Zoom lens and imaging device

Abstract

The present invention provides a compact and lightweight zoom lens that achieves a high magnification ratio, and an imaging device equipped with this zoom lens. [Solution] The zoom lens consists of, 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 multiple lens groups. The second lens group includes an aperture diaphragm on the image side of the lens surface closest to the image, and the lens group closest to the image in the subsequent group includes at least one negative lens whose lens surface on the object side is a concave surface in contact with air. When the zoom is changed, 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 the distance between all adjacent lens groups in the subsequent group changes. The zoom lens satisfies a predetermined conditional equation.

Description

Technical Field

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

Background Art

[0002] As a zoom lens applicable to imaging apparatuses such as digital cameras and video cameras, for example, a lens system described in Patent Document 1 below is known.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

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

[0005] The present disclosure has been made in view of the above circumstances, and an object thereof is to provide a compact and lightweight zoom lens that achieves a high zoom ratio, and an imaging apparatus including this zoom lens.

Means for Solving the Problems

[0006] A first aspect of this 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, wherein the second lens group includes an aperture diaphragm on the image side from the image-side lens surface, and the image-side lens group in the subsequent group includes at least one negative lens whose object-side lens surface is a concave surface in contact with air, and when the magnification is changed, 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 adjacent lens groups in the subsequent group When the spacing changes and magnification occurs, the lens spacing within the first lens group, the second lens group, and multiple lens groups remains constant. If we define fw as the total focal length of the entire system at the wide-angle end when focused on an object at infinity, and Denw as the distance along the optical axis from the lens surface closest to the object in the first lens group to the position of the paraxial entrance pupil at the wide-angle end when focused on an object at infinity, then the sign of Denw is positive if the position of the paraxial entrance pupil is on the image side of the lens surface closest to the object in the first lens group, and negative if the position of the paraxial entrance pupil is on the object side of the lens surface closest to the object in the first lens group, then... 0.7 <fw / Denw<1.5 (1) The condition (1) expressed by is satisfied.

[0007] In the first embodiment described above, when the image is focused on an object at infinity, the distance along the optical axis from the paraxial exit pupil position to the image plane at the wide-angle end is defined as Dexw, and the sign of Dexw is positive if the paraxial exit pupil position is on the object side of the image plane, and negative if the paraxial exit pupil position is on the image side of the image plane. 0.25 <fw / Dexw<1 (2) It is preferable that the condition (2) expressed by is satisfied.

[0008] In the first embodiment described above, if D1 is 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 first lens group, and TLt 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 subsequent lens group, and the back focus in air equivalent distance, then, 0.01 <D1 / TLt<0.1 (3) It is preferable that the condition expressed in equation (3) is satisfied.

[0009] In the first embodiment described above, if the total focal length of the system at the telephoto end when focused on an object at infinity is denoted as ft, 4.9 <ft / fw<12 (4) It is preferable that the condition expressed in equation (4) is satisfied.

[0010] In the first embodiment described above, 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 diaphragm to the image-side lens surface of the Lx lens, when the aperture diaphragm is in focus on an object at infinity, if the absolute value of the reciprocal of the lateral magnification at the wide-angle end is minimized, then the lateral magnification of optical system A is βA. -0.5 < 1 / βA < 0.5 (5) It is preferable that the condition (5) expressed by is satisfied.

[0011] In the first embodiment described above, when the telephoto end is focused on an object at infinity, let HAt be the height of the axial marginal rays from the optical axis at the image-side lens surface of optical system A, and let HSt be the height of the axial marginal rays from the optical axis at the aperture diaphragm at the telephoto end is focused on an object at infinity. 0.73 <HAt / HSt<2.3 (6) It is preferable that the condition expressed in equation (6) is satisfied.

[0012] In the first embodiment described above, if the total focal length of the entire system at the telephoto end when focused on an object at infinity is ft, and the combined focal length from the lens surface closest to the object in the trailing group to the lens surface closest to the image in optical system A at the telephoto end when focused on an object at infinity is fpAt, 3 <ft / fpAt<15 (7) It is preferable that the condition (7) expressed by is satisfied.

[0013] In the first aspect described above, when the height from the optical axis of an axial marginal ray on the most image-side lens surface of the A optical system at the telephoto end in a state focused on an infinite-distance object is defined as HAt, and the height from the optical axis of a principal ray of the maximum image height on the most image-side lens surface of the A optical system at the wide-angle end in a state focused on an infinite-distance object is defined as HAw, 0.35<HAt / HAw<1.6 (8) It is preferable to satisfy the conditional expression (8) represented by

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

[0015] In the first aspect described above, when the distance on the optical axis from the aperture stop to the most image-side lens surface of the A optical system at the telephoto end in a state focused on an infinite-distance object is defined as DSAt, and the sum of the distance on the optical axis from the aperture stop to the most image-side lens surface of the subsequent group at the telephoto end in a state focused on an infinite-distance object and the back focus in terms of air-equivalent distance is defined as DSLt, 0.1<DSAt / DSLt<0.54 (9) It is preferable to satisfy the conditional expression (9) represented by

[0016] In the first aspect described above, when the distance on the optical axis between the most image-side lens surface of the A optical system and the lens surface adjacent to the image side of said lens surface at the telephoto end in a state focused on an infinite-distance object is defined as dA, and the maximum image height at the telephoto end is defined as Yt, 0.015<dA / Yt<0.35 (10) It is preferable to satisfy the conditional expression (10) represented by

[0017] In the first aspect described above, let TLt be the sum of the distance on the optical axis from the most object-side lens surface of the first lens group to the most image-side lens surface of the subsequent group at the telephoto end in a state focused on an infinitely distant object, and the back focus in terms of air-equivalent distance, and let ft be the focal length of the entire system at the telephoto end in a state focused on an infinitely distant object, 0.65<TLt / ft<1.5 (11) It is preferable to satisfy the conditional expression (11) represented by

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

[0019] In the first aspect described above, let BFw be the back focus in terms of air-equivalent distance at the wide-angle end in a state focused on an infinitely distant object, and Yw be the maximum image height at the wide-angle end, 0.38<BFw / Yw<1.5 (12) It is preferable to satisfy the conditional expression (12) represented by

[0020] In the first aspect described above, let ν1 be the Abbe number based on the d-line of the most object-side lens in the first lens group, 10<ν1<50 (13) It is preferable to satisfy the conditional expression (13) represented by

[0021] In the first aspect described above, let N1 be the refractive index for the d-line of the most object-side lens in the first lens group, 1.7<N1<2.3 (14) It is preferable to satisfy the conditional expression (14) represented by

[0022] In the first aspect described above, let N2n be the refractive index for the d-line of the most object-side negative lens among the negative lenses included in the second lens group, 1.6<N2n<2.2 (15) It is preferable to satisfy the conditional expression (15) represented by

[0023] In the first embodiment described above, if N2p is the refractive index of the positive lens with the strongest refractive power among the positive lenses included in the second lens group with respect to the d line, 1.65 <N2p<2 (16) It is preferable that the conditional expression (16) represented by is satisfied.

[0024] In the first embodiment described above, if the Abbe number of the negative lens closest to the image line among the negative lenses included in the successor group is νnL, 27<νnL<102 (17) It is preferable that the conditional expression (17) represented by is satisfied.

[0025] In the first embodiment described above, the subsequent group preferably includes at least one lens group having a positive refractive power.

[0026] In the first embodiment described above, when the lens is in focus on an object at infinity, TLt 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 subsequent lens group, and the back focus in air equivalent distance. When the lens is in focus on an object at infinity, Mp is 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 positive refractive power lenses included in the subsequent lens group. The sign of Mp is positive if the lens group closest to the object moves from the object side to the image side when the zoom is changed 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 that the conditional expression (18) represented by is satisfied.

[0027] In the first embodiment described above, when the lens is in focus on an object at infinity, if the focal length of the lens group closest to the object among the positive refractive power lenses included in the subsequent group is fp, and the focal length of the second lens group is f2, -4.3 <fp / f2<-1.1 (19) It is preferable that the condition expressed in equation (19) is satisfied.

[0028] In the first embodiment described above, when the lens is in focus on an object at infinity, D1pt is the distance along the optical axis from the image-side lens surface of the first lens group to the object-side lens surface of the object-side lens group among the positive refractive power lens groups included in the subsequent group at the telephoto end, and TLt is 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 subsequent group at the telephoto end when the lens is in focus on an object at infinity, and the back focus in air equivalent distance. 0.2 <D1pt / TLt<0.5 (20) It is preferable that the conditional expression (20) represented by is satisfied.

[0029] In the first embodiment described above, the subsequent group includes at least one Lx lens whose image-side lens surface is a convex surface in contact with air, and the optical system A is defined as the optical system that minimizes the absolute value of the reciprocal of the lateral magnification at the wide-angle end when the aperture diaphragm is the object point, among the at least one optical system formed from the lens surface adjacent to the image side of the aperture diaphragm to the image-side lens surface of the subsequent group, when the lens is in focus on an object at infinity, and the combined focal length at the wide-angle end when the lens is in focus on an object at infinity is denoted as fBw, -1.6 <fw / fBw<-0.25 (21) It is preferable that the conditional expression (21) represented by is satisfied.

[0030] In the first embodiment described above, when the image is in focus on an object at infinity, if the maximum half-angle at the wide-angle end 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 that the conditional expression (22) represented by is satisfied.

[0031] In the first embodiment described above, the subsequent group preferably includes a focus group that moves along the optical axis when focusing occurs.

[0032] In the first embodiment described above, the focus group preferably consists of two or fewer lenses.

[0033] In the first embodiment described above, the focus group preferably has a negative refractive power.

[0034] In the first embodiment described above, 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 that the conditional expression (23) represented by is satisfied.

[0035] A second aspect of this disclosure is an imaging device comprising a zoom lens according to the first aspect described above.

[0036] In this specification, the terms "~consisting of" and "~consisting of" 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.

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

[0038] In this specification, "first lens group," "second lens group," and "multiple lens groups" refer to components of a zoom lens, each containing at least one lens, separated by the air gap that changes during magnification. During magnification, the lens groups are moved or fixed in units, and the inter-lens spacing within a single lens group does not change. In other words, in this specification, a lens group is defined as a group in which the spacing between adjacent groups changes during magnification, but the total spacing between adjacent lenses within itself does not change. A "~lens group" is not limited to a configuration consisting of multiple lenses, but may also consist of only one lens.

[0039] A "single lens" refers to a single, unbonded lens. However, 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 bonded lens and is treated as a single lens. For lenses including aspherical surfaces, the sign of the refractive power and the surface shape will be considered in the paraxial region unless otherwise specified.

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

[0041] The values ​​used in the conditional equations are those with the d-line as the reference when the object is in focus at infinity. The "d-line," "C-line," and "F-line" described herein 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 as 656.27 nm (nanometers), and the wavelength of the F-line as 486.13 nm (nanometers). [Effects of the Invention]

[0042] According to this disclosure, it is possible to provide a compact and lightweight zoom lens that achieves a high magnification ratio, and an imaging device equipped with this zoom lens. [Brief explanation of the drawing]

[0043] [Figure 1] This figure shows the cross-sectional configuration and movement trajectory of a zoom lens according to one embodiment, corresponding to the zoom lens of Example 1. [Figure 2] This figure shows the cross-sectional configuration and light beam of the zoom lens shown in Figure 1. [Figure 3] This diagram explains the symbols used in each conditional expression. [Figure 4]This diagram explains the symbols used in each conditional expression. [Figure 5] These are aberration diagrams of the zoom lens of Example 1. [Figure 6] This figure shows the cross-sectional configuration and movement trajectory of the zoom lens in Example 2. [Figure 7] These are aberration diagrams for the zoom lens of Example 2. [Figure 8] This figure shows the cross-sectional configuration and movement trajectory of the zoom lens in Example 3. [Figure 9] These are aberration diagrams for the zoom lens of Example 3. [Figure 10] This figure shows the cross-sectional configuration and movement trajectory of the zoom lens of Example 4. [Figure 11] These are aberration diagrams for the zoom lens of Example 4. [Figure 12] This figure shows the cross-sectional configuration and movement trajectory of the zoom lens in Example 5. [Figure 13] These are aberration diagrams for the zoom lens of Example 5. [Figure 14] This figure shows the cross-sectional configuration and movement trajectory of the zoom lens of Example 6. [Figure 15] These are aberration diagrams for the zoom lens of Example 6. [Figure 16] This figure shows the cross-sectional configuration and movement trajectory of the zoom lens in Example 7. [Figure 17] These are aberration diagrams for the zoom lens of Example 7. [Figure 18] This figure shows the cross-sectional configuration and movement trajectory of the zoom lens of Example 8. [Figure 19] These are aberration diagrams for the zoom lens of Example 8. [Figure 20] This is a front perspective view of an imaging device according to one embodiment. [Figure 21] This is a perspective view of the rear side of an imaging device according to one embodiment. [Modes for carrying out the invention]

[0044] Embodiments of the present disclosure will be described below with reference to the drawings. Figure 1 is a cross-sectional view and movement trajectory of the configuration 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. Figure 2 is a cross-sectional view showing the configuration and light beam of the zoom lens of Figure 1 in each magnification state. In Figure 2, the top section labeled "WIDE" shows the wide-angle end state, the middle section labeled "MIDDLE" shows the intermediate focal length state, and the lower section labeled "TELE" shows the telephoto end state. In Figure 2, the light beams are shown as the axial light beam wa and the light beam wb at the wide-angle end state, the axial light beam ma and the light beam mb at the intermediate focal length state, and the axial light beam ta and the light beam tb at the telephoto end state. 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.

[0045] The zoom lens according to this embodiment 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, and a subsequent group Gr having multiple lens groups. As an example in Figure 1, the subsequent group Gr consists of 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 Figure 1, the first lens group G1 consists of three lenses, L11 to L13, arranged from the object side to the image side. The second lens group G2 consists of four lenses, L21 to L24, arranged from the object side to the image side. The third lens group G3 consists of six lenses, the aperture diaphragm St and L31 to L36, arranged from the object side to the image side. The fourth lens group G4 consists of four lenses, L41 to L44, arranged from the object side to the image side. The fifth lens group G5 consists of two lenses, L51 to L52, arranged from the object side to the image side. The sixth lens group G6 consists of one lens, L61.

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

[0048] In the zoom lens according to this embodiment, when the zoom 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 group Gr changes, and the distance between all adjacent lens groups within the subsequent group Gr changes. However, when the zoom is changed, the distance between lenses within the multiple lens groups included in the first lens group G1, the second lens group G2, and the subsequent group Gr remains constant. In other words, in the zoom lens according to this embodiment, the distance between all adjacent lens groups changes relative to each other, while the distance between lenses within each lens group remains constant. In Figure 1, 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 zooming from the wide-angle end to the telephoto end are shown by arrows between the upper and lower sections.

[0049] As described above, the zoom lens consists of a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, and a subsequent group Gr having multiple lens groups, arranged in order from the object side to the image side. The aperture diaphragm St is located on the image side of the second lens group G2, and when the magnification is changed, the spacing between all 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 magnification ratio.

[0050] The image-side lens group within the subsequent group Gr includes at least one negative lens, where the object-side lens surface is a concave surface in contact with air. Including at least one negative lens, where the object-side lens surface is a concave surface in contact with air, within the image-side lens group within the subsequent group Gr is advantageous for shortening the overall length of the lens system. As an example, Figure 1 shows that the sixth lens group G6, which is the image-side lens group within the subsequent group Gr, includes a lens L61 with a negative refractive power, where the object-side lens surface is a concave surface in contact with air.

[0051] The first lens group G1 preferably includes a negative lens and a positive lens in a continuous sequence from the object side to the image side. This configuration is advantageous for suppressing lateral chromatic aberration at the wide-angle end and axial chromatic aberration at the telephoto end. As an example, Figure 1 shows that the first lens group G1 includes a lens L11 with negative refractive power and a lens L12 with positive refractive power, in a continuous sequence from the object side to the image side.

[0052] The subsequent lens group Gr preferably includes at least one lens group having positive refractive power. Including at least one lens group having positive refractive power in the subsequent lens group Gr is advantageous for achieving a high magnification ratio. As an example, Figure 1 shows that the subsequent lens group Gr includes two lens groups having positive refractive power, namely the third lens group G3 and the fourth lens group G4.

[0053] The subsequent lens group Gr preferably includes a focus group that moves along the optical axis Z during focusing. Here, the focus group consists 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 lens group Gr is advantageous in suppressing variations in aberrations that occur during focusing. The rightward arrows written below lenses L51~L52 in Figure 1 indicate that lenses L51~L52 are a focus group that moves toward the image side when focusing from an object at infinity to an object at close range.

[0054] The focusing group preferably consists of two or fewer lenses. Having two or fewer lenses in the focusing group is advantageous for reducing its weight. Furthermore, it is preferable that the focusing group has negative refractive power. Having negative refractive power in the focusing group is advantageous for reducing the amount of movement of the focusing group during focusing.

[0055] In this embodiment, the zoom lens preferably satisfies the following condition (1) when the total focal length of the system at the wide-angle end when focused on an object at infinity is fw, and the distance on the optical axis Z from the lens surface closest to the object of the first lens group G1 to the paraxial entrance pupil position Penw at the wide-angle end when focused on an object at infinity is Denw. Here, the sign of Denw is positive if the paraxial entrance pupil position Penw is on the image side of the lens surface closest to the object of the first lens group G1, and negative if the paraxial entrance pupil position Penw is on the object side of the lens surface closest to the object of the first lens group G1. Figure 3 is a cross-sectional view showing the configuration and light beam corresponding to the zoom lens at the wide-angle end of Figures 1 and 2, and shows the paraxial entrance pupil position Penw and the distance Denw as an example.

[0056] By ensuring that the corresponding value in condition (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. This allows the height from the optical axis Z when off-axis rays pass through the first lens group G1 to be reduced, suppressing the enlargement of the first lens group G1, which is advantageous for miniaturizing and lightening the first lens group G1. By ensuring that the corresponding value in condition (1) does not exceed the upper limit, rays at each image height are appropriately separated in the first lens group G1, which is advantageous for correcting chromatic aberration. To obtain even better characteristics, it is more preferable to satisfy the following condition (1-1), and even more preferable to satisfy the following condition (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 this embodiment, the zoom lens preferably satisfies the following condition (2), where fw is the total focal length of the 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 on the object side of the image plane Sim, and negative if the paraxial exit pupil position Pexw is on the image side of the image plane Sim. Figure 3 shows the paraxial exit pupil position Pexw and distance Dexw as an example. By ensuring that the corresponding value of condition (2) does not fall below the lower limit, the total length of the lens system can be shortened, which is advantageous for miniaturization. By ensuring that the corresponding value of condition (2) does not exceed the upper limit, the incident angle of off-axis rays on the image plane Sim can be reduced, which is advantageous for securing peripheral light. To obtain better characteristics, it is more preferable to satisfy the following condition (2-1), and even more preferable to satisfy the following condition (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 this embodiment, the zoom lens preferably satisfies the following condition (3), where D1 is the distance along the optical axis Z from the object-side lens surface of the first lens group G1 to the image-side lens surface of the first lens group G1, and TLt is the sum of the distance along the optical axis Z from the object-side lens surface of the first lens group G1 to the image-side lens surface of the subsequent group Gr at the telephoto end when focused on an object at infinity, and the back focus in air equivalent distance. The lower part of Figure 1 shows an example of distance D1 and sum TLt. By ensuring that the corresponding value of condition (3) does not fall below the lower limit, it is advantageous to suppress axial chromatic aberration at the telephoto end. By ensuring that the corresponding value of condition (3) does not exceed the upper limit, the first lens group G1 can be made lighter, which is advantageous to lighten the entire lens system. To obtain even better characteristics, it is more preferable to satisfy the following condition (3-1), and even more preferable to satisfy the following condition (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 this embodiment, when the zoom lens has a total focal length of fw at the wide-angle end when focused on an object at infinity, and a total focal length of ft at the telephoto end when focused on an object at infinity, it is preferable that the following conditional equation (4) is satisfied. By ensuring that the corresponding value of conditional equation (4) does not fall below the lower limit, it is advantageous to increase the magnification ratio. By ensuring that the corresponding value of conditional equation (4) does not exceed the upper limit, the magnification ratio does not become too high, which is advantageous for miniaturizing the entire lens system. To obtain even better characteristics, it is more preferable to satisfy the following conditional equation (4-1), and even more preferable to satisfy the following conditional equation (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 includes at least one Lx lens whose image-side lens surface is a convex surface in contact with air. Of the at least one optical system formed from the lens surface adjacent to the image side of the aperture diaphragm St to the image-side lens surface of the Lx lens, it is preferable that the following condition (5) is satisfied when βA is the lateral magnification of optical system A that minimizes the absolute value of the reciprocal of the lateral magnification at the wide-angle end when the aperture diaphragm St is the object point in a state of focus on an object at infinity. That is, when βx is the lateral magnification of each optical system formed from the lens surface adjacent to the image side of the aperture diaphragm St to the image-side lens surface of each Lx lens, the optical system that minimizes |1 / βx| is "optical system A", and it is preferable that the lateral magnification βA of optical system A satisfies condition (5). Furthermore, the image-side lens surface of the Lx lens in optical system A (i.e., the convex surface in contact with air) is hereinafter referred to as "surface A".

[0061] For example, in the zoom lens shown in Figure 1, the Lx lenses included in the subsequent group Gr, whose image-side lens surface is a convex surface in contact with air, are the six 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 the aperture diaphragm St to the image-side lens surface of each of the above Lx lenses, the optical system that minimizes |1 / βx| 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, "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 as shown in Figures 1 and 3, surface A is the image-side lens surface of lens L44.

[0062] By ensuring that the corresponding value in condition (5) does not fall below the lower limit, the decrease in the angle between the principal ray of the off-axis light beam passing through A-plane A and the optical axis Z can be suppressed, and excessive correction of astigmatism occurring between A-plane A and the image plane Sim can be suppressed. By ensuring that the corresponding value in condition (5) does not exceed the upper limit, the increase in the angle between the principal ray of the off-axis light beam passing through A-plane A and the optical axis Z can be suppressed, which is advantageous for correcting astigmatism occurring between A-plane A and the image plane Sim. To obtain better characteristics, it is more preferable to satisfy the following condition (5-1), and even more preferable to satisfy the following condition (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 this embodiment, when the zoom lens is in focus on an object at infinity, it is preferable to satisfy the following condition (6), where HAt is the height of the on-axial marginal ray from the optical axis Z at the image-side lens surface (i.e., surface A) of the A optical system, and HSt is the height of the on-axial marginal ray from the optical axis Z at the aperture diaphragm St, when the zoom lens is in focus on an object at infinity. Figure 4 is a partial cross-sectional view showing the configuration and on-axial light beam ta corresponding to the zoom lens in the telephoto end state of Figures 1 and 2, and shows heights HAt and HSt as an example. By ensuring that the corresponding value of condition (6) does not fall below the lower limit, it is advantageous to suppress spherical aberration at the telephoto end. By ensuring that the corresponding value of condition (6) does not exceed the upper limit, it is possible to suppress the increase in diameter of the subsequent group Gr, which is advantageous for weight reduction. To obtain better characteristics, it is more preferable to satisfy the following condition (6-1), and even more preferable to satisfy the following condition (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 this embodiment, when the zoom lens is focused on an object at infinity, the total focal length of the entire system at the telephoto end is ft, and the combined focal length from the lens surface closest to the object in the subsequent group Gr to the lens surface closest to the image in the A optical system (i.e., surface A) at the telephoto end is fpAt, it is preferable that the following condition (7) is satisfied. By ensuring that the corresponding value of condition (7) does not fall below the lower limit, it is advantageous to secure peripheral illumination. By ensuring that the corresponding value of condition (7) does not exceed the upper limit, it is advantageous to suppress spherical aberration at the telephoto end. To obtain even better characteristics, it is more preferable to satisfy the following condition (7-1), and even more preferable to satisfy the following condition (7-2). 3 <ft / fpAt<15 (7) 4.5 <ft / fpAt<12 (7-1) 5.7 <ft / fpAt<9 (7-2)

[0065] In this embodiment, when the zoom lens is focused on an object at infinity, it is preferable to satisfy the following condition (8), where HAt is the height of the on-axial marginal ray from the optical axis Z at the image-side lens surface (i.e., surface A) of the A optical system, and HAw is the height of the principal ray of the maximum image height at the image-side lens surface (i.e., surface A) of the A optical system, when it is focused on an object at infinity, and HAw is the height of the principal ray from the optical axis Z at the image-side lens surface (i.e., surface A) of the A optical system, when it is focused on an object at infinity. Figure 3 shows an example of height HAw. By ensuring that the corresponding value of condition (8) does not fall below the lower limit, it is advantageous to suppress astigmatism at the wide-angle end. By ensuring that the corresponding value of condition (8) does not exceed the upper limit, it is advantageous to suppress fluctuations in field curvature during magnification. To obtain even better characteristics, it is more preferable to satisfy the following condition (8-1), and even more preferable to satisfy the following condition (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] The subsequent lens group Gr preferably includes a concave lens surface that is in contact with air, located between the image-side lens surface (i.e., surface A) of the A optical system and the object-side lens surface (a concave surface in contact with air) included in the image-side lens group G6 of the subsequent lens group Gr. This configuration is advantageous for suppressing astigmatism at the wide-angle end while maintaining the overall miniaturization of the lens system. In the example in Figure 1, the image-side lens surface of lens L52 (a concave surface in contact with air) is located between the image-side lens surface of lens L44 (i.e., surface A) of the A optical system and the object-side lens surface of lens L61 (a concave surface in contact with air) included in the sixth lens group G6, the image-side lens group Gr.

[0067] In this embodiment, when the zoom lens is in focus on an object at infinity, the distance on the optical axis Z from the aperture diaphragm St to the image-side lens surface of the A optical system (i.e., surface A) is denoted as DSAt, and when the zoom lens is in focus on an object at infinity, the sum of the distance on the optical axis Z from the aperture diaphragm St to the image-side lens surface of the subsequent lens group Gr and the back focus in air equivalent distance is denoted as DSLt. The lower part of Figure 1 shows the distance DSAt and the sum DSLt as an example. By ensuring that the corresponding value of condition (9) does not fall below the lower limit, the refraction of off-axis rays from surface A to the image plane Sim can be made gentler, which is advantageous in suppressing the occurrence of various off-axis aberrations. By ensuring that the corresponding value of condition (9) does not exceed the upper limit, the diameter of the optical beam on the image side of the aperture diaphragm St can be made smaller, which is advantageous in reducing the diameter of the subsequent lens group Gr. To obtain better characteristics, it is more preferable to satisfy the following condition (9-1), and even more preferable to satisfy the following condition (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 this embodiment, when the zoom lens is in focus on an object at infinity, it is preferable to satisfy the following condition (10) when the distance on the optical axis Z between the image-side lens surface (i.e., surface A) of the A optical system and the lens surface adjacent to the image-side of said lens surface (i.e., surface A) is dA, and the maximum image height at the telephoto end is Yt. The lower part of Figure 1 shows an example of the distance dA, and the lower part of Figure 2 shows an example of the maximum image height Yt. By ensuring that the corresponding value of condition (10) does not fall below the lower limit, it is advantageous to miniaturize the entire lens system. By ensuring that the corresponding value of condition (10) does not exceed the upper limit, it is advantageous to suppress spherical aberration at the telephoto end. To obtain even better characteristics, it is more preferable to satisfy the following condition (10-1), and even more preferable to satisfy the following condition (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 this embodiment, when the zoom lens is in focus on an object at infinity, it is preferable to satisfy the following condition (11), where TLt is the sum of the distance along the optical axis Z from the lens surface closest to the object of the first lens group G1 to the lens surface closest to the image of the subsequent lens group Gr, and the back focus in air equivalent distance, and ft is the focal length of the entire system at the telephoto end when in focus on an object at infinity. By ensuring that the corresponding value of condition (11) does not fall below the lower limit, it is advantageous to suppress axial chromatic aberration at the telephoto end. By ensuring that the corresponding value of condition (11) does not exceed the upper limit, it is advantageous to shorten the overall length of the lens system, which is advantageous for miniaturization. To obtain even better characteristics, it is more preferable to satisfy the following condition (11-1), and even more preferable to satisfy the following condition (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 this embodiment, when the zoom lens is in focus on an object at infinity, it is preferable that the following condition (12) is satisfied, where BFw is the air-equivalent back focus at the wide-angle end and Yw is the maximum image height at the wide-angle end. Ensuring that the corresponding value of condition (12) does not fall below the lower limit is advantageous for securing peripheral illumination. Ensuring that the corresponding value of condition (12) does not exceed the upper limit is advantageous for shortening the overall length of the lens system and for miniaturization. To obtain even better characteristics, it is more preferable to satisfy the following condition (12-1), and even more preferable to satisfy the following condition (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 ν1 is the Abbe number of the lens closest to the object in the first lens group G1, relative to the d line, it is preferable that the following condition (13) is satisfied. By ensuring that the corresponding value of condition (13) does not fall below the lower limit, it is possible to suppress overcorrection of axial chromatic aberration. By ensuring that the corresponding value of condition (13) does not exceed the upper limit, it is advantageous for correcting axial chromatic aberration. To obtain even better characteristics, it is more preferable to satisfy the following condition (13-1), and even more preferable to satisfy the following condition (13-2). In the example in Figure 1, lens L11 satisfies condition (13). 10 < ν1 < 50 (13) 12 < ν1 < 40 (13-1) 14 < ν1 < 27.3 (13-2)

[0072] When N1 is the refractive index of the lens closest to the object in the first lens group G1 with respect to the d line, it is preferable that the following condition (14) is satisfied. By ensuring that the corresponding value of condition (14) does not fall below the lower limit, it is advantageous to suppress astigmatism. By ensuring that the corresponding value of condition (14) does not exceed the upper limit, the availability of lens materials is improved, and materials that are easier to manufacture can be used. To obtain even better characteristics, it is more preferable to satisfy the following condition (14-1), and even more preferable to satisfy the following condition (14-2). In the example in Figure 1, lens L11 satisfies condition (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 is N2n, it is preferable that the following condition (15) is satisfied. By ensuring that the corresponding value of condition (15) does not fall below the lower limit, refractive power can be secured without making the absolute value of the radius of curvature of the negative lens too small, thus preventing the negative lens from becoming bulky in the optical axis direction, which is advantageous for weight reduction. By ensuring that the corresponding value of condition (15) does not exceed the upper limit, the availability of lens materials is improved, and materials that are easier to manufacture can be used. To obtain even better characteristics, it is more preferable to satisfy the following condition (15-1), and even more preferable to satisfy the following condition (15-2). In the example in Figure 1, lens L21 satisfies condition (15). 1.6 <N2n<2.2 (15) 1.65 <N2n<2.11 (15-1) 1.7 <N2n<2.05 (15-2)

[0074] When N2p is the refractive index of the positive lens with the strongest refractive power among the positive lenses included in the second lens group G2 with respect to the d line, it is preferable that the following condition (16) is satisfied. By ensuring that the corresponding value of condition (16) does not fall below the lower limit, it is advantageous to suppress astigmatism. By ensuring that the corresponding value of condition (16) does not exceed the upper limit, the availability of lens materials is improved, and materials that are easier to manufacture can be used. To obtain even better characteristics, it is more preferable to satisfy the following condition (16-1), and even more preferable to satisfy the following condition (16-2). In the example in Figure 1, lens L23 satisfies condition (16). 1.65 <N2p<2 (16) 1.71 <N2p<1.93 (16-1) 1.77 <N2p<1.9 (16-2)

[0075] When the Abbe number of the negative lens closest to the image line among the negative lenses included in the subsequent group Gr is νnL, it is preferable that the following condition (17) is satisfied. By ensuring that the corresponding value of condition (17) does not fall below the lower limit, it is advantageous to suppress lateral chromatic aberration. By ensuring that the corresponding value of condition (17) does not exceed the upper limit, it is possible to suppress overcorrection of lateral chromatic aberration. To obtain even better characteristics, it is more preferable to satisfy the following condition (17-1), and even more preferable to satisfy the following condition (17-2). In the example in Figure 1, lens L61 satisfies condition (17). 27<νnL<102 (17) 50 < νnL < 96 (17-1) 70 < νnL < 88 (17-2)

[0076] In this embodiment, when the zoom lens is in focus on an object at infinity, TLt is the sum of the distance along 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, and the back focus in air equivalent distance. When the zoom lens is in focus on an object at infinity, Mp is 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 lens group closest to the object among the positive refractive power lenses included in the subsequent lens group Gr. It is preferable that the following conditional equation (18) is satisfied. 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 the zoom is changed 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 equation (18) does not fall below the lower limit, the absolute value of Mp does not become too large, which suppresses the large amount of movement of the lens group closest to the object among the positive refractive power lenses included in the subsequent lens group Gr when the zoom is changed, and is advantageous for miniaturization. By ensuring that the corresponding value in condition (18) does not exceed the upper limit, the absolute value of Mp does not become too small, which is advantageous for achieving a high magnification ratio. To obtain even better characteristics, it is more preferable to satisfy the following condition (18-1), and even more preferable to satisfy the following condition (18-2). In the example in Figure 1, for the third lens group G3, which is the lens group closest to the object among the positive refractive power lens groups included in the subsequent group Gr, condition (18) is satisfied when Mp is the difference in the optical axis Z direction between the position at the wide-angle end and the position at the telephoto end. -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 this embodiment, when the zoom lens is in focus on an object at infinity, it is preferable that the following condition (19) is satisfied when the focal length of the lens group closest to the object among the positive refractive power lenses included in the subsequent group Gr is fp, and the focal length of the second lens group G2 is f2. By ensuring that the corresponding value of condition (19) does not fall below the lower limit, the absolute value of f2 does not become too small, which is advantageous in suppressing fluctuations in various aberrations that occur during magnification. By ensuring that the corresponding value of condition (19) does not exceed the upper limit, the absolute value of f2 does not become too large, which is advantageous in shortening the second lens group G2, and is advantageous in miniaturization. To obtain even better characteristics, it is more preferable to satisfy the following condition (19-1), and even more preferable to satisfy the following condition (19-2). In the example in Figure 1, when the focal length of the third lens group G3, which is the lens group closest to the object among the positive refractive power lenses included in the subsequent group Gr, is fp, condition (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 this embodiment, when the zoom lens is in focus on an object at infinity, at the telephoto end, the distance along the optical axis Z from the image-side lens surface of the first lens group G1 to the object-side lens surface of the object-side lens group among the positive refractive power lens groups included in the subsequent group Gr is D1pt, and when the zoom lens is in focus on an object at infinity, at the telephoto end, the sum of the distance along the optical axis Z from the object-side lens surface of the first lens group G1 to the image-side lens surface of the subsequent group Gr to TLt is the back focus in air equivalent distance. The lower part of Figure 1 shows an example of the distance D1pt and the sum TLt. By ensuring that the corresponding value of condition (20) does not fall below the lower limit, it is advantageous to shorten the overall length of the lens system. By ensuring that the corresponding value of condition (20) does not exceed the upper limit, it is advantageous to suppress spherical aberration at the telephoto end. To obtain better characteristics, it is more preferable to satisfy the following condition (20-1), and even more preferable to satisfy the following condition (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, if the subsequent group Gr includes at least one Lx lens whose image-side lens surface is a convex surface in contact with air, then optical system A is defined as the optical system among at least one optical system formed from the lens surface adjacent to the image side of the aperture diaphragm St to the image-side lens surface of the Lx lens, which minimizes the absolute value of the reciprocal of the lateral magnification at the wide-angle end when the aperture diaphragm St is the object point when the lens is in focus on an object at infinity. In this embodiment, when the zoom lens is in focus on an object at infinity, the total focal length of the system at the wide-angle end is fw, and the combined focal length at the wide-angle end when the lens is in focus on an object at infinity is fBw, then it is preferable that the following conditional equation (21) is satisfied. By ensuring that the corresponding value of conditional equation (21) does not fall below the lower limit, it is advantageous to suppress astigmatism at the wide-angle end. By ensuring that the corresponding value in condition (21) does not exceed 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 the subsequent group Gr can be strengthened, thereby reducing the optical beam diameter from the lens surface closest to the object in the subsequent group Gr to surface A, which is advantageous for miniaturization. To obtain even better characteristics, it is more preferable to satisfy the following condition (21-1), and even more preferable to satisfy the following condition (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 this embodiment, when the zoom lens is in focus on an object at infinity, the total focal length of the system at the wide-angle end is fw, the maximum half-angle of view at the wide-angle end is ωw, and the maximum image height at the wide-angle end is Yw, it is preferable that the following conditional equation (22) is satisfied. By ensuring that the corresponding value of conditional equation (22) does not fall below the lower limit, the height of the off-axis rays passing through the lens closest to the object in the first lens group G1 from the optical axis Z can be reduced at the wide-angle end, which is advantageous for reducing the diameter. By ensuring that the corresponding value of conditional equation (22) does not exceed the upper limit, it is advantageous for suppressing various aberrations of off-axis rays at the wide-angle end. To obtain even better characteristics, it is more preferable to satisfy the following conditional equation (22-1), and even more preferable to satisfy the following conditional equation (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 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 equation (23) is satisfied. By ensuring that the corresponding value of conditional equation (23) does not fall below the lower limit, it is advantageous to achieve a high magnification ratio. By ensuring that the corresponding value of conditional equation (23) does not exceed the upper limit, it is advantageous to suppress fluctuations in various aberrations that occur during magnification. To obtain even better characteristics, it is more preferable to satisfy the following conditional equation (23-1), and even more preferable to satisfy the following conditional equation (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 preferred and possible configurations described above, including the configurations related to the conditional expressions, can be combined in any way and are preferably selected as appropriate according to the required specifications. The preferred conditional expressions that the zoom lens of this disclosure satisfies are not limited to those described in formula form, but include all conditional expressions obtained by arbitrarily combining the lower and upper limits from the preferred, more preferred, and even more preferred conditional expressions. Furthermore, the example shown in Figure 1 is just one example, and various modifications are possible without departing from the spirit of the technology of this disclosure. For example, the number of lenses constituting each lens group may be different from the example in Figure 1.

[0083] As an example, a preferred embodiment 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 group Gr having a plurality of lens groups, wherein the second lens group G2 includes an aperture diaphragm St on the image side from the image-side lens surface, and the image-side lens group in the subsequent group Gr includes at least one negative lens whose object-side lens surface is a concave surface in contact with air, and 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 group Gr changes, and the distances between all adjacent lens groups in the subsequent group Gr change, and when the magnification is changed, the lens spacings within the first lens group G1, the second lens group G2 and the plurality of lens groups remain unchanged, satisfying the above condition (1).

[0084] Next, embodiments of the zoom lens of this disclosure will be described with reference to the drawings. Note that the reference numerals attached to the lenses in the cross-sectional views of each embodiment are used independently for each embodiment to avoid increasing the number of digits in the reference numerals and to avoid complexity in the explanation and drawings. Therefore, even if the same reference numerals are used in drawings of different embodiments, the configuration is not necessarily the same. Furthermore, embodiments 4 and 6 below are embodiments of this disclosure, while embodiments 1-3, 5, and 7-8 are reference examples of this disclosure.

[0085] [Example 1] The configuration and movement trajectory of the zoom lens in 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. For the zoom lens in Example 1, the basic lens data is shown in Table 1, the specifications and variable plane spacing are shown in Table 2, and the aspherical coefficient is shown in Table 3.

[0086] Table 1 is described as follows: The Sn column shows the surface numbers, with the surface closest to the object designated as the first surface and the numbers increasing by one as you move toward 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 adjacent surface 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. Table 1 also shows the aperture diaphragm St, and the column for the surface number corresponding to the aperture diaphragm St shows the surface number and the phrase (St). Similarly, the column for the surface number corresponding to the A surface A above shows the surface number and the phrase (A). In Table 1, the sign of the radius of curvature of a surface with a convex shape facing the object side is positive, and the sign of the radius of curvature of a surface with a convex shape facing the image side is negative. In Table 1, the variable interplanar spacing during magnification is represented by the symbol DD[ ], and the surface number on the object side for this spacing is placed inside the [ ] and listed in column D.

[0087] Table 2 shows the zoom magnification Zr, the total focal length f, the back focus BF, the F-number FNo., the maximum angle of view 2ω, and the variable plane spacing during 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 the lens is in focus on an object at infinity. In Table 2, the values ​​for the wide-angle end, intermediate focal length, and telephoto end are shown in the columns labeled WIDE, MIDDLE, and TELE, respectively.

[0088] In Table 1, the aspherical surface numbers are marked with an asterisk (*), and the column for the radius of curvature of the aspherical surface shows the value of the paraxial radius of curvature. In Table 3, the row for Sn shows the aspherical surface number, and the rows for KA and Am (where m is an integer greater than or equal to 3) show the numerical value of the aspherical coefficient for each aspherical surface. In Table 3, the numerical value of the aspherical coefficient "E±n" (where n is an integer) is "×10 ±nThis means "[...]. KA and Am are the aspheric coefficients in the aspheric equation expressed by the following formula. Zd = C × h 2 / {1+(1-KA×C 2 ×h 2 ) 1 / 2}+ΣAm×h m however, Zd: Aspherical depth (length of the perpendicular line drawn from a point on the aspherical surface at height h to a plane perpendicular to the optical axis to which the aspherical vertex is tangent). h: Height (distance from the optical axis to the lens surface) C: Reciprocal of the radius of paraxial curvature KA, Am: Aspherical coefficients Therefore, the Σ in aspherical formulas represents the summation with respect to m.

[0089] In the data in each table, degrees are used as the unit for angles and millimeters (mm) as the unit for lengths. However, since optical systems can be used with proportional magnification or reduction, other appropriate units can also be used. Furthermore, the values ​​in the tables below are rounded to a predetermined number of decimal places.

[0090] [Table 1]

[0091] [Table 2]

[0092] [Table 3]

[0093] Figure 5 shows the aberration diagrams of the zoom lens of Example 1 when it is focused on an object at infinity. From left to right, the diagrams show spherical aberration, astigmatism, distortion, and chromatic aberration. In Figure 5, the upper section labeled "WIDE" shows aberrations at the wide-angle end, the middle section labeled "MIDDLE" shows aberrations at intermediate focal lengths, and the lower section labeled "TELE" shows aberrations at the telephoto end. 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 F-number value is shown after "FNo.=", and in the other aberration diagrams, the half-angle value is shown after "ω=".

[0094] The symbols, meanings, methods of description, and methods of illustration for each data point in Example 1 described above are the same in the following examples unless otherwise specified, so redundant explanations will be omitted below.

[0095] [Example 2] Figure 6 shows a cross-sectional view and movement trajectory of the configuration at the wide-angle end when the zoom lens of Example 2 is in focus on an object at infinity. Note that, compared to Figure 1, Figure 6 omits the illustration of the configuration at the telephoto end, and this is also the case for the cross-sectional views of Examples 3 to 8 below. The zoom lens of Example 2 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, and a subsequent group Gr. The subsequent group Gr consists 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, arranged from the object side to the image side. The second lens group G2 consists of four lenses, L21 to L24, arranged from the object side to the image side. The third lens group G3 consists of five lenses, the aperture diaphragm St and L31 to L35, arranged from the object side to the image side. The fourth lens group G4 consists of six lenses, L41 to L46, arranged from the object side to the image side. The fifth lens group G5 consists of one lens, L51. The focusing group consists of two lenses, L45 to L46.

[0097] For the zoom lens of Example 2, the basic lens data is shown in Table 4, the specifications and variable plane spacing in Table 5, the aspherical coefficient in Table 6, and the aberration diagrams in Figure 7.

[0098] [Table 4]

[0099] [Table 5]

[0100] [Table 6]

[0101] [Example 3] Figure 8 shows a cross-sectional view and movement trajectory of the configuration at the wide-angle end when the zoom lens of Example 3 is in focus on an object at infinity. The zoom lens of Example 3 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, and a subsequent group Gr. The subsequent group Gr consists 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, arranged from the object side to the image side. The second lens group G2 consists of four lenses, L21 to L24, arranged from the object side to the image side. The third lens group G3 consists of five lenses, the aperture diaphragm St and L31 to L35, arranged from the object side to the image side. The fourth lens group G4 consists of six lenses, L41 to L46, arranged from the object side to the image side. The fifth lens group G5 consists of one lens, L51. The focusing group consists of two lenses, L45 to L46.

[0103] For the zoom lens of Example 3, the basic lens data is shown in Table 7, the specifications and variable plane spacing in Table 8, the aspherical coefficient in Table 9, and the aberration diagrams in Figure 9.

[0104] [Table 7]

[0105] [Table 8]

[0106] [Table 9]

[0107] [Example 4] Figure 10 shows a cross-sectional view and movement trajectory of the configuration at the wide-angle end when the zoom lens of Example 4 is in focus on an object at infinity. The zoom lens of Example 4 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, and a subsequent group Gr. The subsequent group Gr consists 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, arranged from the object side to the image side. The second lens group G2 consists of four lenses, L21 to L24, arranged from the object side to the image side. The third lens group G3 consists of five lenses, the aperture diaphragm St and L31 to L35, arranged from the object side to the image side. The fourth lens group G4 consists of four lenses, L41 to L44, arranged from the object side to the image side. The fifth lens group G5 consists of three lenses, L51 to L53, arranged from the object side to the image side. The focusing group consists of two lenses, L51 to L52.

[0109] For the zoom lens of Example 4, the basic lens data is shown in Table 10, the specifications and variable plane spacing are shown in Table 11, the aspherical coefficient is shown in Table 12, and the aberration diagrams are shown in Figure 11.

[0110] [Table 10]

[0111] [Table 11]

[0112] [Table 12]

[0113] [Example 5] Figure 12 shows a cross-sectional view and movement trajectory of the configuration at the wide-angle end when the zoom lens of Example 5 is in focus on an object at infinity. The zoom lens of Example 5 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, and a subsequent group Gr. The subsequent group Gr consists 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, arranged from the object side to the image side. The second lens group G2 consists of four lenses, L21 to L24, arranged from the object side to the image side. The third lens group G3 consists of five lenses, the aperture diaphragm St and L31 to L35, arranged from the object side to the image side. The fourth lens group G4 consists of six lenses, L41 to L46, arranged from the object side to the image side. The focusing group consists of two lenses, L44 to L45.

[0115] For the zoom lens of Example 5, the basic lens data is shown in Table 13, the specifications and variable plane spacing are shown in Table 14, the aspherical coefficient is shown in Table 15, and the aberration diagrams are shown in Figure 13.

[0116] [Table 13]

[0117] [Table 14]

[0118] [Table 15]

[0119] [Example 6] Figure 14 shows a cross-sectional view and movement trajectory of the configuration at the wide-angle end when the zoom lens of Example 6 is in focus on an object at infinity. The zoom lens of Example 6 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, and a subsequent group Gr. The subsequent group Gr consists 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, 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, arranged from the object side to the image side. The second lens group G2 consists of four lenses, L21 and L24, arranged from the object side to the image side. The third lens group G3 consists of the aperture diaphragm St and four lenses, L31 and L34, arranged from the object side to the image side. The fourth lens group G4 consists of three lenses, L41 and L43, arranged 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, arranged from the object side to the image side. The focusing group consists of one lens, L51.

[0121] For the zoom lens of Example 6, the basic lens data is shown in Table 16, 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 15.

[0122] [Table 16]

[0123] [Table 17]

[0124] [Table 18]

[0125] [Example 7] Figure 16 shows a cross-sectional view and movement trajectory of the configuration at the wide-angle end when the zoom lens of Example 7 is in focus on an object at infinity. The zoom lens of Example 7 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, and a subsequent group Gr. The subsequent group Gr consists 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, arranged from the object side to the image side. The second lens group G2 consists of four lenses, L21 to L24, arranged from the object side to the image side. The third lens group G3 consists of six lenses, L31 to L36, and the aperture diaphragm St, arranged from the object side to the image side. The fourth lens group G4 consists of seven lenses, L41 to L47, arranged from the object side to the image side. The focus group consists of one lens, L44. Unlike Example 1, the focus group in Example 7 moves towards the object side when focusing from an object at infinity to an object at close range.

[0127] For the zoom lens of Example 7, the basic lens data is shown in Table 19, the specifications and variable plane spacing are shown in Table 20, the aspherical coefficient is shown in Table 21, and the aberration diagrams are shown in Figure 17.

[0128] [Table 19]

[0129] [Table 20]

[0130] [Table 21]

[0131] [Example 8] Figure 18 shows a cross-sectional view and movement trajectory of the configuration at the wide-angle end when the zoom lens of Example 8 is in focus on an object at infinity. The zoom lens of Example 8 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, and a subsequent group Gr. The subsequent group Gr consists 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, arranged from the object side to the image side. The second lens group G2 consists of four lenses, L21 to L24, arranged from the object side to the image side. The third lens group G3 consists of five lenses, the aperture diaphragm St and L31 to L35, arranged from the object side to the image side. The fourth lens group G4 consists of six lenses, L41 to L46, arranged from the object side to the image side. The focusing group consists of two lenses, L44 to L45.

[0133] For the zoom lens of Example 8, the basic lens data is shown in Table 22, the specifications and variable plane spacing in Table 23, the aspherical coefficient in Table 24, and the aberration diagrams in Figure 19.

[0134] [Table 22]

[0135] [Table 23]

[0136] [Table 24]

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

[0138] [Table 25]

[0139] [Table 26]

[0140] As can be seen from the data described above, the zoom lenses of Examples 1 to 8 have a magnification ratio of 5.5x or more, achieving a high magnification ratio while remaining compact and lightweight.

[0141] Next, an imaging device according to an embodiment of the present disclosure will be described. Figures 20 and 21 show an external view of a camera 30, which is an imaging device according to one embodiment of the present disclosure. Figure 20 shows a perspective view of the camera 30 from the front, and Figure 21 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.

[0142] The camera 30 comprises a camera body 31, the top of which is provided a shutter button 32 and a power button 33. The rear of the camera body 31 is provided with an operation unit 34, an operation unit 35, and a display unit 36. The display unit 36 ​​can display captured images and images within the field of view before capture.

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

[0144] The camera body 31 contains an image sensor 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 image sensor to generate an image, and a recording medium for recording the generated image. The camera 30 can take still images or videos by pressing the shutter button 32, and the image data obtained from this shooting is recorded on the recording medium.

[0145] 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 the above numerical examples, but can take other values.

[0146] Furthermore, the imaging device according to the embodiments of this disclosure is not limited to the above example, and can be of various forms, such as cameras other than mirrorless cameras, film cameras, and video cameras. [Explanation of symbols]

[0147] 1 Zoom lens 20 interchangeable lenses 30 Cameras 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: Light beam at the maximum angle of view. Penw Paraxial entrance pupil position Pexw paraxial exit pupil position Sim image plane St aperture diaphragm TLt 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 subsequent lens group, and the back focus in air equivalent distance, when the lens is focused on an object at infinity at the telephoto end. Yt, Yw Maximum image height Z optical axis ωw Maximum half-angle

Claims

1. It consists of, in order from the object side to the image side, a first lens group with positive refractive power, a second lens group with negative refractive power, and a subsequent group consisting of three or four lens groups. The second lens group includes an aperture diaphragm on the image side of the lens surface closest to the image, The image-side lens group within the aforementioned successor group includes at least one negative lens whose object-side lens surface is a concave surface in contact with air. During magnification, 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 the distance between all adjacent lens groups within the subsequent group changes. During magnification, the lens spacing within the three or four lens groups, namely the first lens group, the second lens group, and the subsequent group, remains constant. The second lens group consists of four lenses. The subsequent group includes, in order from the 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 group closest to the image within the aforementioned successor group has negative refractive power. The lens group closest to the image within the aforementioned successor group consists of two or three lenses. The subsequent group includes a focusing group that is positioned adjacent to the image side of the fourth lens group and moves along the optical axis when focusing occurs. The aforementioned focus group has a negative refractive power, When the system is in focus on an object at infinity, the total focal length of the system at the wide-angle end is fw. When the lens group is in focus on an object at infinity, the distance along the optical axis from the lens surface closest to the object to the object to the position of the paraxial entrance pupil at the wide-angle end is Denw. The sign of Denw is positive if the paraxial entrance pupil position is on the image side of the lens surface closest to the object in the first lens group, and negative if the paraxial entrance pupil position is on the object side of the lens surface closest to the object in the first lens group. The Abbe number of the lens closest to the object in the first lens group is ν1, with respect to the d line. Among the negative lenses included in the second lens group, the refractive index of the negative lens closest to the object is N2n, When the lens group is in focus on an object at infinity, the focal length of the lens group closest to the object among the positive refractive power lenses included in the subsequent group is fp. The focal length of the second lens group is f2, If the focal length of the first lens group is f1, 0.7<fw / Denw<1.5 (1) 14<ν1<27.3 (13-2) 1.6<N2n<2.2 (15) -3.1878 ≤ fp / f² ≤ -2.2138 (19-5) -0.23<f2 / f1≦-0.1645 (23-5) A zoom lens that satisfies the following conditions: (1), (13-2), (15), (19-5), and (23-5).

2. D1 is the distance along 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. When the lens is in focus on an object at infinity, and the telephoto end is set to focus on an object at infinity, if TLt 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 subsequent lens group, and the back focus in air equivalent distance, 0.01<D1 / TLt<0.1 (3) A zoom lens according to claim 1 that satisfies the conditional expression (3) represented by .

3. When focusing on an object at infinity, the back focus in terms of air equivalent distance at the wide-angle end is BFw. If Yw is the maximum image height at the wide-angle end, 0.38<BFw / Yw<1.5 (12) A zoom lens according to claim 1 or claim 2 that satisfies the conditional expression (12) represented by .

4. If N1 is the refractive index of the lens closest to the object in the first lens group with respect to the d line, 1.7<N1<2.3 (14) A zoom lens according to any one of claims 1 to 3 that satisfies the conditional expression (14) represented by .

5. 1.84<N1<2.22 (14-1) A zoom lens according to claim 4 that satisfies the conditional expression (14-1) represented by .

6. 1.65<N2n<2.11 (15-1) A zoom lens according to any one of claims 1 to 5 that satisfies the conditional expression (15-1) represented by .

7. 1.7<N2n<2.05 (15-2) A zoom lens according to claim 6 that satisfies the conditional expression (15-2) represented by .

8. If N2p is the refractive index of the positive lens with the strongest refractive power among the positive lenses included in the second lens group, 1.65<N2p<2 (16) A zoom lens according to any one of claims 1 to 7 that satisfies the conditional expression (16) represented by .

9. 1.71<N2p<1.93 (16-1) A zoom lens according to claim 8 that satisfies the conditional expression (16-1) represented by .

10. 1.77<N2p<1.9 (16-2) A zoom lens according to claim 9 that satisfies the conditional expression (16-2) represented by .

11. If the Abbe number of the negative lens closest to the image line among the negative lenses included in the aforementioned successor group is νnL, 27<νnL<102 (17) A zoom lens according to any one of claims 1 to 10 that satisfies the conditional expression (17) represented by .

12. The aforementioned focusing group consists of two or fewer lenses. A zoom lens according to any one of claims 1 to 11.

13. -0.19<f2 / f1≦-0.1645 (23-6) A zoom lens according to any one of claims 1 to 12 that satisfies the conditional expression (23-6) represented by .

14. An imaging device comprising a zoom lens according to any one of claims 1 to 13.

Images