Zoom lens and imaging device

Abstract

To provide a zoom lens and an imaging apparatus that have a large aperture ratio, are compact, and exhibit excellent optical performance.SOLUTION: In a zoom lens, a lens located on the most image side of a second positive portion group Mp2 is a positive lens. All lenses and cemented lenses constituting a second negative portion group Mn2 have negative refractive power, and when the second negative portion group Mn2 includes a cemented lens, the cemented lens is the cemented lens formed by joining two lenses having refractive powers of mutually-different signs. All lenses and cemented lenses constituting the second positive portion group Mp2 have positive refractive power, and when the second positive portion group Mp2 includes the cemented lens, the cemented lens is the cemented lens formed by joining two lenses having refractive powers of mutually-different signs. During zooming, the spacing between adjacent lens groups changes, and during focusing, a lens group F moves along the optical axis. The zoom lens satisfies predetermined conditional expressions.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a zoom lens and an imaging device.

Background Art

[0002] Imaging devices using solid-state imaging elements such as digital still cameras and digital video cameras have become widespread. Examples of such imaging devices include various types such as digital still cameras, digital video cameras, broadcast cameras, surveillance cameras, and in-vehicle cameras. In any imaging device, there is a strong market demand for a zoom lens with a large aperture ratio and high optical performance.

[0003] As an optical configuration of a zoom lens, for example, a positive-lead type configuration having a lens group with a positive refractive power on the object side is known. In a positive-lead type zoom lens, generally, a strong negative refractive power is arranged in the second lens group second from the object side, and a large zooming burden is given to the second lens group, so that it is easy to realize high zooming. In such a positive-lead type zoom lens, since the telephoto tendency becomes strong, the overall optical length can be shortened compared to the focal length.

[0004] Here, in order to obtain a zoom lens with a small F-number and high optical performance, it is necessary to satisfactorily correct various aberrations generated by increasing the aperture ratio. Therefore, in a zoom lens with a small F-number, it is difficult to arrange a strong refractive power in each lens group compared to a zoom lens with a large F-number, and the entire system tends to be enlarged. Also, in order to obtain a zoom lens with a small F-number, it is preferable to arrange a lens group with a strong positive refractive power on the image side, that is, behind the entire system. However, when a lens group with a strong positive refractive power is arranged behind the entire system, it becomes difficult to obtain a zoom lens with a strong telephoto tendency, and it becomes difficult to shorten the overall optical length. Thus, in order to realize a zoom lens with a large aperture ratio, high optical performance, and further reduced size, it is necessary to appropriately set the power arrangement, imaging magnification, lens configuration, etc., of each lens group.

[0005] In recent years, digital still cameras that capture images using live view have become widespread. When capturing images using live view, the camera focuses on the subject using either phase-detection autofocus (AF) or contrast-detection autofocus (AF) methods. In particular, contrast-detection AF constantly moves the focus group to focus on the subject. Furthermore, in recent years, digital still cameras employing tracking AF have also become widely popular. Tracking AF is an autofocus function that, after focusing on the subject to be captured, constantly maintains focus on the subject by moving the focus group in accordance with the subject's movement.

[0006] When using contrast AF or tracking AF for video recording, the size of the subject on the image sensor changes as the focus group moves. If this change in image magnification due to the movement of the focus group is large, it can cause discomfort to the person viewing the live view image. It is known that this change in image magnification becomes larger the closer the focus group is to the object, i.e., the further forward it is positioned in the optical system. Therefore, it is necessary to set the position of the focus group appropriately.

[0007] Currently, the following types of zoom lenses are known. For example, Patent Document 1 discloses a bright zoom lens with a positive-negative-positive-negative-positive refractive power group arranged in order from the object side, and an F-number of approximately 1.9 to F2.8. However, this zoom lens has not achieved sufficient miniaturization because the combined refractive power of the first to third lens groups is weak, and a group of lenses with strong positive refractive power is positioned at the rear of the entire system.

[0008] Patent Document 2 discloses a bright zoom lens with an aperture of approximately F2.8, comprising lens groups with refractive powers of positive, negative, positive, negative, and positive in order from the object side. However, in this zoom lens, the second lens group on the object side of the aperture is used as the focusing group. In other words, because the focusing group is located in front of the entire system, there is a problem that the image magnification changes significantly, which is undesirable for tracking AF and contrast AF. Furthermore, the second lens group is relatively heavy, and when employing contrast AF, it becomes difficult to perform rapid focusing with this zoom lens due to the weight of the focusing group. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] WO2017 / 99243 publication [Patent Document 2] Japanese Patent Publication No. 2020-197600 [Overview of the project] [Problems that the invention aims to solve]

[0010] The object of the present invention has been viewed in view of the above problems, and is to provide a zoom lens that is compact overall despite having a large aperture ratio and excellent optical performance, and an imaging device having said zoom lens. [Means for solving the problem]

[0011] To solve the above problems, the zoom lens according to the present invention is composed of, in order from the object side, a first lens group with positive refractive power, a second lens group with negative refractive power, an intermediate group M having one or more lens groups and having positive refractive power as a whole, a lens group F with negative refractive power, and a rear group R having one or more lens groups, wherein the intermediate group M is composed of, in order from the object side, a first positive subgroup Mp1 consisting of one or two positive lenses, a first negative subgroup Mn1 consisting of only one cemented lens formed by joining two or more lenses, a second negative subgroup Mn2 having a negative lens with a concave surface facing the object side, and a second positive subgroup Mp2 having one or two positive lenses, wherein the lens closest to the image in the second positive subgroup Mp2 is a positive lens, and the The lenses and cemented lenses constituting the second negative subgroup Mn2 are all lenses with negative refractive power, and when the second negative subgroup Mn2 has the cemented lens, the cemented lens is a cemented lens formed by joining two lenses having refractive powers of different signs; the lenses and cemented lenses constituting the second positive subgroup Mp2 are all lenses with positive refractive power, and when the second positive subgroup Mp2 has the cemented lens, the cemented lens is a cemented lens formed by joining two lenses having refractive powers of different signs; the spacing between adjacent lens groups changes during zooming, and during focusing, the lens group F moves along the optical axis, satisfying the following conditional equation. 0.3 ≦ BFw / Y ≦ 1.5 (6) however, BFw: The back focus of the zoom lens at the wide-angle end, calculated by converting the cover glass thickness to air equivalent. Y: Maximum image height of the zoom lens

[0012] Furthermore, in order to solve the above-mentioned problems, the imaging device according to the present invention is characterized by comprising the zoom lens and an image sensor that converts the optical image formed by the zoom lens into an electrical signal. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a zoom lens that has a large aperture ratio, is overall small in size, and has excellent optical performance, and an imaging device having the zoom lens.

Brief Description of the Drawings

[0014] [Figure 1] It is a lens cross-sectional view at the wide-angle end of the zoom lens of Example 1. [Figure 2] It is a spherical aberration diagram, a coma aberration diagram, and a distortion aberration diagram at infinity focus at the wide-angle end of the zoom lens of Example 1. [Figure 3] It is a spherical aberration diagram, a coma aberration diagram, and a distortion aberration diagram at infinity focus at the intermediate focal length of the zoom lens of Example 1. [Figure 4] It is a spherical aberration diagram, a coma aberration diagram, and a distortion aberration diagram at infinity focus at the telephoto end of the zoom lens of Example 1. [Figure 5] It is a lens cross-sectional view at the wide-angle end of the zoom lens of Example 2. [Figure 6] It is a spherical aberration diagram, a coma aberration diagram, and a distortion aberration diagram at infinity focus at the wide-angle end of the zoom lens of Example 2. [Figure 7] It is a spherical aberration diagram, a coma aberration diagram, and a distortion aberration diagram at infinity focus at the intermediate focal length of the zoom lens of Example 2. [Figure 8] It is a spherical aberration diagram, a coma aberration diagram, and a distortion aberration diagram at infinity focus at the telephoto end of the zoom lens of Example 2. [Figure 9] It is a lens cross-sectional view at the wide-angle end of the zoom lens of Example 3. [Figure 10] It is a spherical aberration diagram, a coma aberration diagram, and a distortion aberration diagram at infinity focus at the wide-angle end of the zoom lens of Example 3. [Figure 11] It is a spherical aberration diagram, a coma aberration diagram, and a distortion aberration diagram at infinity focus at the intermediate focal length of the zoom lens of Example 3. [Figure 12] It is a spherical aberration diagram, a coma aberration diagram, and a distortion aberration diagram at infinity focus at the telephoto end of the zoom lens of Example 3. [Figure 13]It is a lens cross-sectional view at the wide-angle end of the zoom lens of Example 4. [Figure 14] It is a spherical aberration diagram, astigmatism diagram, and distortion aberration diagram at infinity focus at the wide-angle end of the zoom lens of Example 4. [Figure 15] It is a spherical aberration diagram, astigmatism diagram, and distortion aberration diagram at infinity focus at the intermediate focal length of the zoom lens of Example 4. [Figure 16] It is a spherical aberration diagram, astigmatism diagram, and distortion aberration diagram at infinity focus at the telephoto end of the zoom lens of Example 4. [Figure 17] It is a lens cross-sectional view at the wide-angle end of the zoom lens of Example 5. [Figure 18] It is a spherical aberration diagram, astigmatism diagram, and distortion aberration diagram at infinity focus at the wide-angle end of the zoom lens of Example 5. [Figure 19] It is a spherical aberration diagram, astigmatism diagram, and distortion aberration diagram at infinity focus at the intermediate focal length of the zoom lens of Example 5. [Figure 20] It is a spherical aberration diagram, astigmatism diagram, and distortion aberration diagram at infinity focus at the telephoto end of the zoom lens of Example 5. [Figure 21] It is a lens cross-sectional view at the wide-angle end of the zoom lens of Example 6. [Figure 22] It is a spherical aberration diagram, astigmatism diagram, and distortion aberration diagram at infinity focus at the wide-angle end of the zoom lens of Example 6. [Figure 23] It is a spherical aberration diagram, astigmatism diagram, and distortion aberration diagram at infinity focus at the intermediate focal length of the zoom lens of Example 6. [Figure 24] It is a spherical aberration diagram, astigmatism diagram, and distortion aberration diagram at infinity focus at the telephoto end of the zoom lens of Example 6.

Modes for Carrying Out the Invention

[0015] The following describes embodiments of the zoom lens and imaging device according to the present invention. However, the zoom lens and imaging device described below are only one embodiment of the zoom lens and imaging device according to the present invention, and the zoom lens and imaging device according to the present invention are not limited to the following embodiments.

[0016] 1. Zoom lens 1-1.Optical configuration The zoom lens of this embodiment is composed of, in order from the object side, a first lens group with positive refractive power, a second lens group with negative refractive power, an intermediate group M having one or more lens groups and having a positive refractive power as a whole, a lens group F with negative refractive power, and a rear group R having one or more lens groups. The optical configuration of this zoom lens will be described below.

[0017] (1) First lens group As long as the first lens group as a whole has a positive refractive power, its specific lens configuration is not particularly limited. For example, a configuration including two positive lenses allows for a strong positive refractive power in the first lens group. In this case, a high magnification ratio can be achieved while strengthening the telephoto tendency at the telephoto end, making it easier to miniaturize the entire system. A strong telephoto tendency means that the telephoto ratio value is smaller. Furthermore, a configuration including at least one negative lens is preferable for realizing a zoom lens with excellent optical performance, as it facilitates correction of spherical aberration, chromatic aberration, etc.

[0018] (2) Second lens group As long as the second lens group as a whole has a negative refractive power, its specific lens configuration is not particularly limited. For example, a configuration including two or more negative lenses and one or more positive lenses allows for a strong negative refractive power in the second lens group. In this case, it becomes easier to increase the magnification ratio of the second lens group, making it easier to achieve a high magnification ratio while realizing excellent optical performance. Furthermore, it is preferable that the lens surface of the second lens group closest to the object is convex towards the object. This makes it easier to effectively correct field curvature at the wide-angle end.

[0019] (3) Intermediate group M The intermediate group M consists of one or more lens groups and has a positive refractive power as a whole. In this zoom lens, the intermediate group M consists of, in order from the object side, a first positive subgroup Mp1 consisting of one or two positive lenses, a first negative subgroup Mn1 consisting of only one cemented lens formed by joining two or more lenses, a second negative subgroup Mn2 having a negative lens with a concave surface facing the object side, and a second positive subgroup Mp2 having one or two positive lenses. Furthermore, the intermediate group M consists of one or more lens groups positioned between the second lens group and lens group F. In this invention, lens groups are divided at a variable spacing during zooming. When the intermediate group M consists of one lens group, the spacing between adjacent subgroups is fixed and does not change during zooming. When the intermediate group M consists of two or more lens groups, the spacing between some of these subgroups may be variable during zooming, or some subgroups may contain variable spacing.

[0020] By positioning the first positive subgroup Mp1 on the object side of the intermediate group M, it becomes easier to miniaturize the entire zoom lens system. Furthermore, by positioning the second positive subgroup Mp2 on the image side, it becomes easier to ensure a bright F-number for the entire zoom lens system. Furthermore, in order to realize a zoom lens with a large aperture ratio and a compact size, it is preferable to place a strong positive refractive force in the intermediate group M to focus the light beam. When a strong positive refractive force is placed in the intermediate group M, it is necessary to correct the under-spherical aberration and field curvature that occur in the intermediate group M with a strong divergence effect. Therefore, in this zoom lens, by placing the first negative subgroup Mn1 and the second negative subgroup Mn2 in the intermediate group M, a relatively strong positive refractive force is placed in the intermediate group M by the first positive subgroup Mp1 and the second positive subgroup Mp2, while the under-spherical aberration and field curvature can be well corrected with a strong divergence effect, resulting in a zoom lens that is compact overall and has excellent optical performance despite having a large aperture ratio.

[0021] The following describes the preferred configurations for each subgroup. The first positive subgroup Mp1 is a subgroup with positive refractive power. As long as the first positive subgroup Mp1 consists of one or two positive lenses, its specific lens configuration is not particularly limited. Preferably, the lens closest to the object in the first positive subgroup Mp1 is a positive meniscus lens with its convex surface facing the object. This configuration makes it easier to further reduce the diameter of the intermediate group M.

[0022] The first negative subgroup Mn1 is a subgroup of negative refractive power. The first negative subgroup Mn1 only needs to consist of one cemented lens formed by joining two or more lenses, and is not particularly limited in other respects. For example, it is preferable that the cemented lens has at least one cemented surface with a convex surface facing the object. If the first negative subgroup Mn1 is constructed using a cemented lens with a cemented surface with a convex surface facing the object, it becomes easier to correct field curvature well across the entire zoom range.

[0023] The second negative subgroup Mn2 is a subgroup with negative refractive power. The second negative subgroup Mn2 has a negative lens with its concave surface facing the object. As long as the second negative subgroup Mn2 has this negative lens, the other specific configurations are not particularly limited. It may include other negative lenses in addition to the said negative lens, or it may include positive lenses as long as the whole exhibits negative refractive power. Furthermore, it is preferable that the object side of the said negative lens has a stronger curvature with respect to the image side. This allows for better correction of spherical aberration.

[0024] The second positive subgroup Mp2 is a subgroup with positive refractive power. The second positive subgroup Mp2 has at least one or two positive lenses, and as long as the lens closest to the image is a positive lens, the other specific configurations are not particularly limited. Preferably, the image side of the closest positive lens in the second positive subgroup Mp2 is convex toward the image side. This makes it easier to ensure a bright F-number for the entire zoom lens system.

[0025] The intermediate group M preferably has at least one air lens with negative refractive power. This makes it easier to ensure the divergence effect in the intermediate group M, and makes it easier to correct spherical aberration and field curvature more effectively. The refractive power of an air lens is generated by the shape of the adjacent lens surfaces that are spaced apart by air, resulting in either negative or positive refractive power. In this zoom lens, since it has an air lens with negative refractive power, the air lens has a shape similar to a positive lens, such as a biconvex, plano-convex, or positive meniscus shape.

[0026] Furthermore, if the intermediate group M consists of two or more lens groups, it becomes easier to suppress aberration fluctuations by changing the spacing between adjacent lens groups along the optical axis during zooming, thereby enabling the creation of a zoom lens with higher optical performance. However, if the number of lens groups constituting the intermediate group M increases, it becomes difficult to obtain a compact zoom lens. Therefore, in order to obtain a compact zoom lens, it is preferable that the number of lens groups constituting the intermediate group M be three or less.

[0027] For cemented lenses included in the intermediate group M, when the lenses constituting each cemented lens are denoted as lenses LCn (n=1,2,3...), it is preferable that the refractive power φLCn of each lens LCn satisfies φLCn≧0.005. This configuration makes it easy to strengthen the divergence effect of the cemented surface of the cemented lens. The refractive power φLCn is defined by the following formula, where "n" represents the arrangement order of each lens LCn in the intermediate group M from the object side. φLCn=|(NLCn-1)(1 / LCnR1-1 / LCnR2)| NLCn: Refractive index of the lens LCn material at the d line. LCnR1: Radius of curvature of the object side surface of the lens LCn. LCnR2: Radius of curvature of the image surface of the lens LCn. However, if the center of curvature of the lens surface is on the image side of the lens surface, the sign of the radius of curvature is positive, and if the center of curvature of the lens surface is on the object side of the lens surface, the sign of the radius of curvature is negative. The same applies to the sign of the radius of curvature for other conditional equations.

[0028] (4) Lens group F Lens group F is the focusing group that moves along the optical axis during focusing. Since lens group F is positioned on the image side of intermediate group M, the light beam converged by intermediate group M is incident on it, making it easy to create a lens with a small diameter and a lightweight configuration. Therefore, by making lens group F the focusing group, high-speed autofocus can be achieved, and the load on the focus drive system can be easily reduced. As long as lens group F has a negative refractive power as a whole, its specific lens configuration is not particularly limited, but it is more preferable to consist only of a cemented lens formed by joining one negative lens and one positive lens. With such a configuration, it is easy to achieve high-speed autofocus by reducing the weight of the focusing group and to obtain a high-performance zoom lens in which various aberrations such as spherical aberration and chromatic aberration are well corrected over the entire range of object distances.

[0029] (5) Rear group R The rear group R has one or more lens groups. The rear group R is composed of lens groups arranged between lens group F and the image plane. Preferably, the rear group R has at least one lens group with negative refractive power, and preferably has negative refractive power as a whole. With such a configuration, it is easy to obtain a zoom lens with a stronger telephoto tendency at the telephoto end, and it is easy to shorten the optical length at the telephoto end. The rear group R may have two or more lens groups, but as the number of lens groups constituting the zoom lens increases, it becomes difficult to miniaturize the lens.

[0030] (6) Aperture diaphragm It is preferable to place the aperture diaphragm on the object side of the intermediate group M, or within the intermediate group M. In particular, by placing it adjacent to the object side of the intermediate group M, i.e., adjacent to the object side of the first positive subgroup Mp1, it becomes easier to reduce the effective diameter of the first lens group at the wide-angle end.

[0031] 1-2.Operation (1) Zooming The zoom lens achieves magnification by changing the distance between adjacent lens groups along the optical axis during zooming. Each lens group only needs to change the distance between them along the optical axis during zooming; all lens groups may move along the optical axis, or some lens groups may be fixed in the direction of the optical axis.

[0032] While there are no particular limitations on whether or not each lens group moves, it is preferable that the first lens group, at least one of the lens groups constituting the intermediate group M, and lens group F each move toward the object when zooming from the wide-angle end to the telephoto end. Moving these lens groups in this way makes it less likely for the magnification action of each lens group from the second lens group onward to be strained, resulting in a configuration that makes it easier to achieve both high magnification and high performance.

[0033] It is preferable that the second lens group moves toward the image side when zooming from the wide-angle end to the telephoto end. Moving the second lens group toward the image side makes it easier to reduce the outer diameter of the intermediate lens group M at the telephoto end, which in turn facilitates a reduction in the diameter of the aperture unit and a smaller, lighter zoom lens.

[0034] When the rear group R includes a lens group with negative refractive power, it is preferable that this negative refractive power lens group moves toward the object when zooming from the wide-angle end to the telephoto end. By moving in this way during zooming, the magnification effect of the rear group R can be increased. As a result, the amount of movement of each lens group can be reduced, making it easier to obtain a smaller zoom lens with a higher magnification ratio.

[0035] When the rear group R includes two or more lens groups, it is preferable that the lens group located closest to the image sensor in the rear group R be fixed on the optical axis during zooming, in order to avoid complicating the cam structure of the lens barrel.

[0036] (2) Focusing This zoom lens achieves focusing from infinity to close distance by moving lens group F along the optical axis toward the image. Lens group F is located on the image side of the intermediate group M, that is, at the rear of the zoom lens. Therefore, by using lens group F as the focusing group, changes in the angle of view due to the movement of the focusing group can be suppressed. As a result, a zoom lens suitable for video recording using tracking AF functions can be obtained, not only when using contrast AF but also when using image-plane phase-detection AF.

[0037] 1-3. Conditional expression The zoom lens should, in addition to adopting the configuration described above, satisfy at least one of the following conditional equations.

[0038] -1.30 ≦ fM / fMn1 < 0 (1) however, fMn1: Focal length of the first negative subgroup Mn1 fM: Combined focal length of the intermediate group M

[0039] Condition (1) is a condition for appropriately setting the ratio between the focal length of the intermediate group M and the focal length of the first negative subgroup Mn1. By satisfying condition (1), spherical aberration and field curvature can be well corrected across the entire zoom range. Therefore, even when a strong positive refractive force is placed in the intermediate group M, these aberrations can be well corrected, making it possible to realize a compact zoom lens with high optical performance while achieving a large aperture ratio.

[0040] Conversely, if the value of condition equation (1) falls below the lower limit, the negative divergence effect of the first negative subgroup Mn1 becomes too strong, making it difficult to correct spherical aberration and field curvature in a balanced and effective manner. On the other hand, if the value of condition equation (1) exceeds the upper limit, the negative divergence effect of the first negative subgroup Mn1 becomes smaller. If a strong positive refractive force is placed in the intermediate group M, it becomes difficult to effectively correct spherical aberration and field curvature, which tend to be underexposed.

[0041] To obtain the above effect, the value of condition (1) must be negative, and the upper limit of condition (1) is preferably -0.02, and more preferably -0.05. Furthermore, the lower limit of condition (1) is preferably -1.20, and more preferably -1.10.

[0042] 1-3-2. Conditional expression (2) 0.15 ≦ Rmf / ft ≦ 0.70 (2) however, Rmf: Radius of curvature of the lens surface closest to the object in the intermediate group M ft: Focal length of the zoom lens at the telephoto end.

[0043] Condition (2) is a condition for appropriately setting the ratio between the radius of curvature of the lens surface closest to the object in the intermediate group M and the focal length of the zoom lens at the telephoto end. When condition (2) is satisfied, the lens surface closest to the object in the intermediate group M is convex toward the object. Satisfying condition (2) makes it easier to balance miniaturization of the overall length with optical performance. Note that the lens surface closest to the object in the intermediate group M refers to the lens surface closest to the object in the first positive subgroup Mp1.

[0044] Conversely, if the value of condition (2) falls below the lower limit, it becomes easy to reduce the overall length, but the spherical aberration and field curvature occurring at the lens surface closest to the object in the intermediate group M tend to be strongly underexposed, making it difficult to correct them well. On the other hand, if the value of condition (2) exceeds the upper limit, in order to obtain a small zoom lens while increasing the aperture ratio, it becomes necessary to strongly focus the light beam in the intermediate group M, which increases the number of positive refractive power lenses placed in the intermediate group M, making it difficult to reduce the overall length.

[0045] To obtain the above effect, the upper limit of conditional equation (2) is preferably 0.65, more preferably 0.6, and even more preferably 0.55. Furthermore, the lower limit of conditional equation (2) is preferably 0.20, and more preferably 0.25.

[0046] 1-3-3. Conditional expression (3) -0.80 ≦ Rmb / ft ≦ -0.15 (3) however, Rmb: Radius of curvature of the image-side lens surface of the intermediate group M. ft: Focal length of the zoom lens at the telephoto end.

[0047] Condition (3) is a condition for appropriately setting the ratio between the radius of curvature of the image-side lens surface of the intermediate group M and the focal length of the zoom lens at the telephoto end. When condition (3) is satisfied, the image-side lens surface of the intermediate group M is convex towards the image side. By satisfying condition (3), it becomes easy to reduce the overall size of the zoom lens while ensuring the desired brightness. Note that the image-side lens surface of the intermediate group M refers to the image-side lens surface of the second positive subgroup Mp2.

[0048] Conversely, if the value in condition (3) falls below the lower limit, it becomes difficult to ensure sufficient brightness from the first lens group to the intermediate group M. On the other hand, if the value in condition (3) exceeds the upper limit, it becomes easier to reduce the overall length, but the curvature of the image-side lens surface of the intermediate group M becomes too strong, making it difficult to adequately correct spherical aberration and field curvature.

[0049] To obtain the above effect, the upper limit of conditional equation (3) is preferably -0.20, and more preferably -0.25. Furthermore, the lower limit of conditional equation (3) is preferably -0.75, more preferably -0.70, and even more preferably -0.65.

[0050] 1-3-4. Conditional expressions (4) and (5) It is preferable that the positive lens P is located on the object side of the intermediate group M, that is, on the object side of the first positive subgroup Mp1, and that this positive lens P simultaneously satisfies the following conditions (4) and (5). 0.01≦θgF-(-1.618×10 -3 ×νd+0.6415)≦0.06···(4) 10 ≤ νd ≤ 35 ···(5) however, When the refractive indices of the positive lens P for the d, F, C, and g lines are nd, nF, nC, and ng, respectively, θgF: Partial dispersion ratio of positive lens P θgF = (ng - nF) / (nF - nC) νd: Abbe number for the d line of the positive lens P νd = (nd-1) / (nF-nC)

[0051] Condition (4) is a condition for defining the anomalous dispersion of the material of the positive lens P. Condition (5) is a condition for defining the Abbe number of the material of the positive lens P with respect to the d line. By placing the positive lens P that satisfies both conditions (4) and (5) simultaneously on the object side of the intermediate group M, axial chromatic aberration can be well corrected across the entire zoom range. Generally, chromatic aberration is corrected for positive lenses included in a lens group with positive refractive power by using low-dispersion materials. However, the intermediate group M of this zoom lens has a large divergence effect due to its divergence surface, and axial chromatic aberration on the short-wavelength side tends to be excessive. Therefore, by using a high-dispersion glass material for the positive lens P, good chromatic aberration correction becomes easier.

[0052] Conversely, if the value in conditional equation (4) is below the lower limit, or if the value in conditional equation (5) is above the upper limit, the axial chromatic aberration on the short wavelength side, such as the F-line and g-line, tends to be over-corrected, making correction difficult. On the other hand, if the value in conditional equation (4) is above the upper limit, or if the value in conditional equation (5) is below the lower limit, the axial chromatic aberration on the short wavelength side, such as the F-line and g-line, tends to be under-corrected, making correction difficult.

[0053] To obtain the above effect, the upper limit of conditional equation (4) is preferably 0.05. Furthermore, the lower limit of conditional equation (4) is preferably 0.02, and more preferably 0.03. Furthermore, in order to obtain the above effect, the upper limit of conditional expression (5) is preferably 30, more preferably 25, and even more preferably 23. Also, the lower limit of conditional expression (5) is preferably 15, and more preferably 18.

[0054] 1-3-5. Conditional expression (6) 0.3 ≦ BFw / Y ≦ 1.5 (6) however, BFw: The back focus of the zoom lens at the wide-angle end, calculated by converting the cover glass thickness to air equivalent. Y: Maximum image height of the zoom lens

[0055] Condition (6) is a condition that defines the ratio of the back focus of the zoom lens at the wide-angle end to the maximum image height of the zoom lens. By satisfying condition (6), the back focus of the zoom lens at the wide-angle end can be shortened, and the overall length can be reduced.

[0056] If the value in condition (6) falls below the lower limit, the back focus of the zoom lens at the wide-angle end becomes too short, causing the angle of inclination of the incident light on the image sensor with respect to the optical axis to become too large. On the other hand, if the value in condition (6) exceeds the upper limit, the back focus of the zoom lens at the wide-angle end becomes too long, making it difficult to reduce the overall length of the zoom lens.

[0057] To obtain the above effect, the upper limit of conditional expression (6) is preferably 1.3, more preferably 1.2, and even more preferably 1.1. Furthermore, the lower limit of conditional expression (6) is preferably 0.4, more preferably 0.5, and even more preferably 0.6.

[0058] 2. Imaging device Next, the imaging device according to the present invention will be described. The imaging device according to the present invention is characterized by comprising the zoom lens according to the present invention and an image sensor that converts the optical image formed by the zoom lens into an electrical signal. Preferably, the image sensor is provided on the image side of the zoom lens. A CCD (Charge Coupled Device) sensor or a CMOS (Complementary Metal Oxide Semiconductor) sensor can be suitably used as the image sensor.

[0059] In particular, the above-mentioned zoom lens offers a large aperture ratio while remaining compact overall and possessing excellent optical performance. Furthermore, this zoom lens can suppress changes in the angle of view due to the movement of the focus group, making it suitable for video recording using tracking AF functionality, not only when employing contrast AF but also when employing on-sensor phase-detection AF. Therefore, by adopting this zoom lens, an imaging device suitable for video recording with tracking AF functionality can be created.

[0060] Next, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the following examples. [Examples]

[0061] (1) Optical configuration Figure 1 is a cross-sectional view of the zoom lens of Embodiment 1 of the present invention at the wide-angle end when it is in focus at infinity. The zoom lens of Embodiment 1 is composed of, in order from the object side, a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, a fourth lens group G4 with negative refractive power, and a fifth lens group G5 with negative refractive power. The third lens group G3 corresponds to the intermediate group M. The fourth lens group G4 corresponds to the lens group F. The fifth lens group G5 corresponds to the rear group R.

[0062] When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves towards the object, the second lens group G2 moves towards the image, the third lens group G3 moves towards the object, the fourth lens group G4 moves towards the object, and the fifth lens group G5 moves towards the object. Focusing from an object at infinity to an object at close range is achieved by the fourth lens group G4 (lens group F) moving toward the image. The aperture diaphragm S is positioned adjacent to the object side of the third lens group G3.

[0063] The configuration of each lens group is described below. The first lens group G1 consists of, in order from the object side, a cemented lens formed by joining a negative meniscus lens L1 and a biconvex lens L2, both with their convex surfaces facing the object, and a positive meniscus lens L3 with its convex surface facing the object.

[0064] The second lens group G2 consists of, in order from the object side, a negative meniscus lens L4 with its convex surface facing the object, a biconvex lens L5, a biconcave lens L6, a bonded lens formed by joining a biconcave lens L7 and a biconvex lens L8, and a negative meniscus lens L9 with its concave surface facing the object.

[0065] The third lens group G3 consists of, in order from the object side, a positive meniscus lens L10 with its convex surface facing the object, a positive meniscus lens L11 with its convex surface facing the object, a negative meniscus lens L12 with its convex surface facing the object, a cemented lens formed by joining three lenses: a biconvex lens L13 and a biconcave lens L14, a negative meniscus lens L15 with its concave surface facing the object, and a biconvex lens L16. The negative meniscus lens L15 is a glass-molded aspherical lens with an aspherical shape on the object side. The biconvex lens L16 is a glass-molded aspherical lens with aspherical shapes on both sides. The first positive subgroup Mp1 is formed from the positive meniscus lens L10 and the positive meniscus lens L11. The positive meniscus lens L10 is a positive lens P, and its object side is convex towards the object. The first negative subgroup Mn1 is formed by a cemented lens, which consists of three lenses joined together: a negative meniscus lens L12, a biconvex lens L13, and a biconcave lens L14. The bonding surface between the negative meniscus lens L12 and the biconvex lens L13 faces the object side with its convex surface. The second negative subgroup Mn2 is formed by the negative meniscus lens L15. The second positive subgroup Mp2 is formed by the biconvex lens L16. The image surface of the biconvex lens L16 is convex towards the image side. Furthermore, the space between the biconcave lens L14 and the negative meniscus lens L15 is a biconvex air lens, which has a negative refractive power.

[0066] The fourth lens group G4 consists of a cemented lens formed by joining a biconvex lens L17 and a biconcave lens L18.

[0067] The fifth lens group G5 consists of, in order from the object side, a cemented lens formed by joining a negative meniscus lens L19 and a biconvex lens L20 with the convex side facing the object, and a negative meniscus lens L21 with the concave side facing the object. The negative meniscus lens L21 is a glass-molded aspherical lens with aspherical shapes on both sides.

[0068] In Figure 1, "IP" refers to the image plane, specifically the imaging surface of an image sensor such as a CCD sensor or CMOS sensor, or the film surface of a silver halide film. Furthermore, the object side of the image plane IP is equipped with a parallel plate, such as a cover glass CG, that has virtually no refractive power. These points are the same in the cross-sectional lens diagrams shown in other embodiments, and therefore will not be explained further.

[0069] (2) Numerical Examples Next, we will describe a numerical example in which the specific values ​​of the zoom lens are applied. Below, we show the "Lens Data," "Specifications Table," "Variable Interval," "Lens Group Data," and "Aspherical Coefficient." In addition, the values ​​of each conditional equation (1) to (7) (Table 1), the values ​​used to determine each conditional equation, and the φLCn values ​​for each example (Table 2) are shown together after Example 6.

[0070] In the "Lens Data" column, "Surface Number" indicates the order of the lens surfaces counted from the object side, "r" is the radius of curvature of the lens surface, "d" is the lens thickness or air gap on the optical axis, "nd" is the refractive index at the d line (wavelength λ=587.56nm), and "νd" is the Abbe number at the d line. In the "Surface Number" column, "ASPH" following the surface number indicates that the lens surface is aspherical, and "S" indicates that the surface is an aperture diaphragm. In the "d" column, "d(0)", "d(5)", etc., indicate that the spacing of the lens surfaces on the optical axis is a variable spacing that changes when the magnification is changed. Also, "∞" in the radius of curvature column means infinity, and that the lens surface is flat. All units of length in the table are "mm", and all units of angle of view are "°", and the same applies to other tables.

[0071] In the "Specifications Table," "f" represents the focal length of the zoom lens, "FNo." is the F-number, "ω" is the half-angle of view, and "Y" is the image height. The values ​​shown are for the wide-angle end, intermediate focal length, and telephoto end, respectively.

[0072] The "Variable Interval" section shows the values ​​at the wide-angle end, intermediate focal length, telephoto end when in focus at infinity, and when focusing on a close-range object, respectively.

[0073] The [Lens Group Data] section shows the focal length of each lens group.

[0074] The "aspheric coefficient" indicates the aspheric coefficient when the aspheric shape is defined as follows: where x is the displacement from the reference plane in the direction of the optical axis, r is the radius of paraxial curvature, H is the height from the optical axis in the direction perpendicular to the optical axis, k is the conicity coefficient, and An is the nth-order aspheric coefficient. Also, in the table of "aspheric coefficients", "E±XX" represents exponential notation, and "×10 ±XX It means "...".

[0075]

number

[0076] The items in these tables are the same as those in the tables shown in other examples, so we will omit further explanation below.

[0077] Furthermore, Figures 2, 3, and 4 show the longitudinal aberration diagrams of the zoom lens at the wide-angle end, intermediate focal length, and telephoto end when focused at infinity. The longitudinal aberration diagrams shown in each figure, from left to right, represent spherical aberration (mm), astigmatism (mm), and distortion (%), respectively. In the spherical aberration diagram, the solid line represents the spherical aberration at the d line (wavelength 587.56 nm), the dashed line represents the spherical aberration at the C line (wavelength 656.28 nm), and the dashed line represents the spherical aberration at the g line (wavelength 435.84 nm). In the astigmatism diagram, the vertical axis is half-angle of view (ω) and the horizontal axis is defocus, with the solid line representing the sagittal image plane (ds) at the d line and the dashed line representing the meridional image plane (dm) at the d line. In the distortion diagram, the vertical axis is half-angle of view (ω) and the horizontal axis is distortion. These points are the same in the aberration diagrams shown in other embodiments, so we will omit further explanation below.

[0078] [Lens data] Face number rd nd νd Object plane ∞ d(0) 1 192.4282 1.5000 1.91082 35.25 2 100.0065 10.0532 1.49700 81.61 3 -252.2417 0.2000 4 71.5654 6.5650 1.49700 81.61 5 192.2789 d(5) 6 83.7631 1.5000 1.87070 40.73 7 28.8102 8.6177 8 520.2462 4.1099 1.80518 25.46 9 -79.0552 0.4606 10 -180.0295 1.2000 1.87070 40.73 11 128.0584 4.0554 12 -37.2450 1.2000 1.59282 68.62 13 46.6295 5.0613 1.91082 35.25 14 -120.2559 1.9148 15 -42.1599 1.2000 1.72916 54.67 16 -83.9970 d(16) 17S ∞ 1.2000 18 38.6389 5.2507 1.92286 20.88 19 120.0000 0.1500 20 35.4374 5.0901 1.59282 68.62 21 97.2289 0.4000 22 96.5811 1.3000 1.84666 23.78 23 19.5924 13.1150 1.61800 63.39 24 -28.9537 1.3000 1.90366 31.31 25 150.9663 2.2521 26ASPH -112.3666 1.5000 1.80625 40.91 27 -14100.5277 0.2067 28ASPH 40.3440 7.2282 1.77377 47.17 29ASPH -38.9138 d(29) 30 105.0374 3.0753 1.92286 20.88 31 -93.2811 0.9000 1.80100 34.97 32 27.9385 d(32) 33 5​​​​​​​​​​​​​​​​ [Specifications table] Wide-angle end, intermediate, telephoto end f 36.0267 74.9717 145.5296 FNo. 2.0604 2.6090 2.9089 ω 30.9716 15.3720 8.0578 Y 21.6330 21.6330 21.6330

[0080] [Variable interval] Wide-angle end, intermediate, telephoto end, wide-angle end, intermediate, telephoto end d(0) ∞ ∞ ∞ 626.8162 611.5614 586.0399 d(5) 1.0000 29.0327 59.7393 1.0000 29.0327 59.7393 d(16) 34.1032 11.6612 1.3000 34.1032 11.6612 1.3000 d(29) 2.2957 5.3936 3.4962 3.1957 8.3197 11.9612 d(32) 9.3997 9.8819 13.0383 8.4997 6.9558 4.5732 d(37) 13.5000 19.5839 23.5011 13.5000 19.5839 23.5011

[0081] [Lens group data] Group number Focal length G1 142.9320 G2 -30.6227 G3 32.3890 G4 -55.4052 G5 -136.9750

[0082] [Aspherical coefficient] Surface number k A4 A6 A8 A10 A12 26 -4.7618 -1.12558E-05 -5.41558E-09 2.44928E-11 6.66569E-15 -8.00140E-17 28 -2.2576 -4.43682E-06 -2.17277E-09 -1.47235E-11 7.75635E-14 -1.53877E-16 29 0.0000 -1.98686E-06 3.48149E-09 -1.33604E-11 6.20532E-14 -1.57248E-16 36 -0.5742 3.82990E-06 1.75904E-08 -4.02738E-10 1.60174E-12 -2.66841E-15 37 0.0000 -6.60728E-06 -1.46925E-09 -2.17773E-10 7.57891E-13 -1.17814E-15 [Examples]

[0083] (1) Optical configuration Figure 5 is a cross-sectional view of the zoom lens of Embodiment 2 of the present invention at the wide-angle end when it is in focus at infinity. The zoom lens of Embodiment 2 is composed of, in order from the object side, a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, a fourth lens group G4 with negative refractive power, and a fifth lens group G5 with negative refractive power. The third lens group G3 corresponds to the intermediate group M. The fourth lens group G4 corresponds to the lens group F. The fifth lens group G5 corresponds to the rear group R.

[0084] When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves towards the object, the second lens group G2 moves towards the image, the third lens group G3 moves towards the object, the fourth lens group G4 moves towards the object, and the fifth lens group G5 moves towards the object. Focusing from an object at infinity to an object at close range is achieved by the fourth lens group G4 (lens group F) moving toward the image. The aperture diaphragm S is positioned adjacent to the object side of the third lens group G3.

[0085] The configuration of each lens group is described below. The first lens group G1 consists of, in order from the object side, a cemented lens formed by joining a negative meniscus lens L1 and a biconvex lens L2, both with their convex surfaces facing the object, and a positive meniscus lens L3 with its convex surface facing the object.

[0086] The second lens group G2 consists of, in order from the object side, a negative meniscus lens L4 with its convex surface facing the object, a bonded lens formed by joining a biconcave lens L5 and a biconvex lens L6, and a negative meniscus lens L7 with its concave surface facing the object. The negative meniscus lens L4 is a composite resin type aspherical lens in which a composite resin film molded into an aspherical shape is attached to the side surface of the object.

[0087] The third lens group G3 consists of, in order from the object side, a positive meniscus lens L8 with its convex surface facing the object, a biconvex lens L9, a cemented lens formed by joining a biconcave lens L10 and a positive meniscus lens L11 with its convex surface facing the object, a cemented lens formed by joining a biconcave lens L12 and a biconvex lens L13, a biconvex lens L14, and a positive meniscus lens L15 with its convex surface facing the object. The biconvex lens L9 is a glass molded aspherical lens with aspherical shapes on both sides. The biconvex lens L14 is a glass molded aspherical lens with aspherical shapes on both sides. The first positive subgroup Mp1 is formed from the positive meniscus lens L8 and the biconvex lens L9. The positive meniscus lens L8 is a positive lens P, and its object side is convex toward the object. The first negative subgroup Mn1 is formed from a cemented lens formed by joining a biconcave lens L10 and a positive meniscus lens L11. The bonding surface of the bonded lens faces the object. The second negative subgroup Mn2 is formed from the bonded lens, which is formed by bonding a biconcave lens L12 and a biconvex lens L13. The second positive subgroup Mp2 is formed from a biconvex lens L14 and a positive meniscus lens L15. Furthermore, the space between the positive meniscus lens L11 and the biconcave lens L12 is a biconvex air lens, which has a negative refractive power.

[0088] The fourth lens group G4 consists of a cemented lens formed by joining a biconvex lens L16 and a biconcave lens L17.

[0089] The fifth lens group G5 consists of, in order from the object side, a cemented lens formed by joining a negative meniscus lens L18 and a biconvex lens L19 with their convex surfaces facing the object side, and a negative meniscus lens L20 with its concave surface facing the object side. The negative meniscus lens L20 is a glass-molded aspherical lens with aspherical shapes on both sides.

[0090] (2) Numerical Examples Next, we will describe an example of applying the specific numerical values ​​of the zoom lens in question. Below, we show the "Lens Data," "Specifications Table," "Variable Interval," "Lens Group Data," and "Aspherical Coefficient." Figures 6 to 8 also show the longitudinal aberration diagrams at infinity focus at the wide-angle end, intermediate focal length, and telephoto end of the zoom lens.

[0091] [Lens data] Face number rd nd νd Object plane ∞ d(0) 1 145.9494 1.5000 1.91082 35.25 2 83.3622 9.0822 1.49700 81.61 3 -2840.7860 0.2000 4 81.0894 7.9479 1.49700 81.61 5 1168.1206 d(5) 6ASPH 135.2890 0.1800 1.51460 49.96 7 86.2642 1.5000 1.83481 42.72 8 29.7292 12.2200 9 -48.9515 1.3000 1.55032 75.50 10 42.1316 6.5000 1.85025 30.05 11 -110.1752 4.9204 12 -30.5776 1.2000 1.75500 52.32 13 -63.4894 d(13) 14S ∞ 1.2000 15 43.5524 4.5077 1.92286 20.88 16 144.9998 0.3619 17ASPH 33.9965 7.4165 1.69350 53.18 18ASPH -124.7641 0.2000 19 -700.0000 1.2000 1.84666 23.78 20 21.7021 6.9802 1.49700 81.61 21 303.0657 2.4810 22 -50.7442 1.2000 1.90366 31.31 23 49.9653 4.7458 1.49700 81.61 24 -107.3634 0.2000 25 37.9205 7.2355 1.63930 44.87 26 -48.1484 0.2000 27ASPH 48.6112 2.2908 1.85135 40.10 28ASPH 109.5210 d(28) 29 67.5033 2.6442 1.92286 20.88 30 -1897.7939 0.9000 1.83481 42.72 31 23.7581 d(31) 32 111.0428 1.2000 1.90366 31.31 33 22.3542 8.0792 1.63980 34.47 34 -47.3375 6.1126 35ASPH -22.3258 1.8000 1.69350 53.18 36ASPH -59.5481 d(36) 37 ∞ 2.5000 1.51680 64.20 38 ∞ 1.0000 Image plane ∞

[0092] [Table of Elements] The corner end, the middle and the far end f 36.0230 74.9830 145.6157 FNo. 2.0602 2.5529 2.9033 ω 30.9602 15.3672 8.0607 Y 21.6330 21.6330 21.6330

[0093] [Variable interval] Wide-angle end, intermediate, telephoto end, wide-angle end, intermediate, telephoto end d(0) ∞ ∞ ∞ 628.9852 618.3808 589.9625 d(5) 1.0000 27.1468 58.8735 1.0000 27.1468 58.8735 d(13) 34.3410 9.5673 1.3000 34.3410 9.5673 1.3000 d(28) 1.4985 4.9803 2.2040 2.2671 7.5532 9.1951 d(31) 9.6695 10.5918 13.2870 8.9009 8.0189 6.2959 d(36) 13.5000 18.3273 23.3673 13.5000 18.3273 23.3673

[0094] [Lens group data] Group number Focal length G1 140.4610 G2 -30.5472 G3 31.5372 G4 -48.7235 G5 -122.8010

[0095] [Aspherical coefficient] Surface number k A4 A6 A8 A10 A12 6 0.0000 2.89963E-06 -5.51989E-10 7.77888E-12 -1.63823E-14 2.04260E-17 17 -0.1449 5.07906E-07 7.70271E-10 -1.64591E-14 -2.42516E-15 -1.78380E-18 18 0.0000 6.18574E-06 -5.88755E-09 -6.00957E-13 1.47022E-14 -1.55981E-17 27 2.1900 -5.30197E-07 -2.91735E-08 2.10024E-10 -1.92044E-12 2.73199E-15 28 0.0000 1.12776E-05 -2.44800E-08 2.80217E-10 -2.44970E-12 4.02006E-15 35 -0.3058 -9.39037E-07 9.78413E-08 -8.59775E-10 2.96318E-12 -5.69564E-15 36 0.0000 -1.07823E-05 4.00794E-08 -3.65098E-10 8.64536E-13 -1.17458E-15 [Examples]

[0096] (1) Optical configuration Figure 9 is a cross-sectional view of the zoom lens of Embodiment 3 of the present invention at the wide-angle end when it is in focus at infinity. The zoom lens of Embodiment 3 is composed of, in order from the object side, a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, a fourth lens group G4 with positive refractive power, a fifth lens group G5 with negative refractive power, and a sixth lens group G6 with negative refractive power. The intermediate group M is composed of the third lens group G3 and the fourth lens group G4. The fifth lens group G5 corresponds to lens group F. The sixth lens group G6 corresponds to the rear group R.

[0097] When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves towards the object, the second lens group G2 moves towards the image, the third lens group G3 moves towards the object, the fourth lens group G4 moves towards the object, the fifth lens group G5 moves towards the object, and the sixth lens group G6 moves towards the object. Focusing from an object at infinity to an object at close range is achieved by the fifth lens group G5 (lens group F) moving towards the image. The aperture diaphragm S is positioned adjacent to the object side of the third lens group G3.

[0098] The configuration of each lens group is described below. The first lens group G1 consists of, in order from the object side, a cemented lens formed by joining a negative meniscus lens L1 with its convex surface facing the object side and a positive meniscus lens L2 with its convex surface facing the object side, and a positive meniscus lens L3 with its convex surface facing the object side.

[0099] The second lens group G2 consists of, in order from the object side, a negative meniscus lens L4 with its convex surface facing the object, a biconcave lens L5, a biconvex lens L6, and a negative meniscus lens L7 with its concave surface facing the object. The negative meniscus lens L7 is a glass-molded aspherical lens with an aspherical shape on the image side.

[0100] The third lens group G3 consists of, in order from the object side, a positive meniscus lens L8 with its convex surface facing the object, a biconvex lens L9, a cemented lens formed by joining a negative meniscus lens L10 with its convex surface facing the object and a positive meniscus lens L11 with its convex surface facing the object, a cemented lens formed by joining a biconvex lens L12 and a negative meniscus lens L13 with its concave surface facing the object, and a negative meniscus lens L14 with its concave surface facing the object. The negative meniscus lens L14 is a glass molded aspherical lens with aspherical shapes on both sides. The first positive subgroup Mp1 is formed from the positive meniscus lens L8 and the biconvex lens L9. The positive meniscus lens L8 is a positive lens P, and its object side is convex toward the object. The first negative subgroup Mn1 is formed from the cemented lens formed by joining the negative meniscus lens L10 and the positive meniscus lens L11. The bonding surface with the bonded lens faces the object side with its convex surface. The second negative subgroup Mn2 is composed of a bonded lens formed by bonding a biconvex lens L12 and a negative meniscus lens L13, and a negative meniscus lens L14. Furthermore, the space between the positive meniscus lens L11 and the biconvex lens L12 is a positive meniscus-shaped air lens with its convex surface facing the object side. Similarly, the space between the negative meniscus lens L13 and the negative meniscus lens L14 is a positive meniscus-shaped air lens with its concave surface facing the object side. All of these air lenses have negative refractive power.

[0101] The fourth lens group G4 consists of, in order from the object side, a cemented lens formed by joining a biconvex lens L15 and a negative meniscus lens L16 with its concave surface facing the object side, and a biconvex lens L17. The biconvex lens L17 is a glass-molded aspherical lens with aspherical shapes on both sides. This fourth lens group constitutes the second positive subgroup Mp2. Furthermore, the image side of the biconvex lens L17 is convex toward the image side.

[0102] The fifth lens group G5 consists of a negative meniscus lens L18 with its convex surface facing the object.

[0103] The sixth lens group G6 consists of, in order from the object side, a biconvex lens L19, a negative meniscus lens L20 with its concave surface facing the object, and a negative meniscus lens L21 with its concave surface facing the object. The negative meniscus lens L21 is a glass-molded aspherical lens with aspherical shapes on both sides.

[0104] (2) Numerical Examples Next, we will describe an example of applying the specific numerical values ​​of the zoom lens in question. Below, we show the "Lens Data," "Specifications Table," "Variable Interval," "Lens Group Data," and "Aspherical Coefficient." Figures 10 to 12 also show the longitudinal aberration diagrams at infinity focus at the wide-angle end, intermediate focal length, and telephoto end of the zoom lens.

[0105] [Lens data] Face number rd nd νd Object plane ∞ d(0) 1 146.1366 1.5000 1.83400 37.34 2 81.7552 9.3137 1.49700 81.61 3 861.3257 0.2000 4 82.7093 8.3556 1.49700 81.61 5 676.6604 d(5) 6 85.3165 1.3000 1.83481 42.72 7 25.6981 7.5590 8 -142.6415 1.0000 1.74320 49.34 9 55.4796 0.2000 10 47.2962 6.3639 1.85478 24.80 11 -113.4071 7.0406 12 -37.5431 1.2000 1.69350 53.18 13ASPH -134.4780 d(13) 14S ∞ 1.2000 15 63.2111 2.9054 1.92286 20.88 16 226.7728 0.2000 17 38.8943 4.9773 1.59282 68.62 18 -1849.7343 1.4534 19 29.4393 0.9000 1.85478 24.80 20 18.5276 4.1898 1.49700 81.61 21 29.5363 3.1986 22 855.4291 5.1841 1.61800 63.39 23 -25.1253 0.9000 1.90366 31.31 24 -91.9678 2.3316 25ASPH -26.3081 1.2000 1.80139 45.45 26ASPH -167.3759 d(26) 27 31.8380 8.8367 1.61800 63.39 28 -31.7511 1.0000 1.90366 31.31 29 -50.0420 0.2000 30ASPH 44.2400 3.9298 1.69350 53.18 31ASPH -78.2641 d(31) 32 58.2654 0.9000 1.74320 49.34 33 21.9303 d(33) 34 744.8727 4.4762 1.85478 24.80 35 -37.2427 0.2000 36 -51.7059 0.9000 1.69680 55.46 37 1480.1035 4.7920 38ASPH -26.0320 1.5000 1.69350 53.18 39ASPH -126.4177 d(39) 40 ∞ 2.5000 1.51680 64.20 41 ∞ 1.0000 Image plane ∞

[0106] [Specifications table] Wide-angle end, intermediate, telephoto end f 36.0059 74.9901 145.7846 FNo. 2.9006 2.8998 2.8998 ω 31.1279 15.6292 8.1277 Y 21.6330 21.6330 21.6330

[0107] [Variable interval] Wide-angle end, intermediate, telephoto end, wide-angle end, intermediate, telephoto end d(0) ∞ ∞ ∞ 635.0001 611.8245 580.0000 d(5) 0.8000 29.1008 69.2054 0.8000 29.1008 69.2054 d(13) 29.3573 11.3694 1.4150 29.3573 11.3694 1.4150 d(26) 2.2384 1.2452 1.1000 2.2384 1.2452 1.1000 d(31) 1.4465 1.9362 1.3013 2.1191 3.6157 6.5754 d(33) 14.7502 14.2606 14.8955 14.0776 12.5811 9.6214 d(39) 13.4999 27.3558 29.1753 13.4999 27.3558 29.1753

[0108] [Lens group data] Group number Focal length G1 159.7390 G2 -31.9650 G3 126.1290 G4 20.7425 G5 -47.8230 G6 -104.4690

[0109] [Aspherical coefficient] Surface number k A4 A6 A8 A10 A12 13 0.0000 -2.65487E-06 -1.22600E-10 -2.58257E-12 4.62558E-15 0.00000E+00 25 0.5134 1.97238E-05 -2.13070E-08 7.83567E-11 -1.98213E-14 5.86672E-16 26 0.0000 7.14119E-06 -2.93204E-08 3.91664E-11 1.04289E-13 0.00000E+00 30 -0.6513 -1.39550E-05 -3.65922E-08 3.26993E-10 -2.28508E-12 7.69238E-15 31 0.0000 1.03345E-05 -5.83570E-08 5.03203E-10 -2.90518E-12 8.96723E-15 38 0.0000 -1.93371E-05 1.06017E-07 -2.76968E-10 1.71864E-13 0.00000E+00 39 0.0000 -2.32872E-05 8.81158E-08 -2.48036E-10 2.09154E-13 0.00000E+00 [Examples]

[0110] (1) Optical configuration Figure 13 is a cross-sectional view of the zoom lens of Embodiment 4 of the present invention at the wide-angle end when it is in focus at infinity. The zoom lens of Embodiment 4 is composed of, in order from the object side, a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, a fourth lens group G4 with negative refractive power, a fifth lens group G5 with positive refractive power, a sixth lens group G6 with negative refractive power, and a seventh lens group G7 with negative refractive power. The intermediate group M is composed of the third lens group G3, the fourth lens group G4, and the fifth lens group G5. The sixth lens group G6 corresponds to lens group F. The seventh lens group G7 corresponds to the rear group R.

[0111] When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves towards the object, the second lens group G2 moves towards the image, the third lens group G3 moves towards the object, the fourth lens group G4 moves towards the object, the fifth lens group G5 moves towards the object, the sixth lens group G6 moves towards the object, and the seventh lens group G7 moves towards the object. Focusing from an object at infinity to an object at close range is achieved by the sixth lens group G6 (lens group F) moving towards the image. The aperture diaphragm S is positioned adjacent to the object side of the third lens group G3.

[0112] The configuration of each lens group is described below. The first lens group G1 consists of, in order from the object side, a cemented lens formed by joining a negative meniscus lens L1 with its convex surface facing the object side and a positive meniscus lens L2 with its convex surface facing the object side, and a positive meniscus lens L3 with its convex surface facing the object side.

[0113] The second lens group G2 consists of, in order from the object side, a negative meniscus lens L4 with its convex surface facing the object, a biconcave lens L5, a biconvex lens L6, and a negative meniscus lens L7 with its concave surface facing the object. The negative meniscus lens L7 is a glass-molded aspherical lens with an aspherical shape on the image side.

[0114] The third lens group G3 consists of, in order from the object side, a positive meniscus lens L8 with its convex surface facing the object, a positive meniscus lens L9 with its convex surface facing the object, a cemented lens formed by joining a negative meniscus lens L10 with its convex surface facing the object and a positive meniscus lens L11 with its convex surface facing the object, and a negative meniscus lens L12 with its concave surface facing the object. The negative meniscus lens L12 is a glass-molded aspherical lens with an aspherical shape on the object side. The first positive subgroup Mp1 is formed from the positive meniscus lenses L8 and L9. The positive meniscus lens L8 is a positive lens P, and its object side is convex toward the object. The negative subgroup Mn1 is formed from the cemented lens formed by joining the negative meniscus lens L10 and the positive meniscus lens L11. The cemented surface of this cemented lens has its convex surface facing the object. Furthermore, the space between the positive meniscus lens L11 and the negative meniscus lens L12 is a biconvex air lens, which has a negative refractive power.

[0115] The fourth lens group G4 consists of a cemented lens formed by joining a positive meniscus lens L13 and a biconcave lens L14, with the concave surface facing the object side, in that order from the object side. The second negative subgroup Mn2 is formed from the negative meniscus lens L12 included in the third lens group G3 and the fourth lens group G4. In this embodiment, the second negative subgroup Mn2 includes a variable interval during zooming.

[0116] The fifth lens group G5 consists of, in order from the object side, a cemented lens formed by joining a biconvex lens L15 and a negative meniscus lens L16 with its concave surface facing the object side, and a biconvex lens L17. The biconvex lens L17 is a glass-molded aspherical lens with aspherical shapes on both sides. The fifth lens group G5 constitutes the second positive subgroup Mp2. The image side of the biconvex lens L17 is convex towards the image side.

[0117] The sixth lens group G6 consists of a negative meniscus lens L18 with its convex surface facing the object.

[0118] The seventh lens group G7 consists of, in order from the object side, a biconvex lens L19, a biconcave lens L20, and a negative meniscus lens L21 with its concave surface facing the object side. The negative meniscus lens L21 is a glass-molded aspherical lens with aspherical shapes on both sides.

[0119] (2) Numerical Examples Next, we will describe an example of applying the specific numerical values ​​of the zoom lens in question. Below, we show the "Lens Data," "Specifications Table," "Variable Interval," "Lens Group Data," and "Aspherical Coefficient." Figures 14 to 16 also show the longitudinal aberration diagrams at infinity focus at the wide-angle end, intermediate focal length, and telephoto end of the zoom lens.

[0120] [Lens data] Face number rd nd νd Object plane ∞ d(0) 1 139.2743 1.5000 1.83400 37.34 2 80.8526 8.8653 1.49700 81.61 3 803.6530 0.2000 4 81.1675 7.9247 1.49700 81.61 5 583.4053 d(5) 6 87.4206 1.1000 1.83481 42.72 7 25.7644 7.8524 8 -119.3781 0.8000 1.74320 49.34 9 67.2695 0.2000 10 51.6133 7.0019 1.85478 24.80 11 -115.7829 6.8773 12 -39.5414 0.9000 1.69350 53.18 13ASPH -141.6106 d(13) 14S ∞ 1.2000 15 61.7151 3.2551 1.92286 20.88 16 416.2702 0.2000 17 34.7681 4.9378 1.69680 55.46 18 276.0065 0.2000 19 44.9113 0.9000 1.90366 31.31 20 19.2137 6.2102 1.49700 81.61 21 94.1309 4.8400 22ASPH -30.3282 1.0000 1.88202 37.22 23 -93.5565 d(23) 24 -1065.8143 2.4898 1.61800 63.39 25 -80.2742 1.0000 1.80000 29.84 26 103.2242 d(26) 27 29.4295 7.8340 1.61800 63.39 28 -43.6080 1.0000 1.92286 20.88 29 -68.8061 0.2000 30ASPH 42.2696 4.0064 1.69350 53.18 31ASPH -77.3433 d(31) 32 57.6851 0.9000 1.80100 34.97 33 21.1862 d(33) 34 199.3862 5.2186 1.92286 20.88 35 -38.7197 0.2000 36 -55.4247 0.9000 1.78800 47.37 37 108.8800 5.6525 38ASPH -30.23​​​​​​​​​

[0121] [Specifications table] Wide-angle end, intermediate, telephoto end f 36.0004 74.9885 145.7856 FNo. 2.9001 2.8997 2.9998 ω 31.0270 15.5127 8.1372 Y 21.6330 21.6330 21.6330

[0122] [Variable interval] Wide-angle end, intermediate, telephoto end, wide-angle end, intermediate, telephoto end d(0) ∞ ∞ ∞ 635.0001 615.1959 585.5508 d(5) 0.8000 29.7508 64.2989 0.8000 29.7508 64.2989 d(13) 30.8194 11.3507 1.4257 30.8194 11.3507 1.4257 d(23) 1.7599 1.5879 1.0000 1.7599 1.5879 1.0000 d(26) 2.3709 1.0000 1.0000 2.3709 1.0000 1.0000 d(31) 1.2999 2.3225 1.3010 1.8804 3.9105 5.7542 d(33) 14.0840 13.0613 14.0828 13.5035 11.4734 9.6297 d(39) 13.4999 25.3650 30.9748 13.4999 25.3650 30.9748

[0123] [Lens group data] Group number Focal length G1 155.0100 G2 -32.1233 G3 71.8735 G4 -94.1760 G5 20.7231 G6 -42.2663 G7 -124.0100

[0124] [Aspherical coefficient] Surface number k A4 A6 A8 A10 A12 13 0.0000 -2.26600E-06 -5.89495E-10 -1.04773E-13 -7.05346E-17 0.00000E+00 22 1.2368 1.14559E-05 7.55290E-09 6.15810E-11 -2.59015E-13 7.36037E-16 30 0.9420 -1.82076E-05 -6.83016E-08 4.75485E-10 -3.01866E-12 9.80190E-15 31 0.0000 7.35164E-06 -8.00142E-08 6.57393E-10 -3.71202E-12 1.11947E-14 38 0.0000 -4.76863E-05 1.79181E-07 -4.00126E-10 -2.13880E-13 0.00000E+00 39 0.0000 -4.65785E-05 1.80790E-07 -5.00836E-10 3.72019E-13 0.00000E+00 [Examples]

[0125] (1) Optical configuration Figure 17 is a cross-sectional view of the zoom lens of Embodiment 5 of the present invention at the wide-angle end when in focus is achieved at infinity. The zoom lens of Embodiment 5 is composed of, in order from the object side, a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, a fourth lens group G4 with negative refractive power, and a fifth lens group G5 with positive refractive power. The third lens group G3 corresponds to the intermediate group M. The fourth lens group G4 corresponds to the lens group F. The fifth lens group G5 corresponds to the rear group R.

[0126] When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves towards the object, the second lens group G2 moves towards the image, the third lens group G3 moves towards the object, the fourth lens group G4 moves towards the object, and the fifth lens group G5 moves towards the object. Focusing from an object at infinity to an object at close range is achieved by the fourth lens group G4 (lens group F) moving toward the image. The aperture diaphragm S is positioned adjacent to the object side of the third lens group G3.

[0127] The configuration of each lens group is described below. The first lens group G1 consists of, in order from the object side, a cemented lens formed by joining a negative meniscus lens L1 and a biconvex lens L2, both with their convex surfaces facing the object, and a positive meniscus lens L3 with its convex surface facing the object.

[0128] The second lens group G2 consists of, in order from the object side, a negative meniscus lens L4 with its convex surface facing the object, a cemented lens formed by joining a biconcave lens L5 and a biconvex lens L6, and a negative meniscus lens L7 with its concave surface facing the object. The negative meniscus lens L7 is a glass-molded aspherical lens with an aspherical shape on the image side.

[0129] The third lens group G3 consists of, in order from the object side, a positive meniscus lens L8 with its convex surface facing the object, a positive meniscus lens L9 with its convex surface facing the object, a negative meniscus lens L10 with its convex surface facing the object, a cemented lens formed by joining three lenses: a biconvex lens L11 and a biconcave lens L12, a negative meniscus lens L13 with its concave surface facing the object, a biconvex lens L14, and a biconvex lens L15. The negative meniscus lens L13 is a glass-molded aspherical lens with aspherical shapes on both sides. The biconvex lens L15 is a glass-molded aspherical lens with aspherical shapes on both sides. The first positive subgroup Mp1 is formed from the positive meniscus lenses L8 and L9. The positive meniscus lens L8 is a positive lens P, and its side facing the object is convex towards the object. The first negative subgroup Mn1 is formed from a cemented lens, which consists of three lenses joined together: a negative meniscus lens L10, a biconvex lens L11, and a biconcave lens L12. The bonding surface between the negative meniscus lens L10 and the biconvex lens L11 faces the object side with its convex surface. The second negative subgroup Mn2 is formed from a negative meniscus lens L13. The second positive subgroup Mp2 is formed from biconvex lenses L14 and L15. The image surface of the biconvex lens L15 is convex towards the image side. Furthermore, the space between the biconcave lens L12 and the negative meniscus lens L13 is a biconvex air lens, which has a negative refractive power.

[0130] The fourth lens group G4 consists of a cemented lens formed by joining a biconvex lens L16 and a biconcave lens L17.

[0131] The fifth lens group G5 consists of, in order from the object side, a cemented lens formed by joining a negative meniscus lens L18 and a biconvex lens L19 with their convex surfaces facing the object side, and a negative meniscus lens L20 with its concave surface facing the object side. The negative meniscus lens L20 is a glass-molded aspherical lens with aspherical shapes on both sides.

[0132] (2) Numerical Examples Next, we will describe an example of applying the specific numerical values ​​of the zoom lens in question. Below, we show the "Lens Data," "Specifications Table," "Variable Interval," "Lens Group Data," and "Aspherical Coefficient." Figures 18 to 20 also show the longitudinal aberration diagrams at infinity focus at the wide-angle end, intermediate focal length, and telephoto end of the zoom lens.

[0133] [Lens data] Face number rd nd νd Object plane ∞ d(0) 1 297.5731 1.5000 1.92119 23.96 2 137.7580 7.9005 1.59282 68.62 3 -281.1578 0.2000 4 67.1396 5.5565 1.59282 68.62 5 137.6200 d(5) 6 132.8796 1.2000 1.88300 40.80 7 23.3857 7.6843 8 -81.8769 1.2000 1.75500 52.32 9 25.0947 12.3276 1.78880 28.43 10 -45.9757 3.0568 11 -29.1025 1.2000 1.85135 40.10 12ASPH -73.0620 d(12) 13S ∞ 1.2000 14 63.4705 2.8962 1.92286 20.88 15 200.0000 0.2000 16 28.0309 7.3539 1.61800 63.39 17 170.0544 0.3589 18 43.3025 1.2000 1.85478 24.80 19 19.4226 8.6987 1.59282 68.62 20 -68.0000 1.2000 1.90366 31.31 21 40.4480 3.5558 22ASPH -79.5113 1.2000 1.88202 37.22 23ASPH -244.9386 0.2000 24 29.6110 7.1754 1.61800 63.39 25 -50.0966 0.2000 26ASPH 1444.6811 2.5223 1.88202 37.22 27ASPH -78.0022 d(27) 28 222.4190 3.0223 1.92119 23.96 29 -48.0792 0.9000 1.78800 47.37 30 22.7893 d(30) 31 51.4100 1.5000 1.90366 31.31 32 21.4867 8.6463 1.60562 43.71 33 -50.6655 6.4054 34ASPH -24.4947 1.5000 1.69350 53.18 35ASPH -62.5408 d(35) 36 ∞ 2.5000 1.51680 64.20 37 ∞ 1.0000 Image plane ∞

[0134] [Specifications table] Wide-angle end, intermediate, telephoto end f 28.8086 49.9831 101.8857 FNo. 2.9114 2.9094 2.9097 ω 38.4220 22.4917 11.4289 Y 21.6330 21.6330 21.6330

[0135] [Variable interval] Wide-angle end, intermediate, telephoto end, wide-angle end, intermediate, telephoto end d(0) ∞ ∞ ∞ 640.0000 632.4574 605.4345 d(5) 1.0000 19.8699 48.7357 1.0000 19.8699 48.7357 d(12) 30.4980 12.5471 1.3000 30.4980 12.5471 1.3000 d(27) 1.4949 5.7522 7.6084 1.9137 6.8779 11.1287 d(30) 8.2462 8.6536 12.0080 7.8274 7.5279 8.4877 d(35) 13.5000 15.4589 19.6524 13.5000 15.4589 19.6524

[0136] [Lens group data] Group number Focal length G1 133.6850 G2 -24.0282 G3 29.3072 G4 -36.5784 G5 1654.2900

[0137] [Aspherical coefficient] Surface number k A4 A6 A8 A10 A12 12 0.0000 -3.71224E-06 -7.54248E-10 -8.10446E-12 1.58508E-14 0.00000E+00 22 8.7544 -3.73634E-06 -9.94629E-08 2.10401E-10 2.38821E-13 5.85973E-16 The 23 0.oo00 2.23671E-05 -1.20692E-07 7.69895E-11 5.84925E-13 0.00000E+00 26 0.0000 2.26546E-05 -9.986Q20E-08 2.72553E-10 -2.12889E-12 5.61288E-1S It should be noted that there may be some inaccuracies in the original text. For example, in line , "The 23" seems incorrect. It might be a misrepresentation in the original. Also, in line , "9.986Q20E-08" and "5.61288E-1S" seem to have incorrect characters. These are retained as they are in the translation to match the original text as closely as possible.27 0.0000 1.70547E-05 -3.84960E-08 3.62167E-10 -2.64544E-12 6.48480E-15 34 0.0000 2.24163E-06 9.38154E-08 -2.94316E-10 1.98794E-13 0.00000E+00 35 0.0000 -1.23427E-05 6.39381E-08 -2.28462E-10 1.27360E-13 0.00000E+00 [Examples]

[0138] (1) Optical configuration Figure 21 is a cross-sectional view of the zoom lens of Embodiment 6 of the present invention at the wide-angle end when it is in focus at infinity. The zoom lens of Embodiment 6 is composed of, in order from the object side, a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, a fourth lens group G4 with negative refractive power, a fifth lens group G5 with negative refractive power, and a sixth lens group G6 with positive refractive power. The third lens group G3 corresponds to the intermediate group M. The fourth lens group G4 corresponds to the lens group F. The rear group R is composed of the fifth lens group G5 and the sixth lens group G6.

[0139] When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object, the second lens group G2 moves toward the image, the third lens group G3 moves toward the object, the fourth lens group G4 moves toward the object, the fifth lens group G5 moves toward the object, and the sixth lens group G6 remains fixed relative to the optical axis. Focusing from an object at infinity to an object at close range is achieved by the fourth lens group G4 (lens group F) moving toward the image. The aperture diaphragm S is positioned adjacent to the object side of the third lens group G3.

[0140] The configuration of each lens group is described below. The first lens group G1 consists of, in order from the object side, a cemented lens formed by joining a negative meniscus lens L1 with its convex surface facing the object side and a positive meniscus lens L2 with its convex surface facing the object side, and a positive meniscus lens L3 with its convex surface facing the object side.

[0141] The second lens group G2 consists of, in order from the object side, a negative meniscus lens L4 with its convex surface facing the object, a cemented lens formed by joining a biconcave lens L5 and a biconvex lens L6, and a negative meniscus lens L7 with its concave surface facing the object. The negative meniscus lens L4 is a glass-molded aspherical lens with an aspherical shape on the object side. The negative meniscus lens L7 is a glass-molded aspherical lens with an aspherical shape on the image side.

[0142] The third lens group G3 consists of, in order from the object side, a positive meniscus lens L8 with its convex surface facing the object, a positive meniscus lens L9 with its convex surface facing the object, a negative meniscus lens L10 with its convex surface facing the object, a cemented lens formed by joining three lenses: a biconvex lens L11 and a biconcave lens L12, a biconcave lens L13, a biconvex lens L14, and a biconvex lens L15. The biconcave lens L13 is a glass molded aspherical lens with aspherical shapes on both sides. The biconvex lens L15 is a glass molded aspherical lens with aspherical shapes on both sides. The first positive subgroup Mp1 is formed from the positive meniscus lens L8 and the positive meniscus lens L9. The positive meniscus lens L8 is a positive lens P, and its side facing the object is convex towards the object. The first negative subgroup Mn1 is formed from a cemented lens, which consists of three lenses joined together: a negative meniscus lens L10, a biconvex lens L11, and a biconcave lens L12. The bonding surface between the negative meniscus lens L10 and the biconvex lens L11 faces convex toward the object. The second negative subgroup Mn2 is formed from the biconcave lens L13. The second positive subgroup Mp2 is formed from the biconvex lenses L14 and L15. The image surface of the biconvex lens L15 is convex toward the image. Furthermore, the space between the biconcave lens L12 and the biconcave lens L13 is a biconvex air lens, which has a negative refractive power.

[0143] The fourth lens group G4 consists of a cemented lens formed by joining a positive meniscus lens L16 with its convex surface facing the object and a negative meniscus lens L17 with its convex surface facing the object.

[0144] The fifth lens group G5 consists of, in order from the object side, a positive meniscus lens L18 with its concave surface facing the object side, and a negative meniscus lens L19 with its concave surface facing the object side. The negative meniscus lens L19 is a glass-molded aspherical lens with aspherical shapes on both sides.

[0145] The sixth lens group G6 consists solely of the biconvex lens L20.

[0146] (2) Numerical Examples Next, we will describe an example of applying the specific numerical values ​​of the zoom lens in question. Below, we show the "Lens Data," "Specifications Table," "Variable Interval," "Lens Group Data," and "Aspherical Coefficient." Figures 22 to 24 show the longitudinal aberration diagrams at infinity focus at the wide-angle end, intermediate focal length, and telephoto end of the zoom lens.

[0147] [Lens data] Face number rd nd νd Object plane ∞ d(0) 1 111.3081 1.5000 1.90366 31.31 2 75.1868 9.1566 1.49700 81.61 3 1104.9505 0.2000 4 83.4987 7.0088 1.49700 81.61 5 707.9086 d(5) 6ASPH 88.0432 1.2000 1.88300 40.80 7 27.5361 11.1828 8 -67.7941 1.2000 1.72916 54.67 9 31.7213 11.0000 1.85883 30.00 10 -64.9764 3.8058 11 -30.0221 1.2000 1.77250 49.60 12ASPH -85.4425 d(12) 13S ∞ 1.2000 14 41.2797 4.5594 1.92286 20.88 15 138.5471 1.4012 16 33.6292 5.4561 1.65160 58.54 17 159.0629 0.2000 18 96.1876 1.2000 1.92286 20.88 19 24.1514 10.3340 1.59282 68.62 20 -32.5362 1.2000 1.91082 35.25 21 74.8307 2.3933 22ASPH -125.9493 1.2000 1.85135 40.10 23ASPH 5000.0000 0.2000 24 31.7717 8.7182 1.61800 63.39 25 -51.0249 0.2000 26ASPH 153.7912 2.9699 1.80835 40.55 27ASPH -85.7225 d(27) 28 56.9139 2.2573 1.92286 20.88 29 129.2802 0.9000 1.74320 49.34 30 20.9401 d(30) 31 -76.4294 4.0000 1.67270 32.10 32 -34.4896 5.3127 33ASPH -20.4409 1.5000 1.74320 49.29 34ASPH -67.4790 d(34) 35 869.1400 2.8174 1.78800 47.37 36 -160.0237 d(36) 37 ∞ 2.5000 1.51680 64.20 38 ∞ 1.0000 Image plane ∞

[0148] [Specifications table] Wide-angle end, intermediate, telephoto end f 36.0110 74.9870 145.7999 FNo. 2.0606 2.5369 2.9024 ω 31.0557 15.3703 8.1006 Y 21.6330 21.6330 21.6330

[0149] [Variable interval] Wide-angle end, intermediate, telephoto end, wide-angle end, intermediate, telephoto end d(0) ∞ ∞ ∞ 634.4222 620.5667 589.4221 d(5) 1.0000 27.4974 55.8464 1.0000 27.4974 55.8464 d(12) 28.1486 6.5344 1.3000 28.1486 6.5344 1.3000 d(27) 1.4936 5.2182 1.4999 2.2959 7.9572 7.9516 d(30) 11.4620 12.2553 14.4639 10.6597 9.5163 8.0121 d(34) 1.0000 5.4543 14.9942 1.0000 5.4543 14.9942 d(36) 13.5000 13.5000 13.5000 13.5000 13.5000 13.5000

[0150] [Lens group data] Group number Focal length G1 134.0890 G2 -28.2642 G3 30.8961 G4 -50.7816 G5 -76.6750 G6 171.7070

[0151] [Aspherical coefficient] Surface number k A4 A6 A8 A10 A12 6 0.0000 7.30181E-07 8.32971E-10 -7.95708E-13 3.13536E-15 0.00000E+00 12 0.0000 -1.75869E-06 -2.68675E-10 5.29718E-13 -2.70231E-16 0.00000E+00 22 9.3117 4.31374E-06 -6.68223E-08 1.16729E-10 1.24698E-13 -2.13604E-16 23 0.0000 2.18602E-05 -8.37130E-08 5.33051E-11 1.67136E-13 0.00000E+00 26 26.8006 6.75643E-06 -6.84133E-08 3.82555E-10 -2.67822E-12 5.84648E-15 27 0.0000 9.04944E-06 -3.48419E-08 4.16286E-10 -2.73040E-12 5.96512E-15 33 0.0000 1.33881E-05 2.09246E-08 -1.08302E-10 3.04070E-13 0.00000E+00 34 0.0000 5.22704E-07 -8.82903E-09 -4.83789E-11 9.03529E-14 0.00000E+00

[0152] [Table 1] Examples 1 2 3 4 5 6 (1)fM / fMn1 -0.616 -0.603 -0.195 -0.185 -0.562 -0.818 (2)Rmf / ft 0.266 0.299 0.434 0.423 0.623 0.283 (3)Rmb / ft -0.267 0.752 -0.537 -0.531 -0.766 -0.588 (4)θgF-(-1.618×10 -3 ×νd+0.6415) 0.0313 0.0313 0.0313 0.0313 0.0313 0.0313 (5)νd 20.88 20.88 20.88 20.88 20.88 20.88 (6)BFw / Y 0.746 0.746 0.746 0.746 0.746 0.746

[0153] [Table 2] Examples 1 2 3 4 5 6 fM 32.389 31.537 31.915 30.442 29.307 30.896 fMn1 -52.622 -52.334 -163.339 -164.177 -52.164 -37.768 Rmf 38.639 43.552 63.211 61.715 63.471 41.28 Rmb -38.914 109.521 -78.264 -77.343 -78.002 -85.723 θgF 0.639 0.639 0.639 0.639 0.639 0.639 BFw 16.148 16.148 16.148 16.148 16.148 16.148 φLC1 0.034 0.040 0.017 0.027 0.024 0.029 φLC2 0.053 0.021 0.010 0.021 0.039 0.043 φLC3 0.037 0.036 0.025 0.007 0.036 0.040 φLC4 - 0.015 0.026 0.018 - - φLC5 - - 0.039 0.035 - - φLC6 - - 0.010 0.008 - -

[0154] (Note) This specification discloses, in one aspect, the following technologies:

[0155] (Technology 1) Starting from the object side, the system consists of a first lens group with positive refractive power, a second lens group with negative refractive power, an intermediate group M having one or more lens groups and having a positive refractive power as a whole, a lens group F with negative refractive power, and a rear group R having one or more lens groups. The aforementioned intermediate group M is composed of, in order from the object side, a first positive subgroup Mp1 consisting of one or two positive lenses, a first negative subgroup Mn1 consisting of only one cemented lens formed by joining two or more lenses, a second negative subgroup Mn2 having a negative lens with a concave surface facing the object side, and a second positive subgroup Mp2 having one or two positive lenses. The cemented lens constituting the first negative subgroup Mn1 has at least one cemented surface with a convex side facing the object, The lens closest to the image in the second positive subgroup Mp2 is a positive lens. When zooming, the spacing between adjacent lens groups changes. During focusing, the lens group F moves along the optical axis. A zoom lens characterized by satisfying the following condition. -1.30 ≦ fM / fMn1 < 0 (1) however, fMn1: Focal length of the first negative subgroup Mn1 fM: Combined focal length of the intermediate group M

[0156] (Technology 2) The rear group R has a negative refractive power overall, as described in Technology 1, for the zoom lens.

[0157] (Technology 3) The rear group R has at least one lens group with negative refractive power, and when zooming from the wide-angle end to the telephoto end, the lens group with negative refractive power moves toward the object, according to the zoom lens according to Technology 1 or Technology 2.

[0158] (Technology 4) A zoom lens according to any one of Techniques 1 to 3, wherein the first lens group moves toward the object when zooming from the wide-angle end to the telephoto end.

[0159] (Technology 5) A zoom lens described in any one of the following Techniques 1 to 4 that satisfies the following conditional expression. 0.15 ≦ Rmf / ft ≦ 0.70 (2) however, Rmf: Radius of curvature of the lens surface closest to the object in the intermediate group M. ft: Focal length of the zoom lens at the telephoto end.

[0160] (Technology 6) A zoom lens described in any one of the following techniques 1 to 5 that satisfies the following conditional expression. -0.80 ≦ Rmb / ft ≦ -0.15 (3) however, Rmb: Radius of curvature of the image-side lens surface of the intermediate group M. ft: Focal length of the zoom lens at the telephoto end.

[0161] (Technology 7) The zoom lens according to any one of the techniques 1 to 6, wherein the lens surface of the second lens group closest to the object is convex toward the object.

[0162] (Technology 8) The aforementioned intermediate group M is a zoom lens according to any one of the arts 1 to 7, wherein the intermediate group M has at least one air lens having a negative refractive power.

[0163] (Technology 9) The intermediate group M has a positive lens P on the object side, A zoom lens according to any one of the techniques 1 to 8, wherein the positive lens P satisfies both of the following conditions (4) and (5). 0.01 ≤ θgF - (-1.618 × 10⁻³ × νd + 0.6415) ≤ 0.06 ···(4) 10 ≤ νd ≤ 35 ···(5) however, θgF: Partial dispersion ratio of the g-line and F-line of the material of the positive lens P. νd: Abbe number of the material of the positive lens P with respect to the d line

[0164] (Technology 10) A zoom lens described in any one of the following techniques 1 to 9 that satisfies the following conditional expression. 0.3 ≦ BFw / Y ≦ 1.5 (6) however, BFw: The back focus of the zoom lens at the wide-angle end, calculated by converting the cover glass thickness to air equivalent. Y: Maximum image height of the zoom lens

[0165] (Technology 11) An imaging device characterized by comprising a zoom lens according to any one of the technologies 1 to 10, and an image sensor on the image side of the zoom lens that converts the optical image formed by the zoom lens into an electrical signal. [Industrial applicability]

[0166] According to the present invention, it is possible to provide a zoom lens that is compact overall despite having a large aperture ratio, and has excellent optical performance, as well as an imaging device having said zoom lens. [Explanation of Symbols]

[0167] G1 ···First lens group G2 ···Second lens group G3 ···Third lens group G4 ···4th lens group G5 ···5th lens group G6 ···6th lens group G7 ···7th lens group M...middle group F...Focus group (lens group) R...Rear group S ···Opening diaphragm CG ···Cover glass IP...Image plane

Claims

1. Starting from the object side, the system consists of a first lens group with positive refractive power, a second lens group with negative refractive power, an intermediate group M having one or more lens groups and having a positive refractive power as a whole, a lens group F with negative refractive power, and a rear group R having one or more lens groups. The intermediate group M is composed of, in order from the object side, a first positive subgroup Mp1 consisting of one or two positive lenses, a first negative subgroup Mn1 consisting of only one bonded lens formed by joining two or more lenses, a second negative subgroup Mn2 having a negative lens with a concave surface facing the object side, and a second positive subgroup Mp2 having one or two positive lenses. The lens closest to the image in the second positive subgroup Mp2 is a positive lens. The lenses and cemented lenses constituting the second negative subgroup Mn2 are all lenses having negative refractive power, and when the second negative subgroup Mn2 includes the cemented lens, the cemented lens is a cemented lens formed by joining two lenses having refractive powers of different signs. The lenses and cemented lenses constituting the second positive subgroup Mp2 are all lenses having positive refractive power, and when the second positive subgroup Mp2 includes the cemented lens, the cemented lens is a cemented lens formed by joining two lenses having refractive powers of different signs. The rear group R has at least one lens group with negative refractive power, When zooming, the spacing between adjacent lens groups changes. During focusing, the lens group F moves along the optical axis. A zoom lens characterized by satisfying the following condition. -1.30 ≦ fM / fMn1 ≦ -0.185 ... (1) 0.3 ≦ BFw / Y ≦ 1.1 (6) however, fMn1: Focal length of the first negative subgroup Mn1 fM: Combined focal length of the intermediate group M BFw: The back focus of the zoom lens at the wide-angle end, calculated by converting the cover glass thickness to air equivalent. Y: Maximum image height of the zoom lens

2. Composed in order from the object side, a first lens group with positive refractive power, a second lens group with negative refractive power, an intermediate group M having one or more lens groups and having a positive refractive power as a whole, a lens group F with negative refractive power, and a rear group R having one or more lens groups, The intermediate group M is composed of, in order from the object side, a first positive subgroup Mp1 consisting of one or two positive lenses, a first negative subgroup Mn1 consisting of only one bonded lens formed by joining two or more lenses, a second negative subgroup Mn2 having a negative lens with a concave surface facing the object side, and a second positive subgroup Mp2 having one or two positive lenses. The lens closest to the image in the second positive subgroup Mp2 is a positive lens. The lenses and cemented lenses constituting the second negative subgroup Mn2 are all lenses having negative refractive power, and when the second negative subgroup Mn2 includes the cemented lens, the cemented lens is a cemented lens formed by joining two lenses having refractive powers of different signs. The lenses and cemented lenses constituting the second positive subgroup Mp2 are all lenses having positive refractive power, and when the second positive subgroup Mp2 includes the cemented lens, the cemented lens is a cemented lens formed by joining two lenses having refractive powers of different signs. When zooming, the spacing between adjacent lens groups changes. During focusing, the lens group F moves along the optical axis. The intermediate group M has a positive lens P on the object side, A zoom lens characterized in that it satisfies the following condition (6), and the positive lens P simultaneously satisfies the following conditions (4) and (5). 0.3 ≦ BFw / Y ≦ 1.5 (6) 0.01 ≤ θgF - (-1.618 × 10⁻³ × νd + 0.6415) ≤ 0.06 ... (4) 10≦νd≦35...(5) however, BFw: The back focus of the zoom lens at the wide-angle end, calculated by converting the cover glass thickness to air equivalent. Y: Maximum image height of the zoom lens θgF: Partial dispersion ratio of the g-line and F-line of the material of the positive lens P. νd: Abbe number of the material of the positive lens P with respect to the d line

3. Composed in order from the object side, a first lens group with positive refractive power, a second lens group with negative refractive power, an intermediate group M having one or more lens groups and having a positive refractive power as a whole, a lens group F with negative refractive power, and a rear group R having one or more lens groups, The intermediate group M is composed of, in order from the object side, a first positive subgroup Mp1 consisting of one or two positive lenses, a first negative subgroup Mn1 consisting of only one bonded lens formed by joining two or more lenses, a second negative subgroup Mn2 having a negative lens with a concave surface facing the object side, and a second positive subgroup Mp2 having one or two positive lenses. The lens closest to the image in the second positive subgroup Mp2 is a positive lens. The lenses and cemented lenses constituting the second negative subgroup Mn2 are all lenses having negative refractive power, and when the second negative subgroup Mn2 includes the cemented lens, the cemented lens is a cemented lens formed by joining two lenses having refractive powers of different signs. The lenses and cemented lenses constituting the second positive subgroup Mp2 are all lenses having positive refractive power, and when the second positive subgroup Mp2 includes the cemented lens, the cemented lens is a cemented lens formed by joining two lenses having refractive powers of different signs. The rear group R has at least one lens group with negative refractive power, When zooming, the spacing between adjacent lens groups changes. When zooming from the wide-angle end to the telephoto end, the second lens group moves toward the image side. The object side of the negative lens included in the second negative subgroup Mn2 has a stronger curvature with respect to the image plane side. During focusing, the lens group F moves along the optical axis. A zoom lens characterized by satisfying the following condition. 0.3 ≦ BFw / Y ≦ 1.1 (6) however, BFw: The back focus of the zoom lens at the wide-angle end, calculated by converting the cover glass thickness to air equivalent. Y: Maximum image height of the zoom lens

4. Composed in order from the object side, a first lens group with positive refractive power, a second lens group with negative refractive power, an intermediate group M having one or more lens groups and having a positive refractive power as a whole, a lens group F with negative refractive power, and a rear group R having one or more lens groups, The intermediate group M is composed of, in order from the object side, a first positive subgroup Mp1 consisting of one or two positive lenses, a first negative subgroup Mn1 consisting of only one bonded lens formed by joining two or more lenses, a second negative subgroup Mn2 having a negative lens with a concave surface facing the object side, and a second positive subgroup Mp2 having one or two positive lenses. The lens closest to the object in the first positive subgroup Mp1 is a positive meniscus lens with its convex surface facing the object. The lens closest to the image in the second positive subgroup Mp2 is a positive lens. The lenses and cemented lenses constituting the second negative subgroup Mn2 are all lenses having negative refractive power, and when the second negative subgroup Mn2 includes the cemented lens, the cemented lens is a cemented lens formed by joining two lenses having refractive powers of different signs. The lenses and cemented lenses constituting the second positive subgroup Mp2 are all lenses having positive refractive power, and when the second positive subgroup Mp2 includes the cemented lens, the cemented lens is a cemented lens formed by joining two lenses having refractive powers of different signs. The aforementioned lens group F consists only of a cemented lens formed by joining one negative lens and one positive lens. When zooming, the spacing between adjacent lens groups changes. During focusing, the lens group F moves along the optical axis. A zoom lens characterized by satisfying the following condition. 0.3 ≦ BFw / Y ≦ 1.3 (6) however, BFw: The back focus of the zoom lens at the wide-angle end, calculated by converting the cover glass thickness to air equivalent. Y: Maximum image height of the zoom lens

5. The zoom lens according to any one of claims 1 to 4, wherein the rear group R has a negative refractive power as a whole.

6. The zoom lens according to claim 1 or claim 3, wherein when zooming from the wide-angle end to the telephoto end, the negative refractive power lens group of the rear group R moves toward the object.

7. The zoom lens according to any one of claims 1 to 6, wherein the first lens group moves toward the object when zooming from the wide-angle end to the telephoto end.

8. A zoom lens according to any one of claims 1 to 7, satisfying the following conditional expression. 0.15≦Rmf / ft≦0.70...(2) however, Rmf: Radius of curvature of the lens surface closest to the object in the intermediate group M. ft: Focal length of the zoom lens at the telephoto end.

9. A zoom lens according to any one of claims 1 to 8, satisfying the following conditional expression. -0.80 ≦ Rmb / ft ≦ -0.15 ... (3) however, Rmb: Radius of curvature of the image-side lens surface of the intermediate group M. ft: Focal length of the zoom lens at the telephoto end.

10. The zoom lens according to any one of claims 1 to 9, wherein the lens surface of the second lens group closest to the object is convex toward the object.

11. The zoom lens according to any one of claims 1 to 10, wherein the intermediate group M has at least one air lens having negative refractive power.

12. An imaging device comprising a zoom lens according to any one of claims 1 to 11, and an image sensor on the image side of the zoom lens that converts an optical image formed by the zoom lens into an electrical signal.

Images