information on the received reflected waves. The vehicle exterior information detection unit 7400 may perform object detection processing or distance detection processing, such as for a person, a vehicle, an obstacle, a sign, or characters on the road surface, based on the received information. The vehicle exterior information detection unit 7400 may perform environment recognition processing for recognizing rainfall, fog, or road surface conditions, etc., based on the received information. The vehicle exterior information detection unit 7400 may calculate the distance to an object outside the vehicle based on the received information.

[0204] Also, the vehicle exterior information detection unit 7400 may perform image recognition processing or distance detection processing for recognizing a person, a vehicle, an obstacle, a sign, or characters on the road surface, etc., based on the received image data. The vehicle exterior information detection unit 7400 may perform processing such as distortion correction or alignment on the received image data, and may also generate an overhead image or a panoramic image by synthesizing the image data captured by different imaging units 7410. The vehicle exterior information detection unit 7400 may perform viewpoint conversion processing using the image data captured by different imaging units 7410.

[0205] The in-vehicle information detection unit 7500 detects information inside the vehicle. For example, a driver state detection unit 7510 that detects the state of the driver is connected to the in-vehicle information detection unit 7500. The driver state detection unit 7510 may include a camera that images the driver, a biometric sensor that detects the biometric information of the driver, a microphone that collects the voice inside the vehicle cabin, or the like. The biometric sensor is provided, for example, on a seat surface or a steering wheel, and detects the biometric information of a passenger sitting on the seat or a driver holding the steering wheel. The in-vehicle information detection unit 7500 may calculate the degree of driver fatigue or concentration based on the detection information input from the driver state detection unit 7510, or may determine whether the driver is dozing off. The in-vehicle information detection unit 7500 may perform processing such as noise cancellation processing on the collected voice signal.

[0206] The integrated control unit 7600 controls the overall operation within the vehicle control system 7000 according to various programs. An input unit 7800 is connected to the integrated control unit 7600. The input unit 7800 is realized by a device that can be input-operated by a passenger, such as a touch panel, a button, a microphone, a switch, or a lever. Data obtained by voice recognition of the voice input by the microphone may be input to the integrated control unit 7600. The input unit 7800 may be, for example, a remote control device using infrared rays or other radio waves, or an external connection device such as a mobile phone or a PDA (Personal Digital Assistant) corresponding to the operation of the vehicle control system 7000. The input unit 7800 may be, for example, a camera, and in that case, the passenger can input information by gestures. Alternatively, data obtained by detecting the movement of a wearable device worn by the passenger may be input. Further, the input unit 7800 may include, for example, an input control circuit that generates an input signal based on the information input by the passenger or the like using the above input unit 7800 and outputs it to the integrated control unit 7600. The passenger or the like operates this input unit 7800 to input various data to the vehicle control system 7000 or instruct a processing operation.

[0207] The storage unit 7690 may include a ROM (Read Only Memory) that stores various programs executed by the microcomputer, and a RAM (Random Access Memory) that stores various parameters, calculation results, sensor values, etc. Further, the storage unit 7690 may be realized by a magnetic storage device such as an HDD (Hard Disc Drive), a semiconductor storage device, an optical storage device, or a magneto-optical storage device.

[0208] The general-purpose communication I / F 7620 is a general-purpose communication I / F that mediates communication with various devices existing in the external environment 7750. The general-purpose communication I / F 7620 may implement a cellular communication protocol such as GSM (registered trademark) (Global System of Mobile communications), WiMAX (registered trademark), LTE (registered trademark) (Long Term Evolution), or LTE-A (LTE-Advanced), or other wireless communication protocols such as wireless LAN (also referred to as Wi-Fi (registered trademark)) and Bluetooth (registered trademark). The general-purpose communication I / F 7620 may be connected to a device (for example, an application server or a control server) existing on an external network (for example, the Internet, a cloud network, or a carrier-specific network) via, for example, a base station or an access point. Further, the general-purpose communication I / F 7620 may be connected to a terminal existing in the vicinity of the vehicle (for example, a driver, a pedestrian, or a store terminal, or an MTC (Machine Type Communication) terminal) using, for example, P2P (Peer To Peer) technology.

[0209] The dedicated communication I / F 7630 is a communication I / F that supports communication protocols formulated for use in vehicles. The dedicated communication I / F 7630 may implement standard protocols such as WAVE (Wireless Access in Vehicle Environment), DSRC (Dedicated Short Range Communications), which is a combination of the lower-layer IEEE802.11p and the upper-layer IEEE1609, or a cellular communication protocol. The dedicated communication I / F 7630 typically performs V2X communication, which is a concept that includes one or more of vehicle-to-vehicle communication, vehicle-to-infrastructure communication, vehicle-to-home communication, and vehicle-to-pedestrian communication.

[0210] The positioning unit 7640 receives GNSS signals (e.g., GPS signals from GPS (Global Positioning System) satellites) from GNSS (Global Navigation Satellite System) satellites, for example, to perform positioning and generate position information including the latitude, longitude, and altitude of the vehicle. Note that the positioning unit 7640 may also identify the current position by exchanging signals with a wireless access point, or may obtain position information from a terminal such as a mobile phone, PHS, or smartphone having a positioning function.

[0211] The beacon receiver 7650 receives radio waves or electromagnetic waves transmitted from, for example, a wireless station installed on the road, and obtains information such as the current position, traffic jam, road closure, or required time. Note that the function of the beacon receiver 7650 may be included in the dedicated communication I / F 7630 described above.

[0212] The in-vehicle device I / F 7660 is a communication interface that mediates the connection between the microcomputer 7610 and various in-vehicle devices 7760 present in the vehicle. The in-vehicle device I / F 7660 may establish a wireless connection using a wireless communication protocol such as wireless LAN, Bluetooth (registered trademark), NFC (Near Field Communication), or WUSB (Wireless USB). Also, the in-vehicle device I / F 7660 may establish a wired connection such as USB (Universal Serial Bus), HDMI (registered trademark) (High-Definition Multimedia Interface), or MHL (Mobile High-definition Link) via connection terminals (and cables if necessary) not shown in the figure. The in-vehicle devices 7760 may include, for example, at least one of a mobile device or wearable device owned by a passenger, or an information device carried into or attached to the vehicle. Further, the in-vehicle devices 7760 may include a navigation device that performs route search to an arbitrary destination. The in-vehicle device I / F 7660 exchanges control signals or data signals with these in-vehicle devices 7760.

[0213] The in-vehicle network I / F 7680 is an interface that mediates communication between the microcomputer 7610 and the communication network 7010. The in-vehicle network I / F 7680 transmits and receives signals, etc., in accordance with a predetermined protocol supported by the communication network 7010.

[0214] Based on the information acquired through at least one of the general-purpose communication I / F 7620, dedicated communication I / F 7630, positioning unit 7640, beacon reception unit 7650, in-vehicle device I / F 7660, and in-vehicle network I / F 7680, the microcomputer 7610 of the integrated control unit 7600 controls the vehicle control system 7000 according to various programs. For example, based on the acquired information inside and outside the vehicle, the microcomputer 7610 may calculate control target values for the driving force generation device, steering mechanism, or braking device, and output control commands to the drive system control unit 7100. For example, the microcomputer 7610 may perform cooperative control aimed at realizing functions of ADAS (Advanced Driver Assistance System) including collision avoidance or shock mitigation of the vehicle, following driving based on the inter-vehicle distance, vehicle speed maintenance driving, collision warning of the vehicle, or lane departure warning of the vehicle. Also, based on the acquired information around the vehicle, the microcomputer 7610 may perform cooperative control aimed at autonomous driving, etc., which runs independently without relying on the driver's operation, by controlling the driving force generation device, steering mechanism, braking device, etc.

[0215] Based on the information acquired through at least one of the general-purpose communication I / F 7620, dedicated communication I / F 7630, positioning unit 7640, beacon reception unit 7650, in-vehicle device I / F 7660, and in-vehicle network I / F 7680, the microcomputer 7610 may generate three-dimensional distance information between the vehicle and objects such as surrounding structures and people, and create local map information including information around the current position of the vehicle. Also, based on the acquired information, the microcomputer 7610 may predict risks such as collision of the vehicle, approach of pedestrians, etc., or entry into a blocked road, and generate a warning signal. The warning signal may be, for example, a signal for generating a warning sound or lighting a warning lamp.

[0216] The voice and image output unit 7670 transmits an output signal of at least one of voice and image to an output device capable of notifying information visually or aurally to the vehicle occupants or outside the vehicle. In the example of FIG. 29, as the output device, an audio speaker 7710, a display unit 7720, and an instrument panel 7730 are illustrated. The display unit 7720 may include, for example, at least one of an on-board display and a head-up display. The display unit 7720 may have an AR (Augmented Reality) display function. The output device may be other devices such as headphones, wearable devices such as glasses-type displays worn by passengers, projectors, or lamps, in addition to these devices. When the output device is a display device, the display device visually displays the results obtained by various processes performed by the microcomputer 7610 or the information received from other control units in various forms such as text, images, tables, graphs, etc. Further, when the output device is an audio output device, the audio output device converts an audio signal composed of reproduced voice data or acoustic data into an analog signal and outputs it aurally.

[0217] Note that in the example shown in FIG. 29, at least two control units connected via the communication network 7010 may be integrated as one control unit. Alternatively, each control unit may be composed of a plurality of control units. Further, the vehicle control system 7000 may include another control unit not shown in the figure. Also, in the above description, part or all of the functions performed by any one of the control units may be assigned to other control units. That is, as long as information is transmitted and received via the communication network 7010, predetermined arithmetic processing may be performed by any one of the control units. Similarly, a sensor or device connected to any one of the control units may be connected to other control units, and a plurality of control units may transmit and receive detection information to and from each other via the communication network 7010.

[0218] In the vehicle control system 7000 described above, the fish-eye lens and the imaging device of the present disclosure can be applied to the imaging unit 7410 and the imaging units 7910, 7912, 7914, 7916, 7918.

[0219] [5.2 Second application example] The technology according to the present disclosure may be applied to an endoscopic surgery system.

[0220] FIG. 31 is a diagram showing an example of a schematic configuration of an endoscopic surgery system 5000 to which the technology according to the present disclosure can be applied. In FIG. 31, a state in which an operator (doctor) 5067 is performing surgery on a patient 5071 on a patient bed 5069 using the endoscopic surgery system 5000 is illustrated. As shown, the endoscopic surgery system 5000 includes an endoscope 5001, other surgical instruments 5017, a support arm device 5027 that supports the endoscope 5001, and a cart 5037 on which various devices for endoscopic surgery are mounted.

[0221] In endoscopic surgery, instead of cutting open the abdominal wall, a plurality of cylindrical perforating instruments called trocars 5025a to 5025d are punctured into the abdominal wall. Then, from the trocars 5025a to 5025d, the lens barrel 5003 of the endoscope 5001 and other surgical instruments 5017 are inserted into the body cavity of the patient 5071. In the illustrated example, as other surgical instruments 5017, a pneumoperitoneum tube 5019, an energy treatment instrument 5021, and forceps 5023 are inserted into the body cavity of the patient 5071. The energy treatment instrument 5021 is a treatment instrument that performs tissue incision and dissection or blood vessel sealing, etc. by high-frequency current or ultrasonic vibration. However, the illustrated surgical instruments 5017 are merely examples, and as the surgical instruments 5017, for example, various surgical instruments generally used in endoscopic surgery, such as forceps and retractors, may be used.

[0222] An image of the surgical site inside the patient 5071's body cavity taken by the endoscope 5001 is displayed on the display device 5041. While viewing the image of the surgical site displayed on the display device 5041 in real time, the surgeon 5067 performs a procedure such as excising the affected part using the energy treatment instrument 5021 and the forceps 5023. Although not shown in the figure, the pneumoperitoneum tube 5019, the energy treatment instrument 5021, and the forceps 5023 are supported by the surgeon 5067 or an assistant during the operation.

[0223] (Support arm device) The support arm device 5027 includes an arm portion 5031 extending from the base portion 5029. In the illustrated example, the arm portion 5031 is composed of joint portions 5033a, 5033b, 5033c, and links 5035a, 5035b, and is driven by control from the arm control device 5045. The endoscope 5001 is supported by the arm portion 5031, and its position and posture are controlled. Thereby, stable positioning of the endoscope 5001 can be achieved.

[0224] (Endoscope) The endoscope 5001 is composed of a lens barrel 5003 whose region of a predetermined length from the tip is inserted into the body cavity of the patient 5071, and a camera head 5005 connected to the proximal end of the lens barrel 5003. In the illustrated example, the endoscope 5001 configured as a so-called rigid endoscope having a rigid lens barrel 5003 is shown, but the endoscope 5001 may be configured as a so-called flexible endoscope having a flexible lens barrel 5003.

[0225] An opening into which an objective lens is fitted is provided at the tip of the lens barrel 5003. A light source device 5043 is connected to the endoscope 5001, and the light generated by the light source device 5043 is guided to the tip of the lens barrel through a light guide extending inside the lens barrel 5003 and irradiated toward the observation target inside the body cavity of the patient 5071 through the objective lens. Note that the endoscope 5001 may be a direct-view endoscope, or may be an oblique-view endoscope or a side-view endoscope.

[0226] Inside the camera head 5005, an optical system and an imaging element are provided, and the reflected light (observation light) from the observation target is condensed onto the imaging element by the optical system. The observation light is photoelectrically converted by the imaging element, and an electrical signal corresponding to the observation light, that is, an image signal corresponding to the observation image, is generated. The image signal is transmitted as RAW data to a camera control unit (CCU) 5039. Note that the camera head 5005 is equipped with a function to adjust the magnification and focal length by appropriately driving its optical system.

[0227] Note that, for example, in order to support stereoscopic vision (3D display) or the like, a plurality of imaging elements may be provided in the camera head 5005. In this case, inside the lens barrel 5003, a plurality of relay optical systems are provided for guiding the observation light to each of the plurality of imaging elements.

[0228] (Various devices mounted on the cart) The CCU 5039 is composed of a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), etc., and comprehensively controls the operations of the endoscope 5001 and the display device 5041. Specifically, the CCU 5039 performs various image processes for displaying an image based on the image signal, such as development processing (demosaicing processing), on the image signal received from the camera head 5005. The CCU 5039 provides the image signal subjected to the image process to the display device 5041. In addition, the CCU 5039 transmits a control signal to the camera head 5005 and controls its driving. The control signal may include information regarding imaging conditions such as magnification and focal length.

[0229] The display device 5041 displays an image based on an image signal that has been subjected to image processing by the CCU 5039 under the control of the CCU 5039. When the endoscope 5001 is compatible with high-resolution imaging such as 4K (horizontal pixel count 3840 × vertical pixel count 2160) or 8K (horizontal pixel count 7680 × vertical pixel count 4320), and / or when it is compatible with 3D display, as the display device 5041, a device capable of high-resolution display and / or a device capable of 3D display can be used correspondingly. When it is compatible with high-resolution imaging such as 4K or 8K, using a display device 5041 with a size of 55 inches or more can provide a greater sense of immersion. Also, depending on the application, a plurality of display devices 5041 with different resolutions and sizes may be provided.

[0230] The light source device 5043 is composed of a light source such as an LED (light emitting diode), and supplies irradiation light for photographing the surgical site to the endoscope 5001.

[0231] The arm control device 5045 is composed of a processor such as a CPU, and by operating according to a predetermined program, controls the drive of the arm portion 5031 of the support arm device 5027 according to a predetermined control method.

[0232] The input device 5047 is an input interface for the endoscope surgical system 5000. The user can input various information and instruction inputs to the endoscope surgical system 5000 via the input device 5047. For example, the user inputs various information related to the surgery, such as the patient's physical information and information about the surgical procedure, via the input device 5047. Also, for example, the user inputs an instruction to drive the arm portion 5031, an instruction to change imaging conditions (type of irradiation light, magnification, focal length, etc.) by the endoscope 5001, an instruction to drive the energy treatment tool 5021, etc. via the input device 5047.

[0233] The type of the input device 5047 is not limited, and the input device 5047 may be various known input devices. As the input device 5047, for example, a mouse, a keyboard, a touch panel, a switch, a foot switch 5057 and / or a lever, etc. may be applied. When a touch panel is used as the input device 5047, the touch panel may be provided on the display surface of the display device 5041.

[0234] Alternatively, the input device 5047 is a device worn by a user, such as, for example, a glasses-type wearable device or an HMD (Head Mounted Display), and various inputs are performed according to the gestures and gazes of the user detected by these devices. Further, the input device 5047 includes a camera capable of detecting the movement of the user, and various inputs are performed according to the gestures and gazes of the user detected from the video captured by the camera. Furthermore, the input device 5047 includes a microphone capable of picking up the voice of the user, and various inputs are performed by voice through the microphone. In this way, since the input device 5047 is configured to be able to input various information in a non-contact manner, in particular, a user belonging to the clean area (for example, the surgeon 5067) can operate the equipment belonging to the unclean area in a non-contact manner. Also, since the user can operate the equipment without leaving their hands from the surgical instruments they are holding, the convenience of the user is improved.

[0235] The treatment instrument control device 5049 controls the drive of the energy treatment instrument 5021 for cauterizing, incising tissues or sealing blood vessels, etc. The pneumoperitoneum device 5051 sends gas into the body cavity of the patient 5071 through the pneumoperitoneum tube 5019 in order to expand the body cavity of the patient for the purpose of securing the visual field by the endoscope 5001 and securing the working space for the surgeon. The recorder 5053 is a device capable of recording various information related to the surgery. The printer 5055 is a device capable of printing various information related to the surgery in various forms such as text, images or graphs, etc.

[0236] Hereinafter, the particularly characteristic configuration in the endoscope surgery system 5000 will be described in more detail.

[0237] (Support arm device) The support arm device 5027 includes a base portion 5029 that is a base, and an arm portion 5031 that extends from the base portion 5029. In the illustrated example, the arm portion 5031 is composed of a plurality of joint portions 5033a, 5033b, 5033c and a plurality of links 5035a, 5035b that are connected by the joint portion 5033b. However, in FIG. 31, for simplicity, the configuration of the arm portion 5031 is illustrated in a simplified manner. In reality, the shapes, numbers, and arrangements of the joint portions 5033a to 5033c and the links 5035a, 5035b, and the directions of the rotation axes of the joint portions 5033a to 5033c can be appropriately set so that the arm portion 5031 has a desired degree of freedom. For example, the arm portion 5031 can be preferably configured to have a degree of freedom of 6 or more. Thereby, since the endoscope 5001 can be freely moved within the movable range of the arm portion 5031, the lens barrel 5003 of the endoscope 5001 can be inserted into the body cavity of the patient 5071 from a desired direction.

[0238] Actuators are provided on the joint portions 5033a to 5033c, and the joint portions 5033a to 5033c are configured to be rotatable about a predetermined rotation axis by driving of the actuators. By controlling the driving of the actuators by the arm control device 5045, the rotation angles of the respective joint portions 5033a to 5033c are controlled, and the driving of the arm portion 5031 is controlled. Thereby, control of the position and posture of the endoscope 5001 can be realized. At this time, the arm control device 5045 can control the driving of the arm portion 5031 by various known control methods such as force control or position control.

[0239] For example, an operator 5067 may perform appropriate operation inputs via an input device 5047 (including a foot switch 5057). Accordingly, the driving of the arm unit 5031 is appropriately controlled by the arm control device 5045 in response to the operation input, and the position and orientation of the endoscope 5001 may be controlled. By this control, after moving the endoscope 5001 at the tip of the arm unit 5031 from an arbitrary position to an arbitrary position, it can be fixedly supported at the moved position. Note that the arm unit 5031 may be operated in a so-called master-slave system. In this case, the arm unit 5031 can be remotely operated by a user via an input device 5047 installed at a location away from the operating room.

[0240] Also, when force control is applied, the arm control device 5045 may perform so-called power assist control in which it receives an external force from the user and drives the actuators of the respective joint portions 5033a to 5033c so that the arm unit 5031 smoothly moves following the external force. Thereby, when the user moves the arm unit 5031 while directly touching the arm unit 5031, the arm unit 5031 can be moved with a relatively small force. Therefore, it becomes possible to move the endoscope 5001 more intuitively and with a simpler operation, improving the convenience for the user.

[0241] Here, generally, in endoscopic surgery, the endoscope 5001 has been supported by a doctor called a scopist. On the other hand, by using the support arm device 5027, it becomes possible to more reliably fix the position of the endoscope 5001 without relying on human hands. Therefore, an image of the surgical site can be stably obtained, and the surgery can be performed smoothly.

[0242] Note that the arm control device 5045 does not necessarily have to be provided on the cart 5037. Also, the arm control device 5045 does not necessarily have to be a single device. For example, the arm control device 5045 may be provided respectively at each joint portion 5033a to 5033c of the arm portion 5031 of the support arm device 5027, and the drive control of the arm portion 5031 may be realized by a plurality of arm control devices 5045 cooperating with each other.

[0243] (Light source device) The light source device 5043 supplies irradiation light when photographing the surgical site with the endoscope 5001. The light source device 5043 is composed of, for example, a white light source constituted by an LED, a laser light source, or a combination thereof. At this time, when the white light source is constituted by a combination of RGB laser light sources, since the output intensity and output timing of each color (each wavelength) can be controlled with high precision, the white balance of the captured image can be adjusted in the light source device 5043. Also, in this case, the laser light from each of the RGB laser light sources is irradiated to the observation target in a time-division manner, and by controlling the driving of the imaging element of the camera head 5005 in synchronization with the irradiation timing, it is also possible to capture images corresponding to each of RGB in a time-division manner. According to this method, a color image can be obtained without providing a color filter on the imaging element.

[0244] Also, the drive of the light source device 5043 may be controlled so as to change the intensity of the output light at predetermined time intervals. By controlling the driving of the imaging element of the camera head 5005 in synchronization with the timing of the change in the intensity of the light and acquiring images in a time-division manner and synthesizing the images, it is possible to generate a so-called high-dynamic range image without black crushing and white blooming.

[0245] In addition, the light source device 5043 may be configured to supply light in a predetermined wavelength band corresponding to special light observation. In special light observation, for example, by utilizing the wavelength dependence of light absorption in body tissues and irradiating narrow-band light as compared with the irradiation light (i.e., white light) during normal observation, so-called narrow-band imaging is performed to capture a predetermined tissue such as blood vessels in the mucosal surface layer with high contrast. Alternatively, in special light observation, fluorescence observation may be performed to obtain an image by fluorescence generated by irradiating excitation light. In fluorescence observation, excitation light is irradiated onto body tissues to observe the fluorescence from the body tissues (autofluorescence observation), or a reagent such as indocyanine green (ICG) is locally injected into the body tissues and excitation light corresponding to the fluorescence wavelength of the reagent is irradiated onto the body tissues to obtain a fluorescence image. The light source device 5043 may be configured to supply narrow-band light and / or excitation light corresponding to such special light observation.

[0246] (Camera head and CCU) Referring to FIG. 32, the functions of the camera head 5005 and the CCU 5039 of the endoscope 5001 will be described in more detail. FIG. 32 is a block diagram showing an example of the functional configuration of the camera head 5005 and the CCU 5039 shown in FIG. 31.

[0247] Referring to FIG. 32, the camera head 5005 includes, as its functions, a lens unit 5007, an imaging unit 5009, a driving unit 5011, a communication unit 5013, and a camera head control unit 5015. In addition, the CCU 5039 includes, as its functions, a communication unit 5059, an image processing unit 5061, and a control unit 5063. The camera head 5005 and the CCU 5039 are connected to be communicable bidirectionally by a transmission cable 5065.

[0248] First, the functional configuration of the camera head 5005 will be described. The lens unit 5007 is an optical system provided at the connection part with the lens barrel 5003. The observation light taken in from the tip of the lens barrel 5003 is guided to the camera head 5005 and enters the lens unit 5007. The lens unit 5007 is composed of a combination of a plurality of lenses including a zoom lens and a focus lens. The optical characteristics of the lens unit 5007 are adjusted so as to condense the observation light on the light receiving surface of the imaging element of the imaging unit 5009. Also, the zoom lens and the focus lens are configured such that their positions on the optical axis can be moved for adjusting the magnification and focus of the captured image.

[0249] The imaging unit 5009 is composed of an imaging element and is arranged at the subsequent stage of the lens unit 5007. The observation light that has passed through the lens unit 5007 is condensed on the light receiving surface of the imaging element, and an image signal corresponding to the observation image is generated by photoelectric conversion. The image signal generated by the imaging unit 5009 is provided to the communication unit 5013.

[0250] As the imaging element constituting the imaging unit 5009, for example, a CMOS (Complementary Metal Oxide Semiconductor) type image sensor having a Bayer array and capable of color photography is used. Note that, as the imaging element, for example, one capable of corresponding to the shooting of an image with a resolution of 4K or higher may be used. By obtaining a high-resolution image of the surgical site, the surgeon 5067 can grasp the state of the surgical site in more detail and make the surgery proceed more smoothly.

[0251] Also, the imaging element constituting the imaging unit 5009 is configured to have a pair of imaging elements for respectively obtaining right-eye and left-eye image signals corresponding to 3D display. By performing 3D display, the surgeon 5067 can more accurately grasp the depth of the biological tissue at the surgical site. Note that when the imaging unit 5009 is configured in a multi-plate type, a plurality of systems of the lens unit 5007 are also provided corresponding to each imaging element.

[0252] Further, the imaging unit 5009 does not necessarily have to be provided in the camera head 5005. For example, the imaging unit 5009 may be provided inside the lens barrel 5003, immediately behind the objective lens.

[0253] The drive unit 5011 is composed of an actuator, and under the control from the camera head control unit 5015, moves the zoom lens and the focus lens of the lens unit 5007 along the optical axis by a predetermined distance. Thereby, the magnification and focus of the captured image by the imaging unit 5009 can be appropriately adjusted.

[0254] The communication unit 5013 is composed of a communication device for transmitting and receiving various types of information to and from the CCU 5039. The communication unit 5013 transmits the image signal obtained from the imaging unit 5009 as RAW data to the CCU 5039 via the transmission cable 5065. At this time, in order to display the captured image of the surgical site with low latency, it is preferable that the image signal be transmitted by optical communication. During the surgery, since the surgeon 5067 performs the surgery while observing the state of the affected area from the captured image, for a safer and more reliable surgery, it is required that the moving image of the surgical site be displayed in real time as much as possible. When optical communication is performed, the communication unit 5013 is provided with an optoelectronic conversion module that converts an electrical signal into an optical signal. The image signal is converted into an optical signal by the optoelectronic conversion module and then transmitted to the CCU 5039 via the transmission cable 5065.

[0255] In addition, the communication unit 5013 receives, from the CCU 5039, a control signal for controlling the drive of the camera head 5005. The control signal includes information related to imaging conditions, such as information specifying the frame rate of the captured image, information specifying the exposure value during imaging, and / or information specifying the magnification and focus of the captured image. The communication unit 5013 provides the received control signal to the camera head control unit 5015. Note that the control signal from the CCU 5039 may also be transmitted by optical communication. In this case, the communication unit 5013 is provided with an optoelectronic conversion module that converts an optical signal into an electrical signal, and the control signal is converted into an electrical signal by the optoelectronic conversion module and then provided to the camera head control unit 5015.

[0256] Note that the imaging conditions such as the frame rate, exposure value, magnification, and focus are automatically set by the control unit 5063 of the CCU 5039 based on the acquired image signal. That is, so-called AE (Auto Exposure) function, AF (Auto Focus) function, and AWB (Auto White Balance) function are installed in the endoscope 5001.

[0257] The camera head control unit 5015 controls the drive of the camera head 5005 based on the control signal from the CCU 5039 received via the communication unit 5013. For example, the camera head control unit 5015 controls the drive of the imaging element of the imaging unit 5009 based on information specifying the frame rate of the captured image and / or information specifying the exposure during imaging. Also, for example, the camera head control unit 5015 appropriately moves the zoom lens and the focus lens of the lens unit 5007 via the drive unit 5011 based on information specifying the magnification and focus of the captured image. The camera head control unit 5015 may further have a function of storing information for identifying the lens barrel 5003 and the camera head 5005.

[0258] Note that, by arranging components such as the lens unit 5007 and the imaging unit 5009 in a sealed structure with high airtightness and waterproofness, the camera head 5005 can be made resistant to autoclave sterilization treatment.

[0259] Next, the functional configuration of the CCU 5039 will be described. The communication unit 5059 is constituted by a communication device for transmitting and receiving various kinds of information to and from the camera head 5005. The communication unit 5059 receives an image signal transmitted from the camera head 5005 via the transmission cable 5065. At this time, as described above, the image signal can preferably be transmitted by optical communication. In this case, corresponding to the optical communication, the communication unit 5059 is provided with a photoelectric conversion module for converting an optical signal into an electrical signal. The communication unit 5059 provides the image signal converted into an electrical signal to the image processing unit 5061.

[0260] Also, the communication unit 5059 transmits a control signal for controlling the drive of the camera head 5005 to the camera head 5005. The control signal may also be transmitted by optical communication.

[0261] The image processing unit 5061 performs various kinds of image processing on the image signal which is RAW data transmitted from the camera head 5005. Such image processing includes, for example, development processing, high image quality processing (band emphasis processing, super resolution processing, NR (Noise reduction) processing and / or shake correction processing, etc.), and / or enlargement processing (electronic zoom processing), etc., various known signal processes. Also, the image processing unit 5061 performs detection processing on the image signal for performing AE, AF, and AWB.

[0262] The image processing unit 5061 is constituted by a processor such as a CPU or a GPU, and by the processor operating according to a predetermined program, the above-described image processing and detection processing can be performed. Note that when the image processing unit 5061 is constituted by a plurality of GPUs, the image processing unit 5061 appropriately divides information related to the image signal, and performs image processing in parallel by these plurality of GPUs.

[0263] The control unit 5063 performs various controls related to imaging of the surgical site by the endoscope 5001 and display of the captured image. For example, the control unit 5063 generates a control signal for controlling the drive of the camera head 5005. At this time, if the imaging conditions are input by the user, the control unit 5063 generates a control signal based on the input by the user. Alternatively, when the endoscope 5001 is equipped with an AE function, an AF function, and an AWB function, the control unit 5063 appropriately calculates an optimal exposure value, focal length, and white balance according to the result of the detection process by the image processing unit 5061, and generates a control signal.

[0264] In addition, the control unit 5063 causes the display device 5041 to display an image of the surgical site based on the image signal that has been subjected to image processing by the image processing unit 5061. At this time, the control unit 5063 recognizes various objects in the surgical site image using various image recognition techniques. For example, the control unit 5063 can recognize surgical instruments such as forceps, specific biological sites, bleeding, mist during use of the energy treatment device 5021, etc. by detecting the shape, color, etc. of the edges of the objects included in the surgical site image. When the control unit 5063 causes the display device 5041 to display an image of the surgical site, it uses the recognition result to superimpose and display various surgical support information on the image of the surgical site. By superimposing and displaying the surgical support information and presenting it to the surgeon 5067, it becomes possible to proceed with the surgery more safely and reliably.

[0265] The transmission cable 5065 connecting the camera head 5005 and the CCU 5039 is an electrical signal cable corresponding to electrical signal communication, an optical fiber corresponding to optical communication, or a composite cable thereof.

[0266] Here, in the illustrated example, communication was performed wired using the transmission cable 5065, but communication between the camera head 5005 and the CCU 5039 may be performed wirelessly. When communication between the two is performed wirelessly, it is not necessary to lay the transmission cable 5065 in the operating room, so the situation where the movement of medical staff in the operating room is obstructed by the transmission cable 5065 can be resolved.

[0267] The above has described an example of the endoscopic surgery system 5000 to which the technology according to the present disclosure can be applied. Here, although the endoscopic surgery system 5000 has been described as an example, the system to which the technology according to the present disclosure can be applied is not limited to such an example. For example, the technology according to the present disclosure may be applied to a flexible endoscope system for examination or a microscope surgery system.

[0268] Among the configurations described above, the technology according to the present disclosure can be suitably applied to the camera head 5005. In particular, the fish-eye lens of the present disclosure can be suitably applied to the lens unit 5007 of the camera head 5005.

[0269] <6. Other Embodiments> The technology according to the present disclosure is not limited to the descriptions of the above embodiments and examples, and various modifications can be made.

[0270] For example, the shapes and numerical values of each part shown in the above embodiment and example are merely examples of the implementation of the present technology, and the technical scope of the present technology should not be limitedly interpreted by these.

[0271] Also, in the above embodiment and example, a configuration consisting of substantially three or five lens groups as a whole has been described, but a configuration consisting of four or six or more lens groups as a whole may also be used. Furthermore, a configuration further including a lens having substantially no refractive power may also be used.

[0272] Also, for example, the present technology can adopt the following configuration. According to the present technology having the following configuration, in a configuration including a first lens group, an intermediate group, and a rear group, the optimization of the configuration of each group is achieved, so that a fish-eye lens that is small, lightweight, has little change in the viewing angle during wobbling by the inner focusing method, and is suitable for video shooting, and an imaging device can be realized.

[0273] [1] In order from the object side toward the image plane side, a first lens group having refractive power and including a first lens and a second lens in order from the object side toward the image plane side, an intermediate group having refractive power and including at least the second lens group, and a rear group having refractive power are configured, when the object distance changes from infinity to a short distance, the first lens group and the rear group are fixed, and focusing is performed by moving at least the second lens group in the intermediate group in the optical axis direction, satisfying the following conditional expressions a fisheye lens. -1.06 < (fL1 / f) / (TTL / Y) < -0.44 ……(1) 0.19 < (R21 - R22) / (R21 + R22) < 1.05 ……(2) 0.16 < BF / TTL < 0.24 ……(3) 0.85 < Y / Y’ < 1.18 ……(4) However, fL1: the focal length of the first lens f: the focal length of the entire system TTL: the distance on the optical axis from the vertex of the object-side surface of the first lens to the image plane Y: the maximum Half image height at the angle of view R21: the radius of curvature of the object-side lens surface of the second lens R22: the radius of curvature of the image-plane-side lens surface of the second lens BF: the distance on the optical axis from the most image-plane-side lens surface to the image plane Y’: the maximum Half image height at the angle of view θmax calculated by the equal solid angle projection method (Y’ = 2fsin(θmax / 2)) is defined as. [2] satisfying the following conditional expressions the fisheye lens according to [1] above. 0.34 < (R11 - R12) / (R11 + R12) < 0.63……(5) However, R11: Radius of curvature of the lens surface on the object side of the first lens R12: Radius of curvature of the lens surface on the image side of the first lens Let it be so. [3] Satisfy the following conditional expression The fisheye lens according to the above [1] or [2]. 1.64 < nL1 < 1.93 ……(6) However, nL1: Refractive index of the first lens Let it be so. [4] Satisfy the following conditional expression The fisheye lens according to any one of the above [1] to [3]. 3.0 < |f2| / f < 19.0 ……(7) However, f: Focal length of the entire system f2: Focal length of the second lens group Let it be so. [5] Have an aperture stop within the first lens group The fisheye lens according to any one of the above [1] to [4]. [6] Have an aperture stop within the intermediate group The fisheye lens according to any one of the above [1] to [4]. [7] Include a fisheye lens and an image sensor that outputs an imaging signal corresponding to the optical image formed by the fisheye lens, The fisheye lens is In order from the object side to the image side, A first lens group having a refractive power and including a first lens and a second lens in order from the object side to the image side, An intermediate group having a refractive power and including at least a second lens group, A rear group having a refractive power And is composed of When the object distance changes from infinity to a short distance, the first lens group and the rear group are fixed, and at least the second lens group in the intermediate group moves in the optical axis direction to perform focusing. An imaging device that satisfies the following conditional expressions . -1.06 < (fL1 / f) / (TTL / Y) < -0.44......(1) 0.19 < (R21 - R22) / (R21 + R22) < 1.05......(2) 0.16 < BF / TTL < 0.24......(3) 0.85 < Y / Y’ < 1.18......(4) However fL1: Focal length of the first lens f: Focal length of the entire system TTL: Distance on the optical axis from the vertex of the object-side surface of the first lens to the image plane Y: Maximum Half Image height at the angle of view R21: Curvature radius of the object-side lens surface of the second lens R22: Curvature radius of the image-side lens surface of the second lens BF: Distance on the optical axis from the lens surface closest to the image plane to the image plane Y’: Maximum Half Image height at the maximum angle of view θmax calculated by the equal solid angle projection method (Y’ = 2fsin(θmax / 2)) shall be used [8] The fisheye lens according to any one of [1] to [6] above, further comprising a lens having substantially no refractive power . [9] The fisheye lens further comprises a lens having substantially no refractive power The imaging device according to [7] above

[0274] This application claims priority based on Japanese Patent Application No. 2020-118110 filed with the Japan Patent Office on July 8, 2020, and incorporates all the contents of this application by reference

[0275] Those skilled in the art can conceive of various modifications, combinations, sub - combinations, and changes according to design requirements and other factors, and it is understood that they are included within the scope of the appended claims and their equivalents.

Claims

1. In order from the object side toward the image plane side, a first lens group having a positive refractive power and including a first lens and a second lens in order from the object side toward the image plane side, an intermediate group having a refractive power and including at least the second lens group, and a rear group having a refractive power are configured such that when the object distance changes from infinity to a short distance, the first lens group and the rear group are fixed, the distance between the first lens group and the intermediate group, and the distance between the intermediate group and the rear group change, and focusing is performed by moving at least the second lens group in the intermediate group in the optical axis direction, satisfying the following conditional expressions a fisheye lens. −1.06 < (fL1 / f) / (TTL / Y) < −0.44 ……(1) 0.19 < (R21 − R22) / (R21 + R22) < 1.05 ……(2) 0.16 < BF / TTL < 0.24 ……(3) 0.85 < Y / Y’ < 1.18 ……(4) However, fL1: the focal length of the first lens f: the focal length of the entire system TTL: the distance on the optical axis from the vertex of the object-side surface of the first lens to the image plane Y: the image height at the maximum semi-field angle R21: the radius of curvature of the object-side lens surface of the second lens R22: the radius of curvature of the image-plane side lens surface of the second lens BF: the distance on the optical axis from the most image-plane side lens surface to the image plane Y’: the image height at the maximum semi-field angle θmax calculated by the equal solid angle projection method (Y’ = 2f sin(θmax / 2)) is defined as such.

2. satisfying the following conditional expressions the fisheye lens according to Claim 1. 0.34 < (R11 − R12) / (R11 + R12) < 0.63……(5) However, R11: the radius of curvature of the object-side lens surface of the first lens R12: the radius of curvature of the image-plane side lens surface of the first lens is defined as such.

3. satisfying the following conditional expressions the fisheye lens according to Claim 1. 1.64 < nL1 < 1.93 ……(6) However, nL1: the refractive index of the first lens is defined as such.

4. satisfying the following conditional expressions the fisheye lens according to Claim 1. 3.0 < |f2| / f < 19.0 ……(7) However, f: the focal length of the entire system f2: the focal length of the second lens group is defined as such.

5. having an aperture stop within the first lens group the fisheye lens according to Claim 1.

6. The first lens group has five or more lenses the fisheye lens according to Claim 1.

7. including a fisheye lens and an imaging element that outputs an imaging signal corresponding to the optical image formed by the fisheye lens The fish-eye lens is in order from the object side toward the image plane side, a first lens group having a positive refractive power and including a first lens and a second lens in order from the object side toward the image plane side, an intermediate group having a refractive power and including at least the second lens group, and a rear group having a refractive power and is configured such that when the object distance changes from infinity to a short distance, the first lens group and the rear group are fixed, the distance between the first lens group and the intermediate group and the distance between the intermediate group and the rear group change, and focusing is performed by moving at least the second lens group in the optical axis direction in the intermediate group, satisfying the following conditional expressions imaging device. -1.06 < (fL1 / f) / (TTL / Y) < -0.44... (1) 0.19 < (R21 - R22) / (R21 + R22) < 1.05... (2) 0.16 < BF / TTL < 0.24... (3) 0.85 < Y / Y' < 1.18... (4) However, fL1: focal length of the first lens f: focal length of the entire system TTL: distance on the optical axis from the vertex of the object-side surface of the first lens to the image plane Y: image height at the maximum semi-field angle R21: radius of curvature of the object-side lens surface of the second lens R22: radius of curvature of the image-plane side lens surface of the second lens BF: distance on the optical axis from the most image-plane side lens surface to the image plane Y': image height at the maximum semi-field angle θmax calculated by the equal solid angle projection method (Y' = 2f sin(θmax / 2)) is defined as such.

Images