Optical system and imaging device

Abstract

There is a need for a good optical system using composite optical elements. [Solution] The optical system L0 has a composite optical element HB in which resin lenses are bonded to both the object side and the image side of a glass lens. At least one of the resin lenses on the object side and the resin lens on the image side has an aspherical surface. Let the focal length of the optical system be f, and let bf be the air-equivalent distance on the optical axis from the lens surface closest to the image to the image plane when the optical system is in focus on an object at infinity. At this time, 0.00

Description

[Technical Field]

[0001] This invention relates to an optical system suitable for imaging. [Background technology]

[0002] Some optical systems used for imaging employ techniques to shorten the overall length and reduce weight by increasing the refractive power of each lens, while simultaneously reducing the resulting aberrations using aspherical lenses. Aspherical lenses include composite optical elements in which a resin layer forming an aspherical surface is provided on a glass lens. Patent documents 1 and 2 disclose optical systems using composite optical elements. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2012-048199 [Patent Document 2] Japanese Patent Publication No. 2015-215399 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] There is a need for a good optical system using composite optical elements. [Means for solving the problem]

[0005] One aspect of the present invention is an optical system having a composite optical element in which resin lenses are bonded to both the object side and the image side of a glass lens. At least one of the resin lenses on the object side and the resin lens on the image side is characterized by having an aspherical surface. Furthermore, when the focal length of the optical system is f and the air-equivalent distance on the optical axis from the lens surface closest to the image to the image plane when the optical system is in focus on an object at infinity is bf, 0.00 <bf / f≦1.25 It is characterized by satisfying the following conditions. Furthermore, an imaging device equipped with the above optical system also constitutes another aspect of the present invention.

Advantages of the Invention

[0006] According to the present invention, a good optical system using a composite optical element can be provided.

Brief Description of the Drawings

[0007] [Figure 1] Cross-sectional view of the optical system of Example 1 [Figure 2] Longitudinal aberration diagram of the optical system of Example 1 [Figure 3] Cross-sectional view of the optical system of Example 2 [Figure 4] Longitudinal aberration diagram of the optical system of Example 2 [Figure 5] Cross-sectional view of the optical system of Example 3 [Figure 6] Longitudinal aberration diagram of the optical system of Example 3 [Figure 7] Cross-sectional view of the optical system of Example 4 [Figure 8] Longitudinal aberration diagram of the optical system of Example 4 [Figure 9] Cross-sectional view of the optical system of Example 5 [Figure 10] Longitudinal aberration diagram of the optical system of Example 5 [Figure 11] Cross-sectional view of the optical system of Example 6 [Figure 12] Longitudinal aberration diagram of the optical system of Example 6 [Figure 13] Cross-sectional view of the optical system of Example 7 [Figure 14] Longitudinal aberration diagram of the optical system of Example 7 [Figure 15] Cross-sectional view of the optical system of Example 8 [Figure 16] Longitudinal aberration diagram of the optical system of Example 8 [Figure 17] Cross-sectional view of the optical system of Example 9 [Figure 18] Longitudinal aberration diagram at the wide-angle end of the optical system of Example 9 [Figure 19] Longitudinal aberration diagram at the telephoto end of the optical system of Example 9 [Figure 20] Cross-sectional view of the optical system of Example 10 [Figure 21] Longitudinal aberration diagram at the wide-angle end of the optical system of Example 10 [Figure 22] Longitudinal aberration diagram of the optical system of Example 10 at the telephoto end. [Figure 23] Cross-sectional view of the optical system in Example 11 [Figure 24] Longitudinal aberration diagram of the optical system of Example 11 at the wide-angle end. [Figure 25] Longitudinal aberration diagram of the optical system of Example 11 at the telephoto end. [Figure 26] Cross-sectional view of the optical system in Example 12 [Figure 27] Longitudinal aberration diagram at the wide-angle end of the optical system in Example 12 [Figure 28] Longitudinal aberration diagram of the optical system of Example 12 at the telephoto end. [Figure 29] Cross-sectional view of the optical system in Example 13 [Figure 30] Longitudinal aberration diagram at the wide-angle end of the optical system in Example 13 [Figure 31] Longitudinal aberration diagram of the optical system of Example 13 at the telephoto end. [Figure 32] Cross-sectional view of the optical system in Example 14 [Figure 33] Longitudinal aberration diagram at the wide-angle end of the optical system in Example 14 [Figure 34] Longitudinal aberration diagram of the optical system of Example 14 at the telephoto end. [Figure 35] Schematic diagram of an imaging device using the optical systems of Examples 1 to 14 [Modes for carrying out the invention]

[0008] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0009] The optical systems of each embodiment can be used in various imaging devices such as digital video cameras, digital still cameras, television cameras, surveillance cameras, and silver halide film cameras.

[0010] Figures 1, 3, 5, 7, 9, 11, 13, 15, 17, 20, 23, 26, 29, and 32 show cross-sections of the optical systems of Examples 1 to 14 when they are in focus on an object at infinity (hereinafter referred to as the infinity focus state). In each figure, the left side is the object side (front side), and the right side is the image side (back side).

[0011] The optical system of each embodiment has multiple lens groups. A lens group is a collection of one or more lenses that move together or remain stationary in the optical axis direction during zooming and focusing. That is, the distance between adjacent lens groups changes during zooming and focusing. A lens group may include an aperture diaphragm. In a zoom lens, the wide-angle end and telephoto end represent the zoom states of the maximum angle of view (shortest focal length) and minimum angle of view (maximum focal length), respectively, when the moving lens group is positioned at both ends of the range that is mechanically or controllably movable along the optical axis.

[0012] In each diagram, Li represents the i-th lens group when counted from the object side. SP is the aperture diaphragm that determines the light beam at the widest F-number, and IP is the image plane. The image plane IP is where the imaging surface (light-receiving surface) of an image sensor such as a CCD sensor or CMOS sensor, or the film surface (photosensitive surface) of a silver halide film, is located. Furthermore, FP is a flare cut diaphragm that cuts out unwanted light. Note that the parallel plates on the object side of the image plane IP represent optical blocks corresponding to optical filters, faceplates, low-pass filters, infrared cut filters, etc.

[0013] Below the lens group that moves during zooming, the trajectory of the lens group as it zooms from the wide-angle end to the telephoto end is highlighted with an arrow. In addition, one or more lens groups marked "focus" move in the direction of the arrow when focusing from infinity to close distance.

[0014] First, we will describe the aspects common to each embodiment. The optical system of each embodiment uses a composite optical element. In this specification, a composite optical element is an optical element in which three or more optical elements, including a first, second, and third optical element, are joined together to form an integrated element. The optical elements are joined together by bonding means such as an adhesive. The second optical element, which serves as a substrate, is formed from an inorganic glass material. The first optical element, which is joined to one side of the second optical element, is formed from an organic composite material. The third optical element, which is positioned furthest from the first optical element, is also formed from an organic composite material.

[0015] The optical system of each embodiment has a composite optical element in which a first optical element and a third optical element, which are a resin lens on the object side and a resin lens on the image side, are bonded to the object-side and image-side surfaces of a glass lens, which is a second optical element. At least one of the resin lens on the object side and the resin lens on the image side has an aspherical surface.

[0016] In each embodiment, the optical system preferably satisfies the following condition (1), where f is the focal length of the entire optical system and bf is the air-equivalent distance on the optical axis from the image-side lens surface (final surface) to the image plane in the infinity focus state.

[0017] 0.00 <bf / f≦1.25 (1) The conditions in equation (1) indicate an appropriate relationship between the back focus of the optical system at infinity focus and the overall focal length. If bf / f falls below the lower limit of equation (1), the optical system will not be able to form a real image, which is undesirable. If bf / f exceeds the upper limit of equation (1), the back focus will become too large, resulting in an undesirable optical system.

[0018] By having the above configuration and satisfying the conditions of equation (1), it is possible to realize a compact, lightweight optical system with high optical performance and excellent environmental resistance using composite optical elements.

[0019] Furthermore, it is more preferable to set the lower limit of equation (1) to 0.1, 0.2, or 0.3. Also, it is more preferable to set the upper limit of equation (1) to 1.20, 1.15, or 1.12.

[0020] Furthermore, it is preferable that the optical system of each embodiment satisfies at least one of the conditions of the following equations (2) to (12) and conditions not represented by the equations.

[0021] In each embodiment, the optical system preferably satisfies the following condition (2), where Da is the central thickness (thickness on the optical axis) of the resin lens on the object side of the composite optical element and Db is the central thickness of the resin lens on the image side.

[0022] 0.25 ≤ Da / Db ≤ 4.00 (2) The conditions in equation (2) indicate an appropriate relationship between the central thicknesses of the resin lenses on the object side and the image side. If Da / Db falls below the lower limit of equation (2), it is undesirable because the surface shape and optical properties of the image-side resin lens will fluctuate significantly due to changes in the environment such as temperature and humidity, making it difficult to maintain the optical performance of the optical system. If Da / Db exceeds the upper limit of equation (2), it is also undesirable because the surface shape and optical properties of the object-side resin lens will fluctuate significantly due to changes in the environment, making it difficult to maintain the optical performance. In other words, by satisfying these conditions, it is possible to realize an optical system with superior environmental resistance and high optical performance.

[0023] Furthermore, it is more preferable to set the lower limit of equation (2) to 0.50, 0.60, or 0.67. Also, it is more preferable to set the upper limit of equation (2) to 2.00, 1.50, or 1.20.

[0024] In the optical systems of Examples 2, 3, 5, 6, 7, 8, and 11, it is preferable that the composite optical element has a positive refractive power. Satisfying this condition reduces spherical aberration and sagittal image plane tilt, making it easier to obtain a compact, lightweight system with high optical performance.

[0025] The optical systems of Examples 2, 3, 5, 6, 7, 8 and 11 preferably satisfy the following condition of equation (3), where Ndp is the refractive index of the glass lens of the composite optical element having the positive refractive power described above, at the d line.

[0026] 1.45 ≤ Ndp ≤ 2.10 (3) The conditions in equation (3) indicate an appropriate range for the refractive index of the glass lens in a composite optical element. If Ndp exceeds the upper limit of equation (3), the negative Petzval sum becomes too large, resulting in overcorrection of field curvature, which is undesirable. If Ndp falls below the lower limit of equation (3), the positive Petzval sum becomes too large, making it difficult to correct field curvature, which is also undesirable.

[0027] Furthermore, it is more preferable to set the lower limit of equation (3) to 1.46, 1.47, or 1.48. Also, it is more preferable to set the upper limit of equation (3) to 2.05, 2.00, or 1.96.

[0028] In the optical systems of Examples 1, 4, 9, 10, 12, 13, and 14, it is preferable that the composite optical element has a negative refractive power. Satisfying this condition reduces spherical aberration and sagittal image plane tilt, making it easier to obtain a compact, lightweight system with high optical performance.

[0029] In each of the embodiments 1, 4, 9, 10, 12, 13, and 14, it is preferable that the optical systems satisfy the following condition of equation (4), where Ndn is the refractive index of the glass lens of the composite optical element having the negative refractive power described above, at the d line.

[0030] 1.45 ≤ Ndn ≤ 2.10 (4) The conditions in equation (4) indicate an appropriate range for the refractive index of the glass lens in the composite optical element. If Ndn exceeds the upper limit of equation (4), the positive Petzval sum becomes too large, making it difficult to correct for field curvature, which is undesirable. If Ndn falls below the lower limit of equation (4), the negative Petzval sum becomes too large, resulting in overcorrection of field curvature, which is also undesirable.

[0031] Furthermore, it is more preferable to set the lower limit of equation (4) to 1.46, 1.48, or 1.50. Also, it is more preferable to set the upper limit of equation (4) to 2.05, 2.00, or 1.97.

[0032] In each embodiment, the optical system preferably satisfies the following condition (5), where Ndg is the refractive index of the glass lens of the composite optical element at the d line, and Nda is the average of the refractive index Nd1 of the resin lens on the object side at the d line and the refractive index Nd2 of the resin lens on the image side at the d line.

[0033] 0.0 < |Ndg - Nda| ≤ 0.6 (5) The conditions in equation (5) indicate an appropriate relationship between the refractive indices of the resin lens on the object side, the glass lens, and the resin lens on the image side of a composite optical element. Satisfying these conditions makes it possible to effectively correct various aberrations, especially field curvature, at the junction between the glass lens and the resin lens. If |Ndg-Nda| exceeds the upper limit of equation (5), the optical properties of the resin lens will fluctuate significantly due to environmental changes, making it difficult to maintain the optical performance of the optical system, which is undesirable. If |Ndg-Nda| falls below the lower limit of equation (5), it becomes impossible to effectively correct various aberrations at the junction between the glass lens and the resin lens, which is also undesirable.

[0034] Furthermore, it is preferable to set the upper limit of equation (5) to 0.56, 0.52, or 0.48.

[0035] In each embodiment, the optical system preferably satisfies the following condition (6), where νdg is the Abbe number with respect to the d line of the glass lens in the composite optical element, and νda is the average of the Abbe number νd1 with respect to the d line of the resin lens on the object side and the Abbe number νd2 with respect to the d line of the resin lens on the image side.

[0036] 0 < |νdg - νda| ≤ 60 (6) The conditions in equation (6) indicate an appropriate relationship between the Abbe numbers of the resin lens on the object side, the glass lens, and the resin lens on the image side of a composite optical element. Satisfying these conditions makes it possible to effectively correct various aberrations, especially color correction, at the junction between the glass lens and the resin lens. If |νdg-νda| exceeds the upper limit of equation (6), the optical properties of the resin lens will fluctuate significantly due to environmental changes, making it difficult to maintain the optical performance of the optical system, which is undesirable. If |νdg-νda| falls below the lower limit of equation (6), it becomes impossible to effectively correct various aberrations at the junction between the glass lens and the resin lens, which is also undesirable.

[0037] Furthermore, it is preferable to set the upper limit of equation (6) to 58, 56, 54, or 52.

[0038] In each embodiment, the optical system preferably satisfies the following condition (7), where Tmax is the maximum thickness and Tmin is the minimum thickness of the resin lenses on the object side and image side, respectively, on the optical axis within the effective region (effective diameter) of the composite optical element. The effective region (effective diameter) is the region through which the light rays contributing to image formation pass.

[0039] 1.0 ≤ Tmax / Tmin ≤ 10.0 (7) The conditions in equation (7) indicate an appropriate range for the thickness variation ratio of the resin lens in a composite optical element. If Tmax / Tmin exceeds the upper limit of equation (7), the thickness variation ratio of the resin lens becomes too large, making the lens surface more susceptible to deformation due to environmental changes, which is undesirable. If Tmax / Tmin falls below the lower limit of equation (7), the aspherical amount of the resin lens becomes too small, making it difficult to correct various aberrations, which is also undesirable.

[0040] Furthermore, it is preferable to set the upper limit of equation (7) to 9.0, 8.5, 8.0, or 5.0.

[0041] In the optical system of each embodiment, it is preferable that the central thickness Da of the resin lens on the object side and the central thickness Db of the resin lens on the image side of the composite optical element satisfy the following conditions of equations (8) and (9).

[0042] 0.025 ≤ Da ≤ 0.250 (8) 0.025 ≤ Db ≤ 0.250 (9) The conditions in equations (8) and (9) indicate the appropriate range of thickness for the resin lenses on the object side and image side of a composite optical element. If Da and Db exceed the upper limits of equations (8) and (9), the central thickness of each resin lens becomes too large, making the lens surface more susceptible to deformation due to environmental changes, which is undesirable. If Da and Db fall below the lower limits of equations (8) and (9), the aspherical amount of each resin lens becomes too small, making it difficult to correct various aberrations, which is also undesirable.

[0043] Furthermore, it is more preferable to set the lower limit of equations (8) and (9) to 0.030, 0.040, or 0.045. Also, it is more preferable to set the upper limit of equations (8) and (9) to 0.200, 0.150, or 0.120.

[0044] In each embodiment, the optical system preferably satisfies the following condition (10), where Xd is the distance along the optical axis from the lens surface on the aperture side of the composite optical element's resin lens (hereinafter referred to as the aperture-side resin lens surface) to the aperture, and TD is the distance along the optical axis from the lens surface closest to the object (frontmost) of the optical system to the lens surface closest to the image (final surface).

[0045] 0.00 <Xd / TD≦0.80 (10) The conditions in equation (10) indicate an appropriate relationship between the distance from the aperture-side resin lens surface to the aperture diaphragm of the composite optical element and the distance from the frontmost to the final surface of the optical system. As the distance from the aperture-side resin lens surface to the aperture diaphragm increases, the effective diameter of the aperture-side resin lens surface increases, and the aspherical amount increases. If Xd / TD exceeds the upper limit of equation (10), the thickness variation ratio of the resin lens on the aperture diaphragm side becomes too large, making the aperture-side resin lens surface more susceptible to deformation due to environmental changes, which is undesirable. If Xd / TD falls below the lower limit of equation (10), the aperture-side resin lens surface and the aperture diaphragm physically interfere with each other, which is undesirable.

[0046] Furthermore, it is preferable to set the upper limit of equation (10) to 0.70, 0.60, or 0.53.

[0047] In the optical systems of each embodiment, it is preferable that both the resin lens on the object side and the resin lens on the image side of the composite optical element have aspherical surfaces. Having aspherical surfaces on both resin lenses allows for an appropriate amount of aspheric surface on one side, thereby suppressing deformation of the lens surface due to environmental changes.

[0048] In each embodiment, the optical system preferably satisfies the following condition (11), where Tg (°C) is the transition point of the glass lens of the composite optical element.

[0049] 450 ≤ Tg ≤ 800 (11) The conditions in equation (11) indicate an appropriate range for the transition point of a glass lens. The transition point is one of the phase changes of glass, and is the temperature at which it transitions from an amorphous solid to a supercooled liquid. If Tg exceeds the upper limit of equation (11), the molding temperature of the glass lens becomes too high, which is undesirable. If Tg falls below the lower limit of equation (11), the glass lens becomes brittle and difficult to process, which is also undesirable.

[0050] Furthermore, it is preferable to set the lower limit of equation (11) to 455. Also, it is preferable to set the upper limit of equation (11) to 750.

[0051] In the optical systems of each embodiment, the material of the resin lens is preferably a photocurable resin. Compared to thermosetting resins, photocurable resins allow the resin lens to be molded into the required shape at a lower temperature, and also allow for the production of a resin lens that is less prone to deformation, thus providing the optical system with high optical performance.

[0052] The optical system of each embodiment has a tint of the glass lens of the composite optical element λ 80 In this case, it is preferable that the following condition of equation (12) is satisfied.

[0053] 300 ≤ λ 80 ≤450 (12) The conditions in equation (12) indicate an appropriate range for the degree of tint at 80% transmittance of a glass lens. The degree of tint indicates the degree of coloration of the optical glass and is obtained by measuring the spectral transmittance, including reflection loss, of a 10 mm thick glass sample according to JOGIS-02, and calculating the wavelength of 80% transmittance from the resulting spectral transmittance curve. λ 80 If λ exceeds the upper limit of equation (12), the transmittance on the short-wavelength side (blue side) of the optical system decreases, which is undesirable because it reduces the color reproduction of objects. 80 If the value falls below the lower limit of equation (12), it becomes difficult to process the resin lens during photocuring, which is undesirable.

[0054] Furthermore, it is preferable to set the lower limit of equation (12) to 302. Also, it is preferable to set the upper limit of equation (11) to 430.

[0055] Next, the optical systems of each embodiment will be described. [Examples]

[0056] The optical system L0 of Embodiment 1 shown in Figure 1 consists of a front group, an aperture diaphragm SP, and a rear group, arranged in order from the object side to the image side. The composite optical element HB included in the rear group has negative refractive power. When focusing from infinity to near distance, the entire optical system moves towards the object side. [Examples]

[0057] The optical system L0 of Embodiment 2 shown in Figure 3 consists of a front group, an aperture diaphragm SP, and a rear group, arranged in order from the object side to the image side. The composite optical element HB included in the rear group has a positive refractive power. When focusing from infinity to near distance, the entire optical system moves towards the object side. [Examples]

[0058] The optical system L0 of Embodiment 3 shown in Figure 5 consists of a front group, an aperture diaphragm SP, and a rear group, arranged in order from the object side to the image side. The composite optical element HB included in the rear group has a positive refractive power. When focusing from infinity to near distance, the entire optical system moves towards the object side. [Examples]

[0059] The optical system L0 of Embodiment 4 shown in Figure 7 consists of a first lens group L1 with positive refractive power and a second lens group L2 with positive refractive power, arranged sequentially from the object side to the image side. The first lens group L1 includes an aperture diaphragm SP. The composite optical element HB included in the first lens group L1 has negative refractive power. When focusing from infinity to near distance, the first lens group L1 moves towards the object side. [Examples]

[0060] The optical system L0 of Embodiment 5 shown in Figure 9 consists of a first lens group L1 and a second lens group L2, both with positive refractive power, arranged sequentially from the object side to the image side. The first lens group L1 includes an aperture diaphragm SP. The composite optical element HB included in the first lens group L1 has positive refractive power. When focusing from infinity to near distance, the first lens group moves towards the object side. [Examples]

[0061] The optical system L0 of Embodiment 6 shown in Figure 11 consists of a first lens group L1 and a second lens group L2, both with positive refractive power, arranged sequentially from the object side to the image side. The first lens group L1 includes an aperture diaphragm SP. The composite optical element HB included in the first lens group L1 has positive refractive power. When focusing from infinity to near distance, the first lens group L1 moves towards the object side. [Examples]

[0062] The optical system L0 of Embodiment 7 shown in Figure 13 consists of a first lens group L1 and a second lens group L2, both with positive refractive power, arranged sequentially from the object side to the image side. The first lens group L1 includes an aperture diaphragm SP. The composite optical element HB included in the first lens group L1 has positive refractive power. When focusing from infinity to near distance, the first lens group L1 moves towards the object side. [Examples]

[0063] The optical system L0 of Embodiment 8 shown in Figure 15 consists of a first lens group L1 with negative refractive power, a second lens group L2 with positive refractive power, and a third lens group L3 with positive refractive power, arranged in order from the object side to the image side. The third lens group L3 includes an aperture diaphragm SP closest to the object. The composite optical element HB included in the third lens group L3 has positive refractive power. When focusing from infinity to near distance, the second lens group L2 and the third lens group L3 move towards the object side. [Examples]

[0064] The optical system L0 of Embodiment 9 shown in Figure 17 is composed of a first lens group L1 with negative refractive power, a second lens group L2 with positive refractive power, a third lens group L3 with negative refractive power, and a fourth lens group L4 with positive refractive power, arranged in order from the object side to the image side. The second lens group L2 includes an aperture diaphragm SP. The composite optical element HB included in the first lens group L1 has negative refractive power. When zooming from the wide-angle end to the telephoto end, the second lens group L2 and the third lens group L3 move towards the object side. When focusing from infinity to near distance, the third lens group L3 moves towards the image side. [Examples]

[0065] The optical system L0 of Embodiment 10 shown in Figure 20 consists of a first lens group L1 with negative refractive power, a second lens group L2 with positive refractive power, a third lens group L3 with negative refractive power, and a fourth lens group L4 with positive refractive power, arranged in order from the object side to the image side. The second lens group L2 includes an aperture diaphragm SP. The composite optical element HB included in the fourth lens group L4 has negative refractive power. When zooming from the wide-angle end to the telephoto end, the second lens group L2 and the third lens group L3 move towards the object side. When focusing from infinity to near distance, the third lens group L3 moves towards the image side. [Examples]

[0066] The optical system L0 of Embodiment 11 shown in Figure 23 consists of a first lens group L1 with negative refractive power, a second lens group L2 with positive refractive power, a third lens group L3 with negative refractive power, and a fourth lens group L4 with positive refractive power, arranged in order from the object side to the image side. The second lens group L2 includes an aperture diaphragm SP. The composite optical element HB included in the fourth lens group L4 has positive refractive power. When zooming from the wide-angle end to the telephoto end, the second lens group L2 and the third lens group L3 move towards the object side. When focusing from infinity to near distance, the third lens group L3 moves towards the image side. [Examples]

[0067] The optical system L0 of Embodiment 12 shown in Figure 26 consists of a first lens group L1 with negative refractive power, a second lens group L2 with positive refractive power, and a third lens group L3 with positive refractive power, arranged in order from the object side to the image side. The second lens group L2 includes an aperture diaphragm SP. The composite optical element HB included in the first lens group L1 has negative refractive power. When zooming from the wide-angle end to the telephoto end, the first lens group L1 and the second lens group L2 move toward the object side. When focusing from infinity to near distance, the first lens group L1 moves toward the object side. [Examples]

[0068] The optical system L0 of Embodiment 13 shown in Figure 29 is composed of a first lens group L1 with positive refractive power, a second lens group L2 with negative refractive power, a third lens group L3 with positive refractive power, a fourth lens group L4 with positive refractive power, and a fifth lens group L5 with negative refractive power, arranged in order from the object side to the image side. The third lens group L3 includes an aperture diaphragm SP. The composite optical element HB included in the third lens group L3 has negative refractive power. When zooming from the wide-angle end to the telephoto end, the first lens group L1, the third lens group L3, the fourth lens group L4, and the fifth lens group L5 move towards the object side. When focusing from infinity to near distance, the fifth lens group L5 moves towards the image side. [Examples]

[0069] The optical system L0 of Embodiment 14 shown in Figure 32 consists of a first lens group L1 with positive refractive power, a second lens group L2 with negative refractive power, a third lens group L3 with positive refractive power, a fourth lens group L4 with positive refractive power, and a fifth lens group L45 with negative refractive power, arranged in order from the object side to the image side. The third lens group L3 includes an aperture diaphragm SP. The composite optical element HB included in the third lens group L3 has negative refractive power. When zooming from the wide-angle end to the telephoto end, the first lens group L1, the third lens group L3, the fourth lens group L4, and the fifth lens group L5 move toward the object side. When focusing from infinity to near distance, the fifth lens group L5 moves toward the image side.

[0070] [Numerical example] The following shows numerical examples 1 to 14, corresponding to each of Examples 1 to 14. In each numerical example, the surface number i indicates the order of the optical surfaces counted from the object side. r is the radius of curvature of the optical surface (mm), and d is the distance on the optical axis between the i-th optical surface and the (i+1)th optical surface (mm). nd and νd represent the refractive index of the optical material at the d-line and the Abbe number with respect to the d-line of the optical material between the i-th optical surface and the (i+1)th optical surface, respectively. The Abbe number νd with respect to the d-line is given by Nd, NF, and NC, respectively, when the refractive indices of the optical material at the d-line (587.6 nm), F-line (486.1 nm), and C-line (656.3 nm), νd = (Nd-1) / (NF-NC) It is represented by

[0071] In each numerical example, the focal length (mm), F-number, and half angle of view (°) are all values when the optical system of each numerical example is in the infinitely focused state. BF indicates the back focus. The back focus is the air-converted value of the distance on the optical axis from the final surface of the optical system to the paraxial image plane. The overall lens length is the value obtained by adding the back focus to the distance on the optical axis from the frontmost surface to the final surface of the optical system.

[0072] The asterisk attached to the surface number indicates that the optical surface has an aspherical shape. The aspherical shape is defined as follows: when X is the displacement amount from the vertex of the surface in the optical axis direction, h is the height from the optical axis in the direction perpendicular to the optical axis, R is the paraxial radius of curvature, K is the conic constant, and A4, A6, A8, and A10 are the aspherical coefficients of each order, x = (h 2 / R) / [1 + {1 - (1 + K)(h / R) 2} 1 / 2 + A4 × h 4 + A6 × h 6 + A8 × h 8 + A10 × h 10 It is represented by. In the conic constant and aspherical coefficients, "e±XX" means "×10±XX".

[0073] Figures 2, 4, 6, 8, 10, 12, 14, and 16 respectively show the longitudinal aberrations (spherical aberration, astigmatism, distortion, and chromatic aberration) in the infinitely focused state of the optical systems of numerical examples 1 to 8. In the spherical aberration diagram, Fno indicates the F-number. The solid line represents the spherical aberration at the d-line (wavelength 587.6 nm), and the two-dot chain line represents the spherical aberration at the g-line (wavelength 435.8 nm). In the astigmatism diagram, the solid line S represents the astigmatism at the sagittal image plane, and the dashed line M represents the astigmatism at the meridional image plane. The distortion aberration diagram shows the distortion aberration at the d-line. The chromatic aberration diagram shows the lateral chromatic aberration at the g-line. ω is the half angle of view (°).

[0074] Furthermore, Figures 18, 21, 24, 27, 30, and 33 show the lateral aberrations of the optical systems of numerical examples 9 to 14 at the wide-angle end and in focus at infinity, respectively, while Figures 19, 22, 25, 28, 31, and 34 show the lateral aberrations of the optical systems of numerical examples 9 to 14 at the telephoto end and in focus at infinity, respectively.

[0075] [Numerical Example 1] Surface data Face number rd nd νd 1 54.965 5.06 1.72916 54.7 2 454.562 0.20 3 32.840 4.54 2.00100 29.1 4 47.773 1.19 5 64.718 2.50 1.67139 31.3 6 21.630 10.79 7 (aperture) ∞ 8.65 8 -25.507 1.50 1.77830 23.9 9 72.662 8.55 1.87070 40.7 10 -29.623 0.70 11* -27.069 0.05 1.53344 52.7 12 -27.050 1.50 1.63980 34.5 13 310.669 0.05 1.53344 52.7 14* 310.433 1.05 15 -1523.610 5.04 1.88100 40.1 16 -46.917 0.20 17 155.900 6.95 1.85033 42.7 18 -57.600 (variable) 19 ∞ 2.00 1.51633 64.1 20 ∞ (Variable) Image plane ∞ Aspherical data Page 11 K = 0.00000e+00 A 4=-4.61297e-06 A 6= 2.83055e-08 A 8=-9.39948e-11 A10 = 1.18880e-13 Page 14 K = 0.00000e+00 A 4=-3.44332e-07 A 6= 1.88153e-08 A 8=-5.99682e-11 A10 = 6.52219e-14 Various data Focal length 51.70 F-number 1.24 Half-angle (°): 22.71 Image height 21.64 Lens length 96.19 BF 37.67 d18 35.55 d20 0.80 [Numerical Example 2] Surface data Face number rd nd νd 1 44.635 5.83 1.81550 44.5 2 197.963 0.20 3 30.449 3.94 2.00069 25.5 4 36.790 1.57 5 51.856 1.79 1.59270 35.3 6 19.660 11.37 7 (aperture) ∞ 6.85 8 -26.391 1.50 1.80835 22.6 9 39.926 9.48 1.88300 40.8 10 -29.469 0.70 11 -26.465 1.50 1.89286 20.4 12 85.212 6.75 1.90043 37.4 13 -48.591 0.20 14* 153.032 0.05 1.58946 30.6 15 153.120 5.88 1.94594 18.0 16 -51.567 0.05 1.58946 30.6 17* -51.459 (variable) 18 ∞ 2.00 1.51633 64.1 19 ∞ (Variable) Image plane ∞ Aspherical data Page 14 K = 0.00000e+00 A 4=-2.30574e-07 A 6=-1.13612e-08 A 8= 2.91685e-11 A10 = -2.69476e-14 Page 17 K = 0.00000e+00 A 4= 3.31591e-06 A 6=-1.26017e-08 A 8= 3.09562e-11 A10 = -2.84354e-14 Various data Focal length 52.40 F-number 1.24 Half-angle (°): 22.44 Image height 21.64 Lens length 95.65 BF 37.98 d17 35.86 d19 0.80 [Numerical Example 3] Unit: mm Surface data Face number rd nd νd 1 68.403 4.80 1.77250 49.6 2 862.666 0.20 3 30.198 5.28 1.83481 42.7 4 48.498 2.03 5 68.231 2.50 1.63980 34.5 6 20.156 11.23 7 (aperture) ∞ 7.92 8 -23.688 1.50 1.72825 28.5 9 76.550 8.35 1.88300 40.8 10 -30.848 0.70 11 -27.729 1.50 1.69895 30.1 12 -237.463 5.40 1.83481 42.7 13 -39.979 0.20 14* 132.692 0.05 1.53344 52.7 15 133.192 6.44 1.80400 46.5 16 -60.416 0.05 1.53344 52.7 17* -60.754 (variable) 18 ∞ 2.00 1.51633 64.1 19 ∞ (Variable) Image plane ∞ Aspherical data Page 14 K = 0.00000e+00 A 4=-2.29450e-06 A 6= 4.85535e-09 A 8=-1.98213e-11 A10 = 3.76690e-14 Page 17 K = 0.00000e+00 A 4=-1.66138e-08 A 6= 5.29838e-09 A 8=-2.22044e-11 A10 = 4.02437e-14 Various data Focal length 51.70 F-number 1.27 Half-angle (°): 22.71 Image height 21.64 Lens length 96.19 BF 38.04 d17 35.92 d19 0.80 [Numerical Example 4] Unit: mm Surface data Face number rd nd νd 1 63.147 10.01 1.59522 67.7 2 384.278 0.20 3 48.333 12.33 1.72916 54.7 4 100.691 10.57 5* 184.521 0.05 1.53330 52.7 6 184.537 1.50 1.68430 26.8 7 26.879 0.05 1.53330 52.7 8* 26.887 9.54 9 (aperture) ∞ 9.47 10 -27.777 2.00 1.67300 38.3 11 63.471 10.57 1.77250 49.6 12 -38.632 0.15 13 140.770 5.11 1.80400 46.6 14 -132.402 (variable) 15 129.283 4.01 1.72916 54.7 16 328.653 (variable) 17 ∞ 2.00 1.51633 64.1 18 ∞ (Variable) Image plane ∞ Aspherical data 5th page K = 0.00000e+00 A 6=-1.06572e-08 A 8= 4.82531e-11 A10=-6.34975e-14 Side 8 K = 0.00000e+00 A 4= 1.63658e-06 A 6=-1.72693e-08 A 8= 8.95997e-11 A10 = -1.16632e-13 Various data Focal length 82.51 F-number 1.57 Half-angle (°): 14.69 Image height 21.64 Lens length: 119.24 BF 42.06 d14 1.60 d16 39.94 d18 0.80 Lens group data Group starting plane focal length 1 1 98.02 2 15 289.82 [Numerical Example 5] Unit: mm Surface data Face number rd nd νd 1 54.750 11.73 1.48749 70.2 2 259.089 0.15 3 46.261 9.31 1.48749 70.2 4 153.828 1.94 5* 44.713 0.05 1.58946 30.6 6 44.724 10.00 1.69680 55.5 7 61.274 0.05 1.58946 30.6 8* 61.285 2.10 9 111.736 3.00 1.72047 34.7 10 22.892 12.01 11 (aperture) ∞ 5.68 12 -32.128 2.75 1.75211 25.0 13 54.228 14.00 1.92250 36.0 14 -53.495 0.15 15 131.750 6.17 1.92250 36.0 16 -202.296 (variable) 17 135.774 3.90 1.78336 49.5 18 509.842 (variable) 19 ∞ 2.00 1.51633 64.1 20 ∞ (Variable) Image plane ∞ Aspherical data 5th page K = 0.00000e+00 A 4=-3.66307e-07 A 6= 2.10603e-10 A 8=-7.08534e-13 A10 = 5.69368e-16 Side 8 K = 0.00000e+00 A 4= 3.05962e-07 A 6= 1.24384e-09 A 8=-1.77106e-12 A10 = 3.22112e-15 Various data Focal length 80.80 F-number 1.24 Half-angle (°): 14.99 Image height 21.64 Lens length: 117.62 BF 32.66 d16 1.98 d18 30.53 d20 0.81 Lens group data Group starting plane focal length 1 1 95.22 2 17 235.16 [Numerical Example 6] Unit: mm Surface data Face number rd nd νd 1 58.000 11.77 1.48749 70.2 2 301.844 0.15 3 49.736 10.64 1.48749 70.2 4 159.804 2.26 5* 42.778 0.05 1.58946 30.6 6 42.772 10.00 1.59522 67.7 7 52.634 0.05 1.58946 30.6 8* 52.648 2.77 9 113.096 1.95 1.64769 33.8 10 23.655 12.87 11 (aperture) ∞ 5.44 12 -31.787 2.75 1.72825 28.3 13 54.904 14.00 1.88300 40.8 14 -50.479 0.15 15 135.046 6.29 1.88300 40.8 16 -193.910 (variable) 17 138.890 3.73 1.87070 40.7 18 369.505 (variable) 19 ∞ 2.00 1.51633 64.1 20 ∞ (Variable) Image plane ∞ Aspherical data 5th page K = 0.00000e+00 A 4=-2.02977e-07 A 6= 2.10207e-10 A 8=-8.01702e-13 A10 = 2.81219e-16 Side 8 K = 0.00000e+00 A 4= 5.05040e-07 A 6= 1.22596e-09 A 8=-3.17429e-12 A10 = 4.19316e-15 Various data Focal length 82.89 F-number 1.24 Half-angle (°): 14.63 Image height 21.64 Lens length: 122.00 BF 35.17 d16 1.98 d18 33.05 d20 0.80 Lens group data Group starting plane focal length 1 1 97.65 2 17 253.67 [Numerical Example 7] Unit: mm Surface data Face number rd nd νd 1 53.316 11.00 1.48749 70.2 2 267.550 0.15 3 49.459 10.20 1.48749 70.2 4 141.497 1.58 5* 37.116 0.05 1.58946 30.6 6 37.120 10.00 1.49700 81.5 7 55.727 0.05 1.58946 30.6 8* 54.875 2.65 9 121.893 1.95 1.62536 35.6 10 21.803 11.12 11 (aperture) ∞ 5.11 12 -32.919 2.75 1.72825 28.3 13 42.844 14.00 1.87070 40.7 14 -52.439 0.15 15 121.547 5.95 1.95375 32.3 16 -365.679 (variable) 17 114.910 3.91 1.72916 54.7 18 340.332 (variable) 19 ∞ 2.00 1.51633 64.1 20 ∞ (Variable) Image plane ∞ Aspherical data 5th page K = 0.00000e+00 A 4=-2.09789e-07 A 6= 2.82996e-10 A 8=-1.53734e-12 A10 = 1.09717e-15 Side 8 K = 0.00000e+00 A 4= 2.28818e-07 A 6= 5.26069e-10 A 8=-2.36108e-12 A10 = 4.95272e-15 Various data Focal length 81.80 F-number 1.24 Half-angle (°): 14.82 Image height 21.64 Lens length: 116.15 BF 33.55 d16 1.98 d18 31.42 d20 0.81 Lens group data Group starting plane focal length 1 1 96.96 2 17 236.20 [Numerical Example 8] Unit: mm Surface data Face number rd nd νd 1 301.071 2.00 1.67270 32.1 2 34.058 15.47 3 -66.555 2.00 1.63980 34.5 4 107.981 0.30 5 76.507 10.83 1.83481 42.7 6 -72.803 (variable) 7 39.730 5.51 1.95375 32.3 8 111.990 0.30 9 38.448 1.50 1.54814 45.8 10 25.846 1.91 11 32.584 3.02 2.00100 29.1 12 45.998 0.50 13 28.951 7.50 1.72916 54.7 14 -56.796 1.50 1.73800 32.3 15 18.361 (variable) 16 (aperture) ∞ 7.94 17 -17.568 1.60 1.80810 22.8 18 -59.952 0.50 19 -2169.500 6.21 1.72916 54.7 20 -25.655 0.20 21* 149.845 0.05 1.58946 30.6 22 150.271 7.01 1.48749 70.2 23 -56.347 0.05 1.58946 30.6 24* -56.277 0.50 25 78.093 5.62 1.72916 54.7 26 -62961.561 (variable) 27 ∞ 2.00 1.51633 64.1 28 ∞ (Variable) Image plane ∞ Aspherical data Page 21 K = 0.00000e+00 A 4=-2.95874e-06 A 6= 1.36172e-08 A 8=-7.34108e-11 A10 = 8.35850e-14 Page 24 K = 0.00000e+00 A 4= 3.01749e-06 A 6= 1.45121e-08 A 8=-6.41766e-11 A10 = 6.57418e-14 Various data Focal length 34.80 F-number 1.45 Half-angle (°): 31.87 Image height 21.64 Lens length: 117.82 BF 22.13 d 6 5.81 d15 7.88 d26 20.00 d28 0.81 Lens group data Group starting plane focal length 1 1 -156.48 2 7 65.27 3 16 39.28 [Numerical Example 9] Unit: mm Surface data Face number rd nd νd 1 32.832 1.80 1.90043 37.4 2 14.954 9.14 3* 3005.276 0.05 1.58946 30.6 4 320.368 1.50 1.53775 74.7 5 18.095 0.05 1.58946 30.6 6* 16.769 3.28 7 22.699 4.39 1.80518 25.4 8 51.013 (variable) 9 26.337 5.06 1.71300 53.9 10 -78.813 4.28 11 (aperture) ∞ 1.50 12 19.178 4.57 1.49700 81.5 13 -14.287 1.50 1.76200 40.1 14 14.479 0.84 15 19.251 4.63 1.64000 60.1 16 -20.645 (variable) 17* -14.606 2.50 1.58313 59.4 18* -32.319 (variable) 19 -37.227 1.50 1.54814 45.8 20 5651.860 4.98 21 92.367 5.92 1.75500 52.3 22 -60.404 (variable) 23 ∞ 2.00 1.51633 64.1 24 ∞ (Variable) Image plane ∞ Aspherical data 3rd page K = 0.00000e+00 A 4= 1.25864e-06 A 6= 4.68005e-08 A 8=-2.02771e-10 A10 = 5.94646e-13 Side 6 K = 0.00000e+00 A 4=-1.52763e-05 A 6=-1.65351e-08 A 8= 5.68799e-12 A10 = -1.58068e-12 Page 17 K = 0.00000e+00 A 4= 3.74965e-04 A 6=-1.76777e-06 A 8= 1.95658e-08 A10 = -1.44899e-10 Page 18 K = 0.00000e+00 A 4= 3.18452e-04 A 6=-1.20356e-06 A 8= 6.61966e-09 A10 = -3.28881e-11 Various data Wide-angle, Medium, Telephoto Focal length 20.60 27.89 38.80 F-number 4.10 4.99 6.16 Half-angle (°): 46.40, 37.80, 29.14 Image height 21.64 21.64 21.64 Lens length 101.91 101.91 101.91 BF 22.06 22.06 22.06 d 8 17.33 9.40 1.46 d16 1.50 2.34 6.22 d18 3.54 10.63 14.69 d22 19.94 19.94 19.94 d24 0.80 0.80 0.80 Lens group data Group starting plane focal length 1 1 -23.00 2 9 21.80 3 17 -48.21 4 19 126.24 [Numerical Example 10] Unit: mm Surface data Face number rd nd νd 1 34.187 1.80 1.88300 40.8 2 15.902 9.30 3 -218.882 1.50 1.49700 81.5 4 18.999 2.91 5 20.010 3.66 1.80810 22.8 6 31.638 (variable) 7 28.565 2.17 1.90043 37.4 8 -144.791 4.12 9 (aperture) ∞ 1.50 10 21.726 3.28 1.49700 81.5 11 -14.367 1.50 1.74951 35.3 12 12.969 0.50 13 15.332 4.79 1.64000 60.1 14 -20.160 (variable) 15* -20.197 2.50 1.58313 59.4 16* -76.906 (variable) 17* -83.059 0.05 1.53330 52.7 18 -83.316 1.50 1.80810 22.8 19 97.845 0.05 1.53330 52.7 20* 86.058 5.89 21 93.454 5.38 1.96300 24.1 22 -72.091 (variable) 23 ∞ 2.00 1.51633 64.1 24 ∞ (Variable) Image plane ∞ Aspherical data Page 15 K = 0.00000e+00 A 4= 2.61978e-04 A 6=-1.18896e-06 A 8= 2.84565e-08 A10 = -3.16242e-10 Page 16 K = 0.00000e+00 A 4= 2.49514e-04 A 6=-6.15068e-07 A 8= 5.48593e-09 A10 = -1.81844e-11 Page 17 K = 0.00000e+00 A 4=-1.65146e-05 A 6= 1.86780e-07 A 8=-7.99459e-10 A10 = 1.55362e-12 Page 20 K = 0.00000e+00 A 4=-1.24827e-05 A 6= 1.21288e-07 A 8=-4.82262e-10 A10 = 7.14321e-13 Various data Wide-angle, Medium, Telephoto Focal length 20.60 27.88 38.80 F number 4.10 4.95 6.04 Half picture angle (°) 46.40 37.81 29.14 Image height 21.64 21.64 21.64 Overall lens length 96.70 96.70 96.70 BF 22.67 22.67 22.67 d6 17.16 9.71 2.25 d14 1.50 2.03 5.38 d16 2.96 9.89 14.00 d22 20.55 20.55 20.55 d24 0.80 0.80 0.80 Lens group data Group Starting surface Focal length 1 1 -23.25 2 7 20.20 3 15 -47.75 4 17 125.74 [Numerical example 11] Unit: mm Surface data Surface number r d nd νd 1 33.112 1.80 1.72916 54.7 2 16.106 8.79 3 -530.495 1.50 1.49700 81.5 4 18.669 5.00 5 19.351 3.91 1.84666 23.8 6 24.242 (variable) 7 31.448 2.23 1.80400 46.5 8 -152.720 5.31 9 (Aperture) ∞ 1.50 10 19.343 3.24 1.49700 81.5 11 -16.772 1.50 1.76200 40.1 12 13.365 0.50 13 15.637 4.79 1.65160 58.5 14 -21.596 (variable) 15* -141.609 2.50 1.58313 59.4 16 * 36.156 (variable) 17 -76.126 1.50 1.63980 34.5 18 105.172 6.40 19* 86.898 0.05 1.53330 52.7 20 84.249 6.10 1.85026 32.3 21 -77.123 0.05 1.53330 52.7 22* -79.285 (variable) 23 ∞ 2.00 1.51633 64.1 24 ∞ (Variable) Image plane ∞ Aspherical data Page 15 K = 0.00000e+00 A 4= 7.78846e-06 A 6= 8.62470e-07 A 8= 1.64845e-09 A10 = -6.07101e-11 Page 16 K = 0.00000e+00 A 4= 2.49784e-05 A 6= 9.78058e-07 A 8=-8.55929e-09 A10 = 8.21861e-11 Page 19 K = 0.00000e+00 A 4= 4.38512e-06 A 6=-3.73502e-08 A 8= 2.83060e-11 A10 = 1.16739e-13 Page 22 K = 0.00000e+00 A 4= 8.74608e-06 A 6=-3.24818e-08 A 8=-4.94473e-11 A10 = 2.30485e-13 Various data Wide-angle Medium Telephoto Focal length 20.60 27.92 38.80 F-number 4.37 5.27 6.41 Half angle of view (°) 46.40 37.77 29.14 Image height 21.64 21.64 21.64 Overall length of lens 102.56 102.56 102.56 BF 22.28 22.28 22.28 d 6 18.75 10.85 2.95 d14 1.50 2.07 5.63 d16 3.36 10.70 15.04 d22 20.15 20.15 20.15 d24 0.81 0.81 0.81 Lens group data Group Starting surface Focal length 1 1 -24.11 2 7 21.63 3 15 -49.14 4 17 118.74 [Numerical example 12] Unit: mm Surface data Surface number r d nd νd 1* 38.692 0.05 1.53330 52.7 2 34.472 1.80 1.95375 32.3 3 16.033 0.05 1.53330 52.7 4* 15.529 13.32 5 -191.703 1.20 1.49700 81.5 6 19.614 0.10 7 19.099 4.10 1.69895 30.1 8 86.784 (Variable) 9 34.594 3.65 1.88300 40.8 10 -304.063 1.00 11 (aperture) ∞ 1.00 12 23.994 5.02 1.49700 81.5 13 -48.883 0.50 14 -30.134 6.00 1.75520 27.5 15 21.414 0.69 16 517.122 2.22 1.74100 52.6 17 -23.781 0.00 18 ∞ (Variable) 19 1599.497 1.00 1.51823 58.9 20 63.617 8.01 21 109.100 4.71 1.49700 81.5 22 -71.927 (variable) 23 ∞ 2.00 1.51633 64.1 24 ∞ (Variable) Image plane ∞ Aspherical data Front page K = 0.00000e+00 A 4= 4.57667e-07 A 6= 5.58269e-08 A 8=-2.21849e-10 A10 = 3.13059e-13 Side 4 K = 0.00000e+00 A 4=-8.05634e-06 A 6= 4.61275e-08 A 8=-3.64139e-11 A10 = -1.82719e-12 Various data Wide-angle, Medium, Telephoto Focal length 24.48 35.76 47.04 F-numbers: 4.12, 4.99, 5.88 Half-angle (°): 41.47, 31.17, 24.70 Image height 21.64 21.64 21.64 Lens length: 103.03, 102.63, 107.72 BF 22.12 22.12 22.12 d 8 18.39 6.95 1.00 d18 8.10 19.14 30.18 d22 20.00 20.00 20.00 d24 0.80 0.80 0.80 Lens group data Group starting plane focal length 1 1 -30.93 2 9 29.48 3 19 225.97 [Numerical Example 13] Unit: mm Surface data Face number rd nd νd 1 101.215 4.56 1.48749 70.2 2 ∞ 0.15 3 135.966 1.90 1.61340 44.3 4 50.295 7.55 1.49700 81.5 5 308.865 (variable) 6 -102.271 1.20 1.77250 49.6 7 27.454 3.94 2.05090 26.9 8 50.607 (variable) 9 (aperture) ∞ 1.50 10 38.917 4.22 1.48749 70.2 11 -45.868 3.00 12* -34.427 0.10 1.53330 52.7 13 -34.444 1.30 1.91082 35.2 14 -77.628 0.10 1.53330 52.7 15* -66.644 (variable) 16 -78.676 2.73 1.70154 41.2 17 -31.643 0.20 18 128.247 3.89 1.51742 52.4 19 -25.503 1.00 1.95375 32.3 20 -68.986 (variable) 21 -105.373 3.74 2.00069 25.5 22 -39.999 1.00 1.72916 54.7 23 42.695 (Variable) 24 ∞ 2.00 1.51633 64.1 25 ∞ (Variable) Image plane ∞ Aspherical data Side 12 K = 0.00000e+00 A 4= 9.04648e-06 A 6=-5.46812e-08 A 8= 1.27447e-10 Page 15 K = 0.00000e+00 A 4= 1.01477e-05 A 6=-5.26988e-08 A 8= 1.16826e-10 Various data Wide-angle, Medium, Telephoto Focal length 102.62 180.19 388.00 F-number 5.77 6.90 8.24 Half-angle (°): 11.91 6.85 3.19 Image height 21.64 21.64 21.64 Lens length: 179.91 x 219.32 x 258.73 BF 38.51 61.41 102.12 d 5 10.38 49.79 89.20 d 8 29.01 22.87 3.83 d15 24.24 16.71 9.84 d20 35.70 26.48 11.68 d23 36.39 59.29 100.00 d25 0.80 0.80 0.80 Lens group data Group starting plane focal length 1 1 181.99 2 6 -55.16 3 9 94.28 4 16 69.10 5 21 -50.01 [Numerical Example 14] Unit: mm Surface data Face number rd nd νd 1 101.477 4.37 1.48749 70.2 2 ∞ 0.15 3 135.725 1.90 1.61340 44.3 4 47.725 6.88 1.49700 81.5 5 465.472 (variable) 6 -112.247 1.20 1.77250 49.6 7 25.752 2.60 2.05090 26.9 8 47.844 (variable) 9 (aperture) ∞ 1.50 10 38.178 3.81 1.48749 70.2 11 -77.951 5.00 12* -52.963 0.05 1.58946 30.6 13 -58.634 1.30 2.05090 26.9 14 -102.476 0.05 1.58946 30.6 15* -139.209 (variable) 16 -69.915 3.77 1.59270 35.4 17 -31.958 0.20 18 76.081 3.97 1.48749 70.2 19 -28.334 1.00 1.91082 35.2 20 -71.351 (variable) 21 -148.358 2.57 2.00069 25.5 22 -46.992 1.00 1.72916 54.7 23 41.037 (Variable) 24 ∞ 2.00 1.51633 64.1 25 ∞ (Variable) Image plane ∞ Aspherical data Side 12 K = 0.00000e+00 A 4=-4.55538e-06 A 6= 4.32950e-08 A 8=-3.83479e-10 A10 = 1.08449e-12 Page 15 K = 0.00000e+00 A 4=-1.56815e-06 A 6= 4.16736e-08 A 8=-3.66913e-10 A10 = 1.03589e-12 Various data Wide-angle, Medium, Telephoto Focal length 100.00 186.42 388.00 F-number 5.77 7.20 8.24 Half-angle (°): 12.21 6.62 3.19 Image height 21.64 21.64 21.64 Lens length: 183.87 x 221.30 x 258.73 BF 38.74 68.43 115.07 d 5 9.57 47.00 84.43 d 8 30.97 23.90 6.40 d15 26.99 15.78 3.32 d20 36.28 24.88 8.20 d23 36.61 66.30 112.94 d25 0.81 0.81 0.81 Lens group data Group starting plane focal length 1 1 170.25 2 6 -55.63 3 9 101.59 4 16 67.42 5 21 -53.06 The values ​​for equations (1) to (12) in each numerical example are summarized in Tables 1 to 4 below. Note that all numerical examples use the d line as the reference wavelength, and the values ​​shown in Tables 1 to 4 are for this reference wavelength.

[0076] [Table 1]

[0077] [Table 2]

[0078] [Table 3]

[0079] [Table 4]

[0080] [Imaging device] Figure 35 shows an imaging device (digital still camera) 10 equipped with the optical system L0 of each embodiment. The imaging device 10 has a camera body 11 and a lens device 12 that can be attached to or removed from the camera body 11. The lens device 12 has an imaging optical system configured with the optical system L0 of any of embodiments 1 to 14.

[0081] The camera body 11 incorporates an image sensor (photoelectric conversion element) 13, such as a CCD sensor or CMOS sensor, which converts (images) the optical image formed by the imaging optical system into photoelectric form. The camera body 11 may be a single-lens reflex camera with a quick-turn mirror, or a mirrorless camera without a quick-turn mirror. The lens device 12 and the camera body 11 may also be integrated into a single unit.

[0082] By applying the optical system L0 of each embodiment to the imaging device in this way, it is possible to provide an imaging device that is compact, lightweight, has high optical performance, and excellent environmental resistance.

[0083] The above embodiments include the following configuration.

[0084] (Composition 1) An optical system having a composite optical element in which resin lenses are bonded to both the object side and the image side of a glass lens, At least one of the resin lens on the object side and the resin lens on the image side has an aspherical surface. When the focal length of the optical system is f, and the air-equivalent distance along the optical axis from the image-side lens surface to the image plane when the optical system is in focus on an object at infinity is bf, 0.00 <bf / f≦1.25 An optical system characterized by satisfying the following conditions. (Configuration 2) When the thickness of the resin lens on the object side along the optical axis is Da, and the thickness of the resin lens on the image side along the optical axis is Db, 0.25 ≤ Da / Db ≤ 4.00 The optical system according to configuration 1, characterized by satisfying the following conditions. (Composition 3) The optical system according to configuration 1 or 2, characterized in that the composite optical element has a positive refractive power. (Composition 4) When the refractive index of the glass lens at the d-line is Ndp, 1.45 ≤ Ndp ≤ 2.10 The optical system according to configuration 3, characterized by satisfying the following conditions. (Composition 5) The optical system according to configuration 1 or 2, characterized in that the composite optical element has a negative refractive power. (Composition 6) When the refractive index of the glass lens at the d-line is Ndn, 1.45 ≤ Ndn ≤ 2.10 The optical system according to configuration 5, characterized by satisfying the following conditions. (Composition 7) When the refractive index of the glass lens at the d line is Ndg, and the average refractive index of the resin lens on the object side and the resin lens on the image side at the d line is Nda, 0.0 < |Ndg - Nda| ≤ 0.6 An optical system according to any one of configurations 1 to 6, characterized by satisfying the following conditions. (Composition 8) When νdg is the Abbe number with respect to the d line of the glass lens, and νda is the average of the Abbe numbers with respect to the d lines of the resin lens on the object side and the resin lens on the image side, 0 < |νdg - νda| ≤ 60 An optical system according to any one of configurations 1 to 7, characterized by satisfying the following conditions. (Composition 9) When Tmax is the maximum thickness and Tmin is the minimum thickness of the resin lens on the object side and the resin lens on the image side along the optical axis within the effective diameter of the composite optical element, 1.0 ≤ Tmax / Tmin ≤ 10.0 An optical system according to any one of configurations 1 to 8, characterized by satisfying the following conditions. (Composition 10) When the thickness of the resin lens on the object side along the optical axis is Da, and the thickness of the resin lens on the image side along the optical axis is Db, 0.025 ≤ Da ≤ 0.250 0.025 ≤ Db ≤ 0.250 An optical system according to any one of configurations 1 to 9, characterized by satisfying the following conditions. (Composition 11) The optical system has an aperture diaphragm, When Xd is the distance along the optical axis from the lens surface on the aperture side of the resin lens on the aperture side to the aperture among the resin lenses on the object side and the image side, and TD is the distance along the optical axis from the lens surface on the object side of the optical system to the lens surface on the image side of the optical system, 0.00 <Xd / TD≦0.80 An optical system according to any one of configurations 1 to 10, characterized by satisfying the following conditions. (Composition 12) The optical system according to any one of configurations 1 to 11, characterized in that both the resin lens on the object side and the resin lens on the image side have aspherical surfaces. (Composition 13) When the transition point of the glass lens is Tg (°C), 450 ≤ Tg ≤ 800 An optical system according to any one of configurations 1 to 12, characterized by satisfying the following conditions. (Composition 14) The degree of coloration of the glass lens is λ 80 In that case, 300 ≤ λ 80 ≤450 An optical system according to any one of configurations 1 to 13, characterized by satisfying the following conditions. (Composition 15) An optical system having a composite optical element in which a resin lens is bonded to at least one of the object side and image side of a glass lens, wherein the focal length of the optical system is f, and the air-equivalent distance on the optical axis from the lens surface on the image side of the optical system to the image plane when the optical system is in focus on an object at infinity is bf, 0.00 <bf / f≦1.25 An optical system characterized by satisfying the following conditions. (Composition 16) The optical system described in any one of configurations 1 to 15, An imaging device characterized by having an image sensor that captures an image of a subject through the optical system.

[0085] The embodiments described above are merely representative examples, and various modifications and changes can be made to each embodiment when implementing the present invention. [Explanation of Symbols]

[0086] L0 optical system IP image plane SP aperture diaphragm HB composite optical element

Claims

1. An optical system having a composite optical element in which resin lenses are bonded to both the object side and the image side of a glass lens, At least one of the resin lens on the object side and the resin lens on the image side has an aspherical surface. When the focal length of the optical system is f, and the air-equivalent distance on the optical axis from the image-side lens surface to the image plane when the optical system is in focus on an object at infinity is bf, 0.00<bf / f≦1.25 An optical system characterized by satisfying the following conditions.

2. When the thickness of the resin lens on the object side along the optical axis is Da, and the thickness of the resin lens on the image side along the optical axis is Db, 0.25 ≤ Da / Db ≤ 4.00 The optical system according to claim 1, characterized in that it satisfies the following conditions.

3. The optical system according to claim 1, characterized in that the composite optical element has a positive refractive power.

4. When the refractive index of the glass lens at the d-line is Ndp, 1.45 ≤ Ndp ≤ 2.10 The optical system according to claim 3, characterized in that it satisfies the following conditions.

5. The optical system according to claim 1, characterized in that the composite optical element has a negative refractive power.

6. When the refractive index of the glass lens at the d-line is Ndn, 1.45 ≤ Ndn ≤ 2.10 The optical system according to claim 5, characterized in that it satisfies the following conditions.

7. When Ndg is the refractive index of the glass lens at the d line, and Nda is the average of the refractive indices of the resin lens on the object side and the resin lens on the image side at the d line, 0.0<|Ndg−Nda|≦0.6 The optical system according to claim 1, characterized in that it satisfies the following conditions.

8. When νdg is the Abbe number with respect to the d line of the glass lens, and νda is the average of the Abbe numbers with respect to the d lines of the resin lens on the object side and the resin lens on the image side, 0<|νdg−νda|≦60 The optical system according to claim 1, characterized in that it satisfies the following conditions.

9. When Tmax is the maximum thickness and Tmin is the minimum thickness of the resin lens on the object side and the resin lens on the image side along the optical axis within the effective diameter of the composite optical element, 1.0 ≤ Tmax / Tmin ≤ 10.0 The optical system according to claim 1, characterized in that it satisfies the following conditions.

10. When the thickness of the resin lens on the object side along the optical axis is Da, and the thickness of the resin lens on the image side along the optical axis is Db, 0.025 ≤ Da ≤ 0.250 0.025 ≤ Db ≤ 0.250 The optical system according to claim 1, characterized in that it satisfies the following conditions.

11. The optical system has an aperture diaphragm, When Xd is the distance along the optical axis from the lens surface on the aperture side of the resin lens on the aperture side to the aperture among the resin lenses on the object side and the image side, and TD is the distance along the optical axis from the lens surface on the object side of the optical system to the lens surface on the image side of the optical system, 0.00<Xd / TD≦0.80 The optical system according to claim 1, characterized in that it satisfies the following conditions.

12. The optical system according to claim 1, characterized in that both the resin lens on the object side and the resin lens on the image side have an aspherical surface.

13. When the transition point of the glass lens is Tg (°C), 450 ≤ Tg ≤ 800 The optical system according to claim 1, characterized in that it satisfies the following conditions.

14. The degree of coloration of the glass lens is λ ８０ In that case, 300≦λ ８０ ≦450 The optical system according to claim 1, characterized in that it satisfies the following conditions.

15. An optical system having a composite optical element in which a resin lens is bonded to at least one of the object side and image side of a glass lens, wherein the focal length of the optical system is f, and the air-equivalent distance on the optical axis from the lens surface on the image side of the optical system to the image plane when the optical system is in focus on an object at infinity is bf, 0.00<bf / f≦1.25 An optical system characterized by satisfying the following conditions.

16. An optical system according to any one of claims 1 to 15, An imaging device characterized by having an image sensor that captures an image of a subject through the optical system.

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