Zoom lens and imaging device

Abstract

The present invention provides a compact and lightweight zoom lens with good optical performance, and an imaging device equipped with this zoom lens. [Solution] The zoom lens comprises a first lens group located closest to the object, an intermediate group containing multiple lens groups, and a final lens group located closest to the image. During magnification, the first lens group is fixed relative to the image plane, and the spacing between all adjacent lens groups changes. The number of lenses included in the first lens group is four or less. When the back focus of the entire system in air equivalent distance when focused on an object at infinity at the wide-angle end is Bfw, and when the focal length of the entire system when focused on an object at infinity at the wide-angle end is fw, the zoom lens is given by the conditional equation: 0.1

Description

[Technical Field]

[0001] The technology disclosed herein relates to a zoom lens and an imaging device. [Background technology]

[0002] Conventionally, the zoom lens described in Patent Document 1 below is known as a zoom lens that can be used in imaging devices such as cameras. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 08-005913 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] In light of the need to reduce the burden during shooting and improve portability, there is a demand for zoom lenses that are smaller and lighter while maintaining good optical performance. These demands are increasing year by year.

[0005] The present disclosure aims to provide a zoom lens that is compact and lightweight and has good optical performance, and an imaging device equipped with this zoom lens. [Means for solving the problem]

[0006] A zoom lens according to one aspect of this disclosure comprises a first lens group located closest to the object, an intermediate group including multiple lens groups, and a final lens group located closest to the image. During magnification, the first lens group is fixed relative to the image plane, the distance between the first lens group and the intermediate group changes, the distance between the intermediate group and the final lens group changes, the distance between all adjacent lens groups within the intermediate group changes, and the number of lenses included in the first lens group is four or less. 0.1 <Bfw / fw<1.9 (1) The condition (1) expressed by is satisfied. Here, Bfw is the back focus of the entire system in terms of air-equivalent distance when in focus on an object at infinity at the wide-angle end. fw is the focal length of the entire system when in focus on an object at infinity at the wide-angle end.

[0007] The final lens group preferably includes three or more lenses.

[0008] Preferably, at least one of the multiple lens groups included in the intermediate group is an intermediate fixed lens group that is fixed to the image plane during magnification. Preferably, the intermediate fixed lens group includes three or more lenses.

[0009] It is preferable that the lens closest to the object in the first lens group is a negative lens.

[0010] The final lens group may be configured to be fixed to the image plane during magnification.

[0011] When the focal length of the first lens group is f1, the zoom lens in the above configuration is: 0.05 <fw / f1<0.54 (2) It is preferable that the condition (2) expressed by is satisfied.

[0012] The zoom lens of the above embodiment preferably includes an aperture diaphragm and satisfies the following condition (3), and more preferably satisfies the following condition (3-1). 0.5 <DStw / TLw<0.85 (3) 0.61 <DStw / TLw<0.8 (3-1) Here, DStw is defined as the sum of the distance along the optical axis from the aperture diaphragm to the image-side lens surface of the final lens group, when the lens is in focus on an object at infinity at the wide-angle end, and the back focus of the entire system in terms of air-equivalent distance. TLw is defined as the sum of the distance along the optical axis from the object-side lens surface of the first lens group to the image-side lens surface of the final lens group, when the lens is in focus on an object at infinity at the wide-angle end, and the back focus of the entire system in terms of air-equivalent distance.

[0013] The intermediate group preferably includes a focusing group that moves along the optical axis during focusing. The focusing group may be configured to have a negative refractive power.

[0014] The lens surface of the first lens group closest to the object side is preferably convex.

[0015] The intermediate group preferably includes an anti-vibration group that moves in a direction intersecting the optical axis during image shake correction. The anti-vibration group preferably consists of all or part of an intermediate fixed lens group that is fixed with respect to the image plane during zooming. The anti-vibration group may be configured to have a positive refractive power.

[0016] When the maximum half field angle in the state of focusing on an infinite object at the wide-angle end is ωw, the zoom lens of the above aspect satisfies 0.4 < Bfw / (fw × tan ωw) < 1.6 (4) the conditional expression (4) represented by.

[0017] When the focal length of the final lens group is fE, the zoom lens of the above aspect satisfies -0.7 < fw / fE < 0.7 (5) the conditional expression (5) represented by.

[0018] When the maximum value of the Abbe number based on the d line of all the lenses included in the final lens group is νEmax, the zoom lens of the above aspect satisfies 60 < νEmax < 105 (6) the conditional expression (6) represented by.

[0019] The zoom lens of the above aspect satisfies 0.005 < D12w / (fw × tan ωw) < 0.35 (7) the conditional expression (7) represented by. Here, D12w is the on-axis distance between the first lens group and the lens group adjacent to the image side of the first lens group in the state of focusing on an infinite object at the wide-angle end. ωw is the maximum half field angle in the state of focusing on an infinite object at the wide-angle end.

[0020] The zoom lens in the above embodiment includes at least one combination of a group of lenses having negative refractive power and a group of lenses having positive refractive power, which are arranged adjacent to each other in order from the object side to the image side. 0.005 <DNPt / (fw×tanωw)<0.5 (8) It is preferable that the condition (8) expressed by the above equation is satisfied. Here, DNPt is the distance on the optical axis at the telephoto end between the lens group with negative refractive power and the lens group with positive refractive power of the combination closest to the object among the above combinations. ωw is the maximum half-angle of view when in focus on an object at infinity at the wide-angle end.

[0021] The zoom lens in the above configuration is -0.05 <NE+0.0067×νEmax-2<0.13 (9) It is preferable that the condition expressed in equation (9) is satisfied. Here, among the lenses included in the final lens group, the refractive index and Abbe number with respect to the d line of the lens that has the maximum Abbe number with respect to the d line are defined as NE and νEmax, respectively.

[0022] The zoom lens in the above embodiment includes at least one aspherical lens, 0.001 < |ΔsagM| / HaM < 0.07 (10) It is preferable that the condition (10) expressed by the above is satisfied. Here, Δsag is defined as the difference between the sag amount of the lens surface and the sag amount of the paraxial curvature sphere of the lens surface at a height of 70% of the maximum effective radius of the lens surface of the aspherical lens. Among the aspherical lenses included in the zoom lens, ΔsagM is defined as the larger of the absolute values ​​of Δsag of the object-side surface and Δsag of the image-side surface for the aspherical lens closest to the object. Among the aspherical lenses included in the zoom lens, HaM is defined as the larger of the maximum effective radius of the object-side surface and the maximum effective radius of the image-side surface for the aspherical lens closest to the object.

[0023] The zoom lens according to the above embodiment includes at least one lens group having negative refractive power, and it is preferable that the aspherical lens closest to the object is the third lens from the object side of the lens group having negative refractive power closest to the object, among the lens group having negative refractive power included in the zoom lens.

[0024] The zoom lens according to the above embodiment includes at least one lens group having negative refractive power, and it is preferable that the aspherical lens closest to the object is the fourth lens from the object side of the lens group having negative refractive power closest to the object, among the lens group having negative refractive power included in the zoom lens.

[0025] The zoom lens in the above embodiment includes at least one negative lens, and when the refractive index of the negative lens closest to the object among the negative lenses included in the zoom lens is Nn1 with respect to the d line, 1.59 <Nn1<1.99 (11) It is preferable that the conditional expression (11) represented by is satisfied.

[0026] The zoom lens in the above embodiment includes at least one negative lens, 0.02 <Dn1 / Hn1<0.087 (12) It is preferable that the condition (12) expressed by is satisfied. Here, Dn1 and Hn1 are the central thickness and the maximum effective radius of the object-side surface of the negative lens closest to the object among the negative lenses included in the zoom lens.

[0027] The zoom lens in the above embodiment includes at least one lens group having negative refractive power, and among the lens groups having negative refractive power included in the zoom lens, the lens group having negative refractive power closest to the object includes at least one negative lens. 0.02 <Dn2 / Hn2<0.105 (13) It is preferable that the condition (13) expressed by is satisfied. Here, among the negative lenses included in the group of lenses having the negative refractive power closest to the object, the central thickness of the negative lens closest to the object and the maximum effective radius of the surface on the object side are defined as Dn2 and Hn2, respectively.

[0028] The zoom lens in the above embodiment includes at least one negative lens, and the negative lens included in the zoom lens, the one closest to the object, may be configured so that its image-side surface is in contact with the air.

[0029] The zoom lens in the above embodiment preferably includes an aperture diaphragm, and a negative lens is positioned adjacent to the image side of the aperture diaphragm.

[0030] If the focal length of the lens group positioned adjacent to the object side of the final lens group is fFE, then the zoom lens in the above configuration is: -0.8 <fw / fFE<0.4 (14) It is preferable that the conditional expression (14) represented by is satisfied.

[0031] The zoom lens in the above embodiment includes an aperture diaphragm, 1.43 <NStp<1.895 (15) It is preferable to satisfy the conditional expression (15) represented by the following. Here, if the aperture diaphragm is included in the lens group, NStp is defined as the refractive index with respect to the d line of the positive lens closest to the image among the positive lenses included in the lens group including the aperture diaphragm. If the aperture diaphragm is not included in the lens group, NStp is defined as the refractive index with respect to the d line of the positive lens closest to the image among the positive lenses included in the lens group adjacent to the image side of the aperture diaphragm.

[0032] If N1ave is the average value of the refractive index of all lenses included in the first lens group with respect to the d line, then the zoom lens of the above embodiment is: 1.6 <N1ave<1.9 (16) It is preferable that the conditional expression (16) represented by is satisfied.

[0033] The zoom lens in the above configuration is 0.14 < βEt × βFEt < 2.2 (17) It is preferable that the condition (17) expressed by is satisfied. Here, βEt is the lateral magnification of the final lens group when in focus on an object at infinity at the telephoto end. βFEt is the lateral magnification of the lens group adjacent to the object side of the final lens group when in focus on an object at infinity at the telephoto end.

[0034] The zoom lens according to the above embodiment includes a group of lenses having at least one negative refractive power, 15 < νNmin < 25.6 (18) It is preferable that the condition (18) expressed by is satisfied. Here, νNmin is defined as the minimum Abbe number on the d line reference of all lenses in the group of negative refractive power lenses that have the negative refractive power closest to the object among the lens group of negative refractive power lenses included in the zoom lens.

[0035] The zoom lens in the above embodiment includes an aperture diaphragm, 0.3 <fw / fGSt<1.3 (19) It is preferable to satisfy the conditional expression (19) represented by the following equation. Here, if the aperture diaphragm is included in the lens group, the focal length of the lens group including the aperture diaphragm is defined as fGSt. If the aperture diaphragm is not included in the lens group, the focal length of the lens group adjacent to the image side of the aperture diaphragm is defined as fGSt.

[0036] The zoom lens according to the above embodiment includes a group of lenses having at least one negative refractive power, -2.5 <fw / fN<-0.8 (20) It is preferable that the condition (20) expressed by is satisfied. Here, fN is the focal length of the lens group with the most negative refractive power on the object side among the lens groups with negative refractive power included in the zoom lens.

[0037] An imaging device according to another aspect of the present disclosure comprises a zoom lens according to the above aspect of the present disclosure.

[0038] Furthermore, the terms "~consisting of" and "~consisting of" in this specification are intended to include, in addition to the listed components, lenses that substantially have no refractive power, optical elements other than lenses such as apertures, filters, and cover glass, and mechanical parts such as lens flanges, lens barrels, image sensors, and image stabilization mechanisms.

[0039] In this specification, "a group having positive refractive power" and "a group having positive refractive power" mean that the group as a whole has positive refractive power. Similarly, "a group having negative refractive power" and "a group having negative refractive power" mean that the group as a whole has negative refractive power. In this specification, "first lens group," "lens group," "final lens group," "focusing group," "vibration-damping group," "vibration-damping object-side group," and "vibration-damping image-side group" are not limited to configurations consisting of multiple lenses, but may also consist of only one lens.

[0040] A composite aspherical lens (a lens in which a spherical lens and an aspherical film formed on that spherical lens are integrally constructed and function as a single aspherical lens as a whole) is not considered a cemented lens, but is treated as a single lens. Unless otherwise specified, the sign and surface shape of the refractive power for lenses including aspherical surfaces shall be those of the paraxial region.

[0041] In this specification, "entire system" refers to a zoom lens. The "focal length" used in the conditional equations is the paraxial focal length. The "distance on the optical axis" used in the conditional equations is a geometric distance unless otherwise specified. The values ​​used in the conditional equations are, unless otherwise specified, values ​​with respect to the d-line when the lens is in focus on an object at infinity. In this specification, "height" refers to the height from the optical axis unless otherwise specified.

[0042] The terms "d-line," "C-line," "F-line," and "g-line" used herein are emission lines. The wavelength of the d-line is treated as 587.56 nm (nanometers), the wavelength of the C-line as 656.27 nm (nanometers), the wavelength of the F-line as 486.13 nm (nanometers), and the wavelength of the g-line as 435.84 nm (nanometers). [Effects of the Invention]

[0043] According to this disclosure, it is possible to provide a zoom lens that is compact and lightweight and has good optical performance, and an imaging device equipped with this zoom lens. [Brief explanation of the drawing]

[0044] [Figure 1] This figure shows the configuration and movement trajectory of a zoom lens according to one embodiment, corresponding to the zoom lens of Example 1. [Figure 2] Figure 1 is a cross-sectional view of the configuration of the zoom lens at its wide-angle end, and is a diagram used to explain the notation in the conditional expression. [Figure 3] This is a magnified section illustrating the symbols used in conditional expressions. [Figure 4] This is a diagram illustrating the maximum effective radius. [Figure 5] This diagram illustrates sag and aspherical quantities. [Figure 6] These are aberration diagrams of the zoom lens of Example 1. [Figure 7] This figure shows the configuration and movement trajectory of the zoom lens in Example 2. [Figure 8] These are aberration diagrams for the zoom lens of Example 2. [Figure 9] This figure shows the configuration and movement trajectory of the zoom lens in Example 3. [Figure 10] These are aberration diagrams for the zoom lens of Example 3. [Figure 11] This figure shows the configuration and movement trajectory of the zoom lens in Example 4. [Figure 12] These are aberration diagrams for the zoom lens of Example 4. [Figure 13] This figure shows the configuration and movement trajectory of the zoom lens in Example 5. [Figure 14] These are aberration diagrams for the zoom lens of Example 5. [Figure 15] This figure shows the configuration and movement trajectory of the zoom lens in Example 6. [Figure 16] These are aberration diagrams for the zoom lens of Example 6. [Figure 17] This figure shows the configuration and movement trajectory of the zoom lens in Example 7. [Figure 18] These are aberration diagrams for the zoom lens of Example 7. [Figure 19] This figure shows the configuration and movement trajectory of the zoom lens in Example 8. [Figure 20] These are aberration diagrams for the zoom lens of Example 8. [Figure 21] This figure shows the configuration and movement trajectory of the zoom lens in Example 9. [Figure 22] These are aberration diagrams for the zoom lens of Example 9. [Figure 23] This figure shows the configuration and movement trajectory of the zoom lens in Example 10. [Figure 24] These are aberration diagrams of the zoom lens of Example 10. [Figure 25] This figure shows the configuration and movement trajectory of the zoom lens in Example 11. [Figure 26] These are aberration diagrams of the zoom lens of Example 11. [Figure 27] This is a front perspective view of an imaging device according to one embodiment. [Figure 28] This is a perspective view of the rear side of an imaging device according to one embodiment. [Modes for carrying out the invention]

[0045] Embodiments of this disclosure will be described below with reference to the drawings.

[0046] Figure 1 shows the configuration and cross-sectional view of the light beam and the movement trajectory of a zoom lens according to one embodiment of the present disclosure. In Figure 1, the upper section labeled "Wide" shows the wide-angle end state, and the lower section labeled "Tele" shows the telephoto end state. In Figure 1, the light beams are shown as the axial light beam wa and the light beam wb of the maximum half-angle ωw at the wide-angle end, and the axial light beam ta and the light beam tb of the maximum half-angle ωt at the telephoto end. Figure 2 shows a cross-sectional view of the configuration of the zoom lens in Figure 1 at the wide-angle end. Figures 1 and 2 show the state when the lens is in focus on an object at infinity, with the left side being the object side and the right side being the image side. The examples shown in Figures 1 and 2 correspond to the zoom lens of Embodiment 1 described later. The following explanation will mainly refer to Figure 1, and to Figure 2 as needed.

[0047] Figure 1 shows an example where a parallel plate-shaped optical element PP is placed between the zoom lens and the image plane Sim, assuming that a zoom lens is applied to the imaging device. The optical element PP is a component that is intended to be various filters and / or cover glass. The various filters include low-pass filters, infrared cut filters, and / or filters that cut out a specific wavelength range. The optical element PP is a component that does not have refractive power. It is also possible to configure the imaging device without the optical element PP.

[0048] The zoom lens disclosed herein comprises a first lens group G1 located closest to the object, an intermediate group GM including multiple lens groups, and a final lens group GE located closest to the image. This configuration is advantageous in achieving a high magnification ratio while shortening the overall length.

[0049] During magnification, the first lens group G1 is fixed relative to the image plane Sim, the distance between the first lens group G1 and the intermediate group GM changes, the distance between the intermediate group GM and the final lens group GE changes, and the distance between all adjacent lens groups within the intermediate group GM changes. By keeping the first lens group G1 stationary during magnification, the shift in the center of gravity during magnification can be suppressed.

[0050] In this specification, a group of lenses whose distance in the optical axis direction changes when the magnification is varied is defined as one lens group. Within a single lens group, the distance between adjacent lenses does not change when the magnification is varied. That is, a "lens group" is a component of a zoom lens that includes at least one lens and is separated by the air gap that changes when the magnification is varied. When the magnification is varied, each lens group is moved or fixed. A "lens group" may include components other than lenses that do not have refractive power, such as an aperture diaphragm St.

[0051] As an example, the zoom lens in Figure 1 consists of the first lens group G1, the second lens group G2, the third lens group G3, the fourth lens group G4, and the fifth lens group G5, in order from the object side to the image side. In the example in Figure 1, the intermediate group GM consists of the second lens group G2, the third lens group G3, and the fourth lens group G4, and the final lens group GE consists of the fifth lens group G5.

[0052] As an example, each lens group in Figure 1 is configured as follows, with its detailed configuration shown in Figure 2. The first lens group G1 consists of three lenses, L11 to L13, arranged in order from the object side to the image side. The second lens group G2 consists of five lenses, L21 to L25, arranged in order from the object side to the image side. The third lens group G3 consists of an aperture diaphragm St and nine lenses, L31 to L39, arranged in order from the object side to the image side. The fourth lens group G4 consists of three lenses, L41 to L43, arranged in order from the object side to the image side. The fifth lens group G5 consists of five lenses, L51 to L55, arranged in order from the object side to the image side. The aperture diaphragm St in Figures 1 and 2 indicates its position in the optical axis direction, not its shape or size.

[0053] In the example in Figure 1, during magnification, the first lens group G1, the third lens group G3, and the fifth lens group G5 are fixed relative to the image plane Sim, while the second lens group G2 and the fourth lens group G4 move along the optical axis Z. In Figure 1, between the upper and lower diagrams, the approximate movement trajectories of each lens group during magnification, from the wide-angle end to the telephoto end, are shown by solid arrows.

[0054] In the zoom lens disclosed herein, the number of lenses included in the first lens group G1 is configured to be four or less. This configuration is advantageous for reducing weight.

[0055] It is preferable that the lens closest to the object in the first lens group G1 is a negative lens. This is advantageous for widening the angle of view.

[0056] It is preferable that the lens surface closest to the object in the first lens group G1 is a convex surface. This is advantageous in suppressing distortion aberration.

[0057] The zoom lens of this disclosure includes at least one negative lens, and the negative lens closest to the object may be configured so that its image-side surface is in contact with air. In this case, an air lens is formed adjacent to the image side of the negative lens closest to the object, and this air lens is advantageous in suppressing off-axis aberrations at the wide-angle end. In this specification, the air gap sandwiched between two opposing lens surfaces is considered to be a lens with a refractive index of 1, and this air gap is referred to as an air lens. For example, in Figure 2, an air lens is formed between the image-side surface of lens L11 and the object-side surface of lens L12.

[0058] The zoom lens of this disclosure includes at least one lens group having negative refractive power, and the lens group with negative refractive power closest to the object may be configured to include four or more lenses. This configuration is advantageous for suppressing aberration fluctuations during magnification.

[0059] The intermediate group GM preferably includes a focusing group that moves along the optical axis Z during focusing. This is advantageous for reducing the weight of the focusing group.

[0060] As an example, in the zoom lens shown in Figure 1, the focusing group consists of the fourth lens group. The parentheses and rightward arrow attached to the fourth lens group in the lower part of Figure 1 indicate that the lenses enclosed in these parentheses constitute the focusing group, and also indicate the direction in which the focusing group moves when focusing from an object at infinity to the nearest object. Note that the focusing group functions throughout the entire zoom range, including the wide-angle end, but in Figure 1, to avoid complexity, the arrow is only shown in the lower part of the diagram.

[0061] The focusing group may be configured to consist of a single lens group that moves during magnification. This configuration is advantageous for simplifying the movement mechanism.

[0062] The focusing group may be configured to have a negative refractive power. This configuration is advantageous for shortening the overall length. Alternatively, the focusing group may be configured to have a positive refractive power. This configuration is advantageous for suppressing aberration fluctuations during focusing.

[0063] The focusing group may be configured to include three or more lenses. This configuration is advantageous in suppressing aberration variations during focusing.

[0064] Preferably, at least one of the multiple lens groups included in the intermediate group GM is an intermediate fixed lens group that is fixed to the image plane Sim during magnification. In this case, the movement of the center of gravity during magnification can be suppressed. Preferably, the intermediate fixed lens group includes three or more lenses. In this case, it is advantageous for suppressing spherical aberration. As an example, in the example in Figure 1, the third lens group G3 corresponds to the intermediate fixed lens group.

[0065] The intermediate group GM preferably includes an anti-vibration group that moves in a direction intersecting the optical axis Z during image shake correction. In this case, movement of the shooting range when camera shake occurs can be suppressed.

[0066] The vibration-damping group preferably consists of all or part of the intermediate fixed lens group that is fixed to the image plane Sim during magnification. This arrangement is advantageous in reducing the weight of the lens group that moves during magnification.

[0067] The lens group including the image stabilization group may be configured to include an image stabilization object-side group positioned adjacent to the image stabilization group on the object side, and whose distance from the image stabilization group does not change during magnification. This configuration is advantageous for suppressing aberration fluctuations during image shake correction.

[0068] The lens group including the image stabilization group may be configured to include an image-side image stabilization group positioned adjacent to the image side of the image stabilization group, and whose distance from the image stabilization group does not change during magnification. This configuration is advantageous for suppressing aberration fluctuations during image shake correction.

[0069] As an example, the third lens group G3 shown in Figure 2 consists of, in order from the object side to the image side, the vibration-damping object-side group GISf, the vibration-damping group GIS, and the vibration-damping image-side group GISr. As an example, in the example in Figure 2, the vibration-damping object-side group GISf consists of lenses L31 to L33, the vibration-damping group GIS consists of lenses L34 to L36, and the vibration-damping image-side group GISr consists of lenses L37 to L39. In the lower part of Figure 1, parentheses and downward arrows are placed below the lenses corresponding to the vibration-damping groups. Note that the vibration-damping groups function throughout the entire zoom range, including the wide-angle end, but in Figure 1, to avoid complexity, the above arrows are only included in the lower part of the diagram.

[0070] The vibration isolation group may be configured to have a positive refractive force. In this case, it is advantageous to reduce the sensitivity of aberrations caused by the relative positional misalignment between the group adjacent to the object side of the vibration isolation group and the group adjacent to the image side of the vibration isolation group to this misalignment. Alternatively, the vibration isolation group may be configured to have a negative refractive force. In this case, it is advantageous to suppress aberration fluctuations during image shake correction.

[0071] The lens closest to the object in the final lens group GE may be configured to be a positive lens. This configuration is advantageous for reducing the diameter of the final lens group GE.

[0072] The final lens group GE preferably includes three or more lenses. This is advantageous for suppressing off-axis aberrations.

[0073] The final lens group GE may be configured to be fixed to the image plane Sim during magnification. In this case, the movement of the center of gravity during magnification can be suppressed.

[0074] The zoom lens of this disclosure includes an aperture diaphragm St, and may be configured such that a negative lens is positioned adjacent to the image side of the aperture diaphragm St. This configuration is advantageous for creating a lens system with a small F-number.

[0075] The zoom lens of this disclosure includes an aperture diaphragm St, which may be configured to be fixed relative to the image plane Sim during magnification. This configuration is advantageous for reducing the weight of the lens group that moves during magnification.

[0076] Next, preferred and possible configurations of the conditional expressions for the zoom lens of this disclosure will be described. In the following description of the conditional expressions, the same symbols will be used for the same definitions to avoid redundant explanations. Also, in the following, to avoid redundant explanations, "the zoom lens of this disclosure" will also be simply referred to as "the zoom lens."

[0077] Zoom lenses preferably satisfy the following condition (1). Here, Bfw is the back focus of the entire system in terms of air-equivalent distance when focused on an object at infinity at the wide-angle end. fw is the focal length of the entire system when focused on an object at infinity at the wide-angle end. "Back focus of the entire system in terms of air-equivalent distance" is the air-equivalent distance on the optical axis from the image-side lens surface of the final lens group to the image plane Sim. As an example, Figure 2 schematically shows the above back focus Bfw. In Figure 2, parallel plate-shaped optical elements that do not have refractive power to be calculated using air-equivalent distance are shown by dashed lines. Ensuring that the corresponding value of condition (1) does not fall below the lower limit is advantageous for securing peripheral light. Ensuring that the corresponding value of condition (1) does not exceed the upper limit is advantageous for shortening the overall length of the optical system. 0.1 <Bfw / fw<1.9 (1)

[0078] To obtain better characteristics, the lower limit of condition (1) is more preferably 0.3, even more preferably 0.5, and even more preferably 0.57. To obtain better characteristics, the upper limit of condition (1) is more preferably 1.5, even more preferably 1.2, and even more preferably 1.12. For example, a zoom lens is more preferably satisfied with the following condition (1-1), even more preferably satisfied with the following condition (1-2), and even more preferably satisfied with the following condition (1-3). 0.3 <Bfw / fw<1.5 (1-1) 0.5 <Bfw / fw<1.2 (1-2) 0.57 <Bfw / fw<1.12 (1-3)

[0079] When the focal length of the first lens group G1 is f1, it is preferable that the zoom lens satisfies the following condition (2). By ensuring that the corresponding value in condition (2) does not fall below the lower limit, the refractive power of the first lens group G1 can be increased, which is advantageous for shortening the overall length. By ensuring that the corresponding value in condition (2) does not exceed the upper limit, the refractive power of the first lens group G1 does not become too strong, which is advantageous for widening the angle while suppressing aberrations. 0.05 <fw / f1<0.54 (2)

[0080] To obtain better characteristics, the lower limit of condition (2) is more preferably 0.12, even more preferably 0.2, and even more preferably 0.23. To obtain better characteristics, the upper limit of condition (2) is more preferably 0.5, even more preferably 0.42, and even more preferably 0.386. For example, a zoom lens is more preferably satisfied with the following condition (2-1), even more preferably satisfied with the following condition (2-2), and even more preferably satisfied with the following condition (2-3). 0.12 <fw / f1<0.5 (2-1) 0.2 <fw / f1<0.42 (2-2) 0.23 <fw / f1<0.386 (2-3)

[0081] In a configuration where the zoom lens includes an aperture diaphragm St, it is preferable that the zoom lens satisfies the following condition (3). Here, DStw is defined as the sum of the distance along the optical axis from the aperture diaphragm St to the image-side lens surface of the final lens group GE, and the back focus in terms of the air-equivalent distance of the entire system, when the lens is in focus on an object at infinity at the wide-angle end. TLw is defined as the sum of the distance along the optical axis from the object-side lens surface of the first lens group G1 to the image-side lens surface of the final lens group GE, and the back focus in terms of the air-equivalent distance of the entire system, when the lens is in focus on an object at infinity at the wide-angle end. TLw is the total length of the lens system when the lens is in focus on an object at infinity at the wide-angle end. As an example, Figure 2 schematically shows the above distance DStw and total lens system length TLw. By ensuring that the corresponding value of condition (3) does not fall below the lower limit, it becomes advantageous to reduce the diameter of the first lens group G1. By ensuring that the corresponding value in condition (3) does not exceed the upper limit, the separation of the on-axis and off-axis light beams in the first lens group G1 can be greatly increased, which is advantageous for correcting off-axis light beam aberrations while suppressing the overall length of the optical system. 0.5 <DStw / TLw<0.85 (3)

[0082] To obtain better characteristics, the lower limit of condition (3) is more preferably 0.61, even more preferably 0.63, and even more preferably 0.64. To obtain better characteristics, the upper limit of condition (3) is more preferably 0.8, even more preferably 0.72, and even more preferably 0.685. For example, a zoom lens is more preferably satisfied with the following condition (3-1), even more preferably satisfied with the following condition (3-2), and even more preferably satisfied with the following condition (3-3). 0.61 <DStw / TLw<0.8 (3-1) 0.63 <DStw / TLw<0.72 (3-2) 0.64 <DStw / TLw<0.685 (3-3)

[0083] It is preferable that the zoom lens satisfies the following condition (4). Here, ωw is defined as the maximum half-angle of view when in focus on an object at infinity at the wide-angle end. As an example, Figure 1 shows the above maximum half-angle of view ωw. Ensuring that the corresponding value in condition (4) does not fall below the lower limit is advantageous in securing peripheral illumination. Ensuring that the corresponding value in condition (4) does not exceed the upper limit is advantageous in shortening the overall length of the optical system. 0.4 <Bfw / (fw×tanωw)<1.6 (4)

[0084] To obtain better characteristics, the lower limit of conditional equation (4) is more preferably 0.5, even more preferably 0.6, and even more preferably 0.69. To obtain better characteristics, the upper limit of conditional equation (4) is more preferably 1.5, even more preferably 1.4, and even more preferably 1.29. For example, a zoom lens is more preferably satisfied with the following conditional equation (4-1), even more preferably satisfied with the following conditional equation (4-2), and even more preferably satisfied with the following conditional equation (4-3). 0.5 <Bfw / (fw×tanωw)<1.5 (4-1) 0.6 <Bfw / (fw×tanωw)<1.4 (4-2) 0.69 <Bfw / (fw×tanωw)<1.29 (4-3)

[0085] When the focal length of the final lens group GE is fE, it is preferable that the zoom lens satisfies the following condition (5). Ensuring that the corresponding value in condition (5) does not fall below the lower limit is advantageous for securing back focus. Ensuring that the corresponding value in condition (5) does not exceed the upper limit allows for shortening the back focus, which is advantageous for shortening the overall length. -0.7 <fw / fE<0.7 (5)

[0086] To obtain better characteristics, the lower limit of condition (5) is more preferably -0.6, even more preferably -0.5, and even more preferably -0.4. To obtain better characteristics, the upper limit of condition (5) is more preferably 0.6, even more preferably 0.5, and even more preferably 0.36. For example, a zoom lens is more preferably satisfied with the following condition (5-1), even more preferably satisfied with the following condition (5-2), and even more preferably satisfied with the following condition (5-3). -0.6 <fw / fE<0.6 (5-1) -0.5 <fw / fE<0.5 (5-2) -0.4 <fw / fE<0.36 (5-3)

[0087] When νEmax is the maximum value of the d-line reference Abbe number of all lenses included in the final lens group GE, it is preferable that the zoom lens satisfies the following condition (6). By ensuring that the corresponding value in condition (6) does not fall below the lower limit, it is advantageous to suppress chromatic aberration. By ensuring that the corresponding value in condition (6) does not exceed the upper limit, it is possible to use materials with a high refractive index, which reduces the thickness of the lens and is advantageous for miniaturization. 60 < νEmax < 105 (6)

[0088] To obtain better characteristics, the lower limit of condition (6) is more preferably set to 70, even more preferably to 75, and even more preferably to 80. To obtain better characteristics, the upper limit of condition (6) is more preferably set to 100, even more preferably to 98, and even more preferably to 95. For example, a zoom lens is more preferably satisfied with the following condition (6-1), even more preferably satisfied with the following condition (6-2), and even more preferably satisfied with the following condition (6-3). 70 < νEmax < 100 (6-1) 75 < νEmax < 98 (6-2) 80 < νEmax < 95 (6-3)

[0089] It is preferable for the zoom lens to satisfy the following condition (7). Here, D12w is defined as the distance on the optical axis between the first lens group G1 and the lens group adjacent to the image side of the first lens group G1 when in focus on an object at infinity at the wide-angle end. Figure 3 shows a magnified view of a portion of the zoom lens in Figure 1, and as an example, Figure 3 shows the above-mentioned distance D12w. By ensuring that the corresponding value of condition (7) does not fall below the lower limit, contact between lens groups due to impacts, etc., can be avoided, which is advantageous for improving robustness. By ensuring that the corresponding value of condition (7) does not exceed the upper limit, it is advantageous for wide-angle lenses. 0.005 <D12w / (fw×tanωw)<0.35 (7)

[0090] To obtain better characteristics, the lower limit of condition (7) is more preferably 0.01, even more preferably 0.02, and even more preferably 0.03. To obtain better characteristics, the upper limit of condition (7) is more preferably 0.25, even more preferably 0.15, and even more preferably 0.095. For example, a zoom lens is more preferably satisfied with the following condition (7-1), even more preferably satisfied with the following condition (7-2), and even more preferably satisfied with the following condition (7-3). 0.01 <D12w / (fw×tanωw)<0.25 (7-1) 0.02 <D12w / (fw×tanωw)<0.15 (7-2) 0.03 <D12w / (fw×tanωw)<0.095 (7-3)

[0091] In a zoom lens configuration that includes at least one combination of a lens group having negative refractive power and a lens group having positive refractive power, arranged adjacently from the object side to the image side, it is preferable that the zoom lens satisfies the following condition (8). Here, DNPt is defined as the distance on the optical axis at the telephoto end between the lens group having negative refractive power and the lens group having positive refractive power of the combination closest to the object. As an example, Figure 1 shows the above distance DNPt. In the example in Figure 1, the distance on the optical axis at the telephoto end between the second lens group G2 and the third lens group G3 corresponds to DNPt. By ensuring that the corresponding value of condition (8) does not fall below the lower limit, contact between lens groups due to impact, etc., can be avoided, which is advantageous for improving robustness. By ensuring that the corresponding value of condition (8) does not exceed the upper limit, it is advantageous for obtaining a high magnification ratio. 0.005 <DNPt / (fw×tanωw)<0.5 (8)

[0092] To obtain better characteristics, the lower limit of condition (8) is more preferably 0.02, even more preferably 0.04, and even more preferably 0.065. To obtain better characteristics, the upper limit of condition (8) is more preferably 0.35, even more preferably 0.25, and even more preferably 0.19. For example, a zoom lens is more preferably satisfied with the following condition (8-1), even more preferably satisfied with the following condition (8-2), and even more preferably satisfied with the following condition (8-3). 0.02 <DNPt / (fw×tanωw)<0.35 (8-1) 0.04 <DNPt / (fw×tanωw)<0.25 (8-2) 0.065 <DNPt / (fw×tanωw)<0.19 (8-3)

[0093] It is preferable that the zoom lens satisfies the following condition (9). Here, among the lenses included in the final lens group GE, the refractive index and Abbe number with respect to the d line of the lens with the maximum Abbe number based on the d line are defined as NE and νEmax, respectively. Ensuring that the corresponding value in condition (9) does not fall below the lower limit is advantageous for suppressing the second-order spectrum of chromatic aberration. Ensuring that the corresponding value in condition (9) does not exceed the upper limit allows for the selection of materials with a lower specific gravity, which is advantageous for weight reduction. -0.05 <NE+0.0067×νEmax-2<0.13 (9)

[0094] To obtain better characteristics, the lower limit of condition (9) is more preferably -0.03, even more preferably 0, and even more preferably 0.02. To obtain better characteristics, the upper limit of condition (9) is more preferably 0.11, even more preferably 0.09, and even more preferably 0.07. For example, a zoom lens is more preferably satisfied with the following condition (9-1), even more preferably satisfied with the following condition (9-2), and even more preferably satisfied with the following condition (9-3). -0.03 <NE+0.0067×νEmax-2<0.11 (9-1) 0 <NE+0.0067×νEmax-2<0.09 (9-2) 0.02 <NE+0.0067×νEmax-2<0.07 (9-3)

[0095] In a configuration in which a zoom lens includes at least one aspherical lens, it is preferable that the zoom lens satisfies the following condition (10). For the sake of explanation, below, the aspherical lens closest to the object among the aspherical lenses included in the zoom lens will be referred to as the closest object-side aspherical lens. Here, Δsag is defined as the difference between the sag amount of the lens surface and the sag amount of the paraxial curvature sphere of the lens surface at a height of 70% of the maximum effective radius of the lens surface of the aspherical lens. That is, Δsag is the aspherical amount at a height of 70% of the maximum effective radius. In the closest object-side aspherical lens, ΔsagM is defined as the larger of the absolute values ​​of the aspherical amount Δsag of the object-side surface and the aspherical amount Δsag of the image-side surface. In the closest object-side aspherical lens, HaM is defined as the larger of the maximum effective radius of the object-side surface and the maximum effective radius of the image-side surface. By ensuring that the corresponding value in conditional equation (10) does not fall below the lower limit, it is advantageous to suppress fluctuations in off-axis aberrations during magnification. By ensuring that the corresponding value in conditional equation (10) does not exceed the upper limit, it is advantageous to improve the processability of the lens. 0.001 < |ΔsagM| / HaM < 0.07 (10)

[0096] To obtain better characteristics, the lower limit of conditional equation (10) is more preferably 0.002, even more preferably 0.004, and even more preferably 0.006. To obtain better characteristics, the upper limit of conditional equation (10) is more preferably 0.06, even more preferably 0.05, and even more preferably 0.04. For example, a zoom lens is more preferably satisfied with the following conditional equation (10-1), even more preferably satisfied with the following conditional equation (10-2), and even more preferably satisfied with the following conditional equation (10-3). 0.002<|ΔsagM| / HaM<0.06 (10-1) 0.004<|ΔsagM| / HaM<0.05 (10-2) 0.006<|ΔsagM| / HaM<0.04 (10-3)

[0097] Here, the "maximum effective radius" as defined herein will be explained with reference to Figure 4. Figure 4 is an explanatory diagram, with the left side being the object side and the right side being the image side. Figure 4 shows the on-axis luminous flux Xa and the off-axis luminous flux Xb passing through lens Lx. In the example in Figure 4, the ray Xb1, which is the upper ray of the off-axis luminous flux Xb, is the outermost ray. Here, "outside" means radially outward from the optical axis Z, that is, away from the optical axis Z. The position of the intersection of this outermost ray and the lens surface is the position Px of the maximum effective radius. The height of the position Px of the maximum effective radius from the optical axis Z is the maximum effective radius He of the object-side surface of lens Lx. Note that in the example in Figure 4, the upper ray of the off-axis luminous flux Xb is the outermost ray, but which ray is the outermost ray will vary depending on the lens system.

[0098] Furthermore, "sag amount," "paraxial curvature sphere," and the "aspherical amount Δsag" defined above will be explained with reference to Figure 5. Figure 5 is an explanatory diagram, with the left side being the object side and the right side being the image side. Figure 5 shows an aspherical lens LA in which the lens surface LAs1 on the object side has an aspherical shape. In this specification, the "sag amount" of a surface at a certain height refers to the distance in the direction of the optical axis between a plane perpendicular to the optical axis Z that passes through the intersection of that surface and the optical axis Z, and a point on that surface at that height. As an example, Figure 5 shows the sag amount sagA of the lens surface LAs1 at a height H7, which is 70% of the maximum effective radius of the lens surface LAs1. In Figure 5, the plane VP perpendicular to the optical axis Z that passes through the intersection of the lens surface LAs1 and the optical axis Z is shown by a dashed line.

[0099] A "paraxial curvature sphere" of a lens surface refers to a sphere that has the same radius of curvature as the paraxial radius of curvature of that lens surface and passes through the intersection of that lens surface and the optical axis Z. As an example, Figure 5 shows the paraxial curvature sphere Sp of lens surface LAs1 as a dashed line, and the sag amount sagSp of the paraxial curvature sphere Sp at height H7 is shown. Since the aspherical amount Δsag is the difference between the sag amount of the lens surface and the sag amount of the paraxial curvature sphere of the lens surface, the aspherical amount Δsag of lens surface LAs1 at height H7 is the difference between sagSp and sagA, as shown in Figure 5. Note that Figure 5 shows the aspherical amount Δsag for the object-side lens surface LAs1, but the aspherical amount Δsag can be similarly considered for the image-side lens surface LAs2 of the aspherical lens LA.

[0100] When a zoom lens includes at least one lens group having negative refractive power, the aspherical lens closest to the object is preferably arranged as follows, and in particular, the aspherical lens closest to the object that satisfies the above condition (10) is preferably arranged as follows. The aspherical lens closest to the object is preferably the third lens from the object side of the lens group having negative refractive power closest to the object among the lens groups having negative refractive power included in the zoom lens. When arranged in this way, it is advantageous to suppress spherical aberration at the telephoto end while suppressing fluctuations in off-axis aberrations during magnification. Alternatively, the aspherical lens closest to the object is preferably the fourth lens from the object side of the lens group having negative refractive power closest to the object among the lens groups having negative refractive power included in the zoom lens. When arranged in this way, it is advantageous to suppress spherical aberration at the telephoto end.

[0101] In a configuration in which a zoom lens includes at least one negative lens, it is preferable that the zoom lens satisfies the following condition (11). Here, Nn1 is defined as the refractive index with respect to the d line of the negative lens closest to the object among the negative lenses included in the zoom lens. Ensuring that the corresponding value of condition (11) does not fall below the lower limit is advantageous in suppressing field curvature. Ensuring that the corresponding value of condition (11) does not exceed the upper limit allows for the selection of materials with low wear resistance, which is advantageous in improving robustness. 1.59 <Nn1<1.99 (11)

[0102] To obtain better characteristics, the lower limit of condition (11) is more preferably 1.7, even more preferably 1.75, and even more preferably 1.8. To obtain better characteristics, the upper limit of condition (11) is more preferably 1.96, even more preferably 1.87, and even more preferably 1.85. For example, a zoom lens is more preferably satisfied with the following condition (11-1), even more preferably satisfied with the following condition (11-2), and even more preferably satisfied with the following condition (11-3). 1.7 <Nn1<1.96 (11-1) 1.75 <Nn1<1.87 (11-2) 1.8 <Nn1<1.85 (11-3)

[0103] In a configuration in which a zoom lens includes at least one negative lens, it is preferable that the zoom lens satisfies the following condition (12). Here, Dn1 and Hn1 are the central thickness and the maximum effective radius of the object-side face of the negative lens included in the zoom lens that is closest to the object, respectively. As an example, Figure 3 shows the above central thickness Dn1 and maximum effective radius Hn1. Ensuring that the corresponding value of condition (12) does not fall below the lower limit is advantageous for improving robustness. Ensuring that the corresponding value of condition (12) does not exceed the upper limit is advantageous for reducing weight. 0.02 <Dn1 / Hn1<0.087 (12)

[0104] To obtain better characteristics, the lower limit of conditional equation (12) is more preferably 0.03, even more preferably 0.04, and even more preferably 0.048. To obtain better characteristics, the upper limit of conditional equation (12) is more preferably 0.082, even more preferably 0.07, and even more preferably 0.053. For example, a zoom lens is more preferably satisfied with the following conditional equation (12-1), even more preferably satisfied with the following conditional equation (12-2), and even more preferably satisfied with the following conditional equation (12-3). 0.03 <Dn1 / Hn1<0.082 (12-1) 0.04 <Dn1 / Hn1<0.07 (12-2) 0.048 <Dn1 / Hn1<0.053 (12-3)

[0105] In a configuration where a zoom lens includes at least one lens group having negative refractive power, and the lens group with negative refractive power closest to the object among the negative refractive power lenses included in the zoom lens includes at least one negative lens, it is preferable that the zoom lens satisfies the following condition (13). Here, Dn2 and Hn2 are the central thickness and the maximum effective radius of the object-side face of the negative lens included in the negative refractive power lens group closest to the object, respectively. As an example, Figure 3 shows the above central thickness Dn2 and maximum effective radius Hn2. Ensuring that the corresponding value of condition (13) does not fall below the lower limit is advantageous for improving robustness. Ensuring that the corresponding value of condition (13) does not exceed the upper limit is advantageous for reducing weight. 0.02 <Dn2 / Hn2<0.105 (13)

[0106] To obtain better characteristics, the lower limit of conditional equation (13) is more preferably 0.035, even more preferably 0.041. To obtain better characteristics, the upper limit of conditional equation (13) is more preferably 0.073, even more preferably 0.06, and even more preferably 0.045. For example, a zoom lens is more preferably satisfied with the following conditional equation (13-1), even more preferably satisfied with the following conditional equation (13-2), and even more preferably satisfied with the following conditional equation (13-3). 0.03 <Dn2 / Hn2<0.073 (13-1) 0.035 <Dn2 / Hn2<0.06 (13-2) 0.041 <Dn2 / Hn2<0.045 (13-3)

[0107] When the focal length of the lens group adjacent to the object side of the final lens group GE is fFE, it is preferable that the zoom lens satisfies the following condition (14). By ensuring that the corresponding value of condition (14) does not fall below the lower limit, the height of the off-axis light beam to the final lens group GE is reduced, which is advantageous for reducing the weight of the final lens group GE. By ensuring that the corresponding value of condition (14) does not exceed the upper limit, the degree of separation between on-axis and off-axis rays in the final lens group GE is increased, which is advantageous for suppressing off-axis aberrations. -0.8 <fw / fFE<0.4 (14)

[0108] To obtain better characteristics, the lower limit of conditional equation (14) is more preferably -0.7, even more preferably -0.6, and even more preferably -0.56. To obtain better characteristics, the upper limit of conditional equation (14) is more preferably 0, even more preferably -0.32, and even more preferably -0.45. For example, a zoom lens is more preferably satisfied with the following conditional equation (14-1), even more preferably satisfied with the following conditional equation (14-2), and even more preferably satisfied with the following conditional equation (14-3). -0.7 <fw / fFE<0 (14-1) -0.6 <fw / fFE<-0.32 (14-2) -0.56 <fw / fFE<-0.45 (14-3)

[0109] In a configuration in which a zoom lens includes an aperture diaphragm St, it is preferable that the zoom lens satisfies the following condition (15). Here, if the aperture diaphragm St is included in the lens group, NStp is defined as the refractive index with respect to the d line of the positive lens closest to the image among the positive lenses included in the lens group including the aperture diaphragm St. If the aperture diaphragm St is not included in the lens group, NStp is defined as the refractive index with respect to the d line of the positive lens closest to the image among the positive lenses included in the lens group adjacent to the image side of the aperture diaphragm St. By ensuring that the corresponding value of condition (15) does not fall below the lower limit, it is advantageous to suppress spherical aberration. By ensuring that the corresponding value of condition (15) does not exceed the upper limit, the sensitivity to surface shape errors of the corresponding positive lens is reduced, which is advantageous to improve manufacturability. 1.43 <NStp<1.895 (15)

[0110] To obtain better characteristics, the lower limit of conditional equation (15) is more preferably 1.49, even more preferably 1.65, and even more preferably 1.71. To obtain better characteristics, the upper limit of conditional equation (15) is more preferably 1.89, even more preferably 1.87, and even more preferably 1.85. For example, a zoom lens is more preferably satisfied with the following conditional equation (15-1), even more preferably satisfied with the following conditional equation (15-2), and even more preferably satisfied with the following conditional equation (15-3). 1.49 <NStp<1.89 (15-1) 1.65 <NStp<1.87 (15-2) 1.71 <NStp<1.85 (15-3)

[0111] In this specification, "lens group including aperture diaphragm St" refers to a lens group that includes at least one lens adjacent to the aperture diaphragm St and behaves in the same way as the aperture diaphragm St during magnification. "When the aperture diaphragm St is included in the lens group" refers to the case where the above-mentioned "lens group including aperture diaphragm St" exists. For example, the example in Figure 1 is a zoom lens in which the third lens group G3 is the "lens group including aperture diaphragm St," and the aperture diaphragm St is included in the lens group. "When the aperture diaphragm St is not included in the lens group" refers to the case where the above-mentioned "lens group including aperture diaphragm St" does not exist. That is, when the aperture diaphragm St is not included in the lens group, neither the object-side nor the image-side lens adjacent to the aperture diaphragm St behaves in the same way as the aperture diaphragm St during magnification. For example, Example 4 described later is a zoom lens in which the aperture diaphragm St is not included in the lens group. Note that "same behavior" here includes not only integrated movement but also being fixed with respect to the image plane Sim. Furthermore, in this specification, "integrated movement" means moving simultaneously by the same amount and in the same direction.

[0112] When N1ave is the average refractive index of all lenses included in the first lens group G1 with respect to the d line, it is preferable that the zoom lens satisfies the following condition (16). By ensuring that the corresponding value in condition (16) does not fall below the lower limit, it is advantageous to suppress field curvature. By ensuring that the corresponding value in condition (16) does not exceed the upper limit, it is possible to select a material with a low specific gravity, which is advantageous for reducing the weight of the first lens group G1. 1.6 <N1ave<1.9 (16)

[0113] To obtain better characteristics, the lower limit of conditional equation (16) is more preferably 1.65, even more preferably 1.68, and even more preferably 1.7. To obtain better characteristics, the upper limit of conditional equation (16) is more preferably 1.86, even more preferably 1.78, and even more preferably 1.76. For example, a zoom lens is more preferably satisfied with the following conditional equation (16-1), even more preferably satisfied with the following conditional equation (16-2), and even more preferably satisfied with the following conditional equation (16-3). 1.65 <N1ave<1.86 (16-1) 1.68 <N1ave<1.78 (16-2) 1.7 <N1ave<1.76 (16-3)

[0114] It is preferable that the zoom lens satisfies the following condition (17). Here, βEt is the lateral magnification of the final lens group GE when in focus on an object at infinity at the telephoto end. βFEt is the lateral magnification of the lens group adjacent to the object side of the final lens group GE when in focus on an object at infinity at the telephoto end. By ensuring that the corresponding value in condition (17) does not fall below the lower limit, it is advantageous to reduce the weight of the lens group adjacent to the object side of the final lens group GE. By ensuring that the corresponding value in condition (17) does not exceed the upper limit, it is advantageous to suppress aberration fluctuations during magnification that occur in the lens group adjacent to the object side of the final lens group GE. 0.14 < βEt × βFEt < 2.2 (17)

[0115] To obtain better characteristics, the lower limit of conditional equation (17) is more preferably 0.7, even more preferably 1.1, and even more preferably 1.3. To obtain better characteristics, the upper limit of conditional equation (17) is more preferably 2.15, even more preferably 2.05, and even more preferably 1.99. For example, a zoom lens is more preferably satisfied with the following conditional equation (17-1), even more preferably satisfied with the following conditional equation (17-2), and even more preferably satisfied with the following conditional equation (17-3). 0.7 < βEt × βFEt < 2.15 (17-1) 1.1 < βEt × βFEt < 2.05 (17-2) 1.3 < βEt × βFEt < 1.99 (17-3)

[0116] In a configuration in which a zoom lens includes at least one lens group having negative refractive power, it is preferable that the zoom lens satisfies the following condition (18). Here, νNmin is defined as the minimum Abbe number on the d line reference of all lenses included in the lens group having negative refractive power closest to the object among the lens groups having negative refractive power included in the zoom lens. By ensuring that the corresponding value of condition (18) does not fall below the lower limit, it is advantageous to suppress fluctuations in chromatic aberration during magnification. By ensuring that the corresponding value of condition (18) does not exceed the upper limit, it is advantageous to suppress axial chromatic aberration at the telephoto end. 15 < νNmin < 25.6 (18)

[0117] To obtain better characteristics, the lower limit of conditional equation (18) is more preferably 16.5, even more preferably 17, and even more preferably 17.5. To obtain better characteristics, the upper limit of conditional equation (18) is more preferably 24.5, even more preferably 23.7, and even more preferably 20.4. For example, a zoom lens is more preferably satisfied with the following conditional equation (18-1), even more preferably satisfied with the following conditional equation (18-2), and even more preferably satisfied with the following conditional equation (18-3). 16.5 < νNmin < 24.5 (18-1) 17 < νNmin < 23.7 (18-2) 17.5 < νNmin < 20.4 (18-3)

[0118] In a configuration in which a zoom lens includes an aperture diaphragm St, it is preferable that the zoom lens satisfies the following conditional equation (19). Here, if the aperture diaphragm St is included in the lens group, the focal length of the lens group including the aperture diaphragm St is defined as fGSt. If the aperture diaphragm St is not included in the lens group, the focal length of the lens group adjacent to the image side of the aperture diaphragm St is defined as fGSt. Ensuring that the corresponding value of conditional equation (19) does not fall below the lower limit is advantageous for miniaturization. Ensuring that the corresponding value of conditional equation (19) does not exceed the upper limit is advantageous for suppressing aberration changes caused by errors during assembly. 0.3 <fw / fGSt<1.3 (19)

[0119] To obtain better characteristics, the lower limit of conditional equation (19) is more preferably 0.42, even more preferably 0.55, and even more preferably 0.82. To obtain better characteristics, the upper limit of conditional equation (19) is more preferably 1.1, even more preferably 1.03, and even more preferably 0.99. For example, a zoom lens is more preferably satisfied with the following conditional equation (19-1), even more preferably satisfied with the following conditional equation (19-2), and even more preferably satisfied with the following conditional equation (19-3). 0.42 <fw / fGSt<1.1 (19-1) 0.55 <fw / fGSt<1.03 (19-2) 0.82 <fw / fGSt<0.99 (19-3)

[0120] In a configuration in which a zoom lens includes a lens group having at least one negative refractive power, it is preferable that the zoom lens satisfies the following condition (31). By ensuring that the corresponding value of condition (31) does not fall below the lower limit, it is advantageous to obtain a high magnification ratio. By ensuring that the corresponding value of condition (31) does not exceed the upper limit, it is advantageous to miniaturize the lens. -1 <fN / fGSt<-0.28 (31)

[0121] To obtain better characteristics, the lower limit of conditional equation (31) is more preferably -0.9, even more preferably -0.8, and even more preferably -0.74. To obtain better characteristics, the upper limit of conditional equation (31) is more preferably -0.37, even more preferably -0.45, and even more preferably -0.54. For example, a zoom lens is more preferably satisfied with the following conditional equation (31-1), even more preferably satisfied with the following conditional equation (31-2), and even more preferably satisfied with the following conditional equation (31-3). -0.9 <fN / fGSt<-0.37 (31-1) -0.8 <fN / fGSt<-0.45 (31-2) -0.74 <fN / fGSt<-0.54 (31-3)

[0122] In a configuration in which a zoom lens includes a lens group having at least one negative refractive power, it is preferable that the zoom lens satisfies the following condition (20). Ensuring that the corresponding value of condition (20) does not fall below the lower limit is advantageous in suppressing aberration changes caused by assembly errors. Ensuring that the corresponding value of condition (20) does not exceed the upper limit is advantageous in obtaining a high magnification ratio. -2.5 <fw / fN<-0.8 (20)

[0123] To obtain better characteristics, the lower limit of conditional equation (20) is more preferably -2.1, even more preferably -1.9, and even more preferably -1.7. To obtain better characteristics, the upper limit of conditional equation (20) is more preferably -1.1, even more preferably -1.23, and even more preferably -1.26. For example, a zoom lens is more preferably satisfied with the following conditional equation (20-1), even more preferably satisfied with the following conditional equation (20-2), and even more preferably satisfied with the following conditional equation (20-3). -2.1 <fw / fN<-1.1 (20-1) -1.9 <fw / fN<-1.23 (20-2) -1.7 <fw / fN<-1.26 (20-3)

[0124] In a configuration in which a zoom lens includes at least one lens group having negative refractive power, it is preferable that the zoom lens satisfies the following condition (35). By ensuring that the corresponding value of condition (35) does not fall below the lower limit, it is advantageous to shorten the length from the first lens group G1 to the lens group with the most negative refractive power on the object side among the lens groups having negative refractive power included in the zoom lens. By ensuring that the corresponding value of condition (35) does not exceed the upper limit, it is advantageous to widen the angle of view. 0.1 < |fN / f1| < 0.35 (35)

[0125] To obtain better characteristics, the lower limit of conditional equation (35) is more preferably 0.12, even more preferably 0.14, and even more preferably 0.17. To obtain better characteristics, the upper limit of conditional equation (35) is more preferably 0.3, even more preferably 0.27, and even more preferably 0.25. For example, a zoom lens is more preferably satisfied with the following conditional equation (35-1), even more preferably satisfied with the following conditional equation (35-2), and even more preferably satisfied with the following conditional equation (35-3). 0.12 < |fN / f1| < 0.3 (35-1) 0.14 < |fN / f1| < 0.27 (35-2) 0.17 < |fN / f1| < 0.25 (35-3)

[0126] In a zoom lens configuration that includes a focusing group, it is preferable that the zoom lens satisfies the following condition (27). Here, the focal length of the focusing group is denoted as ffoc. By ensuring that the corresponding value of condition (27) does not fall below the lower limit, the amount of movement of the focusing group during focusing can be suppressed, which is advantageous for shortening the overall length. By ensuring that the corresponding value of condition (27) does not exceed the upper limit, it is advantageous for suppressing the error sensitivity of the focusing group. 0.25 <fw / |ffoc|<1.2 (27)

[0127] To obtain better characteristics, the lower limit of conditional equation (27) is more preferably 0.3, even more preferably 0.35, and even more preferably 0.42. To obtain better characteristics, the upper limit of conditional equation (27) is more preferably 1, even more preferably 0.8, and even more preferably 0.66. For example, a zoom lens is more preferably satisfied with the following conditional equation (27-1), even more preferably satisfied with the following conditional equation (27-2), and even more preferably satisfied with the following conditional equation (27-3). 0.3 <fw / |ffoc|<1 (27-1) 0.35 <fw / |ffoc|<0.8 (27-2) 0.42 <fw / |ffoc|<0.66 (27-3)

[0128] In a configuration where a zoom lens includes a focusing group, it is preferable that the zoom lens satisfies the following condition (21). Here, βfw is the lateral magnification of the focusing group when it is in focus on an object at infinity at the wide-angle end. βfRw is the combined lateral magnification of all lenses on the image side of the focusing group when it is in focus on an object at infinity at the wide-angle end. Then, γw = (1 - βfw 2 )×βfRw 2 This is how it is defined. By ensuring that the corresponding value in conditional equation (21) does not fall below the lower limit, the amount of movement of the focusing group during focusing can be suppressed, which is advantageous for shortening the overall length. By ensuring that the corresponding value in conditional equation (21) does not exceed the upper limit, it is advantageous for suppressing the error sensitivity of the focusing group. 1.53 < |γw| < 5.5 (21)

[0129] To obtain better characteristics, the lower limit of conditional equation (21) is more preferably set to 2, even more preferably to 2.2, and even more preferably to 3.1. To obtain better characteristics, the upper limit of conditional equation (21) is more preferably set to 5, even more preferably to 4.5, and even more preferably to 4. For example, a zoom lens is more preferably satisfied with the following conditional equation (21-1), even more preferably satisfied with the following conditional equation (21-2), and even more preferably satisfied with the following conditional equation (21-3). 2 < |γw| < 5 (21-1) 2.2 < |γw| < 4.5 (21-2) 3.1<|γw|<4 (21-3)

[0130] In a configuration where a zoom lens includes a focusing group, it is preferable that the zoom lens satisfies the following condition (28). Here, βft is the lateral magnification of the focusing group when it is in focus on an object at infinity at the telephoto end. βfRt is the combined lateral magnification of all lenses on the image side of the focusing group when it is in focus on an object at infinity at the telephoto end. Then, γt = (1 - βft 2 )×βfRt 2 This is how it is defined. By ensuring that the corresponding value in conditional equation (28) does not fall below the lower limit, the amount of movement of the focusing group during focusing can be suppressed, which is advantageous for shortening the overall length. By ensuring that the corresponding value in conditional equation (28) does not exceed the upper limit, it is advantageous for suppressing the error sensitivity of the focusing group. 1.3 < |γt| < 4.5 (28)

[0131] To obtain better characteristics, the lower limit of conditional equation (28) is more preferably set to 1.42, even more preferably to 2, and even more preferably to 2.8. To obtain better characteristics, the upper limit of conditional equation (28) is more preferably set to 4.2, even more preferably to 3.8, and even more preferably to 3.5. For example, a zoom lens is more preferably satisfied with the following conditional equation (28-1), even more preferably satisfied with the following conditional equation (28-2), and even more preferably satisfied with the following conditional equation (28-3). 1.42 < |γt| < 4.2 (28-1) 2 < |γt| < 3.8 (28-2) 2.8 < |γt| < 3.5 (28-3)

[0132] In a configuration where a zoom lens includes a focusing group, it is preferable that the zoom lens satisfies the following condition (29). Here, ffRt is defined as the combined focal length of all lenses on the image side of the focusing group when in focus on an object at infinity at the telephoto end. Dext is defined as the distance along the optical axis from the paraxial exit pupil position to the image plane Sim when in focus on an object at infinity at the telephoto end. ωt is defined as the maximum half-angle of view when in focus on an object at infinity at the telephoto end. As an example, Figure 1 shows the above maximum half-angle of view ωt. If an optical element that does not have refractive power is placed between the paraxial exit pupil position and the image plane Sim, Dext is calculated using the air equivalent distance for that optical element. Then, BRt is defined as {βft / (ffoc×γt)-1 / (βfRt×ffRt)-(1 / Dext)}. By ensuring that the corresponding value of condition (29) does not fall below the lower limit, it becomes advantageous for miniaturization. By ensuring that the corresponding value in conditional equation (29) does not exceed the upper limit, the angle of view fluctuation during focusing at the telephoto end can be suppressed. 0.001 < |BRt × (ft × tanωt)| < 0.08 (29)

[0133] To obtain better characteristics, the lower limit of conditional equation (29) is more preferably 0.003, even more preferably 0.005, and even more preferably 0.008. To obtain better characteristics, the upper limit of conditional equation (29) is more preferably 0.042, even more preferably 0.025, and even more preferably 0.017. For example, a zoom lens is more preferably satisfied with the following conditional equation (29-1), even more preferably satisfied with the following conditional equation (29-2), and even more preferably satisfied with the following conditional equation (29-3). 0.003 < |BRt × (ft × tanωt)| < 0.042 (29-1) 0.005 < |BRt × (ft × tanωt)| < 0.025 (29-2) 0.008 < |BRt × (ft × tanωt)| < 0.017 (29-3)

[0134] In a zoom lens configuration that includes an image stabilization group, it is preferable that the zoom lens satisfies the following condition (30). Here, the focal length of the image stabilization group is denoted as fIS. By ensuring that the corresponding value of condition (30) does not fall below the lower limit, the amount of movement of the image stabilization group during image shake correction can be suppressed, which is advantageous for reducing the diameter of the lens barrel. By ensuring that the corresponding value of condition (30) does not exceed the upper limit, it is advantageous for suppressing aberrations generated in the image stabilization group. 0.4 <ft / |fIS|<2 (30)

[0135] To obtain better characteristics, the lower limit of conditional equation (30) is more preferably 0.5, even more preferably 0.6, and even more preferably 0.7. To obtain better characteristics, the upper limit of conditional equation (30) is more preferably 1.5, even more preferably 1.3, and even more preferably 1.07. For example, a zoom lens is more preferably satisfied with the following conditional equation (30-1), even more preferably satisfied with the following conditional equation (30-2), and even more preferably satisfied with the following conditional equation (30-3). 0.5 <ft / |fIS|<1.5 (30-1) 0.6 <ft / |fIS|<1.3 (30-2) 0.7 <ft / |fIS|<1.07 (30-3)

[0136] In a configuration where the zoom lens includes an image stabilization group, it is preferable that the zoom lens satisfies the following condition (32). By ensuring that the corresponding value of condition (32) does not fall below the lower limit, it is advantageous to shorten the overall length. By ensuring that the corresponding value of condition (32) does not exceed the upper limit, the amount of movement of the image stabilization group during image shake correction can be suppressed, which is advantageous to reduce the diameter of the lens barrel. 1.2 < |fIS / fGSt| < 4 (32)

[0137] To obtain better characteristics, the lower limit of conditional equation (32) is more preferably 1.8, even more preferably 2.3, and even more preferably 2.6. To obtain better characteristics, the upper limit of conditional equation (32) is more preferably 3.6, even more preferably 3.3, and even more preferably 2.8. For example, a zoom lens is more preferably satisfied with the following conditional equation (32-1), even more preferably satisfied with the following conditional equation (32-2), and even more preferably satisfied with the following conditional equation (32-3). 1.8 < |fIS / fGSt| < 3.6 (32-1) 2.3 < |fIS / fGSt| < 3.3 (32-2) 2.6 < |fIS / fGSt| < 2.8 (32-3)

[0138] In a zoom lens configuration that includes an image stabilization group, it is preferable that the zoom lens satisfies the following condition (22). Here, βISt is the lateral magnification of the image stabilization group when focused on an object at infinity at the telephoto end. βISRt is the combined lateral magnification of all lenses on the image side of the image stabilization group when focused on an object at infinity at the telephoto end. By ensuring that the corresponding value of condition (22) does not fall below the lower limit, the amount of movement of the image stabilization group during image shake correction can be suppressed, which is advantageous for reducing the diameter of the lens barrel. By ensuring that the corresponding value of condition (22) does not exceed the upper limit, it is advantageous for suppressing aberrations generated in the image stabilization group. 0.5<|(1-βISt)×βISRt|<2 (22)

[0139] To obtain better characteristics, the lower limit of conditional equation (22) is more preferably 0.6, even more preferably 0.7, and even more preferably 0.8. To obtain better characteristics, the upper limit of conditional equation (22) is more preferably 1.5, even more preferably 1.3, and even more preferably 1.05. For example, a zoom lens is more preferably satisfied with the following conditional equation (22-1), even more preferably satisfied with the following conditional equation (22-2), and even more preferably satisfied with the following conditional equation (22-3). 0.6<|(1-βISt)×βISRt|<1.5 (22-1) 0.7<|(1-βISt)×βISRt|<1.3 (22-2) 0.8<|(1-βISt)×βISRt|<1.05 (22-3)

[0140] When the focal length of the entire system is ft when focused on an object at infinity at the telephoto end, it is preferable that the zoom lens satisfies the following condition (23). By ensuring that the corresponding value in condition (23) does not fall below the lower limit, space can be secured for the lens group to move during magnification, which is advantageous for increasing the magnification ratio. By ensuring that the corresponding value in condition (23) does not exceed the upper limit, the overall length can be shortened, which is advantageous for miniaturization. 1.5 <TLw / ft<3.8 (23)

[0141] To obtain better characteristics, the lower limit of conditional equation (23) is more preferably 1.75, even more preferably 1.9, and even more preferably 2.1. To obtain better characteristics, the upper limit of conditional equation (23) is more preferably 3.4, even more preferably 3.1, and even more preferably 2.9. For example, a zoom lens is more preferably satisfied with the following conditional equation (23-1), even more preferably satisfied with the following conditional equation (23-2), and even more preferably satisfied with the following conditional equation (23-3). 1.75 <TLw / ft<3.4 (23-1) 1.9 <TLw / ft<3.1 (23-2) 2.1 <TLw / ft<2.9 (23-3)

[0142] It is preferable that the zoom lens satisfies the following condition (24). Ensuring that the corresponding value in condition (24) does not fall below the lower limit is advantageous for obtaining a high magnification ratio. Ensuring that the corresponding value in condition (24) does not exceed the upper limit is advantageous for miniaturization. 1.9 <ft / fw<6 (24)

[0143] To obtain better characteristics, the lower limit of conditional equation (24) is more preferably 2.1, even more preferably 2.3, and even more preferably 2.5. To obtain better characteristics, the upper limit of conditional equation (24) is more preferably 4.5, even more preferably 3.5, and even more preferably 3. For example, a zoom lens is more preferably satisfied with the following conditional equation (24-1), even more preferably satisfied with the following conditional equation (24-2), and even more preferably satisfied with the following conditional equation (24-3). 2.1 <ft / fw<4.5 (24-1) 2.3 <ft / fw<3.5 (24-2) 2.5 <ft / fw<3 (24-3)

[0144] It is preferable that the zoom lens satisfies the following condition (25). Here, the unit of ωw is degrees. By ensuring that the corresponding value in condition (25) does not fall below the lower limit, it is advantageous for wide-angle lenses. By ensuring that the corresponding value in condition (25) does not exceed the upper limit, the height of the light rays passing through the first lens group G1 can be suppressed, which is advantageous for miniaturization. 25<ωw<58 (25)

[0145] To obtain better characteristics, the lower limit of condition (25) is more preferably set to 30, even more preferably to 34, and even more preferably to 36. To obtain better characteristics, the upper limit of condition (25) is more preferably set to 53, even more preferably to 49, and even more preferably to 45. For example, a zoom lens is more preferably satisfied with the following condition (25-1), even more preferably satisfied with the following condition (25-2), and even more preferably satisfied with the following condition (25-3). 30 < ωw < 53 (25-1) 34 < ωw < 49 (25-2) 36 < ωw < 45 (25-3)

[0146] It is preferable that the zoom lens satisfies the following condition (26). Here, Denp is the distance along the optical axis from the lens surface closest to the object to the position of the paraxial entrance pupil when the lens is in focus on an object at infinity at the wide-angle end. By ensuring that the corresponding value of condition (26) does not fall below the lower limit, it becomes easier to separate the on-axial and off-axial light beams in the first lens group G1, which is advantageous for correcting chromatic aberration. By ensuring that the corresponding value of condition (26) does not exceed the upper limit, the entrance pupil is positioned closer to the object, which allows the height of the off-axial rays passing through the first lens group G1 to be lowered, which is advantageous for reducing the diameter and weight. 0.6 <Denp / fw<2 (26)

[0147] To obtain better characteristics, the lower limit of conditional equation (26) is more preferably 0.78, even more preferably 0.86, and even more preferably 1. To obtain better characteristics, the upper limit of conditional equation (26) is more preferably 1.7, even more preferably 1.5, and even more preferably 1.41. For example, a zoom lens is more preferably satisfied with the following conditional equation (26-1), even more preferably satisfied with the following conditional equation (26-2), and even more preferably satisfied with the following conditional equation (26-3). 0.78 <Denp / fw<1.7 (26-1) 0.86 <Denp / fw<1.5 (26-2) 1 <Denp / fw<1.41 (26-3)

[0148] It is preferable that the zoom lens satisfies the following condition (33). Here, FNot is the maximum aperture F-number when the lens is in focus on an object at infinity at the telephoto end. FNow is the maximum aperture F-number when the lens is in focus on an object at infinity at the wide-angle end. By ensuring that the corresponding value in condition (33) does not fall below the lower limit, the axial light beam at the telephoto end can be reduced in diameter, which is advantageous for miniaturizing and lightening the lens. By ensuring that the corresponding value in condition (33) does not exceed the upper limit, fluctuations in the brightness of the optical image associated with magnification can be suppressed. 0.5 <FNot / FNow<2 (33)

[0149] To obtain better characteristics, the lower limit of conditional equation (33) is more preferably 0.6, even more preferably 0.7, and even more preferably 0.8. To obtain better characteristics, the upper limit of conditional equation (33) is more preferably 1.5, even more preferably 1.3, and even more preferably 1.05. For example, a zoom lens is more preferably satisfied with the following conditional equation (33-1), even more preferably satisfied with the following conditional equation (33-2), and even more preferably satisfied with the following conditional equation (33-3). 0.6 <FNot / FNow<1.5 (33-1) 0.7 <FNot / FNow<1.3 (33-2) 0.8 <FNot / FNow<1.05 (33-3)

[0150] It is preferable that the zoom lens satisfies the following condition (34). Here, Dexw is defined as the distance along the optical axis from the position of the paraxial exit pupil to the image plane Sim when the lens is in focus on an object at infinity at the wide-angle end. If an optical element that does not have refractive power is placed between the position of the paraxial exit pupil and the image plane Sim, Dexw is calculated using the air equivalent distance for that optical element. By ensuring that the corresponding value of condition (34) does not fall below the lower limit, the paraxial exit pupil can be positioned closer to the image, which is advantageous for miniaturization. By ensuring that the corresponding value of condition (34) does not exceed the upper limit, the paraxial exit pupil can be positioned closer to the object, which is advantageous for securing peripheral light. 0.08<(fw×tanωw) / Dexw<0.36 (34)

[0151] To obtain better characteristics, the lower limit of conditional equation (34) is more preferably 0.105, even more preferably 0.125, and even more preferably 0.15. To obtain better characteristics, the upper limit of conditional equation (34) is more preferably 0.3, even more preferably 0.27, and even more preferably 0.24. For example, a zoom lens is more preferably satisfied with the following conditional equation (34-1), even more preferably satisfied with the following conditional equation (34-2), and even more preferably satisfied with the following conditional equation (34-3). 0.105<(fw×tanωw) / Dexw<0.3 (34-1) 0.125<(fw×tanωw) / Dexw<0.27 (34-2) 0.15<(fw×tanωw) / Dexw<0.24 (34-3)

[0152] It is preferable that the zoom lens satisfies the following condition (36). Here, φSw is the maximum diameter of the on-axial light beam at the position of the aperture diaphragm St when the lens is in focus on an object at infinity at the wide-angle end. φSt is the maximum diameter of the on-axial light beam at the position of the aperture diaphragm St when the lens is in focus on an object at infinity at the telephoto end. By ensuring that the corresponding value of condition (36) does not fall below the lower limit, the increase in the diameter of the on-axial light beam at the telephoto end can be suppressed, which is advantageous for reducing the diameter of the lens barrel. By ensuring that the corresponding value of condition (36) does not exceed the upper limit, it is advantageous for correcting the fluctuations in spherical aberration caused by the change in the diameter of the on-axial light beam in the group adjacent to the aperture diaphragm St during magnification. 0.5 < φSw / φSt < 2 (36)

[0153] To obtain better characteristics, the lower limit of conditional equation (36) is more preferably 0.6, even more preferably 0.7, and even more preferably 0.8. To obtain better characteristics, the upper limit of conditional equation (36) is more preferably 1.5, even more preferably 1.3, and even more preferably 1.05. For example, a zoom lens is more preferably satisfied with the following conditional equation (36-1), even more preferably satisfied with the following conditional equation (36-2), and even more preferably satisfied with the following conditional equation (36-3). 0.6 < φSw / φSt < 1.5 (36-1) 0.7 < φSw / φSt < 1.3 (36-2) 0.8 < φSw / φSt < 1.05 (36-3)

[0154] The zoom lens preferably satisfies the following condition (37). Here, among the cemented lenses included in the final lens group GE, the temperature coefficient of the refractive index for the d line at a temperature of 25°C is (dNp / dT) × 10 -6 The unit of dNp / dT is °C. -1This is done. By ensuring that the corresponding value in conditional equation (37) does not fall below the lower limit, it is advantageous for correcting fluctuations in off-axis aberrations during temperature changes. By ensuring that the corresponding value in conditional equation (37) does not exceed the upper limit, it is advantageous for suppressing excessive correction of fluctuations in off-axis aberrations during temperature changes. -1 <dNp / dT<7 (37)

[0155] To obtain better characteristics, the lower limit of conditional equation (37) is more preferably 0, even more preferably 0.8, and even more preferably 1.9. To obtain better characteristics, the upper limit of conditional equation (37) is more preferably 6, even more preferably 4.3, and even more preferably 3.5. For example, a zoom lens is more preferably satisfied with the following conditional equation (37-1), even more preferably satisfied with the following conditional equation (37-2), and even more preferably satisfied with the following conditional equation (37-3). 0 <dNp / dT<6 (37-1) 0.8 <dNp / dT<4.3 (37-2) 1.9 <dNp / dT<3.5 (37-3)

[0156] The preferred and possible configurations described above, including the configurations related to the conditional expressions, can be combined in any way within a non-contradictory range and are preferably selectively adopted as appropriate according to the required specifications. Furthermore, the zoom lens of this disclosure can be modified in various ways without departing from the spirit of the technology of this disclosure. For example, the number of lens groups included in the intermediate group GM may be different from that of the example above. The number of lenses included in the first lens group G1, the final lens group GE, each lens group within the intermediate group GM, the image stabilization group, and the focusing group may also be different from that of the example above.

[0157] As an example, a preferred embodiment of the zoom lens of the present disclosure comprises a first lens group G1 located closest to the object, an intermediate group GM including multiple lens groups, and a final lens group GE located closest to the image, satisfying the above condition (1), wherein during magnification, the first lens group G1 is fixed with respect to the image plane Sim, the distance between the first lens group G1 and the intermediate group GM changes, the distance between the intermediate group GM and the final lens group GE changes, the distance between all adjacent lens groups in the intermediate group GM changes, and the number of lenses included in the first lens group G1 is four or less.

[0158] Next, embodiments of the zoom lens of this disclosure will be described with reference to the drawings. Note that the reference numerals assigned to each group in the cross-sectional view of each embodiment are used independently for each embodiment to avoid complexity in the explanation and drawings due to the increasing number of digits in the reference numerals. Therefore, even if the same reference numerals are assigned to drawings of different embodiments, they do not necessarily represent the same configuration.

[0159] [Example 1] The configuration and movement trajectory of the zoom lens of Example 1 are shown in Figure 1, and the method of illustration and configuration are as described above, so some redundant explanations will be omitted here. The zoom lens of Example 1 consists of, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, and a fifth lens group G5 having positive refractive power. The intermediate group GM consists of the second lens group G2, the third lens group G3, and the fourth lens group G4. The final lens group GE consists of the fifth lens group G5.

[0160] When changing magnification from the wide-angle end to the telephoto end, the second lens group G2 and the fourth lens group G4 move along the optical axis Z by changing the spacing between adjacent lens groups, while the other lens groups remain fixed relative to the image plane Sim. The focusing group consists of the fourth lens group G4. When focusing from an object at infinity to the nearest object, the focusing group moves towards the image side. The image stabilization group consists of the 4th to 6th lenses from the object side of the third lens group G3.

[0161] For the zoom lens of Example 1, the basic lens data is shown in Tables 1A and 1B, the specifications and variable plane spacing are shown in Table 2, and the aspherical coefficient is shown in Table 3. Here, in order to avoid making a single table too long, the basic lens data is shown in two tables, Table 1A and Table 1B.

[0162] The basic lens data table is as follows: The "Sn" column shows the surface number, where the surface closest to the object is designated as the 1st surface, and the number increases by one as you move towards the image side. The "R" column shows the radius of curvature of each surface. The "D" column shows the interplanar spacing on the optical axis between each surface and the surface adjacent to it on the image side. The "Nd" column shows the refractive index of each component with respect to the d line. The "νd" column shows the Abbe number of each component with respect to the d line. The "θg,F" column shows the partial dispersion ratio between the g line and the F line of each component. The "dN / dT" column shows the temperature coefficient of the refractive index of each lens with respect to the d line at a temperature of 25°C, multiplied by 10. 6 The value obtained by multiplying by is shown. The unit of dN / dT is °C. -1 The column labeled "ED" shows the maximum effective diameter of each face. The maximum effective diameter is twice the maximum effective radius.

[0163] Furthermore, if the refractive indices of a lens for the g-line, F-line, and C-line are Ng, NF, and NC, respectively, and the partial dispersion ratios between the g-line and F-line of that lens are θg and F, then θg and F are defined by the following equations. θg,F=(Ng-NF) / (NF-NC)

[0164] In the basic lens data table, the sign of the radius of curvature of a surface with a convex shape facing the object is positive, and the sign of the radius of curvature of a surface with a convex shape facing the image is negative. The basic lens data table also shows the aperture diaphragm St and optical component PP. In the column for the surface number of the surface corresponding to the aperture diaphragm St, the surface number and the phrase (St) are entered. The value in the bottom column of column D in Table 1B is the distance between the image-side surface in the table and the image plane Sim. For variable surface spacing during magnification, the symbol DD[ ] is used, and the object-side surface number for this spacing is placed inside the [ ] and entered in the surface spacing column.

[0165] Table 2 shows the variable magnification ratio Zr, focal length f, aperture F-number FNo., maximum full angle 2ω, and variable surface interval based on the d line. The variable magnification ratio is synonymous with the zoom magnification. The [°] in the column of 2ω indicates that the unit is degrees. In Table 2, the values in the columns labeled "Wide", "Middle", and "Tele" represent the values in the wide-angle end state, intermediate focal length state, and telephoto end state, respectively.

[0166] In the table of basic lens data, the aspherical surface numbers are marked with an asterisk (*), and the values of the paraxial curvature radii are described in the column of the aspherical curvature radii. In Table 3, the row of Sn shows the aspherical surface numbers, and the rows of KA and Am (m = 3, 4, 5, ···, 16) show the numerical values of the aspherical coefficients for each aspherical surface. The "E±n" (n: integer) of the numerical values of the aspherical coefficients in Table 3 means "×10 ±n ". KA and Am are the aspherical coefficients in the aspherical formula represented by the following formula. Zd = C × h 2 / {1 + (1 - KA × C 2 × h 2 ) 1 / 2}+ ΣAm × h m However, Zd: Aspherical depth (the length of the perpendicular line dropped from the point on the aspherical surface at height h to the plane perpendicular to the optical axis Z where the aspherical vertex touches) h: Height (the distance from the optical axis Z to the lens surface) C: Reciprocal of the paraxial curvature radius KA, Am: Aspherical coefficients where Σ in the aspherical formula means the sum with respect to m.

[0167] In the data of each table, degrees are used as the unit of angle, and millimeters are used as the unit of length. However, since the optical system can be used even if it is proportionally enlarged or reduced, other appropriate units can also be used. Also, in each of the following tables, the numerical values are rounded to a predetermined number of digits.

[0168]

Table 1A

[0169] [Table 1B]

[0170] [Table 2]

[0171] [Table 3]

[0172] Figure 6 shows the aberration diagrams for the zoom lens of Example 1 when focused on an object at infinity. In Figure 6, the upper section labeled "Wide" shows the aberrations at the wide-angle end, the middle section labeled "Middle" shows the aberrations at intermediate focal lengths, and the lower section labeled "Tele" shows the aberrations at the telephoto end. From left to right in Figure 6, the diagrams show spherical aberration, astigmatism, distortion, and chromatic aberration. In the spherical aberration diagram, the aberrations along the d, C, and F lines are shown as solid lines, long dashed lines, and short dashed lines, respectively. In the astigmatism diagram, the aberration along the d line in the sagittal direction is shown as a solid line, and the aberration along the d line in the tangential direction is shown as a short dashed line. In the distortion diagram, the aberration along the d line is shown as a solid line. In the chromatic aberration diagram, the aberrations along the C and F lines are shown as long dashed lines and short dashed lines, respectively. In the spherical aberration diagram, the value of the wide-open aperture F-number is shown after FNo.=. In other aberration diagrams, the value of the maximum half-angle is shown after ω=.

[0173] The symbols, meanings, methods of description, and methods of illustration for each data point in Example 1 described above are basically the same in the following examples unless otherwise specified, so redundant explanations will be omitted below.

[0174] [Example 2] Figure 7 shows the configuration and movement trajectory of the zoom lens of Example 2. The zoom lens of Example 2 consists of, in order from the object side to the image side, a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, a fourth lens group G4 with positive refractive power, and a fifth lens group G5 with negative refractive power. The intermediate group GM consists of the second lens group G2, the third lens group G3, and the fourth lens group G4. The final lens group GE consists of the fifth lens group G5.

[0175] When changing magnification from the wide-angle end to the telephoto end, the second lens group G2 and the fourth lens group G4 move along the optical axis Z by changing the spacing between adjacent lens groups, while the other lens groups remain fixed relative to the image plane Sim. The focusing group consists of the fourth lens group G4. When focusing from an object at infinity to the nearest object, the focusing group moves towards the object. The image stabilization group consists of the 4th to 6th lenses from the object side of the third lens group G3.

[0176] For the zoom lens of Example 2, the basic lens data is shown in Tables 4A and 4B, the specifications and variable plane spacing are shown in Table 5, the aspherical coefficient is shown in Table 6, and the aberration diagrams are shown in Figure 8.

[0177] [Table 4A]

[0178] [Table 4B]

[0179] [Table 5]

[0180] [Table 6]

[0181] [Example 3] The configuration and movement locus of the zoom lens of Example 3 are shown in FIG. 9. The zoom lens of Example 3 includes, in order from the object side to the image side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, a third lens group G3 having a positive refractive power, a fourth lens group G4 having a negative refractive power, and a fifth lens group G5 having a positive refractive power. The intermediate group GM consists of the second lens group G2, the third lens group G3, and the fourth lens group G4. The final lens group GE consists of the fifth lens group G5.

[0182] When zooming from the wide-angle end to the telephoto end, the distance between the second lens group G2 and the fourth lens group G4 and the adjacent lens groups is changed and they move along the optical axis Z, and the other lens groups are fixed with respect to the image plane Sim. The focusing group consists of the fourth lens group G4. When focusing from an infinite object to the closest object, the focusing group moves toward the image side. The anti-shake group consists of three lenses from the 4th to the 6th on the object side of the third lens group G3.

[0183] [[ID=​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​The configuration and movement locus of the zoom lens of Example 4 are shown in Fig. 11. The zoom lens of Example 4 includes, in order from the object side to the image side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, an aperture stop St, a third lens group G3 having a positive refractive power, a fourth lens group G4 having a positive refractive power, a fifth lens group G5 having a negative refractive power, a sixth lens group G6 having a negative refractive power, and a seventh lens group G7 having a positive refractive power. The intermediate group GM includes the second lens group G2, the aperture stop St, the third lens group G3, the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6. The final lens group GE consists of the seventh lens group G7. In the zoom lens of Example 4, the aperture stop St is not included in any lens group.

[0189] When zooming from the wide-angle end to the telephoto end, the intervals between the second lens group G2, the third lens group G3, the fourth lens group G4, and the sixth lens group G6 and the adjacent lens groups are changed and they move along the optical axis Z, and the other lens groups and the aperture stop St are fixed with respect to the image plane Sim. The focusing group consists of the sixth lens group G6. When focusing from an infinite object to the closest object, the focusing group moves toward the image side. The anti-shake group consists of two lenses, the first and second lenses from the object side of the fifth lens group G5.

[0190] Regarding the zoom lens of Example 4, the basic lens data are shown in Tables 10A and 10B, the specifications and variable surface intervals are shown in Table 11, the aspherical coefficients are shown in Tables 12A and 12B, and each aberration diagram is shown in Fig. 12.

[0191]

Table 10A

[0192]

Table 10B

[0193]

Table 11

[0194]

Table 12A

[0195]

Table 12B

[0196] [Example 5] The configuration and movement locus of the zoom lens of Example 5 are shown in FIG. 13. The zoom lens of Example 5 includes, in order from the object side to the image side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, a third lens group G3 having a positive refractive power, a fourth lens group G4 having a negative refractive power, and a fifth lens group G5 having a positive refractive power. The intermediate group GM includes the second lens group G2, the third lens group G3, and the fourth lens group G4. The final lens group GE consists of the fifth lens group G5.

[0197] When zooming from the wide-angle end to the telephoto end, the distance between the second lens group G2 and the fourth lens group G4 and the adjacent lens groups is changed and they move along the optical axis Z, and the other lens groups are fixed with respect to the image plane Sim. The focusing group consists of the fourth lens group G4. When focusing from an infinite object to the closest object, the focusing group moves toward the image side. The anti-vibration group consists of three lenses from the 4th to the 6th lenses on the object side of the third lens group G3.

[0198] For the zoom lens of Example 5, the basic lens data are shown in Table 13A and Table 13B, the specifications and variable surface intervals are shown in Table 14, the aspherical coefficients are shown in Table 15A and Table 15B, and each aberration diagram is shown in FIG. 14.

[0199]

Table 13A

[0200]

Table 13B

[0201] [Table 14]

[0202] [Table 15A]

[0203] [Table 15B]

[0204] [Example 6] Figure 15 shows the configuration and movement trajectory of the zoom lens of Example 6. The zoom lens of Example 6 consists of, in order from the object side to the image side, a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, a fourth lens group G4 with negative refractive power, and a fifth lens group G5 with positive refractive power. The intermediate group GM consists of the second lens group G2, the third lens group G3, and the fourth lens group G4. The final lens group GE consists of the fifth lens group G5.

[0205] When changing magnification from the wide-angle end to the telephoto end, the second lens group G2 and the fourth lens group G4 move along the optical axis Z by changing the spacing between adjacent lens groups, while the other lens groups remain fixed relative to the image plane Sim. The focusing group consists of the fourth lens group G4. When focusing from an object at infinity to the nearest object, the focusing group moves towards the image side. The image stabilization group consists of the 4th to 6th lenses from the object side of the third lens group G3.

[0206] For the zoom lens of Example 6, the basic lens data is shown in Tables 16A and 16B, the specifications and variable plane spacing are shown in Table 17, the aspherical coefficient is shown in Table 18, and the aberration diagrams are shown in Figure 16.

[0207] [Table 16A]

[0208] [Table 16B]

[0209] [Table 17]

[0210] [Table 18]

[0211] [Example 7] Figure 17 shows the configuration and movement trajectory of the zoom lens of Example 7. The zoom lens of Example 7 consists of, in order from the object side to the image side, a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, a fourth lens group G4 with positive refractive power, a fifth lens group G5 with positive refractive power, a sixth lens group G6 with negative refractive power, and a seventh lens group G7 with positive refractive power. The intermediate group GM consists of the second lens group G2, the third lens group G3, the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6. The final lens group GE consists of the seventh lens group G7.

[0212] When changing magnification from the wide-angle end to the telephoto end, the second lens group G2, the fourth lens group G4, and the sixth lens group G6 move along the optical axis Z by changing the spacing between adjacent lens groups, while the other lens groups remain fixed relative to the image plane Sim. The focusing group consists of the sixth lens group G6. When focusing from an object at infinity to the nearest object, the focusing group moves towards the image side. The image stabilization group consists of the first and second lenses from the object side of the fifth lens group G5.

[0213] For the zoom lens of Example 7, the basic lens data is shown in Tables 19A and 19B, the specifications and variable plane spacing are shown in Table 20, the aspherical coefficient is shown in Tables 21A and 21B, and the aberration diagrams are shown in Figure 18.

[0214] [Table 19A]

[0215] [Table 19B]

[0216] [Table 20]

[0217] [Table 21A]

[0218] [Table 21B]

[0219] [Example 8] Figure 19 shows the configuration and movement trajectory of the zoom lens of Example 8. The zoom lens of Example 8 consists of, in order from the object side to the image side, a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, a fourth lens group G4 with negative refractive power, and a fifth lens group G5 with positive refractive power. The intermediate group GM consists of the second lens group G2, the third lens group G3, and the fourth lens group G4. The final lens group GE consists of the fifth lens group G5.

[0220] When changing magnification from the wide-angle end to the telephoto end, the second lens group G2 and the fourth lens group G4 move along the optical axis Z by changing the spacing between adjacent lens groups, while the other lens groups remain fixed relative to the image plane Sim. The focusing group consists of the fourth lens group G4. When focusing from an object at infinity to the nearest object, the focusing group moves towards the image side. The image stabilization group consists of the 4th and 5th lenses from the object side of the third lens group G3.

[0221] For the zoom lens of Example 8, the basic lens data is shown in Tables 22A and 22B, the specifications and variable plane spacing are shown in Table 23, the aspherical coefficient is shown in Tables 24A and 24B, and the aberration diagrams are shown in Figure 20.

[0222] [Table 22A]

[0223] [Table 22B]

[0224] [Table 23]

[0225] [Table 24A]

[0226] [Table 24B]

[0227] [Example 9] Figure 21 shows the configuration and movement trajectory of the zoom lens of Example 9. The zoom lens of Example 9 consists of, in order from the object side to the image side, a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, a fourth lens group G4 with negative refractive power, and a fifth lens group G5 with positive refractive power. The intermediate group GM consists of the second lens group G2, the third lens group G3, and the fourth lens group G4. The final lens group GE consists of the fifth lens group G5.

[0228] When changing magnification from the wide-angle end to the telephoto end, the second lens group G2, the fourth lens group G4, and the fifth lens group G5 move along the optical axis Z by changing the spacing between adjacent lens groups, while the other lens groups remain fixed relative to the image plane Sim. The focusing group consists of the fourth lens group G4. When focusing from an object at infinity to the nearest object, the focusing group moves towards the image side. The image stabilization group consists of the 4th to 6th lenses from the object side of the third lens group G3.

[0229] For the zoom lens of Example 9, the basic lens data is shown in Tables 25A and 25B, the specifications and variable plane spacing are shown in Table 26, the aspherical coefficient is shown in Table 27, and the aberration diagrams are shown in Figure 22.

[0230] [Table 25A]

[0231] [Table 25B]

[0232] [Table 26]

[0233] [Table 27]

[0234] [Example 10] Figure 23 shows the configuration and movement trajectory of the zoom lens of Example 10. The zoom lens of Example 10 consists of, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, and a fifth lens group G5 having positive refractive power. The intermediate group GM consists of the second lens group G2, the third lens group G3, and the fourth lens group G4. The final lens group GE consists of the fifth lens group G5.

[0235] When changing magnification from the wide-angle end to the telephoto end, the second lens group G2, the third lens group G3, and the fourth lens group G4 move along the optical axis Z by changing the spacing between adjacent lens groups, while the other lens groups remain fixed relative to the image plane Sim. The focusing group consists of the fourth lens group G4. When focusing from an object at infinity to the nearest object, the focusing group moves towards the image side. The image stabilization group consists of the 3rd to 5th lenses from the object side of the third lens group G3.

[0236] For the zoom lens of Example 10, the basic lens data is shown in Tables 28A and 28B, the specifications and variable plane spacing are shown in Table 29, the aspherical coefficient is shown in Table 30, and the aberration diagrams are shown in Figure 24.

[0237] [Table 28A]

[0238] [Table 28B]

[0239] [Table 29]

[0240] [Table 30]

[0241] [Example 11] Figure 25 shows the configuration and movement trajectory of the zoom lens of Example 11. The zoom lens of Example 11 consists of, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, and a fifth lens group G5 having positive refractive power. The intermediate group GM consists of the second lens group G2, the third lens group G3, and the fourth lens group G4. The final lens group GE consists of the fifth lens group G5.

[0242] When changing magnification from the wide-angle end to the telephoto end, the second lens group G2 and the fourth lens group G4 move along the optical axis Z by changing the spacing between adjacent lens groups, while the other lens groups remain fixed relative to the image plane Sim. The focusing group consists of the fourth lens group G4. When focusing from an object at infinity to the nearest object, the focusing group moves towards the image side. The image stabilization group consists of the 3rd to 5th lenses from the object side of the third lens group G3.

[0243] For the zoom lens of Example 11, the basic lens data is shown in Tables 31A and 31B, the specifications and variable plane spacing are shown in Table 32, the aspherical coefficient is shown in Table 33, and the aberration diagrams are shown in Figure 26.

[0244] [Table 31A]

[0245] [Table 31B]

[0246] [Table 32]

[0247] [Table 33]

[0248] Tables 34 to 36 show the corresponding values ​​for conditional formulas (1) to (37) of the zoom lenses in Examples 1 to 11. The corresponding values ​​for the examples shown in Tables 34 to 36 may be used as the upper or lower limits of the conditional formulas to set a preferred range for the formulas.

[0249] [Table 34]

[0250] [Table 35]

[0251] [Table 36]

[0252] Next, an imaging device according to an embodiment of the present disclosure will be described. Figures 27 and 28 show external views of a camera 30, which is an imaging device according to one embodiment of the present disclosure. Figure 27 shows a perspective view of the camera 30 from the front, and Figure 28 shows a perspective view of the camera 30 from the rear. The camera 30 is a so-called mirrorless type digital camera, and an interchangeable lens 20 can be detachably attached. The interchangeable lens 20 is configured to include a zoom lens 1 according to one embodiment of the present disclosure, which is housed in the lens barrel.

[0253] The camera 30 comprises a camera body 31. A shutter button 32 and a power button 33 are provided on the top surface of the camera body 31. An operation unit 34, an operation unit 35, and a display unit 36 ​​are provided on the back surface of the camera body 31. The display unit 36 ​​can display captured images and images within the field of view before the image was captured.

[0254] A shooting aperture is provided in the center of the front of the camera body 31, through which light from the subject being photographed enters. A mount 37 is provided at a position corresponding to the shooting aperture, and the interchangeable lens 20 is attached to the camera body 31 via the mount 37.

[0255] An image sensor 38 is provided inside the camera body 31. The image sensor 38 outputs an imaging signal corresponding to the subject image formed by the interchangeable lens 20. For example, a CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor) can be used as the image sensor 38. The camera body 31 also contains a signal processing circuit (not shown) and a recording medium (not shown). The signal processing circuit processes the imaging signal output from the image sensor 38 to generate an image. The recording medium is for recording the generated image. With the camera 30, still images or videos can be taken by pressing the shutter button 32, and the image data obtained from this shooting is recorded on the recording medium.

[0256] Although the technology of this disclosure has been described above with reference to embodiments and examples, the technology of this disclosure is not limited to the above embodiments and examples, and various modifications are possible. For example, the radius of curvature, interplanar spacing, refractive index, Abbe number, and aspheric coefficient of each lens are not limited to the values ​​shown in each of the above embodiments, but can take other values.

[0257] Furthermore, the imaging device according to the embodiments of this disclosure is not limited to the above examples, and can take various forms, such as cameras other than mirrorless types, cameras in which the imaging lens and camera body are integrally configured, film cameras, video cameras, surveillance cameras, broadcast cameras, movie cameras, FA (Factory Automation) cameras, and MV (Machine Vision) cameras.

[0258] The following additional information is disclosed regarding the above embodiments and examples. [Note 1] It comprises a first lens group located closest to the object, an intermediate group containing multiple lens groups, and a final lens group located closest to the image. During magnification, the first lens group is fixed with respect to the image plane, the distance between the first lens group and the intermediate group changes, the distance between the intermediate group and the final lens group changes, and the distance between all adjacent lens groups within the intermediate group changes. The number of lenses included in the first lens group is four or less. Bfw is the back focus of the entire system in terms of its atmospheric distance when focused on an object at infinity at the wide-angle end. If fw is the focal length of the entire system when in focus on an object at infinity at the wide-angle end, 0.1 <Bfw / fw<1.9 (1) A zoom lens that satisfies the condition (1) represented by . [Note 2] The aforementioned final lens group is a zoom lens as described in Appendix 1, which includes three or more lenses. [Note 3] The zoom lens according to Appendix 1 or Appendix 2, wherein at least one of the plurality of lens groups included in the intermediate group is an intermediate fixed lens group that is fixed to the image plane when the magnification is changed. [Note 4] The aforementioned intermediate fixed lens group is a zoom lens as described in Appendix 3, which includes three or more lenses. [Note 5] The zoom lens described in any one of the appendices 1 to 4, wherein the lens closest to the object in the first lens group is a negative lens. [Note 6] The aforementioned final lens group is a zoom lens described in any one of the appendices 1 to 5, which is fixed to the image plane during magnification. [Note 7] When the focal length of the first lens group is set to f1, 0.05 <fw / f1<0.54 (2) A zoom lens described in any one of the appendices 1 to 6 that satisfies the conditional expression (2) represented by . [Note 8] Including an aperture diaphragm, DStw is the sum of the distance along the optical axis from the aperture diaphragm to the image-side lens surface of the final lens group when the system is in focus on an object at infinity at the wide-angle end, and the back focus in terms of the air-equivalent distance of the entire system. When the system is in focus on an object at infinity at the wide-angle end, if TLw is defined as the sum of the distance along the optical axis from the lens surface closest to the object in the first lens group to the lens surface closest to the image in the final lens group, and the back focus of the entire system in air equivalent distance, 0.5 <DStw / TLw<0.85 (3) A zoom lens described in any one of the appendices 1 to 7 that satisfies the conditional expression (3) represented by . [Note 9] 0.61 <DStw / TLw<0.8 (3-1) A zoom lens as described in Appendix 8 that satisfies the conditional expression (3-1) represented by . [Note 10] The aforementioned intermediate group is a zoom lens according to any one of the appendices 1 to 9, which includes a focusing group that moves along the optical axis when focusing. [Note 11] The focusing group is a zoom lens as described in Appendix 10, having negative refractive power. [Note 12] The zoom lens described in any one of the appendices 1 to 11, wherein the lens surface closest to the object in the first lens group is a convex surface. [Note 13] The aforementioned intermediate group is a zoom lens as described in any one of Appendix 1 to Appendix 12, which includes an image stabilization group that moves in a direction intersecting the optical axis during image shake correction. [Note 14] The aforementioned vibration-damping group is a zoom lens as described in Appendix 13, comprising all or part of an intermediate fixed lens group that is fixed to the image plane during magnification. [Note 15] The vibration-damping group is a zoom lens as described in Appendix 13 or Appendix 14, having a positive refractive power. [Note 16] If ωw is the maximum half-angle when in focus on an object at infinity at the wide-angle end, 0.4 <Bfw / (fw×tanωw)<1.6 (4) A zoom lens described in any one of the appendices 1 to 15 that satisfies the conditional expression (4) represented by . [Note 17] If the focal length of the final lens group is denoted as fE, -0.7 <fw / fE<0.7 (5) A zoom lens described in any one of the appendices 1 to 16 that satisfies the conditional expression (5) represented by . [Note 18] If νEmax is the maximum value of the d-line reference Abbe number of all lenses included in the aforementioned final lens group, 60 < νEmax < 105 (6) A zoom lens described in any one of the appendices 1 to 17 that satisfies the conditional expression (6) represented by . [Note 19] When in focus on an object at infinity at the wide-angle end, the distance on the optical axis between the first lens group and the lens group adjacent to the image side of the first lens group is D12w. If ωw is the maximum half-angle when in focus on an object at infinity at the wide-angle end, 0.005 <D12w / (fw×tanωw)<0.35 (7) A zoom lens described in any one of the appendices 1 to 18 that satisfies the conditional expression (7) represented by . [Note 20] It includes at least one combination consisting of a group of lenses with negative refractive power and a group of lenses with positive refractive power, arranged adjacent to each other in order from the object side to the image side. Among the above combinations, the distance on the optical axis at the telephoto end between the lens group with the negative refractive power and the lens group with the positive refractive power of the combination closest to the object is DNPt. If ωw is the maximum half-angle when in focus on an object at infinity at the wide-angle end, 0.005 <DNPt / (fw×tanωw)<0.5 (8) A zoom lens described in any one of the appendices 1 to 19 that satisfies the conditional expression (8) represented by . [Note 21] Among the lenses included in the final lens group, if the refractive index and Abbe number of the lens with the maximum Abbe number relative to the d-line are denoted as NE and νEmax, respectively, -0.05 <NE+0.0067×νEmax-2<0.13 (9) A zoom lens described in any one of the appendices 1 to 20 that satisfies the conditional expression (9) represented by . [Note 22] Includes at least one aspherical lens, The difference between the sag amount of the lens surface and the sag amount of the paraxial curvature sphere of the lens surface at a height of 70% of the maximum effective radius of the lens surface of the aspherical lens is defined as Δsag. Among the aspherical lenses included in the aforementioned zoom lens, in the aspherical lens closest to the object, the larger of the absolute values ​​of Δsag on the object-side surface and Δsag on the image-side surface is ΔsagM. Among the aspherical lenses included in the aforementioned zoom lens, if the aspherical lens closest to the object is defined as HaM, and the larger of the maximum effective radius of the object-side surface and the maximum effective radius of the image-side surface is defined as follows: 0.001 < |ΔsagM| / HaM < 0.07 (10) A zoom lens described in any one of the appendices 1 to 21 that satisfies the conditional expression (10) represented by . [Note 23] Includes a group of lenses having at least one negative refractive power, The aspherical lens closest to the object is the zoom lens described in Appendix 22, which is the third lens from the object side in the group of negative refractive power lenses closest to the object, among the group of negative refractive power lenses included in the zoom lens. [Note 24] Includes a group of lenses having at least one negative refractive power, The aspherical lens closest to the object is the zoom lens described in Appendix 22, which is the fourth lens from the object side in the group of negative refractive power lenses closest to the object, among the group of negative refractive power lenses included in the zoom lens. [Note 25] Includes at least one negative lens, If Nn1 is the refractive index of the negative lens closest to the object among the negative lenses included in the zoom lens, 1.59 <Nn1<1.99 (11) A zoom lens described in any one of the appendices 1 to 24 that satisfies the conditional expression (11) represented by . [Note 26] Includes at least one negative lens, If, among the negative lenses included in the zoom lens, the central thickness of the negative lens closest to the object and the maximum effective radius of the object-side surface are Dn1 and Hn1, respectively, 0.02 <Dn1 / Hn1<0.087 (12) A zoom lens described in any one of the appendices 1 to 25 that satisfies the conditional expression (12) represented by . [Note 27] Includes a group of lenses having at least one negative refractive power, Among the group of lenses with negative refractive power included in the zoom lens, the group of lenses with the most negative refractive power closest to the object includes at least one negative lens. If, among the negative lenses included in the lens group having the most negative refractive power on the object side, the central thickness and the maximum effective radius of the object-side surface of the negative lens on the object side are Dn2 and Hn2, respectively, 0.02 <Dn2 / Hn2<0.105 (13) A zoom lens described in any one of the appendices 1 to 26 that satisfies the conditional expression (13) represented by . [Note 28] Includes at least one negative lens, Of the negative lenses included in the aforementioned zoom lens, the negative lens closest to the object is the zoom lens described in any one of Appendix 1 to Appendix 27, whose image-side surface is in contact with the air. [Note 29] Including an aperture diaphragm, A zoom lens according to any one of the appendices 1 to 28, wherein a negative lens is positioned adjacent to the image side of the aperture diaphragm. [Note 30] If the focal length of the lens group positioned adjacent to the object side of the final lens group is denoted as fFE, -0.8 <fw / fFE<0.4 (14) A zoom lens described in any one of the appendices 1 to 29 that satisfies the conditional expression (14) represented by . [Note 31] Including an aperture diaphragm, If the aperture diaphragm is included in the lens group, the refractive index of the positive lens closest to the image line among the positive lenses included in the lens group containing the aperture diaphragm is NStp, If the aperture diaphragm is not included in the lens group, then, if the refractive index of the positive lens closest to the image line among the positive lenses included in the lens group adjacent to the image side of the aperture diaphragm is NStp, 1.43 <NStp<1.895 (15) A zoom lens described in any one of the appendices 1 to 30 that satisfies the conditional expression (15) represented by . [Note 32] If N1ave is the average value of the refractive index of all lenses included in the first lens group with respect to the d line, 1.6 <N1ave<1.9 (16) A zoom lens described in any one of the appendices 1 to 31 that satisfies the conditional expression (16) represented by . [Note 33] The lateral magnification of the final lens group when focused on an object at infinity at the telephoto end is βEt. When the lens group adjacent to the object side of the final lens group is in focus on an object at infinity at the telephoto end, let βFEt be the lateral magnification of the lens group adjacent to the object side of the final lens group. 0.14 < βEt × βFEt < 2.2 (17) A zoom lens described in any one of the appendices 1 to 32 that satisfies the conditional expression (17) represented by . [Note 34] Includes a group of lenses having at least one negative refractive power, If νNmin is the minimum Abbe number relative to the d line of all lenses in the group of lenses with negative refractive power that has the most negative refractive power closest to the object, then, 15 < νNmin < 25.6 (18) A zoom lens described in any one of the appendices 1 to 33 that satisfies the conditional expression (18) represented by . [Note 35] Including an aperture diaphragm, If the aperture diaphragm is included in the lens group, the focal length of the lens group including the aperture diaphragm is fGSt, If the aperture diaphragm is not included in the lens group, and the focal length of the lens group adjacent to the image side of the aperture diaphragm is denoted as fGSt, 0.3 <fw / fGSt<1.3 (19) A zoom lens described in any one of the appendices 1 to 34 that satisfies the conditional expression (19) represented by . [Note 36] Includes a group of lenses having at least one negative refractive power, If fN is the focal length of the lens group with the most negative refractive power closest to the object among the lens group with negative refractive power included in the zoom lens, -2.5 <fw / fN<-0.8 (20) A zoom lens described in any one of the appendices 1 to 35 that satisfies the conditional expression (20) represented by . [Note 37] An imaging device equipped with a zoom lens as described in any one of the appendices 1 through 36. [Explanation of Symbols]

[0259] 1 Zoom lens 20 interchangeable lenses 30 Cameras 31 Camera Body 32 Shutter button 33 Power button 34 Control section 35 Control section 36 Display section 37 Mount 38 Image sensor Bfw (Back Focus) D12w spacing Dn1 center thickness Dn2 center thickness DNPt interval DStw distance G1 First Lens Group G2 Second Lens Group G3 3rd lens group G4 4th lens group G5 5th lens group G6 6th lens group G7 7th lens group GE Final Lens Series GIS vibration isolation group GISf Vibration Isolation Object Side Group GISr vibration-isolated image group GM intermediate group H7 Height He Maximum effective radius Hn1 Maximum effective radius Hn2 Maximum effective radius L11~L55 Lenses LA Aspherical Lenses LAs1 lens surface LAs2 lens surface Lx lens PP optical components Px Position of maximum effective diameter sagA Sag amount sagSp sag amount Sim image plane Sp paraxial curvature sphere St aperture diaphragm ta axial luminous flux tb Maximum half-angle luminous flux TLw Lens System Overall Length VP plane wa axial luminous flux WB (white balance) luminous flux at maximum half-angle Xa On-axis luminous flux Xb Off-axis luminous flux Xb1 ray Z optical axis Δsag Aspheric amount ωt Maximum half-angle ωw Maximum half-angle

Claims

1. It comprises a first lens group located closest to the object, an intermediate group including multiple lens groups, and a final lens group located closest to the image. During magnification, the first lens group is fixed with respect to the image plane, the distance between the first lens group and the intermediate group changes, the distance between the intermediate group and the final lens group changes, and the distance between all adjacent lens groups within the intermediate group changes. The number of lenses included in the first lens group is four or less. Bfw is the back focus of the entire system in terms of its atmospheric distance when focused on an object at infinity at the wide-angle end. If the focal length of the entire system when in focus on an object at infinity at the wide-angle end is denoted as fw, 0.1<Bfw / fw<1.9 (1) A zoom lens that satisfies the condition (1) represented by .

2. The zoom lens according to claim 1, wherein the final lens group includes three or more lenses.

3. The zoom lens according to claim 1, wherein at least one of the plurality of lens groups included in the intermediate group is an intermediate fixed lens group that is fixed to the image plane when the zoom is changed.

4. The zoom lens according to claim 1, wherein the lens closest to the object in the first lens group is a negative lens.

5. The zoom lens according to claim 3, wherein the intermediate fixed lens group includes three or more lenses.

6. The zoom lens according to claim 1, wherein the final lens group is fixed to the image plane during magnification.

7. When the focal length of the first lens group is set to f1, 0.05<fw / f1<0.54 (2) A zoom lens according to claim 1 that satisfies the conditional expression (2) represented by .

8. Including an aperture diaphragm, When the system is in focus on an object at infinity at the wide-angle end, the sum of the distance along the optical axis from the aperture diaphragm to the image-side lens surface of the final lens group and the back focus in terms of the air-equivalent distance of the entire system is DStw. When the lens group is in focus on an object at infinity at the wide-angle end, if TLw is the sum of the distance along the optical axis from the lens surface closest to the object in the first lens group to the lens surface closest to the image in the final lens group, and the back focus of the entire system in air equivalent distance, 0.5<DStw / TLw<0.85 (3) A zoom lens according to claim 1 that satisfies the conditional expression (3) represented by .

9. 0.61<DStw / TLw<0.8 (3-1) A zoom lens according to claim 8 that satisfies the conditional expression (3-1) represented by .

10. The zoom lens according to claim 1, wherein the intermediate group includes a focusing group that moves along the optical axis when focusing.

11. The zoom lens according to claim 10, wherein the focusing group has a negative refractive power.

12. The zoom lens according to claim 1, wherein the lens surface of the first lens group closest to the object is a convex surface.

13. The zoom lens according to claim 1, wherein the intermediate group includes an anti-vibration group that moves in a direction intersecting the optical axis during image shake correction.

14. The zoom lens according to claim 13, wherein the vibration-damping group comprises all or part of an intermediate fixed lens group that is fixed to the image plane during magnification.

15. The zoom lens according to claim 13, wherein the vibration-damping group has a positive refractive power.

16. If ωw is the maximum half-angle when in focus on an object at infinity at the wide-angle end, 0.4<Bfw / (fw×tanωw)<1.6 (4) A zoom lens according to claim 1 that satisfies the conditional expression (4) represented by .

17. If the focal length of the final lens group is denoted as fE, -0.7<fw / fE<0.7 (5) A zoom lens according to claim 1 that satisfies the conditional expression (5) represented by .

18. If νEmax is the maximum value of the d-line reference Abbe number of all lenses included in the aforementioned final lens group, 60<νEmax<105 (6) A zoom lens according to claim 1 that satisfies the conditional expression (6) represented by .

19. When in focus on an object at infinity at the wide-angle end, the distance on the optical axis between the first lens group and the lens group adjacent to the image side of the first lens group is D12w. If ωw is the maximum half-angle when in focus on an object at infinity at the wide-angle end, 0.005<D12w / (fw×tanωw)<0.35 (7) A zoom lens according to claim 1 that satisfies the conditional expression (7) represented by .

20. It includes at least one combination consisting of a group of lenses with negative refractive power and a group of lenses with positive refractive power, arranged adjacent to each other in order from the object side to the image side. Among the above combinations, the distance on the optical axis at the telephoto end between the lens group with the negative refractive power and the lens group with the positive refractive power of the combination closest to the object is DNPt. If ωw is the maximum half-angle when in focus on an object at infinity at the wide-angle end, 0.005<DNPt / (fw×tanωw)<0.5 (8) A zoom lens according to claim 1 that satisfies the conditional expression (8) represented by .

21. If, among the lenses included in the final lens group, the lens with the largest Abbe number relative to the d line is denoted as NE and νEmax, respectively, then, -0.05<NE+0.0067×νEmax-2<0.13 (9) A zoom lens according to claim 1 that satisfies the conditional expression (9) represented by .

22. Includes at least one aspherical lens, The difference between the sag amount of the lens surface and the sag amount of the paraxial curvature sphere of the lens surface at a height of 70% of the maximum effective radius of the lens surface of the aspherical lens is defined as Δsag. Among the aspherical lenses included in the aforementioned zoom lens, in the aspherical lens closest to the object, the larger of the absolute values ​​of Δsag on the object-side surface and Δsag on the image-side surface is defined as ΔsagM. In the aforementioned zoom lens, if the aspherical lens closest to the object is defined as HaM, and the maximum effective radius of the object-side surface is greater than the maximum effective radius of the image-side surface, 0.001<|ΔsagM| / HaM<0.07 (10) A zoom lens according to claim 1 that satisfies the conditional expression (10) represented by .

23. Includes a group of lenses having at least one negative refractive power, The zoom lens according to claim 22, wherein the aspherical lens closest to the object is the third lens from the object side of the group of negative refractive power lenses included in the zoom lens, which has the negative refractive power closest to the object.

24. Includes a group of lenses having at least one negative refractive power, The zoom lens according to claim 22, wherein the aspherical lens closest to the object is the fourth lens from the object side of the group of negative refractive power lenses included in the zoom lens, which has the negative refractive power closest to the object.

25. Includes at least one negative lens, If Nn1 is the refractive index of the negative lens closest to the object among the negative lenses included in the zoom lens, 1.59<Nn1<1.99 (11) A zoom lens according to claim 1 that satisfies the conditional expression (11) represented by .

26. Includes at least one negative lens, When the central thickness and the maximum effective radius of the object-side surface of the negative lens included in the zoom lens are Dn1 and Hn1, respectively, 0.02<Dn1 / Hn1<0.087 (12) A zoom lens according to claim 1 that satisfies the conditional expression (12) represented by .

27. Includes a group of lenses having at least one negative refractive power, Among the group of lenses with negative refractive power included in the zoom lens, the group of lenses with the most negative refractive power closest to the object includes at least one negative lens. Among the negative lenses included in the lens group having the most negative refractive power on the object side, if the central thickness and the maximum effective radius of the object-side surface of the negative lens on the object side are Dn2 and Hn2, respectively, 0.02<Dn2 / Hn2<0.105 (13) A zoom lens according to claim 1 that satisfies the conditional expression (13) represented by .

28. Includes at least one negative lens, The zoom lens according to claim 1, wherein the negative lens among the negative lenses included in the zoom lens is the negative lens closest to the object, and its image-side surface is in contact with the air.

29. Including an aperture diaphragm, The zoom lens according to claim 1, wherein a negative lens is arranged adjacent to the image side of the aperture diaphragm.

30. If the focal length of the lens group positioned adjacent to the object side of the final lens group is fFE, -0.8<fw / fFE<0.4 (14) A zoom lens according to claim 1 that satisfies the conditional expression (14) represented by .

31. Including an aperture diaphragm, If the aperture diaphragm is included in the lens group, the refractive index of the positive lens closest to the image line among the positive lenses included in the lens group containing the aperture diaphragm is NStp, If the aperture diaphragm is not included in the lens group, then, among the positive lenses included in the lens group adjacent to the image side of the aperture diaphragm, the refractive index of the positive lens closest to the image line with respect to the d line is NStp. 1.43<NStp<1.895 (15) A zoom lens according to claim 1 that satisfies the conditional expression (15) represented by .

32. If N1ave is the average value of the refractive index of all lenses included in the first lens group with respect to the d line, 1.6<N1ave<1.9 (16) A zoom lens according to claim 1 that satisfies the conditional expression (16) represented by .

33. The lateral magnification of the final lens group when focused on an object at infinity at the telephoto end is βEt. When the lens group adjacent to the object side of the final lens group is in focus on an object at infinity at the telephoto end, let βFEt be the lateral magnification of the lens group adjacent to the object side of the final lens group. 0.14 < βEt × βFEt < 2.2 (17) A zoom lens according to claim 1 that satisfies the conditional expression (17) represented by .

34. Includes a group of lenses having at least one negative refractive power, If νNmin is the minimum value of the d-line reference Abbe number of all lenses in the group of lenses with negative refractive power that has the most negative refractive power closest to the object, among the group of lenses with negative refractive power included in the zoom lens, 15<νNmin<25.6 (18) A zoom lens according to claim 1 that satisfies the conditional expression (18) represented by .

35. Including an aperture diaphragm, If the aperture diaphragm is included in the lens group, the focal length of the lens group including the aperture diaphragm is fGSt, If the aperture diaphragm is not included in the lens group, and the focal length of the lens group adjacent to the image side of the aperture diaphragm is fGSt, 0.3<fw / fGSt<1.3 (19) A zoom lens according to claim 1 that satisfies the conditional expression (19) represented by .

36. Includes a group of lenses having at least one negative refractive power, If, among the group of lenses with negative refractive power included in the zoom lens, the focal length of the lens group with the most negative refractive power closest to the object is denoted as fN, -2.5<fw / fN<-0.8 (20) A zoom lens according to claim 1 that satisfies the conditional expression (20) represented by .

37. An imaging device comprising a zoom lens according to any one of claims 1 to 36.

Images