Zoom lens and imaging device

Abstract

To provide a zoom lens which exhibits a high zoom ratio and is yet compact and lightweight, and an imaging device equipped with this zoom lens.SOLUTION: The zoom lens comprises, in order from object side to image side: a first lens group having positive refractive power; a second lens group having negative refractive power; and a subsequent group having a plurality of lens groups. An aperture diaphragm is included at a position closer to the image side than the most image side lens surface of the second lens group, and the most image side lens group in the subsequent group includes at least one negative lens the object side lens surface of which is a concave in contact with air. At the time of zooming, the interval between the first and second lens groups changes, the interval between the second lens group and the subsequent group changes, and the interval of all of adjacent lens groups in the subsequent group changes. The zoom lens satisfies a predetermined conditional expression.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The technology of the present disclosure relates to a zoom lens and an imaging device. [Background technology]

[0002] 2. Description of the Related Art As a zoom lens applicable to imaging devices such as digital cameras and video cameras, for example, the lens system described in Patent Document 1 below is known. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-113609 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, there has been a demand for a zoom lens that is compact and lightweight while achieving a high zoom ratio.

[0005] The present disclosure has been made in consideration of the above circumstances, and has an object to provide a zoom lens that is small and lightweight while achieving a high zoom ratio, and an imaging device equipped with this zoom lens. [Means for solving the problem]

[0006] A first aspect of the present disclosure is a zoom lens comprising, in order from the object side to the image side, a first lens group having positive refractive power, a second lens group having negative refractive power, and a subsequent group having a plurality of lens groups, and including an aperture stop on the image side of the lens surface of the second lens group closest to the image, the lens group closest to the image side in the subsequent group including at least one negative lens whose lens surface on the object side is a concave surface in contact with air, and during zooming, the distance between the first lens group and the second lens group changes, the distance between the second lens group and the subsequent group changes, and all of the adjacent lens groups in the subsequent group change. The distance between lenses changes, and the distances between lenses within the first lens group, the second lens group, and the plurality of lens groups remain constant during magnification variation. Let fw be the focal length of the entire system at the wide-angle end when focused on an object at infinity, Denw be the distance on the optical axis from the lens surface of the first lens group closest to the object to the paraxial entrance pupil position at the wide-angle end when focused on an object at infinity, and the sign of Denw is positive if the paraxial entrance pupil position is closer to the image than the lens surface of the first lens group closest to the object, and negative if the paraxial entrance pupil position is closer to the object than the lens surface of the first lens group closest to the object. 0.7 <fw / Denw<1.5 (1) The conditional expression (1) expressed as follows is satisfied.

[0007] In the first aspect, when the distance on the optical axis from the paraxial exit pupil position to the image plane at the wide-angle end in a state where the lens is focused on an object at infinity is defined as Dexw, and the sign of Dexw is positive if the paraxial exit pupil position is closer to the object than the image plane, and negative if the paraxial exit pupil position is closer to the image than the image plane, 0.25 <fw / Dexw<1 (2) It is preferable to satisfy conditional expression (2) below.

[0008] In the first aspect, if the distance on the optical axis from the lens surface of the first lens group closest to the object to the lens surface of the first lens group closest to the image is D1, and the sum of the distance on the optical axis from the lens surface of the first lens group closest to the object to the lens surface of the subsequent lens group closest to the image at the telephoto end in a state focused on an object at infinity and the back focus in air equivalent distance is TLt, then: 0.01 <D1 / TLt<0.1 (3) It is preferable to satisfy conditional expression (3) below.

[0009] In the first aspect, when the focal length of the entire system at the telephoto end in a state where the lens is focused on an object at infinity is ft, 4.9 <ft / fw<12 (4) It is preferable to satisfy conditional expression (4) below.

[0010] In the first aspect, the subsequent group includes at least one Lx lens whose image-side lens surface is a convex surface in contact with air, and among at least one optical system configured from a lens surface adjacent to the image side of the aperture stop to a lens surface on the image side of the Lx lens, when the lateral magnification of an A optical system in which the absolute value of the reciprocal of the lateral magnification at the wide-angle end when the aperture stop is the object point in a state focused on an object at infinity is smallest is defined as βA: -0.5<1 / βA<0.5 (5) It is preferable to satisfy conditional expression (5) below.

[0011] In the first aspect, when the height from the optical axis of the on-axis marginal ray at the lens surface closest to the image side of the optical system A at the telephoto end in a state where the lens is focused on an object at infinity is HAt, and when the height from the optical axis of the on-axis marginal ray at the aperture stop at the telephoto end in a state where the lens is focused on an object at infinity is HSt, 0.73 <HAt / HSt<2.3 (6) It is preferable to satisfy conditional expression (6) below.

[0012] In the first aspect, if the focal length of the entire system at the telephoto end when focused on an object at infinity is ft, and the composite focal length from the lens surface of the subsequent lens group closest to the object to the lens surface of the optical system A closest to the image is fpAt when focused on an object at infinity at the telephoto end, then: 3 <ft / fpAt<15 (7) It is preferable to satisfy conditional expression (7) below.

[0013] In the first aspect, when the height from the optical axis of an axial marginal ray on the lens surface closest to the image of the optical system A at the telephoto end in a state where the lens is focused on an object at infinity is HAt, and when the height from the optical axis of a chief ray of a maximum image height on the lens surface closest to the image of the optical system A at the wide-angle end in a state where the lens is focused on an object at infinity is HAw, 0.35 <HAt / HAw<1.6 (8) It is preferable to satisfy conditional expression (8) below.

[0014] In the first aspect, it is preferable that the subsequent group includes a lens surface which is a concave surface facing the image side and is in contact with the air, between the lens surface closest to the image side in the A optical system and a lens surface which is a concave surface facing the object side and is included in the lens group closest to the image side in the subsequent group.

[0015] In the first aspect, if the distance on the optical axis from the aperture stop to the lens surface of the optical system A closest to the image at the telephoto end when focused on an object at infinity is DSAt, and the sum of the distance on the optical axis from the aperture stop to the lens surface of the subsequent lens group closest to the image at the telephoto end when focused on an object at infinity and the back focus in air equivalent distance is DSLt, then: 0.1 <DSAt / DSLt<0.54 (9) It is preferable to satisfy conditional expression (9) below.

[0016] In the first aspect, when the lens element is focused on an object at infinity at the telephoto end, the distance on the optical axis between the lens surface of the optical system A closest to the image side and the lens surface adjacent to the lens surface closest to the image side is dA, and the maximum image height at the telephoto end is Yt. 0.015 <dA / Yt<0.35 (10) It is preferable to satisfy conditional expression (10) below.

[0017] In the first aspect, when the sum of the distance on the optical axis from the lens surface in the first lens group closest to the object to the lens surface in the subsequent lens group closest to the image at the telephoto end in a state where the lens is focused on an object at infinity and the back focus in terms of the air equivalent distance is TLt, and when the focal length of the entire system at the telephoto end in a state where the lens is focused on an object at infinity is ft, 0.65 <TLt / ft<1.5 (11) It is preferable to satisfy conditional expression (11) below.

[0018] In the first aspect, it is preferable that the first lens group includes, in succession from the most object side to the image side, a negative lens and a positive lens.

[0019] In the first aspect, when the back focus in air at the wide-angle end in a state where the lens is focused on an object at infinity is BFw, and the maximum image height at the wide-angle end is Yw, 0.38 <BFw / Yw<1.5 (12) It is preferable to satisfy conditional expression (12) below.

[0020] In the first aspect, when the Abbe number based on the d-line of the lens closest to the object side in the first lens group is ν1, 10<ν1<50 (13) It is preferable to satisfy conditional expression (13) below.

[0021] In the first aspect, when the refractive index of the lens closest to the object side in the first lens group with respect to the d-line is N1, 1.7 <N1<2.3 (14) It is preferable to satisfy conditional expression (14) below.

[0022] In the first aspect, when the refractive index of the negative lens closest to the object among the negative lenses included in the second lens group is N2n with respect to the d-line, 1.6 <N2n<2.2 (15) It is preferable to satisfy conditional expression (15) below.

[0023] In the first aspect, when the refractive index of the positive lens with the strongest refractive power among the positive lenses included in the second lens group is N2p for the d-line, 1.65 <N2p<2 (16) It is preferable to satisfy conditional expression (16) below.

[0024] In the first aspect, when the Abbe number based on the d-line of the negative lens element closest to the image side among the negative lenses included in the subsequent lens group is νnL, 27<νnL<102 (17) It is preferable to satisfy conditional expression (17) below.

[0025] In the first aspect, it is preferable that the subsequent group includes at least one lens group having positive refractive power.

[0026] In the first aspect, when the lens element is focused on an object at infinity, the sum of the distance on the optical axis from the lens surface of the first lens group closest to the object to the lens surface of the subsequent lens group closest to the image and the back focus in terms of air equivalent distance is defined as TLt; when the lens element is focused on an object at infinity, the difference in the optical axis direction between the position at the wide-angle end and the position at the telephoto end of the lens group closest to the object among the lens groups having positive refractive power included in the subsequent lens group is defined as Mp; the sign of Mp is positive if the lens group closest to the object moves from the object side to the image side when changing magnification from the wide-angle end to the telephoto end, and negative if it moves from the image side to the object side; -0.45 <Mp / TLt<-0.06 (18) It is preferable to satisfy conditional expression (18) below.

[0027] In the first aspect, when the lens is focused on an object at infinity, if the focal length of the lens group closest to the object among the lens groups having positive refractive power included in the subsequent lens group is fp and the focal length of the second lens group is f2, then: -4.3 <fp / f2<-1.1 (19) It is preferable to satisfy conditional expression (19) below.

[0028] In the first aspect, when the optical axis distance at the telephoto end in a state focused on an object at infinity is from the lens surface closest to the image in the first lens group to the lens surface closest to the object in the lens group closest to the object among the lens groups having positive refractive power included in the subsequent group, is D1pt, and when the optical axis distance at the telephoto end in a state focused on an object at infinity is from the lens surface closest to the object in the first lens group to the lens surface closest to the image in the subsequent group, and when the optical axis distance at the telephoto end in a state focused on an object at infinity is from the back focus in air equivalent distance, TLt, 0.2 <D1pt / TLt<0.5 (20) It is preferable to satisfy conditional expression (20) expressed as follows:

[0029] In the first aspect, the subsequent group includes at least one Lx lens whose image-side lens surface is a convex surface in contact with air, and among at least one optical system formed from the lens surface adjacent to the image side of the aperture stop to the lens surface of the Lx lens adjacent to the image side of the aperture stop, the optical system A is the optical system that has the smallest absolute value of the reciprocal of the lateral magnification at the wide-angle end when the aperture stop is used as the object point in a state focused on an object at infinity, and when the composite focal length at the wide-angle end in a state focused on an object at infinity, from the lens surface adjacent to the image side of the lens surface closest to the image side of the optical system A to the lens surface closest to the image side of the subsequent group, is fBw: -1.6 <fw / fBw<-0.25 (21) It is preferable to satisfy conditional expression (21) below.

[0030] In the first aspect, when the maximum half angle of view at the wide-angle end in a state where the lens is focused on an object at infinity is ωw and the maximum image height at the wide-angle end is Yw, 0.97 <fw×tanωw / Yw<1.3 (22) It is preferable to satisfy conditional expression (22) below.

[0031] In the first aspect, the subsequent group preferably includes a focus group that moves along the optical axis during focusing.

[0032] In the first aspect, the focus group preferably consists of two or less lenses.

[0033] In the first aspect, the focus group preferably has negative refractive power.

[0034] In the first aspect, if the focal length of the first lens group is f1 and the focal length of the second lens group is f2, -0.3 <f2 / f1<-0.05 (23) It is preferable to satisfy conditional expression (23) below.

[0035] A second aspect of the present disclosure is an imaging device including the zoom lens according to the first aspect.

[0036] In this specification, the terms "consisting of" and "consisting of" are intended to mean that, in addition to the listed components, other components may also be included, such as a lens that has substantially no refractive power, optical elements other than lenses, such as an aperture, a filter, and a cover glass, and mechanical parts, such as a lens flange, a lens barrel, an image sensor, and an image stabilization mechanism.

[0037] In this specification, "a group having positive refractive power" means that the group as a whole has positive refractive power. "a group having negative refractive power" means that the group as a whole has negative refractive power. "A lens having positive refractive power" and "a positive lens" are synonymous. "A lens having negative refractive power" and "a negative lens" are synonymous.

[0038] In this specification, the terms "first lens group," "second lens group," and "plural lens groups" each refer to a component of a zoom lens, including at least one lens, separated by an air gap that changes during zooming. During zooming, each lens group is moved or fixed, and the spacing between lenses within a lens group does not change. In other words, in this specification, one lens group is defined as a group in which the spacing between adjacent groups changes during zooming, but the total spacing between adjacent lenses within the group does not change. A "lens group" is not limited to a configuration consisting of multiple lenses, and may also be a configuration consisting of only one lens.

[0039] A "single lens" refers to a single lens that is not cemented. However, a compound aspherical lens (a lens that is integrally constructed with a spherical lens and an aspherical film formed on the spherical lens, and functions 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 of refractive power and surface shape of lenses that include aspherical surfaces are considered in the paraxial region.

[0040] In this specification, "total system" refers to a zoom lens. The "focal length" used in the conditional expressions is the paraxial focal length. The "distance on the optical axis" used in the conditional expressions is considered to be the geometric length, not the air-equivalent length, unless otherwise specified. The "back focus in air-equivalent distance" is the air-equivalent distance on the optical axis from the lens surface closest to the image side of the zoom lens to the image-side focal position of the zoom lens.

[0041] The values ​​used in the conditional expressions are values ​​based on the d-line when focused on an object at infinity. The "d-line," "C-line," and "F-line" used in this specification are emission lines. In this specification, the wavelength of the d-line is treated as 587.56 nm (nanometers), the wavelength of the C-line is treated as 656.27 nm (nanometers), and the wavelength of the F-line is treated as 486.13 nm (nanometers). [Effects of the Invention]

[0042] According to the present disclosure, it is possible to provide a zoom lens that is small and lightweight while achieving a high zoom ratio, and an imaging device that includes this zoom lens. [Brief explanation of the drawings]

[0043] [Figure 1] 1A and 1B are diagrams illustrating a cross-sectional configuration and a movement locus of a zoom lens according to an embodiment, which corresponds to the zoom lens of Example 1. [Figure 2] 2 is a diagram showing a cross-sectional configuration of the zoom lens shown in FIG. 1 and a light beam. [Figure 3] FIG. 2 is a diagram for explaining symbols in each conditional expression. [Figure 4]FIG. 2 is a diagram for explaining symbols in each conditional expression. [Figure 5] 3A to 3C are diagrams showing various aberrations of the zoom lens of Example 1. [Figure 6] 10A and 10B are diagrams illustrating a cross-sectional configuration and a movement locus of a zoom lens according to a second embodiment. [Figure 7] 10A to 10C are diagrams showing various aberrations of the zoom lens of Example 2. [Figure 8] 10A and 10B are diagrams illustrating a cross-sectional configuration and a movement locus of a zoom lens according to a third embodiment. [Figure 9] 10A to 10C are diagrams illustrating various aberrations of the zoom lens according to the third embodiment. [Figure 10] 10A and 10B are diagrams illustrating a cross-sectional configuration and a movement locus of a zoom lens according to a fourth embodiment. [Figure 11] 10A to 10C are diagrams illustrating various aberrations of the zoom lens according to the fourth embodiment. [Figure 12] 10A and 10B are diagrams illustrating a cross-sectional configuration and a movement locus of a zoom lens according to a fifth embodiment. [Figure 13] 10A to 10C are diagrams showing various aberrations of the zoom lens of Example 5. [Figure 14] 13A and 13B are diagrams illustrating a cross-sectional configuration and a movement locus of a zoom lens according to a sixth embodiment. [Figure 15] 13A to 13C are diagrams illustrating various aberrations of the zoom lens of Example 6. [Figure 16] 13A and 13B are diagrams illustrating a cross-sectional configuration and a movement locus of a zoom lens according to a seventh embodiment. [Figure 17] 10A to 10C are diagrams showing various aberrations of the zoom lens of Example 7. [Figure 18] 13A and 13B are diagrams illustrating a cross-sectional configuration and a movement locus of a zoom lens according to an eighth embodiment. [Figure 19] 13A to 13C are diagrams showing various aberrations of the zoom lens of Example 8. [Figure 20] 1 is a perspective view of the front side of an imaging device according to an embodiment. [Figure 21] FIG. 2 is a perspective view of the rear side of the imaging device according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0044] Embodiments of the present disclosure will be described below with reference to the drawings. FIG. 1 is a diagram illustrating a cross-sectional view of the configuration of a zoom lens according to an embodiment of the present disclosure and a movement trajectory. In FIG. 1, the upper row labeled "WIDE" shows the wide-angle end state, and the lower row labeled "TELE" shows the telephoto end state. FIG. 2 is a cross-sectional view illustrating the configuration and light beams in each magnification state of the zoom lens of FIG. 1. In FIG. 2, the top row labeled "WIDE" shows the wide-angle end state, the middle row labeled "MIDDLE" shows the intermediate focal length state, and the lower row labeled "TELE" shows the telephoto end state. Furthermore, FIG. 2 illustrates the axial light beams wa and wb at the maximum angle of view in the wide-angle end state, the axial light beam ma and mb at the maximum angle of view in the intermediate focal length state, and the axial light beam ta and tb at the maximum angle of view in the telephoto end state. In FIGS. 1 and 2, the state in which an object at infinity is focused is shown, with the left side being the object side and the right side being the image side. The example shown in FIGS. 1 and 2 corresponds to a zoom lens of Example 1, which will be described later.

[0045] The zoom lens according to this embodiment comprises, 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, and a subsequent lens group Gr having multiple lens groups. In Figure 1, as an example, the subsequent lens group Gr comprises a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having negative refractive power, and a sixth lens group G6 having negative refractive power.

[0046] In the example shown in FIG. 1, the first lens group G1 consists of three lenses, L11 to L13, in order from the object side to the image side. The second lens group G2 consists of four lenses, L21 to L24, in order from the object side to the image side. The third lens group G3 consists of an aperture stop St and six lenses, L31 to L36, in order from the object side to the image side. The fourth lens group G4 consists of four lenses, L41 to L44, in order from the object side to the image side. The fifth lens group G5 consists of two lenses, L51 and L52, in order from the object side to the image side. The sixth lens group G6 consists of a single lens, L61.

[0047] The zoom lens according to this embodiment is configured to include an aperture stop St on the image side of the lens surface of the second lens group G2 that is closest to the image side. Note that the aperture stop St in Figures 1 and 2 does not indicate the shape or size, but rather its position in the optical axis direction.

[0048] In the zoom lens according to this embodiment, when the magnification is changed, the distance between the first lens group G1 and the second lens group G2 changes, the distance between the second lens group G2 and the subsequent lens group Gr changes, and all distances between adjacent lens groups in the subsequent lens group Gr change. Furthermore, when the magnification is changed, the distances between lenses within the first lens group G1, the second lens group G2, and the multiple lens groups included in the subsequent lens group Gr remain constant. That is, in the zoom lens according to this embodiment, all distances between adjacent lens groups change, but the distances between lenses within each lens group remain constant. In Figure 1, the arrows between the upper and lower rows indicate the approximate movement trajectories of the first lens group G1, 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 when the magnification is changed from the wide-angle end to the telephoto end.

[0049] As described above, the zoom lens comprises, 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, and a subsequent lens group Gr having a plurality of lens groups, and includes an aperture stop St on the image side of the lens surface of the second lens group G2 closest to the image, and when zooming, the spacing between all of the adjacent lens groups changes relative to each other, while the spacing between lenses within each lens group remains constant, which is advantageous for achieving a high zoom ratio.

[0050] The lens group closest to the image in the subsequent group Gr includes at least one negative lens whose object-side surface is concave and in contact with air. Having the lens group closest to the image in the subsequent group Gr include at least one negative lens whose object-side surface is concave and in contact with air is advantageous for shortening the overall length of the lens system. In Figure 1, as an example, the sixth lens group G6, which is the lens group closest to the image in the subsequent group Gr, includes a lens L61 whose object-side surface is concave and in contact with air and has negative refractive power.

[0051] The first lens group G1 preferably includes, in succession from the object side to the image side, a negative lens and a positive lens. This configuration is advantageous for suppressing lateral chromatic aberration at the wide-angle side and for suppressing axial chromatic aberration at the telephoto side. In FIG. 1, as an example, the first lens group G1 includes, in succession from the object side to the image side, a lens L11 having negative refractive power and a lens L12 having positive refractive power.

[0052] It is preferable that the subsequent group Gr include at least one lens group having positive refractive power. Having at least one lens group having positive refractive power in the subsequent group Gr is advantageous for achieving a high zoom ratio. In Figure 1, as an example, the subsequent group Gr includes two lens groups, the third lens group G3 and the fourth lens group G4, both of which have positive refractive power.

[0053] It is preferable that the subsequent group Gr include a focus group that moves along the optical axis Z during focusing. Here, the focus group is composed of at least one lens that moves during focusing. Focusing is achieved by the movement of the focus group. Including a focus group in the subsequent group Gr is advantageous in suppressing fluctuations in various aberrations that occur during focusing. The right-pointing arrows below lenses L51-L52 in Figure 1 indicate that lenses L51-L52 are focus groups that move toward the image side during focusing from an object at infinity to an object at a close distance.

[0054] The focus group preferably consists of two or fewer lenses. Having the focus group consist of two or fewer lenses is advantageous for reducing the weight of the focus group. The focus group also preferably has negative refractive power. Having the focus group have negative refractive power is advantageous for reducing the amount of movement of the focus group when focusing.

[0055] The zoom lens according to this embodiment preferably satisfies the following conditional expression (1), where fw is the focal length of the entire system at the wide-angle end when focused on an object at infinity, and Denw is the distance on the optical axis Z from the lens surface of the first lens group G1 closest to the object to the paraxial entrance pupil position Penw at the wide-angle end when focused on an object at infinity. Here, the sign of Denw is positive if the paraxial entrance pupil position Penw is closer to the image than the lens surface of the first lens group G1 closest to the object, and negative if the paraxial entrance pupil position Penw is closer to the object than the lens surface of the first lens group G1 closest to the object. Figure 3 is a cross-sectional view showing the configuration and ray bundles corresponding to the zoom lens in the wide-angle end state of Figures 1 and 2, and shows the paraxial entrance pupil position Penw and distance Denw as an example.

[0056] By ensuring that the corresponding value of conditional expression (1) does not fall below the lower limit, the distance Denw does not become too large, and the paraxial entrance pupil position Penw can be brought closer to the object side. This reduces the height from the optical axis Z of off-axial rays passing through the first lens group G1, preventing the diameter of the first lens group G1 from increasing, which is advantageous for making the first lens group G1 more compact and lightweight. By ensuring that the corresponding value of conditional expression (1) does not fall above the upper limit, light rays at each image height are appropriately separated in the first lens group G1, which is advantageous for correcting lateral chromatic aberration. In order to obtain better characteristics, it is more preferable to satisfy the following conditional expression (1-1), and it is even more preferable to satisfy the following conditional expression (1-2). 0.7 <fw / Denw<1.5 (1) 0.83 <fw / Denw<1.35 (1-1) 0.94 <fw / Denw<1.22 (1-2)

[0057] In the zoom lens according to this embodiment, it is preferable to satisfy the following conditional expression (2), where fw is the focal length of the entire system at the wide-angle end when focused on an object at infinity, and Dexw is the distance on the optical axis Z from the paraxial exit pupil position Pexw to the image plane Sim at the wide-angle end when focused on an object at infinity. Here, the sign of Dexw is positive if the paraxial exit pupil position Pexw is closer to the object than the image plane Sim, and negative if the paraxial exit pupil position Pexw is closer to the image than the image plane Sim. FIG. 3 shows an example of the paraxial exit pupil position Pexw and the distance Dexw. By ensuring that the corresponding value of conditional expression (2) is not equal to or less than the lower limit, the overall length of the lens system can be shortened, which is advantageous for compactness. By ensuring that the corresponding value of conditional expression (2) is not equal to or greater than the upper limit, the angle of incidence of off-axial rays on the image plane Sim can be reduced, which is advantageous for ensuring peripheral illumination. In order to obtain better characteristics, it is more preferable to satisfy the following conditional formula (2-1), and it is even more preferable to satisfy the following conditional formula (2-2). 0.25 <fw / Dexw<1 (2) 0.33 <fw / Dexw<0.6 (2-1) 0.39 <fw / Dexw<0.55 (2-2)

[0058] In the zoom lens according to this embodiment, it is preferable to satisfy the following conditional expression (3): D1 is the distance on the optical axis Z from the lens surface of the first lens group G1 closest to the object to the lens surface of the first lens group G1 closest to the image, and TLt is the sum of the distance on the optical axis Z from the lens surface of the first lens group G1 closest to the object to the lens surface of the subsequent lens group Gr closest to the image at the telephoto end when focused on an object at infinity, and the back focus in terms of air equivalent distance. The lower part of FIG. 1 shows an example of the distance D1 and the sum TLt. Ensuring that the corresponding value of conditional expression (3) is not equal to or less than the lower limit is advantageous for suppressing longitudinal chromatic aberration at the telephoto end. Ensuring that the corresponding value of conditional expression (3) is not equal to or greater than the upper limit is advantageous for reducing the weight of the first lens group G1 and the overall weight of the lens system. To obtain better characteristics, it is more preferable to satisfy the following conditional expression (3-1), and even more preferable to satisfy the following conditional expression (3-2). 0.01 <D1 / TLt<0.1 (3) 0.015 <D1 / TLt<0.07 (3-1) 0.02 <D1 / TLt<0.053 (3-2)

[0059] In the zoom lens according to this embodiment, it is preferable to satisfy the following conditional expression (4), where fw is the focal length of the entire system at the wide-angle end when focused on an object at infinity, and ft is the focal length of the entire system at the telephoto end when focused on an object at infinity. Ensuring that the corresponding value of conditional expression (4) does not become equal to or less than the lower limit thereof is advantageous for achieving a higher zoom ratio. Ensuring that the corresponding value of conditional expression (4) does not become equal to or greater than the upper limit thereof prevents the zoom ratio from becoming too high, which is advantageous for reducing the size of the entire lens system. In order to obtain better characteristics, it is more preferable to satisfy the following conditional expression (4-1), and it is even more preferable to satisfy the following conditional expression (4-2). 4.9 <ft / fw<12 (4) 5.7 <ft / fw<10 (4-1) 6.2 <ft / fw<7.5 (4-2)

[0060] The subsequent group Gr preferably includes at least one Lx lens whose image-side lens surface is a convex surface in contact with air, and among at least one optical system formed from a lens surface adjacent to the image side of the aperture stop St to a lens surface on the image side of the Lx lens, when the lateral magnification of the A optical system in which the absolute value of the reciprocal of the lateral magnification at the wide-angle end when the aperture stop St is the object point in a state focused on an object at infinity is smallest when βA is defined as the lateral magnification. That is, when the lateral magnification of each optical system formed from the lens surface adjacent to the image side of the aperture stop St to the image-side lens surfaces of each Lx lens is defined as βx, the optical system in which |1 / βx| is smallest is the "A optical system," and it is preferable that the lateral magnification βA of the A optical system satisfy conditional formula (5). Furthermore, the image-side lens surface of the Lx lens in the A optical system (i.e., the convex surface in contact with air) will hereinafter be referred to as "A surface A."

[0061] For example, in the zoom lens shown in Fig. 1, the six Lx lenses included in the subsequent group Gr whose image-side lens surface is a convex surface in contact with air are lenses L31, L35, L42, L43, L44, and L61. Of the six optical systems formed from the object-side lens surface of lens L31 adjacent to the image side of aperture stop St to the image-side lens surfaces of the above Lx lenses, the optical system for which |1 / βx| is smallest is the optical system formed from the object-side lens surface of lens L31 to the image-side lens surface of lens L44. In this case, the "optical system A" is the optical system formed from the object-side lens surface of lens L31 to the image-side lens surface of lens L44, and surface A is the image-side lens surface of lens L44 as shown in Figs. 1 and 3.

[0062] By ensuring that the corresponding value of conditional expression (5) does not become equal to or smaller than the lower limit, it is possible to prevent a decrease in the angle between the chief ray of the off-axial light beam passing through surface A and the optical axis Z, and to prevent over-correction of astigmatism occurring between surface A and image surface Sim. By ensuring that the corresponding value of conditional expression (5) does not become equal to or larger than the upper limit, it is possible to prevent an increase in the angle between the chief ray of the off-axial light beam passing through surface A and the optical axis Z, which is advantageous for correcting astigmatism occurring between surface A and image surface Sim. In order to obtain better characteristics, it is more preferable to satisfy the following conditional expression (5-1), and it is even more preferable to satisfy the following conditional expression (5-2). -0.5<1 / βA<0.5 (5) -0.4<1 / βA<0.36 (5-1) -0.35<1 / βA<0.13 (5-2)

[0063] In the zoom lens according to this embodiment, it is preferable to satisfy the following conditional expression (6): where HAt is the height from the optical axis Z of an axial marginal ray at the lens surface closest to the image (i.e., surface A) of the A optical system at the telephoto end when focused on an object at infinity, and HSt is the height from the optical axis Z of an axial marginal ray at the aperture stop St at the telephoto end when focused on an object at infinity. FIG. 4 is a partial cross-sectional view showing a configuration corresponding to the zoom lens in the telephoto end state of FIGS. 1 and 2 and an axial ray bundle ta, showing the heights HAt and HSt as examples. Ensuring that the value corresponding to conditional expression (6) is not equal to or less than the lower limit is advantageous for suppressing spherical aberration on the telephoto side. Ensuring that the value corresponding to conditional expression (6) is not equal to or greater than the upper limit is advantageous for suppressing an increase in the diameter of the subsequent lens unit Gr, which is advantageous for reducing the lens weight. In order to obtain better characteristics, it is more preferable to satisfy the following conditional expression (6-1), and it is even more preferable to satisfy the following conditional expression (6-2): 0.73 <HAt / HSt<2.3 (6) 0.83 <HAt / HSt<1.6 (6-1) 0.92 <HAt / HSt<1.37 (6-2)

[0064] In the zoom lens according to this embodiment, it is preferable to satisfy the following conditional expression (7), where ft is the focal length of the entire system at the telephoto end when focused on an object at infinity, and fpAt is the composite focal length from the lens surface of the rear group Gr closest to the object to the lens surface of the A optical system closest to the image (i.e., surface A). Ensuring that the corresponding value of conditional expression (7) is not equal to or less than the lower limit is advantageous for ensuring adequate peripheral light intensity. Ensuring that the corresponding value of conditional expression (7) is not equal to or greater than the upper limit is advantageous for suppressing spherical aberration on the telephoto side. In order to obtain better characteristics, it is more preferable to satisfy the following conditional expression (7-1), and it is even more preferable to satisfy the following conditional expression (7-2). 3 <ft / fpAt<15 (7) 4.5 <ft / fpAt<12 (7-1) 5.7 <ft / fpAt<9 (7-2)

[0065] In the zoom lens according to this embodiment, it is preferable to satisfy the following conditional expression (8): where HAt is the height from the optical axis Z of an on-axis marginal ray on the lens surface of the A optical system closest to the image (i.e., surface A A) at the telephoto end when focused on an object at infinity, and HAw is the height from the optical axis Z of a chief ray of a maximum image height on the lens surface of the A optical system closest to the image (i.e., surface A A) at the wide-angle end when focused on an object at infinity. FIG. 3 shows the height HAw as an example. Ensuring that the corresponding value of conditional expression (8) is not equal to or less than the lower limit is advantageous for suppressing astigmatism on the wide-angle side. Ensuring that the corresponding value of conditional expression (8) is not equal to or greater than the upper limit is advantageous for suppressing fluctuations in field curvature during zooming. In order to obtain better characteristics, it is more preferable to satisfy the following conditional expression (8-1), and it is even more preferable to satisfy the following conditional expression (8-2). 0.35 <HAt / HAw<1.6 (8) 0.65 <HAt / HAw<1.4 (8-1) 0.83 <HAt / HAw<1.25 (8-2)

[0066] It is preferable that the subsequent group Gr include a lens surface that is a concave surface facing the image side and is in contact with the air, between the lens surface closest to the image side of the A optical system (i.e., surface A A) and the lens surface that is a concave surface facing the air and is in contact with the object side of the lens group closest to the image side in the subsequent group Gr. This configuration is advantageous for suppressing astigmatism at the wide-angle side while maintaining the compactness of the entire lens system. In the example of Figure 1, the image side surface of the lens L52 that is a concave surface facing the image side and is in contact with the air is included between the image side surface of the lens L44 that is the lens surface closest to the image side of the A optical system (i.e., surface A A) and the object side surface of the lens L61 that is a concave surface facing the air and is in contact with the object side of the sixth lens group G6 that is closest to the image side in the subsequent group Gr.

[0067] In the zoom lens according to this embodiment, when the distance on the optical axis Z from the aperture stop St to the lens surface of the optical system A closest to the image (i.e., surface A A) at the telephoto end in a state focused on an object at infinity is DSAt, and the sum of the distance on the optical axis Z from the aperture stop St to the lens surface of the subsequent lens unit Gr closest to the image at the telephoto end in a state focused on an object at infinity and the back focus in air equivalent distance is DSLt, it is preferable to satisfy the following conditional expression (9): The lower part of FIG. 1 shows an example of the distance DSAt and the sum DSLt. By ensuring that the value corresponding to conditional expression (9) is not equal to or less than the lower limit, the refraction of off-axial rays from surface A A toward the image plane Sim can be made gentler, which is advantageous for suppressing the occurrence of off-axial aberrations. By ensuring that the value corresponding to conditional expression (9) is not equal to or greater than the upper limit, the diameter of the light beam on the image side of the aperture stop St can be made smaller, which is advantageous for making the diameter of the subsequent lens unit Gr smaller. In order to obtain better characteristics, it is more preferable to satisfy the following conditional formula (9-1), and it is even more preferable to satisfy the following conditional formula (9-2). 0.1 <DSAt / DSLt<0.54 (9) 0.15 <DSAt / DSLt<0.4 (9-1) 0.18 <DSAt / DSLt<0.32 (9-2)

[0068] In the zoom lens according to this embodiment, when focused on an object at infinity at the telephoto end, it is preferable to satisfy the following conditional expression (10), where dA is the distance on the optical axis Z between the lens surface of the A optical system closest to the image (i.e., surface A A) and the lens surface adjacent to the lens surface (i.e., surface A A) on the image side, and Yt is the maximum image height at the telephoto end. The lower part of FIG. 1 shows an example of the distance dA, and the lower part of FIG. 2 shows an example of the maximum image height Yt. Ensuring that the value corresponding to conditional expression (10) is not equal to or smaller than the lower limit is advantageous for reducing the size of the entire lens system. Ensuring that the value corresponding to conditional expression (10) is not equal to or larger than the upper limit is advantageous for suppressing spherical aberration on the telephoto end. To obtain better characteristics, it is more preferable to satisfy the following conditional expression (10-1), and it is even more preferable to satisfy the following conditional expression (10-2). 0.015 <dA / Yt<0.35 (10) 0.025 <dA / Yt<0.2 (10-1) 0.037 <dA / Yt<0.11 (10-2)

[0069] In the zoom lens according to this embodiment, when the sum of the distance on the optical axis Z from the lens surface closest to the object in the first lens group G1 to the lens surface closest to the image in the subsequent lens group Gr at the telephoto end when focused on an object at infinity is TLt and the back focus in air equivalent distance is ft, and the focal length of the entire system at the telephoto end when focused on an object at infinity is ft, it is preferable to satisfy the following conditional expression (11): Ensuring that the corresponding value of conditional expression (11) is not equal to or less than the lower limit is advantageous for suppressing longitudinal chromatic aberration at the telephoto end. Ensuring that the corresponding value of conditional expression (11) is not equal to or greater than the upper limit is advantageous for shortening the overall length of the lens system and for compactness. In order to obtain better characteristics, it is more preferable to satisfy the following conditional expression (11-1), and it is even more preferable to satisfy the following conditional expression (11-2). 0.65 <TLt / ft<1.5 (11) 0.8 <TLt / ft<1.4 (11-1) 0.95 <TLt / ft<1.27 (11-2)

[0070] In the zoom lens according to this embodiment, it is preferable to satisfy the following conditional expression (12), where BFw is the back focus in air equivalent distance at the wide-angle end when focused on an object at infinity, and Yw is the maximum image height at the wide-angle end. Ensuring that the corresponding value of conditional expression (12) is not equal to or less than the lower limit is advantageous for ensuring the amount of peripheral light. Ensuring that the corresponding value of conditional expression (12) is not equal to or greater than the upper limit is advantageous for shortening the overall length of the lens system and for achieving compactness. In order to obtain better characteristics, it is more preferable to satisfy the following conditional expression (12-1), and it is even more preferable to satisfy the following conditional expression (12-2). 0.38 <BFw / Yw<1.5 (12) 0.45 <BFw / Yw<1.2 (12-1) 0.59 <BFw / Yw<0.98 (12-2)

[0071] When the Abbe number based on the d-line of the lens closest to the object in the first lens group G1 is v1, it is preferable to satisfy the following conditional expression (13). By ensuring that the corresponding value of conditional expression (13) is not equal to or less than the lower limit, it is possible to prevent overcorrection of axial chromatic aberration. By ensuring that the corresponding value of conditional expression (13) is not equal to or greater than the upper limit, it is advantageous for correcting axial chromatic aberration. In order to obtain better characteristics, it is more preferable to satisfy the following conditional expression (13-1), and it is even more preferable to satisfy the following conditional expression (13-2). In the example of FIG. 1, lens L11 satisfies conditional expression (13). 10<ν1<50 (13) 12<ν1<40 (13-1) 14<ν1<27.3 (13-2)

[0072] If the refractive index at the d-line of the lens closest to the object in the first lens group G1 is N1, it is preferable to satisfy the following conditional expression (14). Ensuring that the corresponding value of conditional expression (14) is not below the lower limit is advantageous for suppressing astigmatism. Ensuring that the corresponding value of conditional expression (14) is not above the upper limit increases the availability of lens materials, allowing the use of materials that are easier to manufacture. In order to obtain better characteristics, it is more preferable to satisfy the following conditional expression (14-1), and even more preferable to satisfy the following conditional expression (14-2). In the example of FIG. 1, lens L11 satisfies conditional expression (14). 1.7 <N1<2.3 (14) 1.84 <N1<2.22 (14-1) 1.88 <N1<2.16 (14-2)

[0073] When the refractive index of the negative lens closest to the object among the negative lenses included in the second lens group G2 with respect to the d-line is N2n, it is preferable to satisfy the following conditional expression (15). By ensuring that the corresponding value of conditional expression (15) is not below the lower limit, the refractive power can be ensured without the absolute value of the radius of curvature of the negative lens being too small, thereby preventing the negative lens from becoming thicker in the optical axis direction, which is advantageous for weight reduction. By ensuring that the corresponding value of conditional expression (15) is not above the upper limit, the availability of lens materials increases, allowing the use of materials that are easier to manufacture. In order to obtain better characteristics, it is more preferable to satisfy the following conditional expression (15-1), and even more preferable to satisfy the following conditional expression (15-2). In the example of FIG. 1, lens L21 satisfies conditional expression (15). 1.6 <N2n<2.2 (15) 1.65 <N2n<2.11 (15-1) 1.7 <N2n<2.05 (15-2)

[0074] If the refractive index at the d-line of the positive lens with the strongest refractive power among the positive lenses included in the second lens group G2 is N2p, it is preferable to satisfy the following conditional expression (16). Ensuring that the corresponding value of conditional expression (16) is not below the lower limit is advantageous for suppressing astigmatism. Ensuring that the corresponding value of conditional expression (16) is not above the upper limit increases the availability of lens materials, allowing the use of materials that are easier to manufacture. In order to obtain better characteristics, it is more preferable to satisfy the following conditional expression (16-1), and even more preferable to satisfy the following conditional expression (16-2). In the example of FIG. 1, lens L23 satisfies conditional expression (16). 1.65 <N2p<2 (16) 1.71 <N2p<1.93 (16-1) 1.77 <N2p<1.9 (16-2)

[0075] Of the negative lenses included in the subsequent lens group Gr, if the Abbe number based on the d-line of the negative lens closest to the image is vnL, it is preferable to satisfy the following conditional expression (17). Ensuring that the corresponding value of conditional expression (17) is not equal to or less than the lower limit is advantageous for suppressing lateral chromatic aberration. Ensuring that the corresponding value of conditional expression (17) is not equal to or greater than the upper limit can prevent lateral chromatic aberration from being overcorrected. In order to obtain better characteristics, it is more preferable to satisfy the following conditional expression (17-1), and even more preferable to satisfy the following conditional expression (17-2). In the example of FIG. 1, lens L61 satisfies conditional expression (17). 27<νnL<102 (17) 50<νnL<96 (17-1) 70<νnL<88 (17-2)

[0076] In the zoom lens according to this embodiment, it is preferable to satisfy the following conditional expression (18): TLt is the sum of the distance on the optical axis Z from the lens surface closest to the object in the first lens group G1 to the lens surface closest to the image in the subsequent lens group Gr at the telephoto end when focused on an object at infinity, and the back focus in terms of the air equivalent distance; and Mp is the difference in the optical axis Z between the position of the lens group closest to the object among the lens groups having positive refractive power in the subsequent lens group Gr at the wide-angle end and the position at the telephoto end when focused on an object at infinity. Here, the sign of Mp is positive if the lens group closest to the object moves from the object side to the image side when changing magnification from the wide-angle end to the telephoto end, and negative if it moves from the image side to the object side. By ensuring that the corresponding value of conditional expression (18) is not less than the lower limit, the absolute value of Mp does not become too large, thereby preventing the amount of movement of the lens group closest to the object among the lens groups having positive refractive power in the subsequent lens group Gr when changing magnification from the wide-angle end to the telephoto end. This is advantageous for compactness. By ensuring that the corresponding value of conditional expression (18) does not exceed its upper limit, the absolute value of Mp does not become too small, which is advantageous for achieving a high zoom ratio. To obtain better characteristics, it is more preferable to satisfy the following conditional expression (18-1), and it is even more preferable to satisfy the following conditional expression (18-2). In the example of FIG. 1, when the difference in the optical axis Z direction between the position at the wide-angle end and the position at the telephoto end of the third lens group G3, which is the lens group closest to the object among the lens groups having positive refractive power included in the subsequent group Gr, is taken as Mp, conditional expression (18) is satisfied. -0.45 <Mp / TLt<-0.06 (18) -0.39 <Mp / TLt<-0.12 (18-1) -0.33 <Mp / TLt<-0.15 (18-2)

[0077] In the zoom lens according to this embodiment, when focused on an object at infinity, the focal length of the lens group having positive refractive power included in the subsequent group Gr that is closest to the object is denoted by fp, and the focal length of the second lens group G2 is denoted by f2. By ensuring that the corresponding value of conditional expression (19) is not less than the lower limit, the absolute value of f2 does not become too small, which is advantageous for suppressing fluctuations in various aberrations that occur during zooming. By ensuring that the corresponding value of conditional expression (19) is not less than the upper limit, the absolute value of f2 does not become too large, which is advantageous for shortening the second lens group G2 and achieving compactness. To obtain better characteristics, it is more preferable to satisfy the following conditional expression (19-1), and it is even more preferable to satisfy the following conditional expression (19-2). In the example of FIG. 1 , when the focal length of the third lens group G3, which is the lens group having positive refractive power that is closest to the object and is included in the subsequent group Gr, is denoted by fp, conditional expression (19) is satisfied. -4.3 <fp / f2<-1.1 (19) -3.9 <fp / f2<-1.5 (19-1) -3.4 <fp / f2<-1.95 (19-2)

[0078] In the zoom lens according to this embodiment, when the zoom lens is at the telephoto end in a state focused on an object at infinity, the distance on the optical axis Z from the lens surface closest to the image in the first lens group G1 to the lens surface closest to the object in the lens group having positive refractive power included in the subsequent group Gr is defined as D1pt, and the sum of the distance on the optical axis Z from the lens surface closest to the object in the first lens group G1 to the lens surface closest to the image in the subsequent group Gr at the telephoto end in a state focused on an object at infinity and the back focus in air equivalent distance is defined as TLt. The lower part of FIG. 1 shows an example of the distance D1pt and the sum TLt. Making sure that the corresponding value of conditional expression (20) is not equal to or less than the lower limit is advantageous for shortening the overall length of the lens system. Making sure that the corresponding value of conditional expression (20) is not equal to or greater than the upper limit is advantageous for suppressing spherical aberration on the telephoto end. In order to obtain better characteristics, it is more preferable to satisfy the following conditional formula (20-1), and it is even more preferable to satisfy the following conditional formula (20-2). 0.2 <D1pt / TLt<0.5 (20) 0.25 <D1pt / TLt<0.42 (20-1) 0.29 <D1pt / TLt<0.39 (20-2)

[0079] As described above, when the subsequent group Gr includes at least one Lx lens whose image-side lens surface is a convex surface in contact with air, the A optical system is defined as the optical system that, among at least one optical system formed from the lens surface adjacent to the image side of the aperture stop St to the lens surface adjacent to the image side of the Lx lens, has the smallest absolute value of the reciprocal of the lateral magnification at the wide-angle end when the aperture stop St is the object point in a state focused on an object at infinity. In the zoom lens according to this embodiment, it is preferable to satisfy the following conditional expression (21), where fw is the focal length of the entire system at the wide-angle end in a state focused on an object at infinity, and fBw is the combined focal length at the wide-angle end in a state focused on an object at infinity, from the lens surface adjacent to the image side of the lens surface closest to the image side of the A optical system (i.e., surface A A) to the lens surface closest to the image side of the subsequent group Gr. Ensuring that the corresponding value of conditional expression (21) is not below the lower limit is advantageous for suppressing astigmatism at the wide-angle end. By ensuring that the corresponding value of conditional expression (21) is not greater than the upper limit, the negative refractive power from the lens surface adjacent to the image side of surface A to the lens surface closest to the image in subsequent lens unit Gr can be strengthened, thereby reducing the diameter of the light beam from the lens surface closest to the object in subsequent lens unit Gr to surface A, which is advantageous for making the diameter smaller. In order to obtain better characteristics, it is more preferable to satisfy the following conditional expression (21-1), and it is even more preferable to satisfy the following conditional expression (21-2): -1.6 <fw / fBw<-0.25 (21) -1.3 <fw / fBw<-0.37 (21-1) -1.1 <fw / fBw<-0.69 (21-2)

[0080] In the zoom lens according to this embodiment, it is preferable to satisfy the following conditional expression (22), where fw is the focal length of the entire system at the wide-angle end when focused on an object at infinity, ωw is the maximum half angle of view at the wide-angle end when focused on an object at infinity, and Yw is the maximum image height at the wide-angle end. By ensuring that the corresponding value of conditional expression (22) is not equal to or less than the lower limit, it is possible to reduce the height from the optical axis Z of off-axial rays passing through the lens closest to the object in the first lens group G1 on the wide-angle side, which is advantageous for reducing the diameter. By ensuring that the corresponding value of conditional expression (22) is not equal to or greater than the upper limit, it is advantageous for suppressing various aberrations of off-axial rays on the wide-angle side. In order to obtain better characteristics, it is more preferable to satisfy the following conditional expression (22-1), and it is even more preferable to satisfy the following conditional expression (22-2). 0.97 <fw×tanωw / Yw<1.3 (22) 1 <fw×tanωw / Yw<1.19 (22-1) 1.02 <fw×tanωw / Yw<1.11 (22-2)

[0081] In the zoom lens according to this embodiment, when the focal length of the first lens group G1 is f1 and the focal length of the second lens group G2 is f2, it is preferable that the following conditional expression (23) be satisfied. Ensuring that the corresponding value of conditional expression (23) is not below the lower limit is advantageous for achieving a high zoom ratio. Ensuring that the corresponding value of conditional expression (23) is not above the upper limit is advantageous for suppressing fluctuations in various aberrations that occur during zooming. In order to obtain better characteristics, it is more preferable to satisfy the following conditional expression (23-1), and it is even more preferable to satisfy the following conditional expression (23-2). -0.3 <f2 / f1<-0.05 (23) -0.23 <f2 / f1<-0.1 (23-1) -0.19 <f2 / f1<-0.14 (23-2)

[0082] The above-described preferred and possible configurations, including those related to the conditional expressions, can be arbitrarily combined and are preferably selectively adopted as appropriate depending on the required specifications. The conditional expressions that the zoom lens of the present disclosure preferably satisfies are not limited to those written in the form of an expression, but include all conditional expressions obtained by arbitrarily combining lower and upper limits from among the preferred, more preferred, and even more preferred conditional expressions. The example shown in FIG. 1 is merely an example, and various modifications are possible within the scope of the gist of the technology of the present disclosure. For example, the number of lenses constituting each lens group may be different from that shown in FIG. 1.

[0083] As an example, one preferred aspect of the present disclosure is a zoom lens comprising, 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, and a subsequent lens group Gr including multiple lens groups, an aperture stop St located closer to the image side than the lens surface of the second lens group G2 closest to the image, the lens group closest to the image side in the subsequent lens group Gr including at least one negative lens whose object-side lens surface is concave and in contact with air, the distance between the first lens group G1 and the second lens group G2 changes during magnification variation, the distance between the second lens group G2 and the subsequent lens group Gr changes, and all distances between adjacent lens groups in the subsequent lens group Gr change, and the distances between lenses within the first lens group G1, the second lens group G2, and the multiple lens groups remain unchanged during magnification variation, and the zoom lens satisfies conditional expression (1) above.

[0084] Next, examples of the zoom lens of the present disclosure will be described with reference to the drawings. The reference symbols attached to the lenses in the cross-sectional views of each example are used independently for each example to avoid cluttering the explanation and the drawings due to an increase in the number of digits of the reference symbols. Therefore, even if common reference symbols are attached in drawings of different examples, they do not necessarily have the same configuration. Furthermore, the following examples 1 and 4 are examples of the present disclosure, and examples 2, 3, and 5 to 8 are reference examples of the present disclosure.

[0085] [Example 1] The configuration and movement locus of the zoom lens of Example 1 are shown in Figure 1, and since the illustration method and configuration are as described above, some overlapping explanations will be omitted here. For the zoom lens of Example 1, basic lens data is shown in Table 1, specifications and variable surface spacings are shown in Table 2, and aspherical coefficients are shown in Table 3.

[0086] Table 1 is organized as follows. The Sn column lists the surface numbers, with the surface closest to the object designated as surface 1 and the numbers increasing by one toward the image side. The R column lists the radius of curvature of each surface. The D column lists the axial surface spacing between each surface and its adjacent image-side surface. The Nd column lists the refractive index of each component at the d-line. The νd column lists the Abbe number of each component at the d-line. Table 1 also lists the aperture stop St, and the surface number corresponding to the aperture stop St is marked with the surface number and the term (St). Additionally, the surface number corresponding to the above-mentioned surface A is marked with the surface number and the term (A). In Table 1, the sign of the radius of curvature of surfaces with a convex surface facing the object side is positive, and the sign of the radius of curvature of surfaces with a convex surface facing the image side is negative. In Table 1, the variable surface spacing during magnification is indicated by the symbol DD[ ], with the object-side surface number of this spacing listed in the [ ] in the D column.

[0087] Table 2 shows the zoom magnification Zr, focal length f of the entire system, back focal length BF, F-number FNo., maximum total angle of view 2ω, and variable surface spacing when changing magnification. The [°] in the 2ω column indicates that the unit is degrees. The values ​​shown in Table 2 are based on the d-line when focused on an object at infinity. In Table 2, the values ​​for the wide-angle end state, mid-focal length state, and telephoto end state are shown in the columns labeled WIDE, MIDDLE, and TELE, respectively.

[0088] In Table 1, the aspherical surface numbers are marked with an *, and the paraxial radius of curvature is listed in the aspherical radius of curvature column. In Table 3, the Sn row shows the aspherical surface numbers, and the KA and Am (m is an integer of 3 or more) rows show the numerical values ​​of the aspherical coefficients for each aspherical surface. The numerical values ​​of the aspherical coefficients in Table 3, "E±n" (n is an integer), are expressed as "×10 ±n" KA and Am are aspherical coefficients in the aspherical formula given below. Zd=C×h 2 / {1+(1-KA×C 2 ×h 2 ) 1 / 2}+ΣAm×h m however, Zd: Aspheric depth (length of the perpendicular line drawn from a point on the aspheric surface at height h to a plane perpendicular to the optical axis where the vertex of the aspheric surface touches) h: Height (distance from the optical axis to the lens surface) C: Reciprocal of paraxial curvature radius KA, Am: aspherical coefficients In the aspherical formula, Σ means the summation over m.

[0089] In the data in each table, the angle unit is degrees and the length unit is mm (millimeters), but since the optical system can be used with proportional enlargement or reduction, other appropriate units can also be used. Also, in each table below, the values ​​are rounded to a predetermined number of decimal places.

[0090] [Table 1]

[0091] [Table 2]

[0092] [Table 3]

[0093] FIG. 5 shows aberration diagrams of the zoom lens of Example 1 when focused on an object at infinity. From left to right, FIG. 5 shows spherical aberration, astigmatism, distortion, and lateral chromatic aberration. In FIG. 5, the upper row labeled "WIDE" shows aberrations at the wide-angle end, the middle row labeled "MIDDLE" shows aberrations at the intermediate focal length, and the lower row labeled "TELE" shows aberrations at the telephoto end. In the spherical aberration diagram, aberrations at the d-line, C-line, and F-line are shown by solid lines, long-dashed lines, and short-dashed lines, respectively. In the astigmatism diagram, aberrations at the d-line in the sagittal direction are shown by solid lines, and aberrations at the d-line in the tangential direction are shown by short-dashed lines. In the distortion diagram, aberrations at the d-line are shown by solid lines. In the lateral chromatic aberration diagram, aberrations at the C-line and F-line are shown by long-dashed lines and short-dashed lines, respectively. In spherical aberration diagrams, the F-number value is shown after "FNo.=", and in other aberration diagrams, the half angle of view value is shown after "ω=".

[0094] The symbols, meanings, notation methods, and illustration methods of each data item related to the above-mentioned Example 1 are the same in the following Examples unless otherwise specified, and therefore, redundant explanations will be omitted below.

[0095] [Example 2] Figure 6 shows a cross-sectional view of the configuration of a zoom lens of Example 2 at the wide-angle end when focused on an object at infinity, and a diagram illustrating its movement locus. Note that, unlike Figure 1, the configuration at the telephoto end is omitted in Figure 6, and this also applies to the cross-sectional views of Examples 3 to 8 below. The zoom lens of Example 2 is composed 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, and a subsequent lens group Gr. The subsequent lens group Gr is composed of, in order from the object side to the image side, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, and a fifth lens group G5 having negative refractive power.

[0096] The first lens group G1 consists of three lenses, L11 to L13, in order from the object side to the image side. The second lens group G2 consists of four lenses, L21 to L24, in order from the object side to the image side. The third lens group G3 consists of an aperture stop St and five lenses, L31 to L35, in order from the object side to the image side. The fourth lens group G4 consists of six lenses, L41 to L46, in order from the object side to the image side. The fifth lens group G5 consists of one lens, L51. The focus group consists of two lenses, L45 to L46.

[0097] For the zoom lens of Example 2, basic lens data is shown in Table 4, specifications and variable surface spacing are shown in Table 5, aspherical coefficients are shown in Table 6, and aberration diagrams are shown in FIG.

[0098] [Table 4]

[0099] [Table 5]

[0100] [Table 6]

[0101] [Example 3] 8 is a diagram showing a cross-sectional view of the configuration of a zoom lens of Example 3 at the wide-angle end when focused on an object at infinity, and a diagram showing a movement locus. The zoom lens of Example 3 is composed 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, and a subsequent lens group Gr. The subsequent lens group Gr is composed of, in order from the object side to the image side, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, and a fifth lens group G5 having negative refractive power.

[0102] The first lens group G1 consists of three lenses, L11 to L13, in order from the object side to the image side. The second lens group G2 consists of four lenses, L21 to L24, in order from the object side to the image side. The third lens group G3 consists of an aperture stop St and five lenses, L31 to L35, in order from the object side to the image side. The fourth lens group G4 consists of six lenses, L41 to L46, in order from the object side to the image side. The fifth lens group G5 consists of one lens, L51. The focus group consists of two lenses, L45 to L46.

[0103] For the zoom lens of Example 3, basic lens data is shown in Table 7, specifications and variable surface spacings are shown in Table 8, aspherical coefficients are shown in Table 9, and aberration diagrams are shown in FIG.

[0104] [Table 7]

[0105] [Table 8]

[0106] [Table 9]

[0107] [Example 4] 10 is a diagram showing a cross-sectional view of the configuration of a zoom lens of Example 4 at the wide-angle end when focused on an object at infinity, and a diagram showing a movement locus. The zoom lens of Example 4 is composed 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, and a subsequent lens group Gr. The subsequent lens group Gr is composed of, in order from the object side to the image side, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, and a fifth lens group G5 having negative refractive power.

[0108] The first lens group G1 consists of three lenses, L11 to L13, in order from the object side to the image side. The second lens group G2 consists of four lenses, L21 to L24, in order from the object side to the image side. The third lens group G3 consists of an aperture stop St and five lenses, L31 to L35, in order from the object side to the image side. The fourth lens group G4 consists of four lenses, L41 to L44, in order from the object side to the image side. The fifth lens group G5 consists of three lenses, L51 to L53, in order from the object side to the image side. The focus group consists of two lenses, L51 and L52.

[0109] For the zoom lens of Example 4, basic lens data is shown in Table 10, specifications and variable surface spacings are shown in Table 11, aspherical coefficients are shown in Table 12, and aberration diagrams are shown in FIG.

[0110] [Table 10]

[0111] [Table 11]

[0112] [Table 12]

[0113] [Example 5] 12 is a diagram showing a cross-sectional view of the configuration of a zoom lens of Example 5 at the wide-angle end when focused on an object at infinity, and a diagram showing a movement locus. The zoom lens of Example 5 is composed 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, and a subsequent lens group Gr. The subsequent lens group Gr is composed of, in order from the object side to the image side, a third lens group G3 having positive refractive power, and a fourth lens group G4 having positive refractive power.

[0114] The first lens group G1 consists of three lenses, L11 to L13, in order from the object side to the image side. The second lens group G2 consists of four lenses, L21 to L24, in order from the object side to the image side. The third lens group G3 consists of an aperture stop St and five lenses, L31 to L35, in order from the object side to the image side. The fourth lens group G4 consists of six lenses, L41 to L46, in order from the object side to the image side. The focus group consists of two lenses, L44 to L45.

[0115] For the zoom lens of Example 5, basic lens data is shown in Table 13, specifications and variable surface spacing are shown in Table 14, aspherical coefficients are shown in Table 15, and each aberration diagram is shown in FIG.

[0116] [Table 13]

[0117] [Table 14]

[0118] [Table 15]

[0119] [Example 6] 14 is a diagram showing a cross-sectional view of the configuration of a zoom lens of Example 6 at the wide-angle end when focused on an object at infinity and a diagram showing a movement locus. The zoom lens of Example 6 comprises, 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, and a subsequent lens group Gr. The subsequent lens group Gr comprises, in order from the object side to the image side, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having negative refractive power, and a sixth lens group G6 having negative refractive power.

[0120] The first lens group G1 consists of two lenses, L11 and L12, in order from the object side to the image side. The second lens group G2 consists of four lenses, L21 to L24, in order from the object side to the image side. The third lens group G3 consists of an aperture stop St and four lenses, L31 to L34, in order from the object side to the image side. The fourth lens group G4 consists of three lenses, L41 to L43, in order from the object side to the image side. The fifth lens group G5 consists of one lens, L51. The sixth lens group G6 consists of two lenses, L61 and L62, in order from the object side to the image side. The focus group consists of one lens, L51.

[0121] For the zoom lens of Example 6, basic lens data is shown in Table 16, specifications and variable surface spacing are shown in Table 17, aspherical coefficients are shown in Table 18, and aberration diagrams are shown in FIG.

[0122] [Table 16]

[0123] [Table 17]

[0124] [Table 18]

[0125] [Example 7] 16 is a diagram showing a cross-sectional view of the configuration of a zoom lens of Example 7 at the wide-angle end when focused on an object at infinity, and a diagram showing a movement locus. The zoom lens of Example 7 is composed 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, and a subsequent lens group Gr. The subsequent lens group Gr is composed of, in order from the object side to the image side, a third lens group G3 having positive refractive power, and a fourth lens group G4 having positive refractive power.

[0126] The first lens group G1 consists of three lenses, L11 to L13, in order from the object side to the image side. The second lens group G2 consists of four lenses, L21 to L24, in order from the object side to the image side. The third lens group G3 consists of an aperture stop St and six lenses, L31 to L36, in order from the object side to the image side. The fourth lens group G4 consists of seven lenses, L41 to L47, in order from the object side to the image side. The focus group consists of one lens, lens L44. Unlike in Example 1, the focus group in Example 7 moves toward the object side when focusing from an object at infinity to an object at a close distance.

[0127] For the zoom lens of Example 7, basic lens data is shown in Table 19, specifications and variable surface spacing are shown in Table 20, aspherical coefficients are shown in Table 21, and various aberration diagrams are shown in FIG.

[0128] [Table 19]

[0129] [Table 20]

[0130] [Table 21]

[0131] [Example 8] 18 is a diagram showing a cross-sectional view of the configuration of a zoom lens of Example 8 at the wide-angle end when focused on an object at infinity, and a diagram showing a movement locus. The zoom lens of Example 8 is composed 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, and a subsequent lens group Gr. The subsequent lens group Gr is composed of, in order from the object side to the image side, a third lens group G3 having positive refractive power, and a fourth lens group G4 having positive refractive power.

[0132] The first lens group G1 consists of three lenses, L11 to L13, in order from the object side to the image side. The second lens group G2 consists of four lenses, L21 to L24, in order from the object side to the image side. The third lens group G3 consists of an aperture stop St and five lenses, L31 to L35, in order from the object side to the image side. The fourth lens group G4 consists of six lenses, L41 to L46, in order from the object side to the image side. The focus group consists of two lenses, L44 to L45.

[0133] For the zoom lens of Example 8, basic lens data is shown in Table 22, specifications and variable surface spacing are shown in Table 23, aspherical coefficients are shown in Table 24, and each aberration diagram is shown in FIG.

[0134] [Table 22]

[0135] [Table 23]

[0136] [Table 24]

[0137] Tables 25 and 26 show the corresponding values ​​of conditional expressions (1) to (23) for the zoom lenses of Examples 1 to 8.

[0138] [Table 25]

[0139] [Table 26]

[0140] As can be seen from the data explained above, the zoom lenses of Examples 1 to 8 achieve a high zoom ratio of 5.5 or more, yet are constructed to be small and lightweight.

[0141] Next, an imaging device according to an embodiment of the present disclosure will be described. Fig. 20 and Fig. 21 show external views of a camera 30, which is an imaging device according to an embodiment of the present disclosure. Fig. 20 shows a perspective view of the camera 30 as seen from the front side, and Fig. 21 shows a perspective view of the camera 30 as seen from the rear side. The camera 30 is a so-called mirrorless digital camera, to which an interchangeable lens 20 can be removably attached. The interchangeable lens 20 is configured to include a zoom lens 1 according to an embodiment of the present disclosure housed in a lens barrel.

[0142] The camera 30 includes a camera body 31, and 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 a captured image and an image within the angle of view before the image was captured.

[0143] A photographic opening through which light from the subject to be photographed enters is provided in the center of the front face of the camera body 31, and a mount 37 is provided at a position corresponding to the photographic opening, and an interchangeable lens 20 is attached to the camera body 31 via the mount 37.

[0144] The camera body 31 contains an imaging element such as a CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor) that outputs an imaging signal corresponding to the subject image formed by the interchangeable lens 20, a signal processing circuit that processes the imaging signal output from the imaging element to generate an image, and a recording medium for recording the generated image. The camera 30 takes still or moving images by pressing a shutter button 32. The image data obtained by this shooting is recorded on the recording medium.

[0145] Although the technology of the present disclosure has been described above using embodiments and examples, the technology of the present disclosure is not limited to the above embodiments and examples and can be modified in various ways. For example, the radius of curvature, surface spacing, refractive index, Abbe number, aspherical coefficient, etc. of each lens are not limited to the values ​​shown in the above numerical examples and can take other values.

[0146] Furthermore, the imaging device according to the embodiment of the present disclosure is not limited to the above example, and can take various forms, such as a camera other than a mirrorless type, a film camera, and a video camera. [Explanation of symbols]

[0147] 1 zoom lens 20 Interchangeable Lenses 30 Camera 31 Camera Body 32 Shutter button 33 Power button 34, 35 Operation section 36 Display section 37 Mount AA side dA interval D1, D1pt, Denw, Dexw, DSAt, DSLt 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 Gr successor group HAt, HAw, HSt height L11~L62 lenses ma, ta, wa Axial luminous flux mb, tb, wb Maximum angle of view luminous flux Penw Paraxial entrance pupil position Pexw paraxial exit pupil position Sim image plane St aperture stop TLt is the sum of the distance on the optical axis from the lens surface in the first lens group closest to the object to the lens surface in the succeeding lens group closest to the image, and the back focus in air equivalent distance, at the telephoto end when focused on an object at infinity. Yt, Yw Maximum image height Z optical axis ωw Maximum half angle of view

Claims

1. The lens comprises, in order from the object side to the image side, a first lens group having positive refractive power, a second lens group having negative refractive power, and a subsequent group having a plurality of lens groups, an aperture stop is included on the image side of the lens surface of the second lens group that is closest to the image side; the lens group closest to the image side in the subsequent group includes at least one negative lens element whose object-side lens surface is a concave surface in contact with air, During magnification change, the distance between the first lens group and the second lens group changes, the distance between the second lens group and the subsequent lens group changes, and all distances between adjacent lens groups in the subsequent lens group change, During magnification change, the lens intervals within the first lens group, the second lens group, and the plurality of lens groups are unchanged, the first lens group comprises, in order from the object side to the image side, a cemented lens formed by cementing a negative meniscus lens having a convex surface facing the object side to a positive lens, and a positive meniscus lens having a convex surface facing the object side; the second lens group includes a negative meniscus lens, which is not cemented and has a convex surface facing the image side, located closest to the image side; the subsequent group includes, in order from the most object side to the image side, a third lens group having positive refractive power and a fourth lens group having positive refractive power, the lens unit closest to the image side in the subsequent lens group has negative refractive power, the subsequent lens group includes only three cemented lenses each formed by cementing a positive lens and a negative lens together, the subsequent lens group includes a focus group that moves along the optical axis during focusing, and is located closer to the image side than the fourth lens group; The focal length of the entire system at the wide-angle end when focused on an object at infinity is fw. Denw is the distance on the optical axis from the lens surface of the first lens group closest to the object to the paraxial entrance pupil position at the wide-angle end when focused on an object at infinity, The sign of Denw is positive if the paraxial entrance pupil position is closer to the image side than the lens surface of the first lens group closest to the object side, and negative if the paraxial entrance pupil position is closer to the object side than the lens surface of the first lens group closest to the object side. The Abbe number of the lens closest to the object side in the first lens group based on the d-line is ν1, When focused on an object at infinity, the focal length of the lens group having positive refractive power included in the subsequent lens group and closest to the object is designated as fp, The focal length of the second lens group is f2, When the focal length of the first lens group is f1, 0.7<fw / Denw<1.5 (1) 14<ν1<27.3 (13-2) -3.9<fp / f2<-1.95 (19-4) -0.23<f2 / f1≦-0.1645 (23-5) A zoom lens that satisfies the conditional expressions (1), (13-2), (19-4), and (23-5) expressed by the following formulas.

2. The distance on the optical axis from the paraxial exit pupil position to the image plane at the wide-angle end when focused on an object at infinity is Dexw. The sign of Dexw is positive if the paraxial exit pupil position is closer to the object side than the image plane, and negative if the paraxial exit pupil position is closer to the image side than the image plane. 0.25<fw / Dexw<1 (2) 2. The zoom lens according to claim 1, which satisfies conditional expression (2) expressed as follows:

3. D1 is the distance on the optical axis from the lens surface of the first lens group closest to the object side to the lens surface of the first lens group closest to the image side, When the sum of the distance on the optical axis from the lens surface of the first lens group closest to the object to the lens surface of the subsequent lens group closest to the image at the telephoto end in a state where the lens is focused on an object at infinity and the back focus in air equivalent distance is denoted as TLt, 0.01<D1 / TLt<0.1 (3) 3. The zoom lens according to claim 1, wherein conditional expression (3) expressed by the following formula is satisfied:

4. The back focus in air equivalent distance at the wide-angle end when focused on an object at infinity is BFw. If the maximum image height at the wide-angle end is Yw, then 0.38<BFw / Yw<1.5 (12) 4. The zoom lens according to claim 1, which satisfies conditional expression (12) expressed as follows:

5. When the refractive index of the lens closest to the object side in the first lens group is N1 with respect to the d-line, 1.7<N1<2.3 (14) 5. The zoom lens according to claim 1, which satisfies conditional expression (14) expressed as follows:

6. 1.7<N1≦1.963 (14-3) 6. The zoom lens according to claim 5, which satisfies conditional expression (14-3) expressed as follows:

7. When the refractive index of the negative lens closest to the object among the negative lenses included in the second lens group is N2n with respect to the d-line, 1.6<N2n<2.2 (15) 7. The zoom lens according to claim 1, which satisfies conditional expression (15) expressed as follows:

8. 1.65<N2n<2.11 (15-1) 8. The zoom lens according to claim 7, which satisfies conditional expression (15-1) expressed as follows:

9. 1.65<N2n≦1.95375 (15-3) 9. The zoom lens according to claim 8, which satisfies conditional expression (15-3) expressed as follows:

10. When the Abbe number of the negative lens element closest to the image side among the negative lenses included in the subsequent lens group is νnL, the Abbe number based on the d-line is 27<νnL<102 (17) 10. The zoom lens according to claim 1, which satisfies conditional expression (17) expressed as follows:

11. The focus group is disposed adjacent to the image side of the fourth lens group.

11. The zoom lens according to claim 1.

12. The focus group is composed of two or less lenses.

12. The zoom lens according to claim 11.

13. The focus group has a negative refractive power.

13. The zoom lens according to claim 11 or 12.

14. -0.19<f2 / f1≦-0.1645 (23-6) 14. The zoom lens according to claim 1, which satisfies conditional expression (23-6) expressed as follows:

15. The lens closest to the image side in the subsequent group has a convex surface facing the image side.

15. The zoom lens according to claim 1.

16. An imaging device comprising the zoom lens according to any one of claims 1 to 15.

Images