Imaging optical system and imaging device

Abstract

An imaging optical system according to the present disclosure comprises a first lens group, a second lens group, a third lens group, and at least one lens group disposed closer to the image plane side than the third lens group. During focusing, the second lens group and the third lens group, or the second lens group and said one lens group disposed closer to the image plane side than the third lens group move in an optical axis direction. The imaging optical system has, in the first lens group, a vibration-proof lens group that performs blur correction by moving in a direction perpendicular to an optical axis, and satisfies conditional expression (1). f is the focal length of the entire system when focused at infinity, and f2 is the focal length of the second lens group.　(1): f2 / f<0.7

Description

Imaging optical system and imaging device

[0001] This disclosure relates to an imaging optical system and an imaging apparatus.

[0002] In recent years, imaging devices such as digital cameras have seen an increase in the size and pixel count of their image sensors, requiring high optical performance from the imaging lenses used in these devices. At the same time, with the advancement of shorter flange back distances in mirrorless cameras and other devices, there is a demand for smaller optical systems, faster focusing with minimal angle of view fluctuations, and the ability to capture images at higher magnifications. Against this backdrop, various optical systems have been proposed (Patent Documents 1 and 2).

[0003] Japanese Patent Publication No. 2023-134075 Japanese Patent Publication No. 2010-145830

[0004] The optical systems proposed in Patent Documents 1 and 2 are insufficient in terms of optical performance and miniaturization / lightweight design. In particular, it is difficult to achieve miniaturization and lightweight design when trying to create an optical system that has high optical performance during image stabilization while maintaining sufficient distance from the subject during high-magnification shooting.

[0005] Therefore, it is desirable to provide a small, lightweight imaging optical system that has good optical performance across the entire shooting distance range, and an imaging device equipped with such an imaging optical system.

[0006] A first imaging optical system according to one embodiment of the present disclosure comprises, in order from the object side toward the image plane side, a first lens group, a second lens group having positive refractive power, a third lens group, and at least one lens group positioned closer to the image plane than the third lens group. During focusing, the second lens group and the third lens group, or the second lens group and the one lens group positioned closer to the image plane than the third lens group, move in the optical axis direction, and the first lens group has an image-stabilizing lens group that corrects blur by moving perpendicular to the optical axis, satisfying the following condition: f2 / f < 0.7 ... (1) where f: focal length of the entire system when focused at infinity, and f2: focal length of the second lens group.

[0007] A second imaging optical system according to one embodiment of the present disclosure comprises, in order from the object side toward the image plane side, at least a first lens group, a second lens group having positive refractive power, a third lens group, and a positive lens group positioned closer to the image plane than the third lens group, wherein during focusing, the second lens group and the positive lens group positioned closer to the image plane than the third lens group move in the optical axis direction, satisfying the following conditions: f² / f < 0.7 ……(1) -3.0 < f / fl < -0.5 ……(9) where, f: focal length of the entire system when focused at infinity f²: focal length of the second lens group fl: focal length of the lens group closest to the image plane.

[0008] An imaging device according to one embodiment of the present disclosure includes an imaging optical system and an image sensor that outputs an imaging signal corresponding to an optical image formed by the imaging optical system, wherein the imaging optical system is configured by the first or second imaging optical system according to the above embodiment of the present disclosure.

[0009] In one embodiment of the imaging optical system or imaging device according to this disclosure, the configuration of each lens group is optimized to have good optical performance across the entire shooting distance and to enable miniaturization and weight reduction.

[0010] Figure 1 is a lens cross-sectional view showing a first configuration example (Example 1) of an imaging optical system according to one embodiment of the present disclosure. Figure 2 is an aberration diagram showing the longitudinal aberration of the imaging optical system according to Example 1 when it is in focus at infinity. Figure 3 is an aberration diagram showing the longitudinal aberration of the imaging optical system according to Example 1 when it is in focus at close range. Figure 4 is an aberration diagram showing the longitudinal aberration of the imaging optical system according to Example 1 when it is in focus at infinity and vibration is suppressed. Figure 5 is an aberration diagram showing the transverse aberration of the imaging optical system according to Example 1 when it is in focus at infinity. Figure 6 is an aberration diagram showing the transverse aberration of the imaging optical system according to Example 1 when it is in focus at close range. Figure 7 is an aberration diagram showing the transverse aberration of the imaging optical system according to Example 1 when it is in focus at infinity and vibration is suppressed. Figure 8 is a lens cross-sectional view showing a second configuration example (Example 2) of an imaging optical system according to one embodiment. Figure 9 is an aberration diagram showing the longitudinal aberration of the imaging optical system according to Example 2 when it is in focus at infinity. Figure 10 is an aberration diagram showing the longitudinal aberration of the imaging optical system according to Example 2 when it is in focus at close range. Figure 11 is an aberration diagram showing the longitudinal aberration of the imaging optical system according to Example 2 when vibration is suppressed and the system is in focus at infinity. Figure 12 is an aberration diagram showing the transverse aberration of the imaging optical system according to Example 2 when the system is in focus at infinity. Figure 13 is an aberration diagram showing the transverse aberration of the imaging optical system according to Example 2 when the system is in focus at close range. Figure 14 is an aberration diagram showing the transverse aberration of the imaging optical system according to Example 2 when vibration is suppressed and the system is in focus at infinity. Figure 15 is a lens cross-sectional view showing a third configuration example (Example 3) of the imaging optical system according to one embodiment. Figure 16 is an aberration diagram showing the longitudinal aberration of the imaging optical system according to Example 3 when the system is in focus at infinity. Figure 17 is an aberration diagram showing the longitudinal aberration of the imaging optical system according to Example 3 when the system is in focus at close range. Figure 18 is an aberration diagram showing the longitudinal aberration of the imaging optical system according to Example 3 when vibration is suppressed and the system is in focus at infinity. Figure 19 is an aberration diagram showing the transverse aberration of the imaging optical system according to Example 3 when the system is in focus at infinity. Figure 20 is an aberration diagram showing the lateral aberration of the imaging optical system according to Embodiment 3 when it is in close focus. Figure 21 is an aberration diagram showing the lateral aberration of the imaging optical system according to Embodiment 3 when it is in infinity focus and vibration is suppressed. Figure 22 is a lens cross-sectional view showing a fourth configuration example (Embodiment 4) of the imaging optical system according to one embodiment. Figure 23 is an aberration diagram showing the longitudinal aberration of the imaging optical system according to Embodiment 4 when it is in infinity focus.Figure 24 is an aberration diagram showing the longitudinal aberration of the imaging optical system according to Example 4 when it is in close focus. Figure 25 is an aberration diagram showing the longitudinal aberration of the imaging optical system according to Example 4 when it is in infinity focus and vibration is suppressed. Figure 26 is an aberration diagram showing the transverse aberration of the imaging optical system according to Example 4 when it is in infinity focus. Figure 27 is an aberration diagram showing the transverse aberration of the imaging optical system according to Example 4 when it is in close focus. Figure 28 is an aberration diagram showing the transverse aberration of the imaging optical system according to Example 4 when it is in infinity focus and vibration is suppressed. Figure 29 is a lens cross-sectional view showing a fifth configuration example (Example 5) of the imaging optical system according to one embodiment. Figure 30 is an aberration diagram showing the longitudinal aberration of the imaging optical system according to Example 5 when it is in infinity focus. Figure 31 is an aberration diagram showing the longitudinal aberration of the imaging optical system according to Example 5 when it is in close focus. Figure 32 is an aberration diagram showing the longitudinal aberration of the imaging optical system according to Example 5 when it is in infinity focus and vibration is suppressed. Figure 33 is an aberration diagram showing the lateral aberration of the imaging optical system according to Example 5 when it is in focus at infinity. Figure 34 is an aberration diagram showing the lateral aberration of the imaging optical system according to Example 5 when it is in focus at close range. Figure 35 is an aberration diagram showing the lateral aberration of the imaging optical system according to Example 5 when it is in focus at infinity and vibration is suppressed. Figure 36 is a lens cross-sectional view showing a sixth configuration example (Example 6) of the imaging optical system according to one embodiment. Figure 37 is an aberration diagram showing the longitudinal aberration of the imaging optical system according to Example 6 when it is in focus at infinity. Figure 38 is an aberration diagram showing the longitudinal aberration of the imaging optical system according to Example 6 when it is in focus at close range. Figure 39 is an aberration diagram showing the longitudinal aberration of the imaging optical system according to Example 6 when it is in focus at infinity and vibration is suppressed. Figure 40 is an aberration diagram showing the lateral aberration of the imaging optical system according to Example 6 when it is in focus at infinity. Figure 41 is an aberration diagram showing the lateral aberration of the imaging optical system according to Example 6 when it is in focus at close range. Figure 42 is an aberration diagram showing the lateral aberration during vibration isolation in the infinity focus state of the imaging optical system according to Example 6. Figure 43 is a lens cross-sectional view showing a seventh configuration example (Example 7) of the imaging optical system according to one embodiment. Figure 44 is an aberration diagram showing the longitudinal aberration when the imaging optical system according to Example 7 is in focus at infinity. Figure 45 is an aberration diagram showing the longitudinal aberration when the imaging optical system according to Example 7 is in focus at close range. Figure 46 is an aberration diagram showing the longitudinal aberration during vibration isolation in the infinity focus state of the imaging optical system according to Example 7.Figure 47 is an aberration diagram showing the lateral aberration of the imaging optical system according to Example 7 when it is in focus at infinity. Figure 48 is an aberration diagram showing the lateral aberration of the imaging optical system according to Example 7 when it is in focus at close range. Figure 49 is an aberration diagram showing the lateral aberration of the imaging optical system according to Example 7 when it is in focus at infinity and vibration is suppressed. Figure 50 is a lens cross-sectional view showing an eighth configuration example (Example 8) of the imaging optical system according to one embodiment. Figure 51 is an aberration diagram showing the longitudinal aberration of the imaging optical system according to Example 8 when it is in focus at infinity. Figure 52 is an aberration diagram showing the longitudinal aberration of the imaging optical system according to Example 8 when it is in focus at close range. Figure 53 is an aberration diagram showing the longitudinal aberration of the imaging optical system according to Example 8 when it is in focus at infinity and vibration is suppressed. Figure 54 is an aberration diagram showing the lateral aberration of the imaging optical system according to Example 8 when it is in focus at infinity. Figure 55 is an aberration diagram showing the lateral aberration of the imaging optical system according to Example 8 when it is in focus at close range. Figure 56 is an aberration diagram showing the lateral aberration of the imaging optical system according to Example 8 when vibration is suppressed in the infinity focus state. Figure 57 is a lens cross-sectional view showing the ninth configuration example (Example 9) of the imaging optical system according to one embodiment. Figure 58 is an aberration diagram showing the longitudinal aberration of the imaging optical system according to Example 9 when it is in infinity focus. Figure 59 is an aberration diagram showing the longitudinal aberration of the imaging optical system according to Example 9 when it is in close focus. Figure 60 is an aberration diagram showing the longitudinal aberration of the imaging optical system according to Example 9 when vibration is suppressed in the infinity focus state. Figure 61 is an aberration diagram showing the lateral aberration of the imaging optical system according to Example 9 when it is in infinity focus. Figure 62 is an aberration diagram showing the lateral aberration of the imaging optical system according to Example 9 when it is in close focus. Figure 63 is an aberration diagram showing the lateral aberration of the imaging optical system according to Example 9 when vibration is suppressed in the infinity focus state. Figure 64 is a lens cross-sectional view showing the tenth configuration example (Example 10) of the imaging optical system according to one embodiment. Figure 65 is an aberration diagram showing the longitudinal aberration of the imaging optical system according to Example 10 when it is in focus at infinity. Figure 66 is an aberration diagram showing the longitudinal aberration of the imaging optical system according to Example 10 when it is in focus at close range. Figure 67 is an aberration diagram showing the longitudinal aberration of the imaging optical system according to Example 10 when it is in focus at infinity and vibration is suppressed. Figure 68 is an aberration diagram showing the transverse aberration of the imaging optical system according to Example 10 when it is in focus at infinity. Figure 69 is an aberration diagram showing the transverse aberration of the imaging optical system according to Example 10 when it is in focus at close range.Figure 70 is an aberration diagram showing the lateral aberration during vibration isolation in the infinity focus state of the imaging optical system according to Embodiment 10. Figure 71 is a block diagram showing an example configuration of an imaging device. Figure 72 is a block diagram showing an example of a schematic configuration of a vehicle control system. Figure 73 is an explanatory diagram showing an example of the installation position of the external information detection unit and the imaging unit. Figure 74 is a diagram showing an example of a schematic configuration of an endoscope system. Figure 75 is a block diagram showing an example of the functional configuration of the camera and CCU shown in Figure 74. Figure 76 is a diagram showing an example of a schematic configuration of a microsurgical system.

[0011] The embodiments of this disclosure will be described in detail below with reference to the drawings. The description will be in the following order: 0. Comparative Examples 1. Basic Configuration of the Optical System 2. Operation and Effects 3. Application Examples to Imaging Devices 4. Numerical Examples of the Optical System 5. Application Examples 6. Other Embodiments

[0012] <0. Comparative Example> The optical system proposed in Patent Document 1 (Japanese Patent Application Publication No. 2022-171857) has a structure that includes a first positive lens group with positive refractive power, and a first negative lens group and a second negative lens group with negative refractive power that move along the optical axis when focusing, thereby achieving a compact, lightweight, and fast autofocus system.

[0013] Furthermore, the optical system proposed in Patent Document 2 (Japanese Patent Application Publication No. 2010-145830) is composed of, in order from the object side to the image side, a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, a fourth lens group with positive refractive power, and a fifth lens group with negative refractive power. In this optical system, when focusing from an object distance of infinity to a close distance, the first, third, and fifth lens groups remain stationary, the second lens group moves toward the image side, and the fourth lens group moves toward the object side. In addition, in this optical system, the fifth lens group is composed of, in order from the object side to the image side, a fifth a lens group with negative refractive power and a fifth b lens group with positive refractive power, and the fifth a lens group moves so as to have a component perpendicular to the optical axis, thereby displacing the image formation position, and thus good optical performance is achieved in both the reference state and the vibration-damped state.

[0014] Patent Document 1 provides a compact and lightweight optical system capable of rapid autofocus, but the shooting distance is short relative to the close-up magnification, resulting in insufficient distance to the subject. Furthermore, attempting to effectively correct image blur leads to an enlarged optical system. In Patent Document 2, the 5a lens group moves to have a component perpendicular to the optical axis, thereby displacing the image formation position and enabling image blur correction. However, increasing the amount of image blur correction requires increasing the power of the 5a lens group, making aberration correction difficult. Therefore, ensuring good optical performance during image blur correction leads to an enlarged optical system, making miniaturization and weight reduction difficult. Thus, with the optical systems proposed in Patent Documents 1 and 2, it is difficult to achieve miniaturization and weight reduction when attempting to create an optical system that has high optical performance during blur correction while ensuring sufficient distance to the subject during high-magnification shooting.

[0015] Therefore, it is desirable to provide an imaging optical system that has good optical performance across the entire shooting distance range, allows for maintaining a sufficient distance from the subject during high-magnification shooting, and is compact and lightweight. It is also desirable to provide an imaging optical system that has high optical performance even during image stabilization.

[0016] <1. Basic Configuration of the Optical System> Figure 1 shows a first configuration example of an imaging optical system according to one embodiment of the present disclosure, and corresponds to the configuration of Example 1 described later. Figure 8 shows a second configuration example of an imaging optical system according to one embodiment, and corresponds to the configuration of Example 2 described later. Figure 15 shows a third configuration example of an imaging optical system according to one embodiment, and corresponds to the configuration of Example 3 described later. Figure 22 shows a fourth configuration example of an imaging optical system according to one embodiment, and corresponds to the configuration of Example 4 described later. Figure 29 shows a fifth configuration example of an imaging optical system according to one embodiment, and corresponds to the configuration of Example 5 described later. Figure 36 shows a sixth configuration example of an imaging optical system according to one embodiment, and corresponds to the configuration of Example 6 described later. Figure 43 shows a seventh configuration example of an imaging optical system according to one embodiment, and corresponds to the configuration of Example 7 described later. Figure 50 shows an eighth configuration example of an imaging optical system according to one embodiment, and corresponds to the configuration of Example 8 described later. Figure 57 shows a ninth configuration example of an imaging optical system according to one embodiment, and corresponds to the configuration of Example 9 described later. Figure 64 shows a tenth configuration example of an imaging optical system according to one embodiment, and corresponds to the configuration of Example 10 described later.

[0017] The imaging optical system and imaging device according to one embodiment relate to an imaging optical system that is optimal for, for example, digital still cameras and digital mirrorless cameras, and optical equipment having such an imaging optical system. In particular, it relates to a compact, lightweight imaging lens that is high-performance across the entire shooting distance and employs a group configuration that can perform good aberration correction and a focusing trajectory, and to an imaging device equipped with such an imaging lens.

[0018] In Figure 1, etc., Z1 indicates the optical axis. Between the imaging optical systems 1 to 10 according to the first to tenth configuration examples and the image plane, optical elements such as cover glass for protecting the image sensor may be arranged. In addition to cover glass, various optical filters such as low-pass filters and infrared cut filters may also be arranged as optical elements. When the imaging optical system according to one embodiment is applied to a digital still camera or video camera, the image plane of the imaging optical system corresponds to the image plane of an image sensor such as a CCD (Charge Coupled Devices) sensor or a CMOS (Complementary Metal Oxide Semiconductor) sensor. When the imaging optical system according to one embodiment is applied to a film camera, the image plane of the imaging optical system corresponds to the film plane.

[0019] Figure 1, etc., shows the lens configuration when the lens is focused at infinity. Also, in Figure 1, etc., the left side is the object side and the right side is the image plane side.

[0020] Hereinafter, the configuration of an imaging optical system according to one embodiment of this disclosure will be described in correspondence with the imaging optical systems 1 to 10 shown in Figure 1 and other examples as appropriate, but the technology of this disclosure is not limited to the illustrated configuration examples.

[0021] An imaging optical system according to one embodiment comprises, in order from the object side toward the image plane side, a first lens group G1, a second lens group G2 having positive refractive power, a third lens group G3, and at least one lens group positioned closer to the image plane than the third lens group G3. In the imaging optical system according to one embodiment, during focusing, the second lens group G2 and the third lens group G3, or the one lens group positioned closer to the image plane than the second lens group G2 and the third lens group G3, move parallel to the optical axis direction. The first lens group G1 includes an anti-vibration lens group G1a that corrects blur by moving perpendicular to the optical axis Z1.

[0022] In addition, among the imaging optical systems 1 to 10 described later in Examples 1 to 10, in the imaging optical system 4 according to Example 4, the second lens group G2 and the third lens group G3 move parallel to the optical axis direction during focusing. In the imaging optical systems according to the other examples, the second lens group G2 and the fourth lens group G4 move parallel to the optical axis direction during focusing.

[0023] In one embodiment of the imaging optical system, a lens group refers to a lens group that possesses refractive power and whose spacing between adjacent lens groups changes during focusing. A system composed solely of flat plates that do not possess refractive power is not defined as a lens group.

[0024] An imaging optical system according to one embodiment satisfies the following condition: f2 / f < 0.7 ... (1) where f: focal length of the entire system when focused at infinity f2: focal length of the second lens group G2.

[0025] Furthermore, the imaging optical system according to one embodiment may also satisfy predetermined conditional formulas and the like, which will be described later.

[0026] <2. Function and Effects> Next, the function and effects of an imaging optical system according to one embodiment of the present disclosure will be described. In addition, a more preferred configuration of the imaging optical system according to one embodiment of the present disclosure, and its function and effects will be described. Note that the effects described herein are merely illustrative and not limiting, and other effects may also exist.

[0027] According to one embodiment of the imaging optical system, the configuration of each lens group is optimized to have good optical performance across the entire shooting distance range and to enable miniaturization and weight reduction. This makes it possible to provide a compact and lightweight imaging optical system with good optical performance across the entire shooting distance range, and an imaging device equipped with such an imaging optical system.

[0028] According to one embodiment of the imaging optical system, it includes, in order from the object side, a first lens group G1, a second lens group G2 having positive refractive power, and a third lens group G3. During focusing, the second lens group G2 having positive refractive power and some lens groups from the third lens group G3 onward move in the direction of the optical axis. This allows for a high degree of freedom in aberration correction during focusing, enabling high optical performance across the entire shooting distance range while increasing the magnification. Furthermore, by including an anti-vibration lens group G1a within the first lens group G1 that corrects blur by moving perpendicular to the optical axis, high optical performance can be ensured even during blur correction.

[0029] Conditional equation (1) is defined to ensure both the maximum magnification of the optical system and miniaturization of the optical system, as well as the shooting distance during close-up photography. It is a conditional equation for appropriately setting the focal length of the second lens group G2 relative to the total focal length of the system when focused at infinity. If the upper limit of conditional equation (1) is exceeded, the positive refractive power of the second lens group G2 decreases, and the focusing stroke increases, making it difficult to achieve both the maximum magnification and miniaturization of the optical system. In addition, it becomes difficult to ensure the shooting distance during close-up photography.

[0030] Furthermore, by setting the upper limit to 0.6 in conditional equation (1), a greater effect can be obtained.

[0031] Furthermore, the imaging optical system according to one embodiment may satisfy the following condition (2): βm < -0.5 ……(2) where βm is the lateral magnification of the entire system at the shortest shooting distance.

[0032] Conditional equation (2) is defined to increase the magnification of the optical system and is a conditional equation for appropriately setting the lateral magnification of the entire system at the shortest focusing distance. If the upper limit of conditional equation (2) is exceeded, the magnification at the shortest focusing distance will be low, making it difficult to magnify the subject.

[0033] Furthermore, by setting the upper limit in conditional equation (2) to -0.6, a greater effect can be obtained, and by setting it to -0.8, an even greater effect can be obtained.

[0034] In addition, the imaging optical system according to an embodiment may satisfy the following conditional expression (3). 1.0 < f2 / l2 < 9.0 …… (3) However, f2: The focal length of the second lens group G2 l2: The stroke amount in the optical axis direction from infinity to the shortest shooting distance of the second lens group G2

[0035] The conditional expression (3) is defined for miniaturization of the optical system and ensuring the shooting distance at the shortest shooting distance, and is a conditional expression for appropriately setting the stroke amount in the optical axis direction during focusing from infinity to the shortest shooting distance of the second lens group G2 with respect to the focal length of the second lens group G2. If the upper limit value of the conditional expression (3) is exceeded, the positive refractive power of the second lens group G2 becomes weak, so it becomes difficult to make the principal point position of the entire optical system on the object side, and it becomes difficult to ensure the shooting distance at the shortest shooting distance. On the other hand, if the lower limit value of the conditional expression (3) is exceeded, the stroke in the optical axis direction during focusing of the second lens group G2 becomes long, and the miniaturization of the optical system is insufficient.

[0036] From the viewpoint of miniaturization of the optical system, a higher effect can be obtained by setting the upper limit value to 8.8 in the conditional expression (3), and an even higher effect can be obtained by setting it to 8.5. Also, from the viewpoint of miniaturization of the optical system, a higher effect can be obtained by setting the lower limit value to 1.1 in the conditional expression (3), and an even higher effect can be obtained by setting it to 1.2.

[0037] In addition, the imaging optical system according to an embodiment may satisfy the following conditional expression (4). 0.5 < |B1a| < 2.0 …… (4) However, B1a: The shake correction coefficient of the anti-shake lens group G1a in the infinity focus state, defined by the following formula B1a = β1a × (1 - βb) β1a: The lateral magnification of the anti-shake lens group G1a βb: The lateral magnification of the lens on the image plane side with respect to the anti-shake lens group G1a

[0038] Conditional expression (4) is defined for a high shake correction function and miniaturization of the optical system, and is a conditional expression for appropriately setting the shake correction coefficient of the anti-shake lens group G1a. If the upper limit value of conditional expression (4) is exceeded, the absolute value of the shake correction coefficient increases, which causes overcorrection and undercorrection of the shake correction function due to errors when moving in a direction perpendicular to the optical axis direction. On the other hand, if it is below the lower limit value of conditional expression (4), the absolute value of the shake correction coefficient becomes small, and the movement amount in the direction perpendicular to the optical axis direction for shake correction increases, making it difficult to miniaturize the optical system.

[0039] Note that by setting the upper limit value to 1.9 in conditional expression (4), higher effects can be obtained, and when it is set to 1.8, even higher effects can be obtained. Also, by setting the lower limit value to 0.60 in conditional expression (4), higher effects can be obtained, and when it is set to 0.7, even higher effects can be obtained.

[0040] Further, the imaging optical system according to an embodiment may satisfy the following conditional expression (5). 2.0 < |P2| < 5.0... (5) However, P2: The focus sensitivity of the second lens group G2 in the infinite focus state, defined by the following formula P2 = β2 ２ ×(1 - βc ２ ) β2: The lateral magnification of the second lens group G2 βc: The lateral magnification of the lens on the image plane side of the second lens group G2.

[0041] Conditional expression (5) defines the focus sensitivity of the second lens group G2 within a preferable range. If the upper limit value of conditional expression (5) is exceeded, the refractive power of the second lens group G2 increases, making it difficult to correct coma aberration. On the other hand, if it is below the lower limit value of conditional expression (5), the movement amount of the second lens group G2 during focusing increases, making it difficult to miniaturize the optical system.

[0042] Note that by setting the upper limit value to 4. |P2| < 5.0... (5) However, P2: The focus sensitivity of the second lens group G2 in the infinite focus state, defined by the following formula P2 = β2

[0043] Furthermore, the imaging optical system according to one embodiment may satisfy the following condition (6): |f2 / f1| < 0.5 ……(6) where f1 is the focal length of the first lens group G1 and f2 is the focal length of the second lens group G2.

[0044] Conditional equation (6) specifies a preferred range for the ratio of the focal length of the first lens group G1 to the focal length of the second lens group G2. If the upper limit of conditional equation (6) is exceeded, the refractive power of the first lens group G1 increases, making it difficult to correct aberrations during image stabilization by the image stabilization lens group G1a placed within the first lens group G1. The upper limit of conditional equation (6) can be set to 0.45, more preferably, and even more preferably to 0.4 or 0.35.

[0045] Furthermore, by setting the upper limit of condition (6) to 0.45, a higher effect can be obtained, and by setting it to 0.4, and even higher, an even higher effect can be obtained by setting it to 0.35.

[0046] Furthermore, the imaging optical system according to one embodiment may satisfy the following condition (7): 0.5 < |f1a / f| < 2.5 ……(7) where, f: focal length of the entire system when focused at infinity f1a: focal length of the vibration-damping lens group G1a.

[0047] Conditional equation (7) is defined to suppress aberrations in the optical system during image stabilization, and is a conditional equation for appropriately setting the focal length of the entire system when shooting at infinity with respect to the focal length of the image stabilization lens group G1a. If the upper limit of conditional equation (7) is exceeded, the refractive power of the image stabilization lens group G1a weakens, and the image stabilization coefficient becomes smaller, resulting in a larger shift amount for image stabilization, making it difficult to miniaturize the optical system. On the other hand, if the lower limit of conditional equation (7) is exceeded, the positive refractive power of the image stabilization lens group G1a becomes too strong, making it difficult to correct aberrations during image stabilization.

[0048] Furthermore, setting the upper limit of condition (7) to 2.4 will yield a higher effect, and setting it to 2.2 will yield an even higher effect. Also, setting the lower limit of condition (7) to 0.6 will yield a higher effect.

[0049] Furthermore, the imaging optical system according to one embodiment may satisfy the following condition (8): BF / f < 0.5 ... (8) where BF: distance on the optical axis from the lens surface closest to the image plane to the image plane when in focus at infinity (back focus) f: focal length of the entire system when in focus at infinity.

[0050] Conditional equation (8) specifies a desirable range for the ratio of the back focus BF to the total focal length f of the system when focused at infinity. If the ratio exceeds the upper limit of conditional equation (8), the back focus BF becomes too long, making it difficult to shorten the overall length.

[0051] Furthermore, by setting the upper limit to 0.4 in conditional equation (8), the back focus BF can be shortened further, thereby shortening the overall length.

[0052] Furthermore, in the imaging optical system according to one embodiment, a fourth lens group G4 may be provided as a lens group positioned closer to the image plane than the third lens group G3, and the second lens group G2 and the fourth lens group G4 may move in the optical axis direction during focusing.

[0053] As a result, the presence of a fixed third lens group G3 between the second lens group G2 and the fourth lens group G4, which move in the optical axis direction during focusing, makes it possible to correct axial aberrations at both infinity focus and the shortest focusing distance, thereby ensuring high optical performance.

[0054] Furthermore, as a second example of the configuration of the imaging optical system according to one embodiment, the system may be configured to include, in order from the object side toward the image plane, at least a first lens group G1, a second lens group G2 having positive refractive power, a third lens group G3, and a positive lens group positioned closer to the image plane than the third lens group G3. In this case, when focusing, the second lens group G2 and the positive lens group positioned closer to the image plane than the third lens group G3 move in the optical axis direction, satisfying the following conditions: f2 / f < 0.7 ... (1) -3.0 < f / fl < -0.5 ... (9) where, f: focal length of the entire system when focused at infinity f2: focal length of the second lens group fl: focal length of the lens group closest to the image plane.

[0055] The function and effect of conditional equation (1) are as described above. Conditional equation (9) specifies a favorable range for the ratio of the total focal length f of the entire system at infinity focus to the focal length fl of the lens group closest to the image plane. If the upper limit of conditional equation (9) is exceeded, the refractive power of the final group, the lens group closest to the image plane, decreases, and the diameter of the light beam of the final group widens, making it difficult to miniaturize the optical system. On the other hand, if the lower limit is exceeded, the refractive power of the final group becomes strong, making it difficult to suppress aberrations by the final group.

[0056] Furthermore, by setting the upper limit of condition (9) to -0.6, a greater effect can be obtained, and by setting it to -0.7, an even greater effect can be obtained. Also, by setting the lower limit of condition (9) to -2.6, a greater effect can be obtained, and by setting it to -2.3, an even greater effect can be obtained.

[0057] Furthermore, in the second configuration example of the imaging optical system according to one embodiment, the first lens group G1 may include an image-stabilizing lens group G1a that corrects blur by moving in a direction perpendicular to the optical axis Z1. In addition, the above-described conditions (2) to (8) may be further satisfied.

[0058] <3. Examples of Application to Imaging Devices> Next, specific examples of the application of an imaging optical system according to one embodiment of the present disclosure to an imaging device will be described.

[0059] Figure 71 shows an example configuration of an imaging device 100 to which an imaging optical system according to one embodiment is applied. This imaging device 100 is, for example, a digital still camera and comprises a camera block 110, 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.

[0060] The camera block 110 is responsible for the imaging function and includes an imaging lens 111 and an image sensor 112 such as a CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor). The image sensor 112 converts the optical image formed by the imaging lens 111 into an electrical signal, thereby outputting an imaging signal (image signal) corresponding to the optical image. As the imaging lens 111, the imaging optical systems 1 to 10 according to the various configuration examples shown in Figure 1 and other figures can be applied.

[0061] The camera signal processing unit 20 performs various signal processing on the image signal output from the image sensor 112, such as analog-to-digital conversion, noise reduction, image quality correction, and conversion to brightness and color difference signals.

[0062] The image processing unit 30 performs recording and playback processing of image signals, and is configured to perform compression encoding, decompression and decoding processing of image signals based on a predetermined image data format, as well as conversion processing of data specifications such as resolution.

[0063] The LCD 40 has the function of displaying various data such as the user's operation status to the input unit 70 and captured images. The R / W 50 writes image data encoded by the image processing unit 30 to the memory card 1000 and reads image data recorded on the memory card 1000. The memory card 1000 is, for example, a semiconductor memory that can be inserted into and removed from a slot connected to the R / W 50.

[0064] The CPU 60 functions as a control processing unit that controls each circuit block provided in the imaging device 100, and controls each circuit block based on instruction input signals from the input unit 70. The input unit 70 consists of various switches and the like that the user can operate as needed. For example, the input unit 70 consists of a shutter release button for operating the shutter and a selection switch for selecting an operating mode, and outputs instruction input signals to the CPU 60 according to the user's operation. The lens drive control unit 80 controls the drive of the lenses arranged in the camera block 110, and controls motors (not shown) that drive each lens of the imaging lens 111 based on control signals from the CPU 60.

[0065] The operation of the imaging device 100 is described below. In the standby state for shooting, under the control of the CPU 60, an image signal corresponding to the image captured by the camera block 110 is output to the LCD 40 via the camera signal processing unit 20 and 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 111 moves based on the control of the lens drive control unit 80.

[0066] When the shutter of the camera block 110 (not shown) 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, where it is compressed and encoded, 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.

[0067] Focusing is performed, for example, when the shutter release button on 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 111 based on a control signal from the CPU 60.

[0068] When playing back image data recorded on the memory card 1000, in response to an operation on the input unit 70, the R / W 50 reads predetermined image data from the memory card 1000, the image processing unit 30 performs decompression and decoding processing, and then the playback image signal is output to the LCD 40 and the playback image is displayed.

[0069] In the embodiments described above, an example of applying the imaging device to a digital still camera was shown. However, the scope of application 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 SLR cameras, digital non-reflex cameras, digital video cameras, and surveillance cameras. It can also be widely applied as the camera section of digital input / output devices such as mobile phones with cameras and information terminals with cameras. Furthermore, it can be applied to interchangeable lens cameras.

[0070] <4. Numerical Examples of Optical Systems> Next, specific numerical examples of imaging optical systems according to one embodiment of the present disclosure will be described. Here, examples in which specific numerical values ​​are applied to imaging optical systems 1 to 10 according to each configuration example shown in Figure 1, etc., will be described.

[0071] Note that the meanings of the symbols shown in the following tables and explanations are as follows. "Si" indicates the number of the i-th surface numbered sequentially 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 of the material of the optical element having the i-th surface with respect to the d-line (wavelength 587.6 nm). "νdi" indicates the value of the Abbe number of the material of the optical element having the i-th surface at the d-line. "φi" indicates the value (mm) of the effective diameter of the i-th surface. The part where the value of "ri" is "∞" indicates a plane, an aperture surface, or the like. "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 (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 value (F number). "ω" indicates the semi-field angle (unit: °). "Y" indicates the maximum image height that determines the semi-field angle (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).

[0072] Also, 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, "10 －ｉ ", and for example, "0.12345E-05" represents "0.12345×10 －５ ".

[0073] (Formula of aspherical surface) x = c ２ y ２ / (1 + (1 - (1 + k)c ２ y ２ )) + A4·y １／２ + A6·y ４ + A8·y ６ + A10·y ８ + A12·y １０ + A12·y １２Here, let "x" be the distance from the vertex of the lens surface to the optical axis (sag), "y" be the height perpendicular to the optical axis, "c" be the paraxial curvature (reciprocal of the radius of curvature) at the vertex of the lens surface, and "k" be the conic constant. A4, A6, A8, A10, and A12 are the 4th, 6th, 8th, 10th, and 12th order aspherical coefficients, respectively.

[0074] [Example 1] Table 1 shows the basic lens data of the imaging optical system 1 according to Example 1 shown in Figure 1. Table 2 shows the values ​​of the total focal length f, F-number, total angle of view 2ω, image height Y, and total optical length L for the imaging optical system 1 according to Example 1. Table 3 shows the data of the plane spacing that becomes variable during focusing in the imaging optical system 1 according to Example 1. Note that Table 2 shows the values ​​when the shooting distance and object distance (d0) are at infinity. Table 3 shows the values ​​when the shooting distance and object distance (d0) are at infinity and at close range. Table 4 shows the coefficient values ​​representing the shape of the aspherical surface in the imaging optical system 1 according to Example 1. Table 5 shows the starting surface and focal length (unit: mm) of each lens group of the imaging optical system 1 according to Example 1.

[0075] The imaging optical system 1 according to Embodiment 1 is configured such that, in order from the object side toward the image plane side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative refractive power, an aperture diaphragm St, a fourth lens group G4 having positive refractive power, and a fifth lens group G5 having negative refractive power are arranged.

[0076] When focusing from infinity to near distance, the first lens group G1, the third lens group G3, and the fifth lens group G5 are fixed relative to the image plane, while the second lens group G2 and the fourth lens group G4 move parallel to the object in the optical axis direction. In this case, the second lens group G2 moves parallel to the object in the optical axis direction, and the fourth lens group G4 also moves parallel to the object in the optical axis direction.

[0077] The first lens group G1 consists of, in order from the object side to the image plane side, a biconvex positive lens L11, a negative meniscus lens L12 with its convex side facing the object, a positive meniscus lens L13 with its concave side facing the object, a biconcave negative lens L14, and a biconvex positive lens L15 with an aspherical surface facing the object. The negative lens L13 and the positive lens L14 are bonded together to form a cemented lens. Furthermore, the negative lens L13 and the positive lens L14 form an image-stabilizing lens group G1a that corrects blur by moving in a direction perpendicular to the optical axis Z1.

[0078] The second lens group G2 consists of, in order from the object side to the image plane side, a biconvex positive lens L21, a negative meniscus lens L22 with its concave side facing the object side, and a biconvex positive lens L23. Lenses L21 and L22 are bonded together to form a cemented lens.

[0079] The third lens group G3 consists of a biconvex positive lens L31 and a biconcave negative lens L32, arranged in order from the object side to the image plane side. Lenses L31 and L32 are bonded together to form a cemented lens.

[0080] The fourth lens group G4 consists of, in order from the object side to the image plane side, a biconvex positive lens L41, a negative meniscus lens L42 with its convex side facing the object, and a positive meniscus lens L43 with its convex side facing the object. Lenses L42 and L43 are bonded together to form a cemented lens.

[0081] The fifth lens group G5 consists of, in order from the object side toward the image plane side, a negative meniscus lens L51 with a convex surface facing the object side, a positive lens L52 with a biconvex shape, a negative lens L53 with a biconcave shape, and a negative meniscus lens L54 with both sides being aspherical and with a concave surface facing the object side.

[0082] With the above configuration, an imaging optical system is realized that offers excellent optical performance across the entire shooting distance range, a high image stabilization coefficient and high optical performance during image stabilization, and allows for maintaining a safe distance from the subject during high-magnification shooting, while also being compact and lightweight.

[0083]

[0084]

[0085]

[0086]

[0087]

[0088] Figure 2 shows the longitudinal aberration of the imaging optical system 1 according to Example 1 when it is in focus at infinity. Figure 3 shows the longitudinal aberration of the imaging optical system 1 according to Example 1 when it is in focus at close range. Figure 4 shows the longitudinal aberration of the imaging optical system 1 according to Example 1 when it is in focus at infinity and vibration is suppressed. Figure 5 shows the transverse aberration of the imaging optical system 1 according to Example 1 when it is in focus at infinity. Figure 6 shows the transverse aberration of the imaging optical system 1 according to Example 1 when it is in focus at close range. Figure 7 shows the transverse aberration of the imaging optical system 1 according to Example 1 when it is in focus at infinity and vibration is suppressed.

[0089] Figures 2, 3, and 4 show longitudinal aberrations, specifically spherical aberration, astigmatism (field curvature), and distortion. In the spherical aberration diagrams in Figures 2, 3, and 4, and the transverse aberration diagrams in Figures 5, 6, and 7, the solid line represents the value at the d line (587.56 nm), the dashed line represents the value at the g line (435.84 nm), and the dashed line represents the value at the C line (656.27 nm). In the astigmatism diagrams in Figures 2, 3, and 4, S represents the value at the sagittal image plane, and T represents the value at the tangential image plane. In the astigmatism and distortion diagrams in Figures 2, 3, and 4, the value at the d line is shown. The same applies to the aberration diagrams in other embodiments that follow.

[0090] Note that the longitudinal aberration diagram in Figure 4 and the transverse aberration diagram in Figure 7 show the aberrations when the vertical shift amount of the vibration-damping lens group G1a with respect to the optical axis Z1 is 0.87 mm.

[0091] As can be seen from each aberration diagram, the imaging optical system 1 according to Example 1 has good correction of various aberrations and excellent imaging performance.

[0092] [Example 2] Table 6 shows the basic lens data of the imaging optical system 2 according to Example 2 shown in Figure 8. Table 7 shows the values ​​of the total focal length f, F-number, total angle of view 2ω, image height Y, and total optical length L for the imaging optical system 2 according to Example 2. Table 8 shows the data of the plane spacing that becomes variable during focusing in the imaging optical system 2 according to Example 2. Note that Table 7 shows the values ​​when the shooting distance and object distance (d0) are at infinity. Table 8 shows the values ​​when the shooting distance and object distance (d0) are at infinity and at close range. Table 9 shows the coefficient values ​​representing the shape of the aspherical surface in the imaging optical system 2 according to Example 2. Table 10 shows the starting surface and focal length (unit: mm) of each lens group of the imaging optical system 2 according to Example 2.

[0093] The imaging optical system 2 according to Embodiment 2 is configured such that, in order from the object side toward the image plane side, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative refractive power and having an aperture diaphragm St, a fourth lens group G4 having positive refractive power, and a fifth lens group G5 having negative refractive power are arranged.

[0094] When focusing from infinity to near distance, the first lens group G1, the third lens group G3, and the fifth lens group G5 are fixed relative to the image plane, while the second lens group G2 and the fourth lens group G4 move parallel to the object in the optical axis direction. In this case, the second lens group G2 moves parallel to the object in the optical axis direction, and the fourth lens group G4 also moves parallel to the object in the optical axis direction.

[0095] The first lens group G1 consists of, in order from the object side to the image plane side, a biconvex positive lens L11, a negative meniscus lens L12 with its convex surface facing the object side, a biconcave negative lens L13, and a biconvex positive lens L14 with both sides being aspherical. The negative lens L13 is an image-stabilizing lens group G1a that corrects blur by moving in a direction perpendicular to the optical axis Z1.

[0096] The second lens group G2 consists of, in order from the object side to the image plane side, a biconvex positive lens L21, a negative meniscus lens L22 with its concave side facing the object side, and a biconvex positive lens L23. Lenses L21 and L22 are bonded together to form a cemented lens.

[0097] The third lens group G3 consists of, in order from the object side to the image plane side, a negative lens L31 with a biconcave shape consisting of aspherical surfaces on both sides, an aperture diaphragm St, a positive meniscus lens L32 with its concave surface facing the object side, and a negative meniscus lens L33 with its concave surface facing the object side. Lenses L32 and L33 are bonded together to form a cemented lens.

[0098] The fourth lens group G4 consists of, in order from the object side to the image plane side, a biconvex positive lens L41, a negative meniscus lens L42 with its convex side facing the object, and a positive meniscus lens L43 with its convex side facing the object. Lenses L42 and L43 are bonded together to form a cemented lens.

[0099] The fifth lens group G5 consists of, in order from the object side toward the image plane side, a negative meniscus lens L51 with a convex surface facing the object side, a positive meniscus lens L52 with a convex surface facing the object side, a negative meniscus lens L53 with a concave surface facing the object side, and a positive meniscus lens L54 with a convex surface facing the object side, both of which are aspherical.

[0100] With the above configuration, an imaging optical system is realized that offers excellent optical performance across the entire shooting distance range, a high image stabilization coefficient and high optical performance during image stabilization, and allows for maintaining a safe distance from the subject during high-magnification shooting, while also being compact and lightweight.

[0101]

[0102]

[0103]

[0104]

[0105]

[0106] Figure 9 shows the longitudinal aberration of the imaging optical system 2 according to Example 2 when it is in focus at infinity. Figure 10 shows the longitudinal aberration of the imaging optical system 2 according to Example 2 when it is in focus at close range. Figure 11 shows the longitudinal aberration of the imaging optical system 2 according to Example 2 when it is in focus at infinity and vibration is suppressed. Figure 12 shows the transverse aberration of the imaging optical system 2 according to Example 2 when it is in focus at infinity. Figure 13 shows the transverse aberration of the imaging optical system 2 according to Example 2 when it is in focus at close range. Figure 14 shows the transverse aberration of the imaging optical system 2 according to Example 2 when it is in focus at infinity and vibration is suppressed.

[0107] Note that the longitudinal aberration diagram in Figure 11 and the transverse aberration diagram in Figure 14 show the aberrations when the vertical shift amount of the vibration-damping lens group G1a with respect to the optical axis Z1 is 1.2 mm.

[0108] As can be seen from each aberration diagram, the imaging optical system 2 according to Example 2 has good correction of various aberrations and excellent imaging performance.

[0109] [Example 3] Table 11 shows the basic lens data of the imaging optical system 3 according to Example 3 shown in Figure 15. Table 12 shows the values ​​of the total focal length f, F-number, total angle of view 2ω, image height Y, and total optical length L for the imaging optical system 3 according to Example 3. Table 13 shows the data of the plane spacing that becomes variable during focusing in the imaging optical system 3 according to Example 3. Note that Table 12 shows the values ​​when the shooting distance and object distance (d0) are at infinity. Table 13 shows the values ​​when the shooting distance and object distance (d0) are at infinity and at close range. Table 14 shows the coefficient values ​​representing the shape of the aspherical surface in the imaging optical system 3 according to Example 3. Table 15 shows the starting surface and focal length (unit: mm) of each lens group of the imaging optical system 3 according to Example 3.

[0110] The imaging optical system 3 according to Embodiment 3 is configured such that, in order from the object side toward the image plane side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having positive refractive power, an aperture diaphragm St, a fourth lens group G4 having negative refractive power, and a fifth lens group G5 having negative refractive power are arranged.

[0111] When focusing from infinity to near distance, the first lens group G1, the third lens group G3, and the fifth lens group G5 are fixed relative to the image plane, while the second lens group G2 and the fourth lens group G4 move parallel to the object side in the optical axis direction. In this case, the second lens group G2 moves parallel to the object side in the optical axis direction, and the fourth lens group G4 moves parallel to the image plane side in the optical axis direction.

[0112] The first lens group G1 consists of, in order from the object side toward the image plane side, a biconvex positive lens L11, a biconcave negative lens L12, and a biconvex positive lens L13. The positive lens L13 is an image-stabilizing lens group G1a that corrects blur by moving in a direction perpendicular to the optical axis Z1.

[0113] The second lens group G2 consists of, in order from the object side toward the image plane side, a negative meniscus lens L21 with its concave surface facing the object side, a biconvex positive lens L22, and a biconvex positive lens L23.

[0114] The third lens group G3 consists of, in order from the object side toward the image plane side, a biconcave negative lens L31 and a biconvex positive lens L32 whose two surfaces are aspherical.

[0115] The fourth lens group G4 consists of, in order from the object side to the image plane side, a biconvex positive lens L41, a biconcave negative lens L42, and a negative meniscus lens L43 with both sides being aspherical and with the concave side facing the object. Lenses L41 and L42 are bonded together to form a cemented lens.

[0116] The fifth lens group G5 consists of, in order from the object side to the image plane side, a positive lens L51 with a biconvex shape consisting of aspherical surfaces on both sides, a negative meniscus lens L52 with a concave surface facing the object side, a positive meniscus lens L53 with a convex surface facing the object side, a negative meniscus lens L54 with a concave surface facing the object side, and a positive meniscus lens L55 with a convex surface facing the object side.

[0117] With the above configuration, an imaging optical system is realized that offers excellent optical performance across the entire shooting distance range, a high image stabilization coefficient and high optical performance during image stabilization, and allows for maintaining a safe distance from the subject during high-magnification shooting, while also being compact and lightweight.

[0118]

[0119]

[0120]

[0121]

[0122]

[0123] Figure 16 shows the longitudinal aberration of the imaging optical system 3 according to Example 3 when it is in focus at infinity. Figure 17 shows the longitudinal aberration of the imaging optical system 3 according to Example 3 when it is in focus at close range. Figure 18 shows the longitudinal aberration of the imaging optical system 3 according to Example 3 when it is in focus at infinity and vibration is suppressed. Figure 19 shows the transverse aberration of the imaging optical system 3 according to Example 3 when it is in focus at infinity. Figure 20 shows the transverse aberration of the imaging optical system 3 according to Example 3 when it is in focus at close range. Figure 21 shows the transverse aberration of the imaging optical system 3 according to Example 3 when it is in focus at infinity and vibration is suppressed.

[0124] Note that the longitudinal aberration diagram in Figure 18 and the transverse aberration diagram in Figure 21 show the aberrations when the vertical shift amount of the vibration-damping lens group G1a with respect to the optical axis Z1 is 0.9 mm.

[0125] As can be seen from each aberration diagram, the imaging optical system 3 according to Example 3 has good correction of various aberrations and excellent imaging performance.

[0126] [Example 4] Table 16 shows the basic lens data of the imaging optical system 4 according to Example 4 shown in Figure 22. Table 17 shows the values ​​of the total focal length f, F-number, total angle of view 2ω, image height Y, and total optical length L for the imaging optical system 4 according to Example 4. Table 18 shows the data of the plane spacing that becomes variable during focusing in the imaging optical system 4 according to Example 4. Note that Table 17 shows the values ​​when the shooting distance and object distance (d0) are at infinity. Table 18 shows the values ​​when the shooting distance and object distance (d0) are at infinity and at close range. Table 19 shows the coefficient values ​​representing the shape of the aspherical surface in the imaging optical system 4 according to Example 4. Table 20 shows the starting surface and focal length (unit: mm) of each lens group of the imaging optical system 4 according to Example 4.

[0127] The imaging optical system 4 according to Embodiment 4 is configured such that, in order from the object side toward the image plane side, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, an aperture diaphragm St, a third lens group G3 having negative refractive power, and a fourth lens group G4 having positive refractive power are arranged.

[0128] When focusing from infinity to near distance, the first lens group G1 and the fourth lens group G4 are fixed relative to the image plane, while the second lens group G2 and the third lens group G3 move parallel to the object side in the optical axis direction. In this case, the second lens group G2 moves parallel to the object side in the optical axis direction, and the third lens group G3 moves parallel to the image plane side in the optical axis direction.

[0129] The first lens group G1 consists of, in order from the object side toward the image plane side, a positive meniscus lens L11 with its convex surface facing the object side, a negative meniscus lens L12 with its convex surface facing the object side, and a biconvex positive lens L13. The positive lens L13 is an image-stabilizing lens group G1a that corrects blur by moving in a direction perpendicular to the optical axis Z1.

[0130] The second lens group G2 consists of, in order from the object side toward the image plane side, a negative meniscus lens L21 with its concave surface facing the object side, a positive meniscus lens L22 with its concave surface facing the object side, and a biconvex positive lens L23.

[0131] The third lens group G3 consists of, in order from the object side to the image plane side, a biconvex positive lens L31, a biconcave negative lens L32, and a biconcave negative lens L33 whose two surfaces are aspherical. Lenses L31 and L32 are bonded together to form a cemented lens.

[0132] The fourth lens group G4 consists of, in order from the object side to the image plane side, a positive lens L41 with a biconvex shape and aspherical surfaces on both sides, a negative meniscus lens L42 with a concave surface facing the object side, a positive meniscus lens L43 with a convex surface facing the object side, a negative lens L44 with a biconcave shape, and a positive meniscus lens L45 with a convex surface facing the object side.

[0133] With the above configuration, an imaging optical system is realized that offers excellent optical performance across the entire shooting distance range, a high image stabilization coefficient and high optical performance during image stabilization, and allows for maintaining a safe distance from the subject during high-magnification shooting, while also being compact and lightweight.

[0134]

[0135]

[0136]

[0137]

[0138]

[0139] Figure 23 shows the longitudinal aberration of the imaging optical system 4 according to Example 4 when it is in focus at infinity. Figure 24 shows the longitudinal aberration of the imaging optical system 4 according to Example 4 when it is in focus at close range. Figure 25 shows the longitudinal aberration of the imaging optical system 4 according to Example 4 when it is in focus at infinity and vibration is suppressed. Figure 27 shows the transverse aberration of the imaging optical system 4 according to Example 4 when it is in focus at infinity. Figure 28 shows the transverse aberration of the imaging optical system 4 according to Example 4 when it is in focus at close range. Figure 28 shows the transverse aberration of the imaging optical system 4 according to Example 4 when it is in focus at infinity and vibration is suppressed.

[0140] Note that the longitudinal aberration diagram in Figure 25 and the transverse aberration diagram in Figure 28 show the aberrations when the vertical shift amount of the vibration-damping lens group G1a with respect to the optical axis Z1 is 0.9 mm.

[0141] As can be seen from each aberration diagram, the imaging optical system 4 according to Example 4 has good correction of various aberrations and excellent imaging performance.

[0142] [Example 5] Table 21 shows the basic lens data of the imaging optical system 5 according to Example 5 shown in Figure 29. Table 22 shows the values ​​of the total focal length f, F-number, total angle of view 2ω, image height Y, and total optical length L for the imaging optical system 5 according to Example 5. Table 23 shows the data of the plane spacing that becomes variable during focusing in the imaging optical system 5 according to Example 5. Note that Table 22 shows the values ​​when the shooting distance and object distance (d0) are at infinity. Table 23 shows the values ​​when the shooting distance and object distance (d0) are at infinity and at close range. Table 24 shows the coefficient values ​​representing the shape of the aspherical surface in the imaging optical system 5 according to Example 5. Table 25 shows the starting surface and focal length (unit: mm) of each lens group of the imaging optical system 5 according to Example 5.

[0143] The imaging optical system 5 according to Embodiment 5 is configured such that, in order from the object side toward the image plane side, a first lens group G1 having negative refractive power, an aperture diaphragm St, a second lens group G2 having positive refractive power, a third lens group G3 having negative refractive power, a fourth lens group G4 having positive refractive power, and a fifth lens group G5 having negative refractive power are arranged.

[0144] When focusing from infinity to near distance, the first lens group G1, the third lens group G3, and the fifth lens group G5 are fixed relative to the image plane, while the second lens group G2 and the fourth lens group G4 move parallel to the object in the optical axis direction. In this case, the second lens group G2 moves parallel to the object in the optical axis direction, and the fourth lens group G4 also moves parallel to the object in the optical axis direction.

[0145] The first lens group G1 consists of a biconvex positive lens L11, a biconcave negative lens L12, a biconvex positive lens L13, a negative meniscus lens L14 with its concave surface facing the object, and a biconvex positive lens L15. The positive lens L13 is an image-stabilizing lens group G1a that corrects blur by moving in a direction perpendicular to the optical axis Z1.

[0146] The second lens group G2 consists of, in order from the object side toward the image plane side, a negative meniscus lens L21 with its convex surface facing the object side, a positive meniscus lens L22 with its convex surface facing the object side, and a biconvex positive lens L23. Lenses L21 and L22 are bonded together to form a cemented lens.

[0147] The third lens group G3 consists of a negative lens L31 with a biconcave shape, where both sides are aspherical.

[0148] The fourth lens group G4 consists of, in order from the object side toward the image plane side, a negative meniscus lens L41 with a convex surface facing the object side, and a positive lens L42 with a biconvex shape consisting of an aspherical surface on the image side. Lenses L41 and L42 are bonded together to form a cemented lens.

[0149] The fifth lens group G5 consists of, in order from the object side toward the image plane side, a negative meniscus lens L51 with a convex surface facing the object side, a positive meniscus lens L52 with a convex surface facing the object side and made of aspherical surfaces on both sides, a negative lens L53 with a biconcave shape, a positive lens L54 with a biconvex shape, and a negative meniscus lens L55 with a concave surface facing the object side.

[0150] With the above configuration, an imaging optical system is realized that offers excellent optical performance across the entire shooting distance range, a high image stabilization coefficient and high optical performance during image stabilization, and allows for maintaining a safe distance from the subject during high-magnification shooting, while also being compact and lightweight.

[0151]

[0152]

[0153]

[0154]

[0155]

[0156] Figure 30 shows the longitudinal aberration of the imaging optical system 5 according to Example 5 when it is in focus at infinity. Figure 31 shows the longitudinal aberration when it is in focus at close range. Figure 32 shows the longitudinal aberration of the imaging optical system 5 according to Example 5 when it is in focus at infinity and vibration is suppressed. Figure 33 shows the transverse aberration of the imaging optical system 5 according to Example 5 when it is in focus at infinity. Figure 34 shows the transverse aberration of the imaging optical system 5 according to Example 5 when it is in focus at close range. Figure 35 shows the transverse aberration of the imaging optical system 5 according to Example 5 when it is in focus at infinity and vibration is suppressed.

[0157] Note that the longitudinal aberration diagram in Figure 32 and the transverse aberration diagram in Figure 35 show the aberrations when the vertical shift amount of the vibration-damping lens group G1a with respect to the optical axis Z1 is 0.87 mm.

[0158] As can be seen from each aberration diagram, the imaging optical system 5 according to Example 5 has good correction of various aberrations and excellent imaging performance.

[0159] [Example 6] Table 26 shows the basic lens data of the imaging optical system 6 according to Example 6 shown in Figure 36. Table 27 shows the values ​​of the total focal length f, F-number, total angle of view 2ω, image height Y, and total optical length L for the imaging optical system 6 according to Example 6. Table 28 shows the data of the plane spacing that becomes variable during focusing for the imaging optical system 6 according to Example 6. Note that Table 27 shows the values ​​when the shooting distance and object distance (d0) are at infinity. Table 28 shows the values ​​when the shooting distance and object distance (d0) are at infinity and at close range. Table 29 shows the coefficient values ​​representing the shape of the aspherical surface for the imaging optical system 6 according to Example 6. Table 30 shows the starting surface and focal length (unit: mm) of each lens group of the imaging optical system 6 according to Example 6.

[0160] The imaging optical system 6 according to Embodiment 6 is configured such that, in order from the object side toward the image plane side, it comprises a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative refractive power and an aperture diaphragm St, a fourth lens group G4 having positive refractive power, and a fifth lens group G5 having negative refractive power.

[0161] When focusing from infinity to near distance, the first lens group G1, the third lens group G3, and the fifth lens group G5 are fixed relative to the image plane, while the second lens group G2 and the fourth lens group G4 move parallel to the object in the optical axis direction. In this case, the second lens group G2 moves parallel to the object in the optical axis direction, and the fourth lens group G4 also moves parallel to the object in the optical axis direction.

[0162] The first lens group G1 consists of, in order from the object side to the image plane side, a biconvex positive lens L11, a biconcave negative lens L12, a biconvex positive lens L13, and a negative meniscus lens L14 with its concave side facing the object side. Lenses L11 and L12 are bonded together to form a cemented lens. Lenses L13 and L14 are also bonded together to form a cemented lens. Furthermore, the positive lens L13 and the negative meniscus lens L14 form an image-stabilizing lens group G1a that corrects blur by moving in a direction perpendicular to the optical axis Z1.

[0163] The second lens group G2 consists of, in order from the object side toward the image plane side, a positive meniscus lens L21 with both sides being aspherical and with the convex side facing the object, a negative meniscus lens L22 with the convex side facing the object, and a biconvex positive lens L23. Lenses L22 and L23 are bonded together to form a cemented lens.

[0164] The third lens group G3 consists of, in order from the object side to the image plane side, a biconcave negative lens L31 with an aspherical surface on the image side, an aperture diaphragm St, a positive meniscus lens L32 with its concave surface facing the object side, and a biconcave negative lens L33. Lenses L32 and L33 are bonded together to form a cemented lens.

[0165] The fourth lens group G4 consists of, in order from the object side to the image plane side, a biconvex positive lens L41, a negative meniscus lens L42 with its convex side facing the object side, a biconvex positive lens L43, and a biconcave negative lens L44. Lenses L42 and L43 are bonded together to form a cemented lens.

[0166] The fifth lens group G5 consists of, in order from the object side toward the image plane side, a positive meniscus lens L51 with its concave surface facing the object side, and a negative lens L52 with a biconcave shape consisting of aspherical surfaces on both sides.

[0167] With the above configuration, an imaging optical system is realized that offers excellent optical performance across the entire shooting distance range, a high image stabilization coefficient and high optical performance during image stabilization, and allows for maintaining a safe distance from the subject during high-magnification shooting, while also being compact and lightweight.

[0168]

[0169]

[0170]

[0171]

[0172]

[0173] Figure 37 shows the longitudinal aberration of the imaging optical system 6 according to Example 6 when it is in focus at infinity. Figure 38 shows the longitudinal aberration when it is in focus at close range. Figure 39 shows the longitudinal aberration of the imaging optical system 6 according to Example 6 when it is in focus at infinity and vibration is suppressed. Figure 40 shows the transverse aberration of the imaging optical system 6 according to Example 6 when it is in focus at infinity. Figure 41 shows the transverse aberration of the imaging optical system 6 according to Example 6 when it is in focus at close range. Figure 42 shows the transverse aberration of the imaging optical system 6 according to Example 6 when it is in focus at infinity and vibration is suppressed.

[0174] Note that the longitudinal aberration diagram in Figure 39 and the transverse aberration diagram in Figure 42 show the aberrations when the vertical shift amount of the vibration-damping lens group G1a with respect to the optical axis Z1 is 1.2 mm.

[0175] As can be seen from each aberration diagram, the imaging optical system 6 according to Example 6 has good correction of various aberrations and excellent imaging performance.

[0176] [Example 7] Table 31 shows the basic lens data of the imaging optical system 7 according to Example 7 shown in Figure 43. Table 32 shows the values ​​of the total focal length f, F-number, total angle of view 2ω, image height Y, and total optical length L for the imaging optical system 7 according to Example 7. Table 33 shows the data of the plane spacing that becomes variable during focusing in the imaging optical system 7 according to Example 7. Note that Table 32 shows the values ​​when the shooting distance and object distance (d0) are at infinity. Table 33 shows the values ​​when the shooting distance and object distance (d0) are at infinity and at close range. Table 34 shows the coefficient values ​​representing the shape of the aspherical surface in the imaging optical system 7 according to Example 7. Table 35 shows the starting surface and focal length (unit: mm) of each lens group of the imaging optical system 7 according to Example 7.

[0177] The imaging optical system 7 according to Embodiment 7 is configured such that, in order from the object side toward the image plane side, a first lens group G1 having negative refractive power, an aperture diaphragm St, a second lens group G2 having positive refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, and a fifth lens group G5 having negative refractive power are arranged.

[0178] When focusing from infinity to near distance, the first lens group G1, the third lens group G3, and the fifth lens group G5 are fixed relative to the image plane, while the second lens group G2 and the fourth lens group G4 move parallel to the object side in the optical axis direction. In this case, the second lens group G2 moves parallel to the object side in the optical axis direction, and the fourth lens group G4 moves parallel to the image plane side in the optical axis direction.

[0179] The first lens group G1 consists of, in order from the object side toward the image plane side, a positive meniscus lens L11 with its concave surface facing the object side, a negative meniscus lens L12 with its concave surface facing the object side, a biconcave negative lens L13, a positive meniscus lens L14 with its convex surface facing the object side, and a biconvex positive lens L15. The negative lens L13 and the positive meniscus lens L14 form an image-stabilizing lens group G1a that corrects blur by moving perpendicular to the optical axis Z1.

[0180] The second lens group G2 consists of, in order from the object side toward the image plane side, a standard plano-convex lens L21 with its convex surface facing the object side, a biconcave negative lens L22, a biconvex positive lens L23, a negative meniscus lens L24 with both sides made of aspherical surfaces and its convex surface facing the object side, and a positive meniscus lens L25 with both sides made of aspherical surfaces and its convex surface facing the object side.

[0181] The third lens group G3 consists of, in order from the object side toward the image plane side, a negative meniscus lens L31 with a convex surface facing the object side, a negative meniscus lens L32 with a concave surface facing the object side, a positive lens L33 with a biconvex shape, and a positive meniscus lens L34 with a concave surface facing the object side, whose both surfaces are aspherical.

[0182] The fourth lens group G4 consists of, in order from the object side toward the image plane side, a negative meniscus lens L41 with its concave surface facing the object side and a positive lens L42 with a biconvex shape.

[0183] The fifth lens group G5 consists of a biconcave negative lens L51.

[0184] With the above configuration, an imaging optical system is realized that offers excellent optical performance across the entire shooting distance range, a high image stabilization coefficient and high optical performance during image stabilization, and allows for maintaining a safe distance from the subject during high-magnification shooting, while also being compact and lightweight.

[0185]

[0186]

[0187]

[0188]

[0189]

[0190] Figure 44 shows the longitudinal aberration of the imaging optical system 7 according to Example 7 when it is in focus at infinity. Figure 45 shows the longitudinal aberration when it is in focus at close range. Figure 46 shows the longitudinal aberration of the imaging optical system 7 according to Example 7 when it is in focus at infinity and vibration is suppressed. Figure 47 shows the transverse aberration of the imaging optical system 7 according to Example 7 when it is in focus at infinity. Figure 48 shows the transverse aberration of the imaging optical system 7 according to Example 7 when it is in focus at close range. Figure 49 shows the transverse aberration of the imaging optical system 7 according to Example 7 when it is in focus at infinity and vibration is suppressed.

[0191] Note that the longitudinal aberration diagram in Figure 46 and the transverse aberration diagram in Figure 49 show the aberrations when the vertical shift amount of the vibration-damping lens group G1a with respect to the optical axis Z1 is 1.2 mm.

[0192] As can be seen from each aberration diagram, the imaging optical system 7 according to Example 7 has good correction of various aberrations and excellent imaging performance.

[0193] [Example 8] Table 36 shows the basic lens data of the imaging optical system 8 according to Example 8 shown in Figure 50. Table 37 shows the values ​​of the total focal length f, F-number, total angle of view 2ω, image height Y, and total optical length L for the imaging optical system 8 according to Example 8. Table 38 shows the data of the plane spacing that becomes variable during focusing for the imaging optical system 8 according to Example 8. Note that Table 37 shows the values ​​when the shooting distance and object distance (d0) are at infinity. Table 38 shows the values ​​when the shooting distance and object distance (d0) are at infinity and at close range. Table 39 shows the coefficient values ​​representing the shape of the aspherical surface for the imaging optical system 8 according to Example 8. Table 40 shows the starting surface and focal length (unit: mm) of each lens group of the imaging optical system 8 according to Example 8.

[0194] The imaging optical system 8 according to Embodiment 8 is configured such that, in order from the object side toward the image plane side, a first lens group G1 having negative refractive power, an aperture diaphragm St, a second lens group G2 having positive refractive power, a third lens group G3 having negative refractive power, a fourth lens group G4 having negative refractive power, and a fifth lens group G5 having negative refractive power are arranged.

[0195] When focusing from infinity to near distance, the first lens group G1, the third lens group G3, and the fifth lens group G5 are fixed relative to the image plane, while the second lens group G2 and the fourth lens group G4 move parallel to the object in the optical axis direction. In this case, the second lens group G2 moves parallel to the object in the optical axis direction, and the fourth lens group G4 also moves parallel to the object in the optical axis direction.

[0196] The first lens group G1 consists of, in order from the object side toward the image plane side, a positive meniscus lens L11 with its concave surface facing the object side, a negative lens L12 with a biconcave shape, a positive meniscus lens L13 with its convex surface facing the object side, a positive lens L14 with a biconvex shape, and a negative meniscus lens L15 with its concave surface facing the object side. The positive meniscus lens L13 is an image-stabilizing lens group G1a that corrects blur by moving in a direction perpendicular to the optical axis Z1.

[0197] The second lens group G2 consists of, in order from the object side toward the image plane side, a positive meniscus lens L21 with its convex surface facing the object side, a negative meniscus lens L22 with its convex surface facing the object side, a negative meniscus lens L23 with its convex surface facing the object side and made up of aspherical surfaces on both sides, and a positive lens L24 with a biconvex shape.

[0198] The third lens group G3 consists of, in order from the object side toward the image plane, a biconvex positive lens L31, a biconcave negative lens L32, a biconcave negative lens L33, and a biconvex positive lens L34. Lenses L31 and L32 are bonded together to form a cemented lens. Lenses L33 and L34 are bonded together to form a cemented lens.

[0199] The fourth lens group G4 consists of a negative meniscus lens L41, which has aspherical surfaces on both sides and a concave surface facing the object.

[0200] The fifth lens group G5 consists of, in order from the object side toward the image plane side, a negative lens L51 with a biconcave shape consisting of aspherical surfaces on both sides, and a positive meniscus lens L52 with a convex surface facing toward the object side.

[0201] With the above configuration, an imaging optical system is realized that offers excellent optical performance across the entire shooting distance range, a high image stabilization coefficient and high optical performance during image stabilization, and allows for maintaining a safe distance from the subject during high-magnification shooting, while also being compact and lightweight.

[0202]

[0203]

[0204]

[0205]

[0206]

[0207] Figure 51 shows the longitudinal aberration of the imaging optical system 8 according to Example 8 when it is in focus at infinity. Figure 52 shows the longitudinal aberration when it is in focus at close range. Figure 53 shows the longitudinal aberration of the imaging optical system 8 according to Example 8 when it is in focus at infinity and vibration is suppressed. Figure 54 shows the transverse aberration of the imaging optical system 8 according to Example 8 when it is in focus at infinity. Figure 55 shows the transverse aberration of the imaging optical system 8 according to Example 8 when it is in focus at close range. Figure 56 shows the transverse aberration of the imaging optical system 8 according to Example 8 when it is in focus at infinity and vibration is suppressed.

[0208] Note that the longitudinal aberration diagram in Figure 53 and the transverse aberration diagram in Figure 56 show the aberrations when the vertical shift amount of the vibration-damping lens group G1a with respect to the optical axis Z1 is 1.15 mm.

[0209] As can be seen from each aberration diagram, the imaging optical system 8 according to Example 8 has good correction of various aberrations and excellent imaging performance.

[0210] [Example 9] Table 41 shows the basic lens data of the imaging optical system 9 according to Example 9 shown in Figure 57. Table 42 shows the values ​​of the total focal length f, F-number, total angle of view 2ω, image height Y, and total optical length L for the imaging optical system 9 according to Example 9. Table 43 shows the data of the plane spacing that becomes variable during focusing for the imaging optical system 9 according to Example 9. Note that Table 42 shows the values ​​when the shooting distance and object distance (d0) are at infinity. Table 43 shows the values ​​when the shooting distance and object distance (d0) are at infinity and at close range. Table 44 shows the coefficient values ​​representing the shape of the aspherical surface for the imaging optical system 9 according to Example 9. Table 45 shows the starting surface and focal length (unit: mm) of each lens group of the imaging optical system 9 according to Example 9.

[0211] The imaging optical system 9 according to Embodiment 9 is configured such that, in order from the object side toward the image plane side, a first lens group G1 having negative refractive power, an aperture diaphragm St, a second lens group G2 having positive refractive power, a third lens group G3 having negative refractive power, a fourth lens group G4 having positive refractive power, and a fifth lens group G5 having negative refractive power are arranged.

[0212] When focusing from infinity to near distance, the first lens group G1, the third lens group G3, and the fifth lens group G5 are fixed relative to the image plane, while the second lens group G2 and the fourth lens group G4 move parallel to the object side in the optical axis direction. In this case, the second lens group G2 moves parallel to the object side in the optical axis direction, and the fourth lens group G4 moves parallel to the image plane side in the optical axis direction.

[0213] The first lens group G1 consists of, in order from the object side to the image plane side, a biconvex positive lens L11, a negative meniscus lens L12 with its concave surface facing the object side, a negative meniscus lens L13 with its convex surface facing the object side, a positive meniscus lens L14 with its concave surface facing the object side, a biconcave negative lens L15, and a positive meniscus lens L16 with its convex surface facing the object side. The negative meniscus lens L13, positive meniscus lens L14, negative lens L15, and positive meniscus lens L16 form an image-stabilizing lens group G1a that corrects blur by moving in a direction perpendicular to the optical axis Z1.

[0214] The second lens group G2 consists of, in order from the object side toward the image plane side, a positive meniscus lens L21 with its convex surface facing the object side, a positive meniscus lens L22 with its convex surface facing the object side and made up of aspherical surfaces on both sides, a negative meniscus lens L23 with its convex surface facing the object side, and a positive lens L24 with a biconvex shape and an aspherical surface on the image side. Lenses L23 and L24 are bonded together to form a cemented lens.

[0215] The third lens group G3 consists of, in order from the object side toward the image plane side, a biconcave negative lens L31 and a positive meniscus lens L32 with both sides being aspherical and with the convex side facing the object.

[0216] The fourth lens group G4 consists of, in order from the object side toward the image plane side, a positive meniscus lens L41 with its concave surface facing the object side, a biconvex positive lens L42, and a positive meniscus lens L43 with its concave surface facing the object side.

[0217] The fifth lens group G5 consists of, in order from the object side toward the image plane side, a biconcave negative lens L51 and a positive meniscus lens L52 with its convex side facing the object side.

[0218] With the above configuration, an imaging optical system is realized that offers excellent optical performance across the entire shooting distance range, a high image stabilization coefficient and high optical performance during image stabilization, and allows for maintaining a safe distance from the subject during high-magnification shooting, while also being compact and lightweight.

[0219]

[0220]

[0221]

[0222]

[0223]

[0224] Figure 58 shows the longitudinal aberration of the imaging optical system 9 according to Example 9 when it is in focus at infinity. Figure 59 shows the longitudinal aberration when it is in focus at close range. Figure 60 shows the longitudinal aberration of the imaging optical system 9 according to Example 9 when it is in focus at infinity and vibration is suppressed. Figure 61 shows the transverse aberration of the imaging optical system 9 according to Example 9 when it is in focus at infinity. Figure 62 shows the transverse aberration of the imaging optical system 9 according to Example 9 when it is in focus at close range. Figure 63 shows the transverse aberration of the imaging optical system 9 according to Example 9 when it is in focus at infinity and vibration is suppressed.

[0225] Note that the longitudinal aberration diagram in Figure 60 and the transverse aberration diagram in Figure 63 show the aberrations when the vertical shift amount of the vibration-damping lens group G1a with respect to the optical axis Z1 is 1.16 mm.

[0226] As can be seen from each aberration diagram, the imaging optical system 9 according to Example 9 has good correction of various aberrations and excellent imaging performance.

[0227] [Example 10] Table 46 shows the basic lens data of the imaging optical system 10 according to Example 10 shown in Figure 64. Table 47 shows the values ​​of the total focal length f, F-number, total angle of view 2ω, image height Y, and total optical length L for the imaging optical system 10 according to Example 10. Table 48 shows the data of the plane spacing that becomes variable during focusing for the imaging optical system 10 according to Example 10. Note that Table 47 shows the values ​​when the shooting distance and object distance (d0) are at infinity. Table 48 shows the values ​​when the shooting distance and object distance (d0) are at infinity and at close range. Table 49 shows the coefficient values ​​representing the shape of the aspherical surface for the imaging optical system 10 according to Example 10. Table 50 shows the starting surface and focal length (unit: mm) of each lens group of the imaging optical system 10 according to Example 10.

[0228] The imaging optical system 10 according to Embodiment 10 is configured such that, in order from the object side toward the image plane side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative refractive power, an aperture diaphragm St, a fourth lens group G4 having positive refractive power, and a fifth lens group G5 having negative refractive power are arranged.

[0229] When focusing from infinity to near distance, the first lens group G1, the third lens group G3, and the fifth lens group G5 are fixed relative to the image plane, while the second lens group G2 and the fourth lens group G4 move parallel to the object in the optical axis direction. In this case, the second lens group G2 moves parallel to the object in the optical axis direction, and the fourth lens group G4 also moves parallel to the object in the optical axis direction.

[0230] The first lens group G1 consists of, in order from the object side to the image plane side, a biconvex positive lens L11, a negative meniscus lens L12 with its convex side facing the object, a positive meniscus lens L13 with its concave side facing the object, a biconcave negative lens L14, and a biconvex positive lens L15 with an aspherical surface facing the object. Lenses L13 and L14 are bonded together to form a cemented lens. Furthermore, the positive meniscus lens L13 and the negative lens L14 form an image stabilization lens group G1a that corrects blur by moving in a direction perpendicular to the optical axis Z1.

[0231] The second lens group G2 consists of, in order from the object side toward the image plane side, a biconvex positive lens L21, a negative meniscus lens L22 with its concave side facing the object side, and a positive meniscus lens L23 with its convex side facing the object side. Lenses L21 and L22 are bonded together to form a cemented lens.

[0232] The third lens group G3 consists of, in order from the object side toward the image plane side, a positive meniscus lens L31 with its convex surface facing the object side, and a negative meniscus lens L32 with its convex surface facing the object side. Lenses L31 and L32 are bonded together to form a cemented lens.

[0233] The fourth lens group G4 consists of, in order from the object side toward the image plane side, a positive meniscus lens L41 with its convex surface facing the object side, a negative meniscus lens L42 with its convex surface facing the object side, and a biconvex positive lens L43. Lenses L42 and L43 are bonded together to form a cemented lens.

[0234] The fifth lens group G5 consists of, in order from the object side toward the image plane side, a negative meniscus lens L51 with a convex surface facing the object side, a positive lens L52 with a biconvex shape, a negative lens L53 with a biconcave shape, and a negative meniscus lens L54 with both sides being aspherical and with a concave surface facing the object side.

[0235] With the above configuration, an imaging optical system is realized that offers excellent optical performance across the entire shooting distance range, a high image stabilization coefficient and high optical performance during image stabilization, and allows for maintaining a safe distance from the subject during high-magnification shooting, while also being compact and lightweight.

[0236]

[0237]

[0238]

[0239]

[0240]

[0241] Figure 65 shows the longitudinal aberration of the imaging optical system 10 according to Example 10 when it is in focus at infinity. Figure 66 shows the longitudinal aberration when it is in focus at close range. Figure 67 shows the longitudinal aberration of the imaging optical system 10 according to Example 10 when it is in focus at infinity and vibration is suppressed. Figure 68 shows the transverse aberration of the imaging optical system 10 according to Example 10 when it is in focus at infinity. Figure 69 shows the transverse aberration of the imaging optical system 10 according to Example 10 when it is in focus at close range. Figure 70 shows the transverse aberration of the imaging optical system 10 according to Example 10 when it is in focus at infinity and vibration is suppressed.

[0242] Note that the longitudinal aberration diagram in Figure 67 and the transverse aberration diagram in Figure 70 show the aberrations when the vertical shift amount of the vibration-damping lens group G1a with respect to the optical axis Z1 is 0.58 mm.

[0243] As can be seen from each aberration diagram, the imaging optical system 10 according to Example 10 has good correction of various aberrations and excellent imaging performance.

[0244] [Other numerical data for each embodiment] Table 51 shows the values ​​for each of the above-mentioned conditional expressions for each embodiment. As can be seen from Table 51, for conditional expressions (1) to (8), the values ​​for each embodiment fall within the numerical range. For conditional expression (9), the values ​​for each embodiment, excluding embodiments 3 and 4, fall within the numerical range.

[0245]

[0246] <5. Application Examples> [5.1 First Application Example] The technology relating to this disclosure can be applied to a variety of products. For example, the technology relating to this disclosure may be implemented as a device mounted on any type of mobile vehicle such as automobiles, electric vehicles, hybrid electric vehicles, motorcycles, bicycles, personal mobility devices, airplanes, drones, ships, robots, construction machinery, or agricultural machinery (tractors).

[0247] Figure 72 is a block diagram showing a schematic configuration example of a vehicle control system 7000, which is an example of a mobile control system to which the technology of this disclosure may be applied. The vehicle control system 7000 comprises a plurality of electronic control units connected via a communication network 7010. In the example shown in Figure 72, the vehicle control system 7000 comprises a drive system control unit 7100, a body system control unit 7200, a battery control unit 7300, an external information detection unit 7400, an internal 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 conforming to any standard such as CAN (Controller Area Network), LIN (Local Interconnect Network), LAN (Local Area Network), or FlexRay®.

[0248] Each control unit comprises a microcomputer that performs calculations according to various programs, a storage unit that stores programs executed by the microcomputer or parameters used in various calculations, and a drive circuit that drives various controlled devices. Each control unit is equipped with a network interface for communication with other control units via the communication network 7010, and a communication interface for communication with devices or sensors inside or outside the vehicle via wired or wireless communication. Figure 72 shows the functional configuration of the integrated control unit 7600, which includes a microcomputer 7610, a general-purpose communication interface 7620, a dedicated communication interface 7630, a positioning unit 7640, a beacon receiver 7650, an in-vehicle equipment interface 7660, an audio / image output unit 7670, an in-vehicle network interface 7680, and a storage unit 7690. Other control units similarly include a microcomputer, a communication interface, and a storage unit.

[0249] The drivetrain control unit 7100 controls the operation of devices related to the vehicle's drivetrain according to various programs. For example, the drivetrain control unit 7100 functions as a control device for generating driving force for the vehicle, such as an internal combustion engine or a drive motor; a driving force transmission mechanism for transmitting driving force to the wheels; a steering mechanism for adjusting the steering angle of the vehicle; and a braking device for generating braking force for the vehicle. The drivetrain control unit 7100 may also function as a control device such as an ABS (Antilock Brake System) or an ESC (Electronic Stability Control).

[0250] A vehicle state detection unit 7110 is connected to the drive system control unit 7100. The vehicle state detection unit 7110 includes, for example, a gyro sensor for detecting the angular velocity of the axial rotation motion of the vehicle body, an acceleration sensor for detecting the acceleration of the vehicle, or at least one of the sensors for detecting the amount of operation of the accelerator pedal, the amount of operation 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 calculation processing using the signals input from the vehicle state detection unit 7110 and controls the internal combustion engine, drive motor, electric power steering system, brake system, etc.

[0251] The body system control unit 7200 controls the operation of various devices mounted on 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 system, or various lamps such as headlights, reverse lights, brake lights, turn signals, or fog lights. In this case, the body system control unit 7200 may receive radio waves transmitted from a portable device that replaces a key or signals from various switches. The body system control unit 7200 receives these radio waves or signals and controls the vehicle's door lock system, power window system, lamps, etc.

[0252] The battery control unit 7300 controls the secondary battery 7310, which is the power source for the drive motor, according to various programs. For example, the battery control unit 7300 receives information such as battery temperature, battery output voltage, or remaining battery capacity from the battery device equipped with the secondary battery 7310. The battery control unit 7300 uses these signals to perform calculations and controls the temperature of the secondary battery 7310 or the cooling device provided in the battery device.

[0253] The external information detection unit 7400 detects information from outside the vehicle equipped with the vehicle control system 7000. For example, at least one of the imaging unit 7410 and the external information detection unit 7420 is connected to the external information detection unit 7400. The imaging unit 7410 includes at least one of the following: a Time of Flight (ToF) camera, a stereo camera, a monocular camera, an infrared camera, and other cameras. The external information detection unit 7420 includes at least one of the following: an environmental sensor for detecting the current weather or climate, or an ambient information detection sensor for detecting other vehicles, obstacles, or pedestrians around the vehicle equipped with the vehicle control system 7000.

[0254] The environmental sensor may be at least one of the following: a raindrop sensor for detecting rain, a fog sensor for detecting fog, a sunshine sensor for detecting the degree of sunlight, and a snow sensor for detecting snowfall. The ambient information detection sensor may be at least one of the following: an ultrasonic sensor, a radar device, and a LIDAR (Light Detection and Ranging, Laser Imaging Detection and Ranging) device. These imaging unit 7410 and external information detection unit 7420 may be provided as independent sensors or devices, or as a device in which multiple sensors or devices are integrated.

[0255] Here, Figure 73 shows an example of the installation location of the imaging unit 7410 and the external information detection unit 7420. The imaging units 7910, 7912, 7914, 7916, and 7918 are installed, for example, at least one of the following locations on the vehicle 7900: the front nose, side mirrors, rear bumper, back door, and the upper part of the windshield inside the passenger compartment. The imaging unit 7910 installed on the front nose and the imaging unit 7918 installed on the upper part of the windshield inside the passenger compartment mainly acquire images of the front of the vehicle 7900. The imaging units 7912 and 7914 installed on the side mirrors mainly acquire images of the sides of the vehicle 7900. The imaging unit 7916 installed on the rear bumper or back door mainly acquires images of the rear of the vehicle 7900. The imaging unit 7918 installed on the upper part of the windshield inside the passenger compartment is mainly used for detecting preceding vehicles, pedestrians, obstacles, traffic lights, traffic signs, or lanes.

[0256] Figure 73 shows an example of the imaging range of each imaging unit 7910, 7912, 7914, and 7916. Imaging range a shows the imaging range of imaging unit 7910 located on the front nose, imaging ranges b and c show the imaging ranges of imaging units 7912 and 7914 located on the side mirrors, respectively, and imaging range d shows the imaging range of imaging unit 7916 located on the rear bumper or back door. For example, by superimposing the image data captured by imaging units 7910, 7912, 7914, and 7916, an overhead view image of the vehicle 7900 can be obtained.

[0257] The external information detection units 7920, 7922, 7924, 7926, 7928, and 7930, which are installed on the front, rear, sides, corners, and the upper part of the windshield inside the vehicle 7900, may be, for example, ultrasonic sensors or radar devices. The external information detection units 7920, 7926, and 7930, which are installed on the front nose, rear bumper, back door, and the upper part of the windshield inside the vehicle 7900, may be, for example, LIDAR devices. These external information detection units 7920 to 7930 are mainly used for detecting preceding vehicles, pedestrians, or obstacles.

[0258] Returning to Figure 72, the explanation continues. The external information detection unit 7400 causes the imaging unit 7410 to capture images of the area outside the vehicle and receives the captured image data. The external information detection unit 7400 also receives detection information from the connected external information detection unit 7420. If the external information detection unit 7420 is an ultrasonic sensor, radar device, or LIDAR device, the external information detection unit 7400 emits ultrasonic waves or electromagnetic waves and receives information on the received reflected waves. Based on the received information, the external information detection unit 7400 may perform object detection processing such as detecting people, vehicles, obstacles, signs, or characters on the road surface, or distance detection processing. Based on the received information, the external information detection unit 7400 may perform environmental recognition processing to recognize rainfall, fog, or road surface conditions. Based on the received information, the external information detection unit 7400 may calculate the distance to an object outside the vehicle.

[0259] Furthermore, the external information detection unit 7400 may perform image recognition processing or distance detection processing to recognize people, vehicles, obstacles, signs, or characters on the road surface based on the received image data. The external information detection unit 7400 may perform distortion correction or alignment processing on the received image data, and may also synthesize image data captured by different imaging units 7410 to generate an overhead view image or a panoramic image. The external information detection unit 7400 may also perform viewpoint transformation processing using image data captured by different imaging units 7410.

[0260] The in-vehicle information detection unit 7500 detects information inside the vehicle. The in-vehicle information detection unit 7500 is connected to, for example, a driver status detection unit 7510 that detects the driver's state. The driver status detection unit 7510 may include a camera that images the driver, a biosensor that detects the driver's biometric information, or a microphone that collects sounds inside the vehicle. The biosensor is installed, for example, on the seat or steering wheel and detects the biometric information of an occupant sitting in the seat or a driver holding the steering wheel. Based on the detection information input from the driver status detection unit 7510, the in-vehicle information detection unit 7500 may calculate the driver's level of fatigue or concentration, or determine whether the driver is dozing off. The in-vehicle information detection unit 7500 may perform processing such as noise cancellation on the collected audio signals.

[0261] The integrated control unit 7600 controls the overall operation of 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 implemented by a device that can be operated by the passenger, such as a touch panel, buttons, a microphone, a switch, or a lever. The integrated control unit 7600 may also receive data obtained by voice recognition of voice input from the microphone. The input unit 7800 may be, for example, a remote control device using infrared or other radio waves, or an externally connected device such as a mobile phone or PDA (Personal Digital Assistant) that is compatible with the operation of the vehicle control system 7000. The input unit 7800 may be, for example, a camera, in which case the passenger can input information by gesture. Alternatively, data obtained by detecting the movement of a wearable device worn by the passenger may be input. Furthermore, 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 using the above input unit 7800 and outputs it to the integrated control unit 7600. Passengers and others can input various data or instruct the vehicle control system 7000 to perform processing operations by operating this input unit 7800.

[0262] The storage unit 7690 may include a ROM (Read Only Memory) for storing various programs executed by a microcomputer, and a RAM (Random Access Memory) for storing various parameters, calculation results, or sensor values. The storage unit 7690 may also be implemented using a magnetic storage device such as an HDD (Hard Disk Drive), a semiconductor storage device, an optical storage device, or a magneto-optical storage device.

[0263] The general-purpose communication interface 7620 is a general-purpose communication interface that mediates communication between the external environment 7750 and various devices present in the external environment 7750. The general-purpose communication interface 7620 may implement cellular communication protocols such as GSM (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 known as Wi-Fi (registered trademark)) and Bluetooth (registered trademark). The general-purpose communication interface 7620 may connect, for example, to devices (e.g., application servers or control servers) located on an external network (e.g., the Internet, a cloud network, or a carrier-specific network) via a base station or access point. Furthermore, the general-purpose communication I / F 7620 may connect to terminals located near the vehicle (for example, terminals belonging to the driver, pedestrians, or shops, or MTC (Machine Type Communication) terminals) using, for example, P2P (Peer To Peer) technology.

[0264] The dedicated communication interface 7630 is a communication interface that supports communication protocols developed for use in vehicles. The dedicated communication interface 7630 may implement standard protocols such as WAVE (Wireless Access in Vehicle Environment), DSRC (Dedicated Short Range Communications), or cellular communication protocols, which are combinations of lower-layer IEEE 802.11p and upper-layer IEEE 1609. The dedicated communication interface 7630 typically performs V2X communication, a concept that includes one or more of the following: vehicle-to-vehicle communication, vehicle-to-infrastructure communication, vehicle-to-home communication, and vehicle-to-pedestrian communication.

[0265] The positioning unit 7640 performs positioning by receiving, for example, GNSS (Global Navigation Satellite System) signals from GNSS satellites (for example, GPS signals from GPS (Global Positioning System) satellites) and generates location information including the vehicle's latitude, longitude, and altitude. The positioning unit 7640 may also determine its current location by exchanging signals with a wireless access point, or it may acquire location information from a terminal such as a mobile phone, PHS, or smartphone that has a positioning function.

[0266] The beacon receiver 7650 receives radio waves or electromagnetic waves transmitted from, for example, a radio station installed on a road, and acquires information such as the current location, traffic congestion, road closures, or travel time. The functions of the beacon receiver 7650 may also be included in the dedicated communication interface 7630 described above.

[0267] The in-vehicle equipment interface 7660 is a communication interface that mediates connections between the microcomputer 7610 and various in-vehicle equipment 7760 located inside the vehicle. The in-vehicle equipment interface 7660 may establish a wireless connection using wireless communication protocols such as wireless LAN, Bluetooth®, NFC (Near Field Communication), or WUSB (Wireless USB). Alternatively, the in-vehicle equipment interface 7660 may establish a wired connection such as USB (Universal Serial Bus), HDMI® (High-Definition Multimedia Interface), or MHL (Mobile High-definition Link) via connection terminals (and cables if necessary) not shown. The in-vehicle equipment 7760 may include, for example, at least one of the following: a mobile device or wearable device owned by a passenger, or information equipment brought into or installed in the vehicle. The in-vehicle equipment 7760 may also include a navigation device that searches for a route to any destination. The in-vehicle equipment interface 7660 exchanges control signals or data signals with these in-vehicle equipment units 7760.

[0268] The in-vehicle network interface 7680 is an interface that mediates communication between the microcomputer 7610 and the communication network 7010. The in-vehicle network interface 7680 transmits and receives signals and other data in accordance with a predetermined protocol supported by the communication network 7010.

[0269] The microcomputer 7610 of the integrated control unit 7600 controls the vehicle control system 7000 according to various programs based on information acquired via at least one of the general-purpose communication I / F 7620, dedicated communication I / F 7630, positioning unit 7640, beacon receiver 7650, in-vehicle equipment I / F 7660, and in-vehicle network I / F 7680. For example, the microcomputer 7610 may calculate control target values ​​for the drive force generator, steering mechanism, or braking device based on acquired information from inside and outside the vehicle, and output control commands to the drive system control unit 7100. For example, the microcomputer 7610 may perform coordinated control aimed at realizing ADAS (Advanced Driver Assistance System) functions, including vehicle collision avoidance or impact mitigation, following driving based on distance between vehicles, maintaining vehicle speed, vehicle collision warning, or vehicle lane departure warning. Furthermore, the microcomputer 7610 may perform cooperative control for purposes such as autonomous driving, where the vehicle drives autonomously without driver intervention, by controlling the drive force generating device, steering mechanism, or braking device, etc., based on the acquired information about the vehicle's surroundings.

[0270] The microcomputer 7610 may generate three-dimensional distance information between the vehicle and surrounding structures, people, and other objects based on information acquired via at least one of the general-purpose communication I / F 7620, dedicated communication I / F 7630, positioning unit 7640, beacon receiver 7650, in-vehicle equipment I / F 7660, and in-vehicle network I / F 7680, and create local map information including surrounding information of the vehicle's current location. The microcomputer 7610 may also predict dangers such as vehicle collision, proximity of pedestrians, or entry into a closed road based on the acquired information, and generate a warning signal. The warning signal may be, for example, a signal to generate a warning sound or to illuminate a warning lamp.

[0271] The audio-image output unit 7670 transmits at least one of audio and image output signals to an output device capable of visually or audibly notifying the vehicle's occupants or those outside the vehicle. In the example of Figure 72, the output devices are exemplified as an audio speaker 7710, a display unit 7720, and an instrument panel 7730. The display unit 7720 may include, for example, at least one of an onboard display and a head-up display. The display unit 7720 may also have an AR (Augmented Reality) display function. The output device may be other devices other than these, such as headphones, wearable devices such as glasses-type displays worn by occupants, projectors, or lamps. If the output device is a display device, the display device visually displays the results obtained from various processes performed by the microcomputer 7610 or information received from other control units in various formats such as text, images, tables, and graphs. If the output device is an audio output device, the audio output device converts the audio signal, consisting of reproduced audio data or sound data, into an analog signal and outputs it audibly.

[0272] In the example shown in Figure 72, at least two control units connected via the communication network 7010 may be integrated into a single control unit. Alternatively, each control unit may be composed of multiple control units. Furthermore, the vehicle control system 7000 may include other control units not shown. Also, in the above description, some or all of the functions performed by one control unit may be assigned to other control units. In other words, as long as information is transmitted and received via the communication network 7010, predetermined calculation processing may be performed by any of the control units. Similarly, a sensor or device connected to one control unit may be connected to another control unit, and multiple control units may transmit and receive detection information to each other via the communication network 7010.

[0273] In the vehicle control system 7000 described above, the imaging optical system and imaging device of this disclosure can be applied to the imaging unit 7410 and the imaging units 7910, 7912, 7914, 7916, and 7918.

[0274] [5.2 Second Application Example] The technology relating to this disclosure can be applied to medical imaging systems. A medical imaging system is a medical system that uses imaging technology, such as an endoscope system or a microscope system.

[0275] [Endoscopic System] An example of an endoscopic system will be explained using Figures 74 and 75. Figure 74 is a diagram showing an example of the schematic configuration of an endoscopic system 5000 to which the technology of this disclosure can be applied. Figure 75 is a diagram showing an example of the configuration of an endoscope 5001 and a CCU (Camera Control Unit) 5039. Figure 74 illustrates a surgeon (e.g., a physician) 5067, who is a participant in the surgery, performing surgery on a patient 5071 on a patient bed 5069 using the endoscopic system 5000. As shown in Figure 74, the endoscopic system 5000 consists of an endoscope 5001, which is a medical imaging device, a CCU 5039, a light source device 5043, a recording device 5053, an output device 5055, and a support device 5027 that supports the endoscope 5001.

[0276] In endoscopic surgery, an insertion aid called a trocca 5025 is inserted into the patient 5071. Then, via the trocca 5025, the scope 5003 connected to the endoscope 5001 and surgical instruments 5021 are inserted into the body of the patient 5071. The surgical instruments 5021 include, for example, energy devices such as electrosurgical units or forceps.

[0277] Surgical images, which are medical images of the inside of the patient's body (5071) taken by the endoscope (5001), are displayed on the display device (5041). The surgeon (5067) performs the procedure on the surgical target using the surgical instruments (5021) while viewing the surgical images displayed on the display device (5041). Note that the medical images are not limited to surgical images; they may also be diagnostic images taken during the diagnosis.

[0278] [Endoscope] The endoscope 5001 is an imaging unit that images the inside of the patient 5071's body. For example, as shown in Figure 75, it is a camera 5005 that includes a focusing optical system 50051 that focuses incident light, a zoom optical system 50052 that changes the focal length of the imaging unit to enable optical zoom, a focusing optical system 50053 that changes the focal length of the imaging unit to enable focus adjustment, and a light-receiving element 50054. The endoscope 5001 generates a pixel signal by focusing light onto the light-receiving element 50054 via the connected scope 5003 and outputs the pixel signal to the CCU 5039 via a transmission system. The scope 5003 has an objective lens at its tip and is an insertion unit that guides light from the connected light source device 5043 into the patient 5071's body. The scope 5003 is, for example, a rigid scope in the case of a rigid endoscope, and a flexible scope in the case of a flexible endoscope. The scope 5003 may be a straight-viewing endoscope or an oblique-viewing endoscope. Furthermore, the pixel signal can be any signal based on the signal output from the pixel, such as a RAW signal or an image signal. Alternatively, the transmission system connecting the endoscope 5001 and the CCU 5039 may be equipped with memory to store parameters related to the endoscope 5001 and the CCU 5039. The memory may be located, for example, at the connection point of the transmission system or on the cable. For example, the factory settings of the endoscope 5001 and parameters that change during power-up may be stored in the transmission system's memory, and the operation of the endoscope may be modified based on the parameters read from the memory. The endoscope and transmission system may also be referred to as a set. The photodetector 50054 is a sensor that converts received light into a pixel signal, and is, for example, a CMOS (Complementary Metal Oxide Semiconductor) type image sensor. Preferably, the photodetector 50054 is a color image sensor having a Bayer array. Furthermore, the light-receiving element 50054 is preferably an image sensor having a number of pixels corresponding to a resolution of, for example, 4K (3840 horizontal pixels × 2160 vertical pixels), 8K (7680 horizontal pixels × 4320 vertical pixels), or square 4K (3840 or more horizontal pixels × 3840 or more vertical pixels). The light-receiving element 50054 may be a single sensor chip or multiple sensor chips.For example, a prism may be provided to separate the incident light into predetermined wavelength bands, and each wavelength band may be imaged by a different photodetector. Alternatively, multiple photodetectors may be provided for stereoscopic viewing. The photodetector 50054 may be a sensor that includes an image processing circuit within its chip structure, or it may be a Time of Flight (ToF) sensor. The transmission system may be, for example, an optical fiber cable or wireless transmission. Wireless transmission is only required if the pixel signals generated by the endoscope 5001 can be transmitted. For example, the endoscope 5001 and the CCU 5039 may be wirelessly connected, or the endoscope 5001 and the CCU 5039 may be connected via a base station in the operating room. In this case, the endoscope 5001 may simultaneously transmit not only the pixel signals but also information related to the pixel signals (for example, the processing priority of the pixel signals or synchronization signals). The endoscope may integrate the scope and camera, or a photodetector may be provided at the tip of the scope.

[0279] [CCU (Camera Control Unit)] The CCU 5039 is a control device that comprehensively controls the connected endoscope 5001 and light source device 5043. For example, as shown in Figure 75, it is an information processing device having an FPGA 50391, CPU 50392, RAM 50393, ROM 50394, GPU 50395, and I / F 50396. The CCU 5039 may also comprehensively control the connected display device 5041, recording device 5053, and output device 5055. For example, the CCU 5039 controls the irradiation timing, irradiation intensity, and type of light source of the light source device 5043. The CCU 5039 also performs image processing such as development processing (e.g., demosaicing) and correction processing on the pixel signals output from the endoscope 5001, and outputs the processed pixel signals (e.g., images) to an external device such as the display device 5041. Furthermore, the CCU 5039 transmits control signals to the endoscope 5001 to control its operation. The control signals include, for example, information regarding imaging conditions such as the magnification and focal length of the imaging unit. The CCU 5039 may also have an image downconversion function and be configured to simultaneously output high-resolution (e.g., 4K) images to the display device 5041 and low-resolution (e.g., HD) images to the recording device 5053.

[0280] Furthermore, the CCU 5039 may be connected to external devices (e.g., recording devices, display devices, output devices, support devices) via an IP converter that converts signals to a predetermined communication protocol (e.g., IP (Internet Protocol)). The connection between the IP converter and the external devices may consist of a wired network, or part or all of the network may be constructed as a wireless network. For example, the IP converter on the CCU 5039 side may have a wireless communication function and transmit the received video to an IP switcher or output-side IP converter via a wireless communication network such as a fifth-generation mobile communication system (5G) or a sixth-generation mobile communication system (6G).

[0281] [Light Source Device] The light source device 5043 is a device capable of irradiating light in a predetermined wavelength band, and includes, for example, a plurality of light sources and a light source optical system that guides the light from the plurality of light sources. The light sources are, for example, xenon lamps, LED light sources, and LD light sources. The light source device 5043 has, for example, LED light sources corresponding to each of the three primary colors R, G, and B, and emits white light by controlling the output intensity and output timing of each light source. In addition, the light source device 5043 may have a light source capable of irradiating special light used for special light observation, separate from the light source that irradiates normal light used for normal light observation. Special light is light in a predetermined wavelength band different from the normal light used for normal light observation, and includes, for example, near-infrared light (light with a wavelength of 760 nm or more), infrared light, blue light, and ultraviolet light. Normal light is, for example, white light or green light. In narrow-band light observation, which is a type of special light observation, by irradiating blue light and green light alternately, the wavelength dependence of light absorption in body tissue can be utilized to image predetermined tissues such as blood vessels on the surface of mucous membranes with high contrast. Furthermore, in fluorescence observation, a type of special light observation, excitation light is irradiated onto a drug injected into body tissue to excite it, and a fluorescence image is obtained by receiving the fluorescence emitted by the body tissue or the labeling drug. This makes it easier for the operator to visualize body tissues and other areas that are difficult to see with normal light. For example, in fluorescence observation using infrared light, infrared light having an excitation wavelength band is irradiated onto a drug such as indocyanine green (ICG) injected into body tissue, and the structure of the body tissue and the affected area can be made easier to visualize by receiving the fluorescence of the drug. In addition, in fluorescence observation, a drug that is excited by special light in the blue wavelength band and emits fluorescence in the red wavelength band (e.g., 5-ALA) may be used. The type of irradiation light of the light source device 5043 is set by the control of the CCU 5039. The CCU 5039 may have a mode in which normal light observation and special light observation are performed alternately by controlling the light source device 5043 and the endoscope 5001. In this case, it is preferable to superimpose information based on the pixel signals obtained by special light observation onto the pixel signals obtained by normal light observation. Furthermore, the special light observation may be infrared light observation, which involves irradiating with infrared light to view areas deeper than the organ surface, or multispectral observation utilizing hyperspectral spectroscopy. In addition, photodynamic therapy may be combined.

[0282] [Recording Device] The recording device 5053 is a device that records pixel signals (e.g., images) acquired from the CCU 5039, and is, for example, a recorder. The recording device 5053 records the images acquired from the CCU 5039 onto an HDD, SSD, or optical disc. The recording device 5053 may be connected to a hospital network and made accessible from equipment outside the operating room. The recording device 5053 may also have an image down-conversion or up-conversion function.

[0283] [Display Device] The display device 5041 is a device capable of displaying images, such as a display monitor. The display device 5041 displays a display image based on the pixel signals acquired from the CCU 5039. The display device 5041 may also function as an input device that enables eye-tracking, voice recognition, and gesture-based instruction input by equipping it with a camera and microphone.

[0284] [Output device] The output device 5055 is a device that outputs information acquired from the CCU 5039, and is, for example, a printer. The output device 5055 prints a print image on paper based on the pixel signals acquired from the CCU 5039.

[0285] [Support device] The support device 5027 is a multi-joint arm comprising a base portion 5029 having an arm control device 5045, an arm portion 5031 extending from the base portion 5029, and a holding portion 5032 attached to the tip of the arm portion 5031. The arm control device 5045 is composed of a processor such as a CPU and controls the driving of the arm portion 5031 by operating according to a predetermined program. The support device 5027 controls the position and orientation of the endoscope 5001 held by the holding portion 5032, for example, by controlling parameters such as the length of each link 5035 constituting the arm portion 5031 and the rotation angle and torque of each joint 5033 using the arm control device 5045. This allows the endoscope 5001 to be changed to a desired position or orientation, the scope 5003 to be inserted into the patient 5071, and the observation area inside the body to be changed. The support device 5027 functions as an endoscope support arm that supports the endoscope 5001 during surgery. As a result, the support device 5027 can act as a substitute for the scopist, who is an assistant holding the endoscope 5001. The support device 5027 may also be a device that supports the microscope device 5301, which will be described later, and can also be called a medical support arm. The support device 5027 may be controlled autonomously by the arm control device 5045, or it may be controlled by the arm control device 5045 based on user input. For example, the control method may be a master-slave system in which the support device 5027, acting as a slave device (replica device) which is a patient cart, is controlled based on the movement of the master device (primary device), which is the operator console at the user's location. Furthermore, the support device 5027 may be controlled remotely from outside the operating room.

[0286] The above describes an example of an endoscopic system 5000 to which the technology relating to this disclosure may be applied. For example, the technology relating to this disclosure may be applied to a microscope system.

[0287] [Microscope System] Figure 76 is a diagram showing an example of a schematic configuration of a microscope surgery system to which the technology of this disclosure may be applied. In the following description, components similar to those in the endoscope system 5000 are denoted by the same reference numerals, and redundant explanations thereof are omitted.

[0288] Figure 76 schematically shows a surgeon 5067 performing surgery on a patient 5071 on a patient bed 5069 using a microsurgical system 5300. For simplicity, Figure 76 omits the cart 5037 from the configuration of the microsurgical system 5300, and the microscope device 5301, which replaces the endoscope 5001, is shown in a simplified form. However, in this description, the microscope device 5301 may refer to the microscope unit 5303 located at the tip of the link 5035, or it may refer to the entire configuration including the microscope unit 5303 and the support device 5027.

[0289] As shown in Figure 76, during surgery, the image of the surgical site captured by the microscope device 5301 is displayed on a display device 5041 installed in the operating room using the microsurgery system 5300. The display device 5041 is positioned opposite the surgeon 5067, and the surgeon 5067 observes the surgical site through the image displayed on the display device 5041 and performs various procedures on the site, such as excising the affected area. The microsurgery system is used, for example, in ophthalmic surgery and neurosurgery.

[0290] Examples of endoscopic systems 5000 and microsurgical systems 5300 to which the technology relating to this disclosure may be applied have been described above. However, the systems to which the technology relating to this disclosure may be applied are not limited to these examples. For example, the support device 5027 may support other observation devices or other surgical instruments at its tip in place of the endoscope 5001 or the microscope unit 5303. Examples of such other observation devices include forceps, clamps, insufflation tubes for pneumoperitoneum, or energy treatment instruments for tissue incision or blood vessel sealing by cauterization. By supporting these observation devices and surgical instruments with the support device, it becomes possible to fix their position more stably than when medical staff support them manually, and the burden on medical staff can be reduced. The technology relating to this disclosure may also be applied to a support device that supports components other than the microscope unit.

[0291] The technology relating to this disclosure can be suitably applied to the camera 5005 among the configurations described above. In particular, the imaging optical system of this disclosure can be suitably applied to at least some of the optical systems in the camera 5005, including the condensing optical system 50051, the zoom optical system 50052, and the focusing optical system 50053.

[0292] <6. Other Embodiments> The technology described herein is not limited to the above-described embodiment and examples, and various modifications are possible.

[0293] For example, the shapes and numerical values ​​of each part shown in the above embodiment and example are merely examples of how to implement this technology, and the technical scope of this technology should not be interpreted in a restrictive way based on these.

[0294] Furthermore, the configuration may include a different number of lenses than those shown in the above embodiment and example. It may also include a lens that is substantially free of refractive power. Here, a lens that is substantially free of refractive power is a lens that does not have refractive power that would, in principle, affect the optical performance achieved by the lens system, such as a flat lens.

[0295] For example, this technology can also take the following configuration. According to this configuration, the configuration of each lens group is optimized to achieve good optical performance across the entire shooting distance range and enable miniaturization and weight reduction. This makes it possible to provide a compact and lightweight imaging optical system with good optical performance across the entire shooting distance range, and an imaging device equipped with such an imaging optical system.

[0296] [1] An imaging optical system comprising, in order from the object side toward the image plane side, a first lens group, a second lens group having positive refractive power, a third lens group, and at least one lens group positioned closer to the image plane than the third lens group, wherein during focusing, the second lens group and the third lens group, or the one lens group positioned closer to the image plane than the second lens group and the third lens group, move in the optical axis direction, and the first lens group has an image stabilization lens group that corrects blur by moving perpendicular to the optical axis, and satisfying the following condition: f2 / f < 0.7 ……(1) where f: focal length of the entire system when focused at infinity, f2: focal length of the second lens group. [2] The imaging optical system according to [1] above, further satisfying the following condition: βm < -0.5 ……(2) where βm: lateral magnification of the entire system at the shortest shooting distance. [3] The imaging optical system according to [1] or [2] above, further satisfying the following condition: 1.0 < f2 / l2 < 9.0 ... (3) where, f2: focal length of the second lens group l2: stroke amount in the optical axis direction from infinity to the shortest shooting distance of the second lens group. [4] Furthermore, an imaging optical system according to any one of [1] to [3] above that satisfies the following condition: 0.5 < |B1a| < 2.0 ... (4) where, B1a: blur correction coefficient of the image-stabilizing lens group in the infinity focus state defined by the following formula B1a = β1a × (1 - βb) β1a: lateral magnification of the image-stabilizing lens group βb: lateral magnification of the lens on the image plane side of the image-stabilizing lens group. [5] Furthermore, an imaging optical system according to any one of [1] to [4] above that satisfies the following condition: where, P2: focus sensitivity of the second lens group in the infinity focus state defined by the following formula P2 = β2 ２ × (1-βc ２) β2: Lateral magnification of the second lens group βc: Lateral magnification of the lens on the image plane side of the second lens group. [6] Furthermore, an imaging optical system according to any one of [1] to [5] above that satisfies the following condition: |f2 / f1| < 0.5 ……(6) where f1: focal length of the first lens group f2: focal length of the second lens group. [7] Furthermore, an imaging optical system according to any one of [1] to [6] above that satisfies the following condition: 0.5 < |f1a / f| < 2.5 ……(7) where f: focal length of the entire system when focused at infinity f1a: focal length of the vibration-damping lens group. [8] Furthermore, an imaging optical system according to any one of [1] to [7] above that satisfies the following condition: BF / f < 0.5 ……(8) where BF: distance on the optical axis from the lens surface closest to the image plane to the image plane when in focus at infinity (back focus) f: focal length of the entire system when in focus at infinity. [9] The imaging optical system according to any one of [1] to [8] above, further comprising a fourth lens group as the one lens group positioned closer to the image plane than the third lens group, wherein the second lens group and the fourth lens group move in the direction of the optical axis when focusing.

[10] The imaging optical system comprising, in order from the object side toward the image plane side, a first lens group, a second lens group having positive refractive power, a third lens group, and a positive lens group positioned closer to the image plane than the third lens group, wherein the second lens group and the positive lens group positioned closer to the image plane than the third lens group move in the direction of the optical axis when focusing, and satisfying the following conditional equation. f² / f < 0.7 ……(1) -3.0 < f / fl < -0.5 ……(9) where, f: focal length of the entire system when focused at infinity f²: focal length of the second lens group fl: focal length of the lens group closest to the image plane.

[11] Furthermore, the imaging optical system described in

[10] above that satisfies the following condition: βm < -0.5 ……(2) where, βm: lateral magnification of the entire system at the shortest shooting distance.

[12] Furthermore, the imaging optical system described in

[10] or

[11] above that satisfies the following condition:1.0 < f2 / l2 < 9.0 ……(3) where, f2: focal length of the second lens group l2: stroke amount in the optical axis direction from infinity to the shortest shooting distance of the second lens group.

[13] An imaging optical system according to any one of

[10] to

[12] above, having an image stabilizing lens group in the first lens group that corrects blur by moving in a direction perpendicular to the optical axis.

[14] An imaging optical system according to any one of

[10] to

[13] above, having an image stabilizing lens group in the first lens group that corrects blur by moving in a direction perpendicular to the optical axis, and further satisfying the following condition: 0.5 < |B1a| < 2.0 ……(4) where, B1a: blur correction coefficient of the image stabilizing lens group in the infinity focus state, defined by the following formula B1a = β1a × (1 - βb) β1a: lateral magnification of the image stabilizing lens group βb: lateral magnification of the lens on the image plane side of the image stabilizing lens group.

[15] Furthermore, an imaging optical system according to any one of

[10] to

[14] above that satisfies the following condition: 2.0 < |P2| < 5.0 ……(5) where P2: the focusing sensitivity of the second lens group in the infinity focus state, defined by the following formula P2 = β2. ２ × (1-βc ２) β2: Lateral magnification of the second lens group βc: Lateral magnification of the lens on the image plane side of the second lens group.

[16] Furthermore, an imaging optical system according to any one of

[10] to

[15] above that satisfies the following condition: |f2 / f1| < 0.5 ……(6) where f1: focal length of the first lens group f2: focal length of the second lens group.

[17] An imaging optical system according to any one of

[10] to

[16] above that has a vibration-damping lens group in the first lens group that corrects blur by moving in a direction perpendicular to the optical axis, and further satisfies the following condition: 0.5 < |f1a / f| < 2.5 ……(7) where f: focal length of the entire system when focused at infinity f1a: focal length of the vibration-damping lens group.

[18] Furthermore, an imaging optical system according to any one of

[10] to

[17] above that satisfies the following condition: BF / f < 0.5 ... (8) where BF: distance on the optical axis from the lens surface closest to the image plane to the image plane when in focus at infinity (back focus) f: focal length of the entire system when in focus at infinity.

[19] An imaging device that includes an imaging optical system and an image sensor that outputs an imaging signal corresponding to the optical image formed by the imaging optical system, wherein the imaging optical system comprises, in order from the object side toward the image plane side, a first lens group, a second lens group having positive refractive power, a third lens group, and at least one lens group positioned closer to the image plane than the third lens group, and when focusing, the second lens group and the third lens group, or the one lens group positioned closer to the image plane than the second lens group and the third lens group, move in the optical axis direction, and the first lens group has an anti-vibration lens group that corrects blur by moving perpendicular to the optical axis, and satisfies the following conditional equation. f2 / f < 0.7 ... (1) where f: focal length of the entire system when focused at infinity, and f2: focal length of the second lens group.

[20] An imaging device comprising an imaging optical system and an image sensor that outputs an imaging signal corresponding to an optical image formed by the imaging optical system, wherein the imaging optical system comprises, in order from the object side toward the image plane side, at least a first lens group, a second lens group having positive refractive power, a third lens group, and a positive lens group positioned closer to the image plane than the third lens group, and during focusing, the second lens group and the positive lens group positioned closer to the image plane than the third lens group move in the optical axis direction, satisfying the following conditions: f2 / f < 0.7 ... (1) -3.0 < f / fl < -0.5 ... (9) where, f: focal length of the entire system when focused at infinity f2: focal length of the second lens group fl: focal length of the lens group closest to the image plane.

[21] An imaging optical system according to any one of [1] to

[18] above, further comprising a lens that substantially has no refractive power.

[22] The imaging apparatus according to

[19] or

[20] , further comprising a lens that has substantially no refractive power as the imaging optical system.

[0297] This application claims priority based on Japanese Patent Application No. 2025-019556, filed with the Japan Patent Office on 7 February 2025, and all contents of that application are incorporated herein by reference.

[0298] Those skilled in the art will understand that various modifications, combinations, subcombinations, and changes can be conceived depending on design requirements and other factors, and that these fall within the scope of the attached claims and their equivalents.

Claims

Starting from the object side and moving towards the image plane side, The first lens group, A second lens group having positive refractive power, The third lens group, At least one lens group positioned closer to the image plane than the third lens group and Equipped with, During focusing, the second lens group and the third lens group, or the one lens group positioned closer to the image plane than the second and third lens groups, move in the optical axis direction. The first lens group includes an image-stabilizing lens group that corrects blur by moving in a direction perpendicular to the optical axis, The following conditions must be met: Imaging optical system. f2 / f<0.7...(1) however, f: Total focal length of the system when focused at infinity 　 f2: Focal length of the second lens group Let's assume that. 　 Furthermore, the following conditions must be met: The imaging optical system according to claim 1. βm<-0.5...(2) however, βm: Horizontal magnification of the entire system at the shortest focusing distance. Let's assume that. Furthermore, the following conditions must be met: The imaging optical system according to claim 1. 1.0<f2 / l2<9.0...(3) however, f2: Focal length of the second lens group 　 l2: The amount of stroke in the optical axis direction of the second lens group from infinity to the shortest focusing distance. Let's assume that. Furthermore, the following conditions must be met: The imaging optical system according to claim 1. 0.5<|B1a|<2.0...(4) however, B1a: The vibration correction coefficient of the vibration-damping lens group in the infinity focus state, as defined by the following formula. B1a=β1a×(1-βb) β1a: Lateral magnification of the vibration-damping lens group βb: Lateral magnification of the lens on the image plane side of the vibration-damping lens group. Let's assume that. Furthermore, the following conditions must be met: The imaging optical system according to claim 1. 2.0<|P2|<5.0...(5) however, P2: The focusing sensitivity of the second lens group in the infinity focus state, as defined by the following formula. P2=β2 ２ ×(1-βc ２ ) β2: Lateral magnification of the second lens group. βc: Lateral magnification of the lens on the image plane side of the second lens group. Let's assume that. Furthermore, the following conditions must be met: The imaging optical system according to claim 1. |f2 / f1|<0.5...(6) however, f1: Focal length of the first lens group 　 f2: Focal length of the second lens group Let's assume that. 　 Furthermore, the following conditions must be met: The imaging optical system according to claim 1. 0.5<|f1a / f|<2.5...(7) however, f: Total focal length of the system when focused at infinity f1a: Focal length of the vibration-damping lens group Let's assume that. 　 Furthermore, the following conditions must be met: The imaging optical system according to claim 1. BF / f<0.5...(8) however, BF: The distance along the optical axis from the lens surface closest to the image plane to the image plane when the image is focused at infinity (back focus). f: Total focal length of the system when focused at infinity Let's assume that. 　 The system includes a fourth lens group, which is positioned closer to the image plane than the third lens group. During focusing, the second lens group and the fourth lens group move in the direction of the optical axis. The imaging optical system according to claim 1. 　 Starting from the object side and moving towards the image plane side, The first lens group, A second lens group having positive refractive power, The third lens group, A positive lens group positioned closer to the image plane than the third lens group and It has at least the following features: During focusing, the positive lens group, which is positioned closer to the image plane than the second lens group and the third lens group, moves in the optical axis direction. The following conditions must be met: Imaging optical system. f2 / f<0.7...(1) -3.0<f / fl<-0.5...(9) however, f: Total focal length of the system when focused at infinity 　 f2: Focal length of the second lens group fl: Focal length of the lens group closest to the image plane Let's assume that. 　 Furthermore, the following conditions must be met: The imaging optical system according to claim 10. βm<-0.5...(2) however, βm: Horizontal magnification of the entire system at the shortest focusing distance. Let's assume that. Furthermore, the following conditions must be met: The imaging optical system according to claim 10. 1.0<f2 / l2<9.0...(3) however, f2: Focal length of the second lens group 　 l2: The amount of stroke in the optical axis direction of the second lens group from infinity to the shortest focusing distance. Let's assume that. 　 The first lens group includes an image-stabilizing lens group that corrects blur by moving in a direction perpendicular to the optical axis. The imaging optical system according to claim 10. 　 The first lens group includes an image-stabilizing lens group that corrects blur by moving in a direction perpendicular to the optical axis, Furthermore, the following conditions must be met: The imaging optical system according to claim 10. 0.5<|B1a|<2.0...(4) however, B1a: The vibration correction coefficient of the vibration-damping lens group in the infinity focus state, as defined by the following formula. B1a=β1a×(1-βb) β1a: Lateral magnification of the vibration-damping lens group βb: Lateral magnification of the lens on the image plane side of the vibration-damping lens group. Let's assume that. Furthermore, the following conditions must be met: The imaging optical system according to claim 10. 2.0<|P2|<5.0...(5) however, P2: The focusing sensitivity of the second lens group in the infinity focus state, as defined by the following formula. P2=β2 ２ ×(1-βc ２ ) β2: Lateral magnification of the second lens group. βc: Lateral magnification of the lens on the image plane side of the second lens group. Let's assume that. Furthermore, the following conditions must be met: The imaging optical system according to claim 10. |f2 / f1|<0.5...(6) however, f1: Focal length of the first lens group 　 f2: Focal length of the second lens group Let's assume that. 　 The first lens group includes an image-stabilizing lens group that corrects blur by moving in a direction perpendicular to the optical axis, Furthermore, the following conditions must be met: The imaging optical system according to claim 10. 0.5<|f1a / f|<2.5...(7) however, f: Total focal length of the system when focused at infinity f1a: Focal length of the vibration-damping lens group Let's assume that. 　 Furthermore, the following conditions must be met: The imaging optical system according to claim 10. BF / f<0.5...(8) however, BF: The distance along the optical axis from the lens surface closest to the image plane to the image plane when the image is focused at infinity (back focus). f: Total focal length of the system when focused at infinity Let's assume that. 　 It includes an imaging optical system and an image sensor that outputs an imaging signal corresponding to the optical image formed by the imaging optical system, The aforementioned yard optical system is Starting from the object side and moving towards the image plane side, The first lens group, A second lens group having positive refractive power, The third lens group, At least one lens group positioned closer to the image plane than the third lens group and Equipped with, During focusing, the second lens group and the third lens group, or the one lens group positioned closer to the image plane than the second and third lens groups, move in the optical axis direction. The first lens group includes an image-stabilizing lens group that corrects blur by moving in a direction perpendicular to the optical axis, The following conditions must be met: Imaging device. f2 / f<0.7...(1) however, f: Total focal length of the system when focused at infinity 　 f2: Focal length of the second lens group Let's assume that. 　 It includes an imaging optical system and an image sensor that outputs an imaging signal corresponding to the optical image formed by the imaging optical system, The aforementioned yard optical system is Starting from the object side and moving towards the image plane side, The first lens group, A second lens group having positive refractive power, The third lens group, A positive lens group positioned closer to the image plane than the third lens group and It has at least the following features: During focusing, the positive lens group, which is positioned closer to the image plane than the second lens group and the third lens group, moves in the optical axis direction. The following conditions must be met: Imaging device. f2 / f<0.7...(1) -3.0<f / fl<-0.5...(9) however, f: Total focal length of the system when focused at infinity 　 f2: Focal length of the second lens group fl: Focal length of the lens group closest to the image plane Let's assume that.

Images