Zoom lens and imaging device

Abstract

The present invention provides a zoom lens that is miniaturized and has high magnification, 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 positive refractive power, a third lens group having negative refractive power, a fourth lens group, and a subsequent group consisting of two or more lens groups. When the zoom is changed, the spacing between all adjacent lens groups changes. The subsequent group has a focusing group that moves along the optical axis when focusing. If the focal length of the first lens group is f1 and the focal length of the zoom lens when focused on an object at infinity at the telephoto end is ft, then 0.4

Description

[Technical Field]

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

[0002] Conventionally, zoom lenses that can be used in imaging devices such as digital cameras, video cameras, broadcast cameras, film cameras, and surveillance cameras are known, as described in Patent Documents 1 and 2 below. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2019-040020 [Patent Document 2] Japanese Patent Publication No. 2015-156010 [Overview of the project] [Problems that the invention aims to solve]

[0004] There is a demand for compact zoom lenses with high magnification. These demands are increasing year by year.

[0005] This disclosure provides a zoom lens that is miniaturized and has high magnification, and an imaging device equipped with this zoom lens. [Means for solving the problem]

[0006] A zoom lens according to one aspect of this disclosure comprises, in order from the object side to the image side, a first lens group having positive refractive power, a second lens group having positive refractive power, a third lens group having negative refractive power, a fourth lens group, and a successor group consisting of two or more lens groups, wherein when the zoom is changed, the spacing between all adjacent lens groups changes, and the successor group has a focusing group that moves along the optical axis when focusing, and when the focal length of the first lens group is f1 and the focal length of the zoom lens when focused on an object at infinity at the telephoto end is ft, 0.4 <f1 / ft<1 (1) The condition (1) expressed by is satisfied.

[0007] The zoom lens in the above configuration is 0.5 <f1 / ft<0.9 (1-1) It is preferable that the condition expressed in equation (1-1) is satisfied.

[0008] Let FNo be the maximum aperture F-number when focused on an object at infinity at the telephoto end, β2 be the lateral magnification of the second lens group when focused on an object at infinity at the telephoto end, β2R be the combined lateral magnification of all lenses on the image side from the second lens group when focused on an object at infinity at the telephoto end, β3 be the lateral magnification of the third lens group when focused on an object at infinity at the telephoto end, and β3R be the combined lateral magnification of all lenses on the image side from the third lens group when focused on an object at infinity at the telephoto end. S2=(1-β2 2 )×β2R 2 S3=(1-β3 2 )×β3R 2 When S2 and S3 are defined as shown above, the zoom lens of the above embodiment preferably satisfies the following condition (2), and more preferably satisfies the following condition (2-1). 0.1 < |S2 + S3| / FNo < 0.7 (2) 0.2 < |S2 + S3| / FNo < 0.65 (2-1)

[0009] When the focal length of the second lens group is set to f2, the zoom lens in the above configuration is: 1.02 < f1 / f2 < 2 (3) It is preferable to satisfy the conditional expression (3) represented by the following formula.

[0010] When the minimum value of the refractive index with respect to the d-line of all the lenses included in the third lens group is N3min, the zoom lens of the above aspect is 1.65 < N3min < 1.95 (4) It is preferable to satisfy the conditional expression (4) represented by the following formula.

[0011] When the average value of the partial dispersion ratio between the g-line and the F-line of all the positive lenses included in the third lens group is θgFp, the zoom lens of the above aspect preferably satisfies the following conditional expression (5), and more preferably satisfies the following conditional expression (5-1). 0.615 < θgFp < 0.66 (5) 0.62 < θgFp < 0.65 (5-1)

[0012] When the refractive index with respect to the d-line of the negative lens included in the first lens group is N1n, the zoom lens of the above aspect is 1.85 < N1n < 2.15 (6) It is preferable to include at least one negative lens that satisfies the conditional expression (6) represented by the following formula.

[0013] When the Abbe number based on the d-line of the positive lens included in the second lens group is ν2p, the zoom lens of the above aspect is 65 < ν2p < 99 (7) It is preferable to include at least one positive lens that satisfies the conditional expression (7) represented by the following formula.

[0014] When the focal length of the third lens group is f3, the zoom lens of the above aspect is -15 < f1 / f3 < -10 (8) It is preferable to satisfy the conditional expression (8) represented by the following formula.

[0015] If D2 is the difference in the optical axis direction between the position of the second lens group when focused on an object at infinity at the wide-angle end and the position when focused on an object at infinity at the telephoto end, and D3 is the difference in the optical axis direction between the position of the third lens group when focused on an object at infinity at the wide-angle end and the position when focused on an object at infinity at the telephoto end, then the zoom lens of the above embodiment is: 2 <D3 / D2<3 (9) It is preferable that the condition expressed in equation (9) is satisfied.

[0016] The fourth lens group preferably has a positive refractive power.

[0017] The focal group preferably has a positive refractive power.

[0018] When the focal length of the fourth lens group is f4 and the focal length of the focusing group is fF, the zoom lens in the above configuration is: 1.8 <f4 / fF<3 (10) It is preferable that the conditional expression (10) represented by is satisfied.

[0019] It is preferable that the first lens group is fixed to the image plane during magnification.

[0020] The second lens group preferably consists of a single positive lens.

[0021] The focusing group preferably includes at least one aspherical lens.

[0022] The third lens group preferably includes at least three negative lenses.

[0023] Another aspect of the present disclosure is an imaging device equipped with the zoom lens of the above aspect.

[0024] In this specification, "~consisting of" and "~consisting of" are intended to include, in addition to the listed components, lenses that have substantially no refractive power, as well as 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.

[0025] "A group of lenses with positive refractive power" and "The group of lenses has positive refractive power" mean 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. "A group of lenses," "a group of lenses," and "a focusing group" are not limited to a configuration consisting of multiple lenses, but may also consist of only one lens.

[0026] The number of lenses mentioned above refers to the number of constituent lenses. For example, in a cemented lens formed by joining multiple single lenses of different materials, the number of lenses is expressed as the number of single lenses that make up the cemented lens. However, a composite aspherical lens (i.e., a lens in which a lens (e.g., a spherical lens) and an aspherical film formed on that lens are integrally constructed and function as a single aspherical lens as a whole) is not considered a cemented lens and is treated as a single lens. Unless otherwise specified, the sign and surface shape of the refractive power of optical components including aspherical surfaces are considered in the paraxial region.

[0027] The "focal length" used in the conditional equations is the paraxial focal length. Unless otherwise specified, 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," "F-line," and "g-line" described herein are emission lines. The wavelength of the d-line is treated as 587.56 nm (nanometers), the wavelength of the C-line as 656.27 nm (nanometers), the wavelength of the F-line as 486.13 nm (nanometers), and the wavelength of the g-line as 435.84 nm (nanometers). [Effects of the Invention]

[0028] According to this disclosure, it is possible to provide a zoom lens that is miniaturized and has high magnification, and an imaging device equipped with this zoom lens. [Brief explanation of the drawing]

[0029] [Figure 1] This figure shows the configuration and movement trajectory of a zoom lens according to one embodiment, corresponding to the zoom lens of Example 1. [Figure 2] This is a cross-sectional view of the configuration of the zoom lens of Example 1 at its wide-angle end. [Figure 3] These are aberration diagrams of the zoom lens of Example 1. [Figure 4] This figure shows the configuration and movement trajectory of the zoom lens in Example 2. [Figure 5] These are aberration diagrams for the zoom lens of Example 2. [Figure 6] This figure shows the configuration and movement trajectory of the zoom lens in Example 3. [Figure 7] These are aberration diagrams for the zoom lens of Example 3. [Figure 8] This figure shows the configuration and movement trajectory of the zoom lens in Example 4. [Figure 9] These are aberration diagrams for the zoom lens of Example 4. [Figure 10] This figure shows the configuration and movement trajectory of the zoom lens in Example 5. [Figure 11] These are aberration diagrams for the zoom lens of Example 5. [Figure 12] This figure shows the configuration and movement trajectory of the zoom lens in Example 6. [Figure 13] These are aberration diagrams for the zoom lens of Example 6. [Figure 14] This figure shows the configuration and movement trajectory of the zoom lens in Example 7. [Figure 15] These are aberration diagrams for the zoom lens of Example 7. [Figure 16] This figure shows the configuration and movement trajectory of the zoom lens in Example 8. [Figure 17]These are aberration diagrams for the zoom lens of Example 8. [Figure 18] This is a schematic diagram of an imaging device according to one embodiment. [Figure 19] This is a front perspective view of an imaging device according to one embodiment. [Figure 20] This is a perspective view of the rear side of an imaging device according to one embodiment. [Modes for carrying out the invention]

[0030] Embodiments of this disclosure will be described below with reference to the drawings.

[0031] Figure 1 shows the configuration and cross-sectional view of the light beam and the movement trajectory of a zoom lens according to one embodiment of the present disclosure. In Figure 1, the upper section labeled "Wide" shows the wide-angle end state, and the lower section labeled "Tele" shows the telephoto end state. In Figure 1, the light beams shown are the axial light beam and the light beam of the maximum half-angle ωw at the wide-angle end, and the axial light beam and the light beam of the maximum half-angle ωt at the telephoto end. Figure 2 shows a cross-sectional view of the configuration of the zoom lens in Figure 1 at the wide-angle end. Figures 1 and 2 show the state when the lens is in focus on an object at infinity, with the left side being the object side and the right side being the image side. The examples shown in Figures 1 and 2 correspond to the zoom lens of Embodiment 1 described later. The following explanation will mainly refer to Figure 1, and to Figure 2 as needed.

[0032] Figure 1 shows an example where a parallel plate-shaped optical element PP is placed between the zoom lens and the image plane Sim, assuming that a zoom lens is applied to the imaging device. The optical element PP is a component that is intended to be various filters and / or cover glass. The various filters include low-pass filters, infrared cut filters, and / or filters that cut out a specific wavelength range. The optical element PP is a component that does not have refractive power. It is also possible to configure the imaging device without the optical element PP.

[0033] The zoom lens of this disclosure 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 positive refractive power, a third lens group G3 having negative refractive power, a fourth lens group G4, and a subsequent group GR consisting of two or more lens groups. When the magnification is changed, the spacing between all adjacent lens groups changes. By making the first lens group G1, which is closest to the object, a lens group having positive refractive power, the overall length of the lens system can be easily shortened, which is advantageous for miniaturization. By making the second lens group G2 a lens group having positive refractive power, and by changing the spacing between the object side and the image side of the second lens group G2 when the magnification is changed, the increase in the effective diameter of the first lens group G1 at the telephoto end can be suppressed. As a result, the increase in the outer diameter of the first lens group G1 can be suppressed, and thus miniaturization can be achieved. In particular, since portability is required for cameras used for photography and broadcasting, miniaturizing the first lens group G1, which tends to be large in diameter and heavy, is effective. Furthermore, by moving multiple lens groups during magnification, it becomes easier to achieve high magnification.

[0034] In this specification, a group of lenses whose distance in the optical axis direction changes when the magnification is varied is defined as one lens group. Within a single lens group, the distance between adjacent lenses does not change when the magnification is varied. That is, a "lens group" is a component of a zoom lens that includes at least one lens and is separated by the air gap that changes when the magnification is varied. When the magnification is varied, each lens group is moved or fixed. A "lens group" may include components other than lenses that do not have refractive power, such as an aperture diaphragm St.

[0035] The subsequent group GR has a focusing group that moves along the optical axis Z during focusing. By placing the focusing group within the subsequent group GR, the effective diameter of the focusing group can be reduced, which is advantageous for miniaturizing the focusing group unit.

[0036] As an example, the zoom lens in Figure 1 consists of the first lens group G1, the second lens group G2, the third lens group G3, the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6, in order from the object side to the image side. In the example in Figure 1, the subsequent group GR consists of the fifth lens group G5 and the sixth lens group G6.

[0037] As an example, each lens group in Figure 1 is configured as follows, with its detailed configuration shown in Figure 2. The first lens group G1 consists of three lenses, L11 to L13, arranged from the object side to the image side. The second lens group G2 consists of one lens, L21. The third lens group G3 consists of five lenses, L31 to L35, arranged from the object side to the image side. The fourth lens group G4 consists of an aperture diaphragm St and 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 sixth lens group G6 consists of two lenses, L61 to L62, arranged from the object side to the image side. The aperture diaphragm St in Figures 1 and 2 does not indicate shape or size, but rather indicates position in the optical axis direction.

[0038] As an example, in the zoom lens shown in Figure 1, the first lens group G1, the fourth lens group G4, and the sixth lens group G6 are fixed relative to the image plane Sim during magnification. Also, during magnification, the second lens group G2, the third lens group G3, and the fifth lens group G5 move along the optical axis Z. In Figure 1, between the upper and lower diagrams, the approximate movement trajectories of each lens group during magnification, from the wide-angle end to the telephoto end, are shown by solid arrows.

[0039] As an example, in the zoom lens shown in Figure 1, the focusing group consists of the fifth lens group G5. The parentheses and left-pointing arrow attached to the fifth lens group G5 in the lower part of Figure 1 indicate that the lenses enclosed in these parentheses constitute the focusing group, and also indicate the direction in which the focusing group moves when focusing from an object at infinity to the nearest object. Note that the focusing group functions throughout the entire zoom range, including the wide-angle end, but in Figure 1, to avoid complexity, the arrow is only shown in the lower part of the diagram.

[0040] It is preferable that the first lens group G1 is fixed to the image plane Sim during magnification. By keeping the first lens group G1 immobile during magnification, the overall length of the lens system does not change, and the shift in the center of gravity during magnification can be suppressed.

[0041] The second lens group G2 preferably consists of a single positive lens. This is advantageous for reducing the weight of the second lens group G2. Furthermore, since the thickness of the second lens group G2 can be suppressed, sufficient movement can be secured during magnification, which is advantageous for increasing magnification.

[0042] The third lens group G3 preferably includes at least three negative lenses. This is advantageous in suppressing chromatic aberration fluctuations during magnification.

[0043] The third lens group G3 preferably includes at least two positive lenses. This is advantageous in suppressing chromatic aberration fluctuations during magnification.

[0044] It is preferable that the fourth lens group G4 has a positive refractive power. In this case, the effective diameter of the focusing group located in the subsequent group GR on the image side of the fourth lens group G4 can be suppressed, which is advantageous for miniaturizing the focusing group unit.

[0045] It is preferable that the fourth lens group G4 is fixed to the image plane Sim during magnification. In this case, the number of lens groups that move during magnification can be reduced, which is advantageous in suppressing focus shift during magnification.

[0046] It is preferable that the lens group closest to the image plane is fixed relative to the image plane Sim during magnification. In this case, the number of lens groups that move during magnification can be reduced, which is advantageous in suppressing focus shift during magnification.

[0047] The focusing group preferably has positive refractive power. This is advantageous in suppressing shading because it reduces the angle at which off-axis principal rays enter the image plane (Sim). It also helps ensure sufficient back focus.

[0048] The focusing group preferably includes at least one aspherical lens. This is advantageous in suppressing aberration variations during focusing.

[0049] The focusing group may be configured to consist of a single lens group that moves during magnification. This configuration is advantageous for simplifying the movement mechanism.

[0050] The zoom lens of this disclosure may consist of six lens groups having positive, positive, negative, positive, positive, and negative refractive powers in order from the object side to the image side, with the focusing group being the fifth lens group G5. In this way, by giving the sixth lens group G6, which is closest to the image, a negative refractive power, it becomes easy to strengthen the positive refractive power of the fifth lens group G5, which moves during focusing. Therefore, this is advantageous for shortening the closest focusing distance at the telephoto end. Examples 1-2 and 4-6 described later correspond to this configuration.

[0051] Furthermore, the zoom lens of this disclosure may consist of six lens groups having positive, positive, negative, positive, positive, and positive refractive powers in order from the object side to the image side, with the focusing group being the fifth lens group G5. In this way, by giving the sixth lens group G6, which is closest to the image, a positive refractive power, it becomes easier to weaken the positive refractive power of the fifth lens group G5, which moves during focusing. Therefore, it becomes easier to suppress the focusing sensitivity of the focusing group, which is advantageous in suppressing focus shift during focusing. Examples 3 and 8, described later, correspond to this configuration.

[0052] Furthermore, the zoom lens of this disclosure may be configured with seven lens groups having refractive forces of positive, positive, negative, positive, negative, positive, and negative in order from the object side to the image side. In this way, having two lens groups that move when the subsequent group GR changes magnification is advantageous in suppressing fluctuations in field curvature when changing magnification in the intermediate zoom range. Embodiment 7, described later, corresponds to this configuration.

[0053] Next, preferred and possible configurations of the conditional formulas for the zoom lens of this disclosure will be described. In the following description of the conditional formulas, the same symbols will be used for the same definitions to avoid redundant explanations. Also, in the following, to avoid redundant explanations, "the zoom lens of this disclosure" will also simply be referred to as "the zoom lens."

[0054] When the focal length of the first lens group G1 is f1 and the focal length of the zoom lens when focused on an object at infinity at the telephoto end is ft, it is preferable that the zoom lens satisfies the following condition (1). By ensuring that the corresponding value in condition (1) does not fall below the lower limit, the refractive power of the first lens group G1 does not become too strong, which is advantageous in suppressing aberrations occurring in the first lens group G1, especially spherical aberration at the telephoto end. By ensuring that the corresponding value in condition (1) does not exceed the upper limit, the refractive power of the first lens group G1 does not become too weak, which allows the height of the light rays incident on the second lens group G2 from the optical axis Z to be reduced, which is advantageous in miniaturizing the optical system. 0.4 <f1 / ft<1 (1)

[0055] To obtain better characteristics, the lower limit of condition (1) is more preferably 0.5, even more preferably 0.55, and even more preferably 0.6. To obtain better characteristics, the upper limit of condition (1) is more preferably 0.9, even more preferably 0.85, and even more preferably 0.75. For example, a zoom lens is more preferably satisfied with the following condition (1-1), even more preferably satisfied with the following condition (1-2), and even more preferably satisfied with the following condition (1-3). 0.5 <f1 / ft<0.9 (1-1) 0.55 <f1 / ft<0.85 (1-2) 0.6 <f1 / ft<0.75 (1-3)

[0056] It is preferable that the zoom lens satisfies the following condition (2). Here, FNo is the maximum aperture F number when the lens is in focus on an object at infinity at the telephoto end. β2 is the lateral magnification of the second lens group G2 when the lens is in focus on an object at infinity at the telephoto end. β2R is the combined lateral magnification of all lenses on the image side of the second lens group G2 when the lens is in focus on an object at infinity at the telephoto end. β3 is the lateral magnification of the third lens group G3 when the lens is in focus on an object at infinity at the telephoto end. β3R is the combined lateral magnification of all lenses on the image side of the third lens group G3 when the lens is in focus on an object at infinity at the telephoto end. Then, S2 and S3 are defined as shown in the following equations. S2=(1-β2 2 )×β2R 2 S3=(1-β3 2 )×β3R 2 S2 represents the amount of image plane position movement (so-called focus sensitivity) for a unit movement of the second lens group G2 when in focus on an object at infinity at the telephoto end. Similarly, S3 represents the focus sensitivity of the third lens group G3 when in focus on an object at infinity at the telephoto end. Keeping the corresponding value in condition (2) above the lower limit is advantageous for increasing magnification. Keeping the corresponding value in condition (2) above the upper limit reduces the focus sensitivity of the second lens group G2 and the third lens group G3, which is advantageous for suppressing focus shifts during magnification changes. 0.1 < |S2 + S3| / FNo < 0.7 (2)

[0057] To obtain better characteristics, the lower limit of condition (2) is more preferably 0.2, even more preferably 0.3, and even more preferably 0.4. To obtain better characteristics, the upper limit of condition (2) is more preferably 0.65, even more preferably 0.6, and even more preferably 0.55. For example, a zoom lens is more preferably satisfied with the following condition (2-1), even more preferably satisfied with the following condition (2-2), and even more preferably satisfied with the following condition (2-3). 0.2 < |S2 + S3| / FNo < 0.65 (2-1) 0.3 < |S2 + S3| / FNo < 0.6 (2-2) 0.4 < |S2 + S3| / FNo < 0.55 (2-3)

[0058] When the focal length of the second lens group G2 is f2, it is preferable that the zoom lens satisfies the following condition (3). By ensuring that the corresponding value in condition (3) does not fall below the lower limit, the refractive power of the first lens group G1 does not become too strong, which is advantageous in suppressing aberrations occurring in the first lens group G1, especially spherical aberration at the telephoto end. By ensuring that the corresponding value in condition (3) does not exceed the upper limit, the refractive power of the first lens group G1 does not become too weak, which allows the height of the light rays incident on the second lens group G2 from the optical axis Z to be reduced, which is advantageous in miniaturizing the optical system. 1.02 <f1 / f2<2 (3)

[0059] To obtain better characteristics, the lower limit of condition (3) is more preferably 1.05, even more preferably 1.07, and even more preferably 1.1. To obtain better characteristics, the upper limit of condition (3) is more preferably 1.5, even more preferably 1.4, and even more preferably 1.3. For example, a zoom lens is more preferably satisfied with the following condition (3-1), even more preferably satisfied with the following condition (3-2), and even more preferably satisfied with the following condition (3-3). 1.05 <f1 / f2<1.5 (3-1) 1.07 <f1 / f2<1.4 (3-2) 1.1 <f1 / f2<1.3 (3-3)

[0060] When N3min is defined as the minimum refractive index of all lenses in the third lens group G3 with respect to the d line, it is preferable that the zoom lens satisfies the following condition (4). By ensuring that the corresponding value in condition (4) does not fall below the lower limit, the refractive power of the lenses in the third lens group G3 does not become too weak, which is advantageous for increasing magnification. By ensuring that the corresponding value in condition (4) does not exceed the upper limit, it is possible to select materials with low dispersion for the lenses in the third lens group G3, which is advantageous for suppressing chromatic aberration fluctuations during magnification. 1.65 <N3min<1.95 (4)

[0061] To obtain better characteristics, the lower limit of condition (4) is more preferably set to 1.7, and even more preferably to 1.75. To obtain better characteristics, the upper limit of condition (4) is more preferably set to 1.9, and even more preferably to 1.85. For example, a zoom lens is more preferably satisfied with the following condition (4-1), and even more preferably satisfied with the following condition (4-2). 1.7 <N3min<1.9 (4-1) 1.75 <N3min<1.85 (4-2)

[0062] When θgFp is the average value of the partial dispersion ratio between the g-line and F-line of all positive lenses included in the third lens group G3, it is preferable that the zoom lens satisfies the following condition (5). By keeping the corresponding value of condition (5) within the range of condition (5), it is possible to select a material with appropriate anomalous dispersion for the positive lenses included in the third lens group G3, which is advantageous in suppressing chromatic aberration fluctuations during magnification. 0.615 < θgFp < 0.66 (5)

[0063] To obtain better characteristics, the lower limit of condition (5) is more preferably set to 0.62, and even more preferably to 0.625. To obtain better characteristics, the upper limit of condition (5) is more preferably set to 0.65, and even more preferably to 0.64. For example, a zoom lens is more preferably satisfied with the following condition (5-1), and even more preferably satisfied with the following condition (5-2). 0.62 < θgFp < 0.65 (5-1) 0.625 < θgFp < 0.64 (5-2)

[0064] Furthermore, if the refractive indices of a certain lens for the g-line, F-line, and C-line are Ng, NF, and NC, respectively, and the partial dispersion ratio between the g-line and F-line of that lens is θgF, then θgF is defined by the following formula. θgF = (Ng - NF) / (NF - NC)

[0065] A zoom lens preferably includes at least one negative lens that satisfies the following condition (6). Here, N1n is the refractive index of the negative lens included in the first lens group G1 with respect to the d line. By ensuring that the corresponding value of condition (6) does not fall below the lower limit, it is advantageous to suppress aberrations occurring in the first lens group G1, particularly spherical aberration at the telephoto end and astigmatism at the wide-angle end. By ensuring that the corresponding value of condition (6) does not exceed the upper limit, it is possible to select a material with high transmittance for the negative lens included in the first lens group G1. 1.85 <N1n<2.15 (6)

[0066] To obtain better characteristics, the lower limit of condition (6) is more preferably set to 1.95, and even more preferably to 2. To obtain better characteristics, the upper limit of condition (6) is more preferably set to 2.1, and even more preferably to 2.07. For example, a zoom lens is more preferably set to include at least one negative lens that satisfies the following condition (6-1), and even more preferably set to include at least one negative lens that satisfies the following condition (6-2). 1.95 <N1n<2.1 (6-1) 2 <N1n<2.07 (6-2)

[0067] A zoom lens preferably includes at least one positive lens that satisfies the following condition (7). Here, the d-line reference Abbe number of the positive lens included in the second lens group G2 is denoted as ν2p. Ensuring that the corresponding value of condition (7) does not fall below the lower limit is advantageous for suppressing axial chromatic aberration at the telephoto end. Ensuring that the corresponding value of condition (7) does not exceed the upper limit allows for the selection of a material with a high refractive index for the positive lens included in the second lens group G2, thereby increasing the refractive power of the second lens group G2 and being advantageous for miniaturizing the optical system. 65 < ν²p < 99 (7)

[0068] To obtain better characteristics, the lower limit of condition (7) is more preferably set to 70, and even more preferably to 75. To obtain better characteristics, the upper limit of condition (7) is more preferably set to 95, and even more preferably to 91. For example, a zoom lens more preferably includes at least one positive lens satisfying the following condition (7-1), and even more preferably includes at least one positive lens satisfying the following condition (7-2). 70 < ν²p < 95 (7-1) 75 < ν²p < 91 (7-2)

[0069] When the focal length of the third lens group G3 is set to f3, it is preferable that the zoom lens satisfies the following condition (8). By ensuring that the corresponding value in condition (8) does not fall below the lower limit, the refractive power of the third lens group G3 does not become too strong, which is advantageous in suppressing aberration fluctuations during magnification. By ensuring that the corresponding value in condition (8) does not exceed the upper limit, the refractive power of the third lens group G3 does not become too weak, which suppresses the amount of movement of the third lens group G3 during magnification, which is advantageous in shortening the overall length of the lens system. -15 <f1 / f3<-10 (8)

[0070] To obtain better characteristics, the lower limit of condition (8) is more preferably -14, and even more preferably -13.5. To obtain better characteristics, the upper limit of condition (8) is more preferably -11, and even more preferably -12. For example, a zoom lens is more preferably satisfied with the following condition (8-1), and even more preferably satisfied with the following condition (8-2). -14 <f1 / f3<-11 (8-1) -13.5 <f1 / f3<-12 (8-2)

[0071] It is preferable that the zoom lens satisfies the following condition (9). Here, D2 is the difference in the Z-axis direction between the position of the second lens group G2 when it is in focus on an object at infinity at the wide-angle end and the position when it is in focus on an object at infinity at the telephoto end. D3 is the difference in the Z-axis direction between the position of the third lens group G3 when it is in focus on an object at infinity at the wide-angle end and the position when it is in focus on an object at infinity at the telephoto end. Figure 1 shows D2 and D3. By ensuring that the corresponding value of condition (9) does not fall below the lower limit, the amount of movement of the second lens group G2 during zoom variation can be suppressed, which is advantageous in suppressing aberration fluctuations during zoom variation, especially fluctuations in spherical aberration at the telephoto end. By ensuring that the corresponding value of condition (9) does not exceed the upper limit, the amount of movement of the third lens group G3 during zoom variation can be suppressed, which is advantageous in miniaturizing the optical system. 2 <D3 / D2<3 (9)

[0072] To obtain better characteristics, the lower limit of condition (9) is more preferably set to 2.2, and even more preferably to 2.5. To obtain better characteristics, the upper limit of condition (9) is more preferably set to 2.9, and even more preferably to 2.8. For example, a zoom lens is more preferably satisfied with the following condition (9-1), and even more preferably satisfied with the following condition (9-2). 2.2 <D3 / D2<2.9 (9-1) 2.5 <D3 / D2<2.8 (9-2)

[0073] When the focal length of the fourth lens group G4 is f4 and the focal length of the focusing group is fF, it is preferable that the zoom lens satisfies the following condition (10). By ensuring that the corresponding value in condition (10) does not fall below the lower limit, the refractive power of the focusing group does not become too weak, making it easier to suppress the amount of movement during focusing and advantageous for shortening the overall length of the lens system. By ensuring that the corresponding value in condition (10) does not exceed the upper limit, the refractive power of the focusing group does not become too strong, which is advantageous for suppressing aberration fluctuations during focusing. 1.8 <f4 / fF<3 (10)

[0074] To obtain better characteristics, the lower limit of condition (10) is more preferably set to 1.85, and even more preferably to 1.9. To obtain better characteristics, the upper limit of condition (10) is more preferably set to 2.8, and even more preferably to 2.7. For example, a zoom lens is more preferably satisfied with the following condition (10-1), and even more preferably satisfied with the following condition (10-2). 1.85 <f4 / fF<2.8 (10-1) 1.9 <f4 / fF<2.7 (10-2)

[0075] When the lateral magnification of the third lens group is β3w in a state where it is focused on an object at infinity at the wide-angle end, it is preferable that the zoom lens satisfies the following condition (11). By ensuring that the corresponding value of condition (11) does not fall below the lower limit, the magnification effect of the third lens group G3 does not become too weak, which is advantageous for increasing magnification. By ensuring that the corresponding value of condition (11) does not exceed the upper limit, the magnification effect of the third lens group G3 does not become too strong, which is advantageous for suppressing aberration fluctuations during magnification. 20 < β3 / β3w < 40 (11)

[0076] In order to obtain better characteristics, the lower limit value of conditional expression (11) is more preferably 23, and even more preferably 25. In order to obtain better characteristics, the upper limit value of conditional expression (11) is more preferably 35, and even more preferably 30. For example, it is more preferable for the zoom lens to satisfy the following conditional expression (11-1), and even more preferable to satisfy the following conditional expression (11-2). 23 < β3 / β3w < 35 (11-1) 25 < β3 / β3w < 30 (11-2)

[0077] It is preferable for the zoom lens to satisfy the following conditional expression (12). Here, let the open F-number in the state of focusing on an infinite object at the wide-angle end be FNow. Let the lateral magnification of the focusing group in the state of focusing on an infinite object at the wide-angle end be βFw. Let the combined lateral magnification of all the lenses on the image side of the focusing group in the state of focusing on an infinite object at the wide-angle end be βFRw. And define SFw represented by the following formula. SFw = (1 - βFw 2 ) × βFRw 2 SFw indicates the amount of movement of the image plane position with respect to the amount of movement of the focusing group during focusing (so-called focus sensitivity). By preventing the corresponding value of conditional expression (12) from falling below the lower limit, it becomes easier to suppress the amount of movement of the focusing group during focusing, which is advantageous for shortening the overall length of the lens system. By preventing the corresponding value of conditional expression (12) from exceeding the upper limit, it becomes easier to suppress the focus sensitivity of the focusing group, which is advantageous for suppressing focus deviation during focusing. 0.5 < SFw / FNow < 1.2 (12)

[0078] In order to obtain better characteristics, the lower limit value of conditional expression (12) is more preferably 0.7, and even more preferably 0.9. In order to obtain better characteristics, the upper limit value of conditional expression (12) is more preferably 1.1, and even more preferably 1. For example, it is more preferable for the zoom lens to satisfy the following conditional expression (12-1), and even more preferable to satisfy the following conditional expression (12-2). 0.7 <SFw / FNow<1.1 (12-1) 0.9 <SFw / FNow<1 (12-2)

[0079] In a configuration where the focusing group moves toward the object when focusing from an object at infinity to the nearest object, it is preferable that the zoom lens satisfies the following condition (13). Here, dFf is the air distance on the optical axis Z between the lens adjacent to the object side of the focusing group and the focusing group when it is in focus on an object at infinity at the telephoto end. TL is the sum of the distance on the optical axis Z from the lens surface on the object side of the first lens group G1 to the lens surface on the image side of the subsequent lens group GR when it is in focus on an object at infinity at the telephoto end, and the back focus in air equivalent distance of the zoom lens. By ensuring that the corresponding value of condition (13) does not fall below the lower limit, space can be secured for the focusing group to move when focusing, which is advantageous for shortening the nearest focusing distance. By ensuring that the corresponding value of condition (13) does not exceed the upper limit, the space for the focusing group to move when focusing does not become too large, which is advantageous for miniaturizing the optical system. 0.05 <dFf / TL<0.2 (13)

[0080] To obtain better characteristics, the lower limit of conditional equation (13) is more preferably set to 0.08, and even more preferably to 0.1. To obtain better characteristics, the upper limit of conditional equation (13) is more preferably set to 0.17, and even more preferably to 0.15. For example, a zoom lens is more preferably satisfied with the following conditional equation (13-1), and even more preferably satisfied with the following conditional equation (13-2). 0.08 <dFf / TL<0.17 (13-1) 0.1 <dFf / TL<0.15 (13-2)

[0081] The preferred and possible configurations described above, including the configurations related to the conditional expressions, can be combined in any way within a non-contradictory range and are preferably selectively adopted as appropriate according to the required specifications. Furthermore, the zoom lens of this disclosure can be modified in various ways without departing from the spirit of the technology of this disclosure. For example, the number of lens groups included in the subsequent group GR may be different from that of the example above. The number of lenses included in the first lens group G1, the second lens group G2, the third lens group G3, the fourth lens group G4, each lens group in the subsequent group GR, and the focusing group may be different from that of the example above.

[0082] As an example, a preferred embodiment of the zoom lens 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 positive refractive power, a third lens group G3 having negative refractive power, a fourth lens group G4, and a subsequent group GR consisting of two or more lens groups, wherein when the magnification is changed, the spacing between all adjacent lens groups changes, and the subsequent group GR has a focusing group that moves along the optical axis Z when focusing, satisfying the above condition (1).

[0083] Next, embodiments of the zoom lens of this disclosure will be described with reference to the drawings. Note that the reference numerals assigned to each group in the cross-sectional view of each embodiment are used independently for each embodiment to avoid complexity in the explanation and drawings due to the increasing number of digits in the reference numerals. Therefore, even if the same reference numerals are assigned to drawings of different embodiments, they do not necessarily represent the same configuration.

[0084] [Example 1] The configuration and movement trajectory of the zoom lens of Example 1 are shown in Figure 1, and the method of illustration and configuration are as described above, so some redundant explanations will be omitted here. The zoom lens of Example 1 consists of, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having positive refractive power, and a sixth lens group G6 having negative refractive power. The subsequent group GR consists of the fifth lens group G5 and the sixth lens group G6.

[0085] When changing magnification from the wide-angle end to the telephoto end, the second lens group G2, the third lens group G3, and the fifth lens group G5 move along the optical axis Z by changing the spacing between adjacent lens groups, while the other lens groups remain fixed relative to the image plane Sim. The focusing group consists of the fifth lens group G5. When focusing from an object at infinity to the nearest object, the focusing group moves toward the object.

[0086] For the zoom lens of 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.

[0087] The basic lens data table is as follows: The "Sn" column shows the surface number, with the surface closest to the object being designated as the 1st surface and the number increasing by one as you move towards the image side. The "R" column shows the radius of curvature of each surface. The "D" column shows the interplanar spacing on the optical axis between each surface and the surface adjacent to it on the image side. The "Nd" column shows the refractive index of each component with respect to the d line. The "νd" column shows the Abbe number of each component with respect to the d line. The "θgF" column shows the partial dispersion ratio between the g line and the F line of each component. The "Material" column shows the material name and the manufacturer name of each component, separated by a period. The manufacturer name is shown in general terms. "CDGM" stands for Chengdu Guangming Optoelectronics, "HIKARI" stands for Hikari Glass Co., Ltd., "HOYA" stands for HOYA Corporation, "NHG" stands for Hubei Xinhua Optoelectronics Information Materials Co., Ltd., "OHARA" stands for Ohara Corporation, "SCHOTT" stands for SCHOTT Company, and "SUMITA" stands for Sumita Optical Glass Co., Ltd. The "ED" column indicates the effective diameter of each face.

[0088] In the basic lens data table, the sign of the radius of curvature of a surface with a convex shape facing the object is positive, and the sign of the radius of curvature of a surface with a convex shape facing the image is negative. The basic lens data table also shows the aperture diaphragm St and optical element PP. In the column for the surface number of the surface corresponding to the aperture diaphragm St, the surface number and the phrase (St) are entered. The value in the bottom column of column D is the distance between the image-side surface in the table and the image plane Sim. For variable surface spacing during magnification, the symbol DD[ ] is used, and the object-side surface number for this spacing is placed inside the [ ] and entered in the surface spacing column.

[0089] Table 2 shows the zoom magnification Zr, focal length f, back focus Bf in air equivalent distance, maximum aperture F-number FNo., maximum angle of view 2ω, and variable plane spacing relative to the d line. The zoom magnification Zr is synonymous with the magnification ratio. The [°] in the 2ω column indicates that the unit is degrees. Table 2 shows the values ​​for the wide-angle end, intermediate focal length, and telephoto end for both the in-focus state and the close-up state. When the in-focus state is an object at infinity, "Infinity" is written in the object distance column, and when the close-up state is an object at infinity, the object distance to the close-up object is written in the object distance column. The object distance is the distance on the optical axis between the object being photographed by the zoom lens and the lens surface closest to the object. However, f and Bf are shown only for the in-focus state. In the magnification status column, "Wide," "Middle," and "Tele" refer to the wide-angle end, intermediate focal length, and telephoto end, respectively.

[0090] In the basic lens data table, the aspherical surface number is 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 (m=3, 4, 5, ..., 16) show the numerical value of the aspherical coefficient for each aspherical surface. The value of the aspherical coefficient in Table 3, "E±n" (n: integer), is multiplied by 10. ±n This 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 ×h2 ) 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 Z to which the aspherical surface tangent is located). h: Height (distance from the optical axis Z 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.

[0091] In the data in each table, degrees are used as the unit of angle, and millimeters are used as the unit of length, except for object distances in the specifications table. However, since optical systems can be used even with proportional enlargement or reduction, other appropriate units can also be used. In addition, the values ​​shown in the following tables are rounded to a predetermined number of decimal places.

[0092] [Table 1]

[0093] [Table 2]

[0094] [Table 3]

[0095] Figure 3 shows the aberration diagrams for the zoom lens of Example 1 when focused on an object at infinity. In Figure 3, the upper section labeled "Wide" shows the aberrations at the wide-angle end, the middle section labeled "Middle" shows the aberrations at intermediate focal lengths, and the lower section labeled "Tele" shows the aberrations at the telephoto end. From left to right in Figure 3, the diagrams show spherical aberration, astigmatism, distortion, and chromatic aberration. In the spherical aberration diagram, the aberrations along the d, C, F, and g lines are shown as solid lines, long dashed lines, short dashed lines, and dashed lines, respectively. In the astigmatism diagram, the aberration along the d line in the sagittal direction is shown as a solid line, and the aberration along the d line in the tangential direction is shown as a short dashed line. In the distortion diagram, the aberration along the d line is shown as a solid line. In the chromatic aberration diagram, the aberrations along the C and F lines are shown as long dashed lines and short dashed lines, respectively. In the spherical aberration diagram, the value of the wide-open aperture F-number is shown after FNo.=. In other aberration diagrams, the value of the maximum half-angle is shown after ω=.

[0096] The symbols, meanings, methods of description, and methods of illustration for each data point in Example 1 described above are basically the same in the following examples unless otherwise specified, so redundant explanations will be omitted below.

[0097] [Example 2] Figure 4 shows the configuration and movement trajectory of the zoom lens of Example 2. The zoom lens of Example 2 consists of, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having positive refractive power, and a sixth lens group G6 having negative refractive power. The subsequent group GR consists of the fifth lens group G5 and the sixth lens group G6.

[0098] When changing magnification from the wide-angle end to the telephoto end, the second lens group G2, the third lens group G3, and the fifth lens group G5 move along the optical axis Z by changing the spacing between adjacent lens groups, while the other lens groups remain fixed relative to the image plane Sim. The focusing group consists of the fifth lens group G5. When focusing from an object at infinity to the nearest object, the focusing group moves toward the object.

[0099] 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 5.

[0100] [Table 4]

[0101] [Table 5]

[0102] [Table 6]

[0103] [Example 3] Figure 6 shows the configuration and movement trajectory of the zoom lens of Example 3. 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 positive refractive power, a third lens group G3 having negative refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having positive refractive power, and a sixth lens group G6 having positive refractive power. The subsequent group GR consists of the fifth lens group G5 and the sixth lens group G6.

[0104] When changing magnification from the wide-angle end to the telephoto end, the second lens group G2, the third lens group G3, and the fifth lens group G5 move along the optical axis Z by changing the spacing between adjacent lens groups, while the other lens groups remain fixed relative to the image plane Sim. The focusing group consists of the fifth lens group G5. When focusing from an object at infinity to the nearest object, the focusing group moves toward the object.

[0105] 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 7.

[0106] [Table 7]

[0107] [Table 8]

[0108] [Table 9]

[0109] [Example 4] Figure 8 shows the configuration and movement trajectory of the zoom lens of Example 4. 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 positive refractive power, a third lens group G3 having negative refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having positive refractive power, and a sixth lens group G6 having negative refractive power. The subsequent group GR consists of the fifth lens group G5 and the sixth lens group G6.

[0110] When changing magnification from the wide-angle end to the telephoto end, the second lens group G2, the third lens group G3, and the fifth lens group G5 move along the optical axis Z by changing the spacing between adjacent lens groups, while the other lens groups remain fixed relative to the image plane Sim. The focusing group consists of the fifth lens group G5. When focusing from an object at infinity to the nearest object, the focusing group moves toward the object.

[0111] 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 9.

[0112] [Table 10]

[0113] [Table 11]

[0114] [Table 12]

[0115] [Example 5] Figure 10 shows the configuration and movement trajectory of the zoom lens of Example 5. 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 positive refractive power, a third lens group G3 having negative refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having positive refractive power, and a sixth lens group G6 having negative refractive power. The subsequent group GR consists of the fifth lens group G5 and the sixth lens group G6.

[0116] When changing magnification from the wide-angle end to the telephoto end, the second lens group G2, the third lens group G3, and the fifth lens group G5 move along the optical axis Z by changing the spacing between adjacent lens groups, while the other lens groups remain fixed relative to the image plane Sim. The focusing group consists of the fifth lens group G5. When focusing from an object at infinity to the nearest object, the focusing group moves toward the object.

[0117] 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 11.

[0118] [Table 13]

[0119] [Table 14]

[0120] [Table 15]

[0121] [Example 6] Figure 12 shows the configuration and movement trajectory of the zoom lens of Example 6. The zoom lens of Example 6 consists of, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having positive refractive power, and a sixth lens group G6 having negative refractive power. The subsequent group GR consists of the fifth lens group G5 and the sixth lens group G6.

[0122] When changing magnification from the wide-angle end to the telephoto end, the second lens group G2, the third lens group G3, and the fifth lens group G5 move along the optical axis Z by changing the spacing between adjacent lens groups, while the other lens groups remain fixed relative to the image plane Sim. The focusing group consists of the fifth lens group G5. When focusing from an object at infinity to the nearest object, the focusing group moves toward the object.

[0123] 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 13.

[0124] [Table 16]

[0125] [Table 17]

[0126] [Table 18]

[0127] [Example 7] Figure 14 shows the configuration and movement trajectory of the zoom lens of Example 7. The zoom lens of Example 7 consists of, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having negative refractive power, a sixth lens group G6 having positive refractive power, and a seventh lens group G7 having negative refractive power. The subsequent group GR consists of the fifth lens group G5, the sixth lens group G6, and the seventh lens group G7.

[0128] When changing magnification from the wide-angle end to the telephoto end, the second lens group G2, the third lens group G3, the fifth lens group G5, and the sixth lens group G6 move along the optical axis Z by changing the spacing between adjacent lens groups, while the other lens groups remain fixed relative to the image plane Sim. The focusing group consists of the sixth lens group G6. When focusing from an object at infinity to the nearest object, the focusing group moves toward the object.

[0129] 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 15.

[0130] [Table 19]

[0131] [Table 20]

[0132] [Table 21]

[0133] [Example 8] Figure 16 shows the configuration and movement trajectory of the zoom lens of Example 8. The zoom lens of Example 8 consists of, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having positive refractive power, and a sixth lens group G6 having positive refractive power. The subsequent group GR consists of the fifth lens group G5 and the sixth lens group G6.

[0134] When changing magnification from the wide-angle end to the telephoto end, the second lens group G2, the third lens group G3, and the fifth lens group G5 move along the optical axis Z by changing the spacing between adjacent lens groups, while the other lens groups remain fixed relative to the image plane Sim. The focusing group consists of the fifth lens group G5. When focusing from an object at infinity to the nearest object, the focusing group moves toward the object.

[0135] 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 17.

[0136] [Table 22]

[0137] [Table 23]

[0138] [Table 24]

[0139] Table 25 shows the corresponding values ​​for conditional equations (1) to (13) of the zoom lenses in Examples 1 to 8. The corresponding values ​​for the examples shown in Table 25 may be used as the upper or lower limits of the conditional equations to set a preferred range for the conditional equations.

[0140] [Table 25]

[0141] The zoom lenses in Examples 1-8, while being compact in design, achieve a zoom magnification of 20x or more, thus realizing high magnification.

[0142] Next, an imaging device according to an embodiment of this disclosure will be described. Figure 18 shows a schematic configuration diagram of an imaging device 500 according to one embodiment of this disclosure. The imaging device 500 comprises a zoom lens 1 according to one embodiment of this disclosure, a filter 2 disposed on the image side of the zoom lens 1, and an image sensor 3 disposed on the image side of the filter 2. In Figure 18, the multiple lenses provided by the zoom lens 1 are schematically shown.

[0143] The image sensor 3 converts the optical image formed by the zoom lens 1 into an electrical signal, and can be, for example, a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor). The image sensor 3 is positioned so that its imaging surface coincides with the image plane of the zoom lens 1.

[0144] The imaging device 500 also includes a signal processing unit 5, a display unit 6, a magnification control unit 7, and a focus control unit 8. The signal processing unit 5 performs calculations on the output signal from the image sensor 3. The display unit 6 displays the image formed by the signal processing unit 5. The magnification control unit 7 controls the magnification of the zoom lens 1. The focus control unit 8 controls the focusing of the zoom lens 1. Although only one image sensor 3 is shown in Figure 18, the imaging device may also be a so-called three-chip system having three image sensors.

[0145] Next, an imaging device according to an embodiment of the present disclosure will be described. Figures 19 and 20 show external views of a camera 30, which is an imaging device according to one embodiment of the present disclosure. Figure 19 shows a perspective view of the camera 30 from the front, and Figure 20 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 to it. 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.

[0146] The camera 30 comprises a camera body 31. A shutter button 32 and a power button 33 are provided on the top surface of the camera body 31. An operation unit 34, an operation unit 35, and a display unit 36 ​​are provided on the back surface of the camera body 31. The display unit 36 ​​can display captured images and images within the field of view before capturing.

[0147] A shooting aperture is provided in the center of the front of the camera body 31, through which light from the subject being photographed enters. A mount 37 is provided at a position corresponding to the shooting aperture, and the interchangeable lens 20 is attached to the camera body 31 via the mount 37.

[0148] An image sensor 38 is provided inside the camera body 31. The image sensor 38 outputs an imaging signal corresponding to the subject image formed by the interchangeable lens 20. For example, a CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor) can be used as the image sensor 38. A signal processing circuit (not shown) and a recording medium (not shown) are provided inside the camera body 31. The signal processing circuit processes the imaging signal output from the image sensor 38 to generate an image. The recording medium is for recording the generated image. With the camera 30, still images or videos can be taken by pressing the shutter button 32, and the image data obtained from this shooting is recorded on the recording medium.

[0149] Although the technology of this disclosure has been described above with reference to embodiments and examples, the technology of this disclosure is not limited to the above embodiments and examples, and various modifications are possible. For example, the radius of curvature, interplanar spacing, refractive index, Abbe number, and aspheric coefficient of each lens are not limited to the values ​​shown in each of the above embodiments, but can take other values.

[0150] Furthermore, the imaging device according to the embodiments of this disclosure is not limited to the above examples, and can take various forms, such as cameras other than mirrorless types, cameras in which the imaging lens and camera body are integrally configured, film cameras, video cameras, surveillance cameras, broadcast cameras, movie cameras, FA (Factory Automation) cameras, and MV (Machine Vision) cameras.

[0151] The following additional information is disclosed regarding the above embodiments and examples. [Note 1] 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 positive refractive power, a third lens group having negative refractive power, a fourth lens group, and a subsequent group consisting of two or more lens groups, When magnification is applied, the spacing between all adjacent lens groups changes. The aforementioned successor group has a focusing group that moves along the optical axis when focusing occurs. The focal length of the first lens group is f1, If the focal length of the zoom lens when it is in focus on an object at infinity at the telephoto end is denoted as ft, 0.4 <f1 / ft<1 (1) A zoom lens that satisfies the condition (1) represented by . [Note 2] The maximum aperture F-number when focusing on an object at infinity at the telephoto end is called FNo. The lateral magnification of the second lens group when focused on an object at infinity at the telephoto end is β2, When the telephoto end is focused on an object at infinity, the combined lateral magnification of all lenses on the image side from the second lens group is β2R. The lateral magnification of the third lens group when focused on an object at infinity at the telephoto end is β3, When the lens group is in focus on an object at infinity at the telephoto end, the combined lateral magnification of all lenses on the image side from the third lens group is defined as β3R. S2=(1-β2 2 )×β2R 2 S3=(1-β3 2 )×β3R 2 If we define S2 and S3 as represented by, 0.1 < |S2 + S3| / FNo < 0.7 (2) A zoom lens as described in Appendix 1 that satisfies the conditional expression (2) represented by . [Note 3] When the focal length of the second lens group is set to f2, 1.02 <f1 / f2<2 (3) A zoom lens as described in Appendix 1 or Appendix 2 that satisfies the conditional expression (3) represented by . [Note 4] 0.5 <f1 / ft<0.9 (1-1) A zoom lens described in any one of the appendices 1 to 3 that satisfies the conditional expression (1-1) represented by . [Note 5] 0.2 < |S2 + S3| / FNo < 0.65 (2-1) A zoom lens as described in Appendix 2 that satisfies the conditional expression (2-1) represented by . [Note 6] If the minimum refractive index of all lenses included in the third lens group with respect to the d line is N3min, 1.65 <N3min<1.95 (4) A zoom lens described in any one of the appendices 1 to 5 that satisfies the conditional expression (4) represented by . [Note 7] If θgFp is the average value of the partial dispersion ratio between the g-line and the F-line of all positive lenses included in the third lens group, 0.615 < θgFp < 0.66 (5) A zoom lens described in any one of the appendices 1 to 6 that satisfies the conditional expression (5) represented by . [Note 8] 0.62 < θgFp < 0.65 (5-1) A zoom lens as described in Appendix 7 that satisfies the conditional expression (5-1) represented by . [Note 9] If the refractive index of the negative lens included in the first lens group with respect to the d line is N1n, 1.85 <N1n<2.15 (6) A zoom lens as described in any one of Appendix 1 to Appendix 8, which includes at least one negative lens that satisfies the conditional expression (6) represented by . [Note 10] If the Abbe number of the positive lens included in the second lens group, with respect to the d line, is ν2p, then 65 < ν²p < 99 (7) A zoom lens as described in any one of the appendices 1 to 9, which includes at least one positive lens that satisfies the conditional expression (7) represented by . [Note 11] When the focal length of the third lens group is set to f3, -15 <f1 / f3<-10 (8) A zoom lens described in any one of the appendices 1 to 10 that satisfies the conditional expression (8) represented by . [Note 12] The difference in the optical axis direction between the position of the second lens group when it is in focus on an object at infinity at the wide-angle end and the position of it when it is in focus on an object at infinity at the telephoto end is D2. If D3 is the difference in the optical axis direction between the position of the third lens group when it is in focus on an object at infinity at the wide-angle end and the position of it when it is in focus on an object at infinity at the telephoto end, 2 <D3 / D2<3 (9) A zoom lens described in any one of the appendices 1 to 11 that satisfies the conditional expression (9) represented by . [Note 13] The fourth lens group has positive refractive power A zoom lens as described in any one of the notes 1 through 12. [Note 14] The focusing group has positive refractive power A zoom lens as described in any one of the notes 1 through 13. [Note 15] The focal length of the fourth lens group is set to f4. If the focal length of the aforementioned focusing group is fF, 1.8 <f4 / fF<3 (10) A zoom lens described in any one of the appendices 1 to 14 that satisfies the conditional expression (10) represented by . [Note 16] The first lens group is fixed to the image plane during magnification. A zoom lens as described in any one of the notes 1 through 15. [Note 17] The second lens group consists of a single positive lens. A zoom lens as described in any one of the notes 1 through 16. [Note 18] The focusing group includes at least one aspherical lens. A zoom lens as described in any one of the notes 1 through 17. [Note 19] The third lens group includes at least three negative lenses. A zoom lens as described in any one of the notes 1 through 18. [Note 20] An imaging device equipped with a zoom lens as described in any one of the appendices 1 through 19. [Explanation of symbols]

[0152] 1 Zoom lens 2 filters 3 Image sensor 5. Signal Processing Unit 6 Display section 7. Multiplication Control Unit 8. Focusing Control Unit 20 interchangeable lenses 30 Cameras 31 Camera Body 32 Shutter button 33 Power button 34 Control section 35 Control section 36 Display section 37 Mount 38 Image sensor 500 Imaging device The difference in the optical axis direction between the position of the second lens group of D2 at the wide-angle end and the position at the telephoto end. Difference in the optical axis direction between the position of the third lens group of the D3 at the wide-angle end and the position at the telephoto end. G1 First Lens Group G2 Second Lens Group G3 3rd lens group G4 4th lens group G5 5th lens group G6 6th lens group G7 7th lens group GR follow-up group L11~L62 Lenses PP optical components Sim image plane St aperture diaphragm Z optical axis ωt Maximum half-angle ωw Maximum half-angle

Claims

1. 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 positive refractive power, a third lens group having negative refractive power, a fourth lens group, and a subsequent group consisting of two or more lens groups, When magnification is applied, the spacing between all adjacent lens groups changes. The aforementioned successor group has a focusing group that moves along the optical axis when focusing occurs. The focal length of the first lens group is f1, If the focal length of the zoom lens when it is in focus on an object at infinity at the telephoto end is denoted as ft, 0.4<f1 / ft<1 (1) A zoom lens that satisfies the condition (1) represented by .

2. The maximum aperture F-number when focusing on an object at infinity at the telephoto end is denoted as FNo. The lateral magnification of the second lens group when focused on an object at infinity at the telephoto end is β2, When the telephoto end is focused on an object at infinity, the combined lateral magnification of all lenses on the image side from the second lens group is β2R. The lateral magnification of the third lens group when focused on an object at infinity at the telephoto end is β3, When the telephoto end is focused on an object at infinity, the combined lateral magnification of all lenses on the image side from the third lens group is set to β3R. S2=(1-β2 ２ )×β2R ２ S3=(1-β3 ２ )×β3R ２ If S2 and S3 are defined as shown, 0.1<|S2+S3| / FNo.<0.7 (2) A zoom lens according to claim 1 that satisfies the conditional expression (2) represented by .

3. When the focal length of the second lens group is set to f2, 1.02<f1 / f2<2 (3) A zoom lens according to claim 1 that satisfies the conditional expression (3) represented by .

4. 0.5<f1 / ft<0.9 (1-1) A zoom lens according to claim 1 that satisfies the conditional expression (1-1) represented by .

5. 0.2<|S2+S3| / FNo<0.65 (2-1) A zoom lens according to claim 2 that satisfies the conditional expression (2-1) represented by .

6. If N3min is the minimum value of the refractive index for the d line of all lenses included in the third lens group, 1.65<N3min<1.95 (4) A zoom lens according to claim 1 that satisfies the conditional expression (4) represented by .

7. If θgFp is the average value of the partial dispersion ratio between the g-line and the F-line of all positive lenses included in the third lens group, 0.615<θgFp<0.66 (5) A zoom lens according to claim 1 that satisfies the conditional expression (5) represented by .

8. 0.62<θgFp<0.65 (5-1) A zoom lens according to claim 7 that satisfies the conditional expression (5-1) represented by .

9. When the refractive index of the negative lens included in the first lens group with respect to the d line is N1n, 1.85<N1n<2.15 (6) The zoom lens according to claim 1, which includes at least one negative lens that satisfies the conditional expression (6) represented by .

10. If the Abbe number of the positive lens included in the second lens group, with respect to the d line, is ν²p, 65<ν2p<99 (7) The zoom lens according to claim 1, which includes at least one positive lens that satisfies the conditional expression (7) represented by .

11. When the focal length of the third lens group is set to f3, -15<f1 / f3<-10 (8) A zoom lens according to claim 1 that satisfies the conditional expression (8) represented by .

12. The difference in the optical axis direction between the position of the second lens group when it is in focus on an object at infinity at the wide-angle end and the position of it when it is in focus on an object at infinity at the telephoto end is D2. If D3 is the difference in the optical axis direction between the position of the third lens group when it is in focus on an object at infinity at the wide-angle end and the position of it when it is in focus on an object at infinity at the telephoto end, 2<D3 / D2<3 (9) A zoom lens according to claim 1 that satisfies the conditional expression (9) represented by .

13. The fourth lens group has positive refractive power The zoom lens according to claim 1.

14. The focusing group has positive refractive power The zoom lens according to claim 1.

15. The focal length of the fourth lens group is f4, When the focal length of the aforementioned focusing group is fF, 1.8<f4 / fF<3 (10) A zoom lens according to claim 1 that satisfies the conditional expression (10) represented by .

16. The first lens group is fixed to the image plane during magnification. The zoom lens according to claim 1.

17. The second lens group consists of a single positive lens. The zoom lens according to claim 1.

18. The focusing group includes at least one aspherical lens. The zoom lens according to claim 1.

19. The third lens group includes at least three negative lenses. The zoom lens according to claim 1.

20. An imaging device comprising a zoom lens according to any one of claims 1 to 19.

Images