Zoom lens and imaging device

Abstract

To provide a zoom lens that is small as a whole and has excellent optical performance while having a large aperture ratio, and an imaging apparatus having the zoom lens.SOLUTION: An imaging apparatus comprises a zoom lens. The zoom lens includes, in order from an object side, a first lens group having positive refractive power, a second lens group having 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 having negative refractive power, and a rear group R having one or more lens groups. The first lens group includes two positive lenses, the intermediate group M includes at least two lens surfaces Si, each of which is a cemented surface and is a diverging surface, a space between adjacent lens groups changes in zooming, at least one lens group of the lens groups constituting the intermediate group M moves to the object side in zooming from a wide-angle end to a telephoto end, the lens group F moves on an optical axis in focusing, and predetermined conditional expressions are satisfied.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Imaging devices using solid-state imaging elements, such as digital still cameras and digital video cameras, are becoming increasingly popular. These imaging devices include a variety of types, such as digital still cameras, digital video cameras, broadcast cameras, surveillance cameras, and vehicle-mounted cameras. For all of these imaging devices, there is strong market demand for zoom lenses with large aperture ratios and high optical performance.

[0003] One known optical configuration for zoom lenses is the positive lead type, which has a lens group with positive refractive power closest to the object. In a positive lead type zoom lens, a strong negative refractive power is generally placed in the second lens group, which is the second lens group from the object side, and this allows the second lens group to shoulder a large burden in zooming, making it easier to achieve a high zoom ratio. Such positive lead type zoom lenses tend to be more telephoto, allowing the overall optical length to be shortened relative to the focal length.

[0004] To achieve a zoom lens with a small F-number and high optical performance, it is necessary to effectively correct various aberrations that occur due to a large aperture ratio. Therefore, in a zoom lens with a small F-number, it is difficult to assign strong refractive power to each lens group compared to a zoom lens with a large F-number, and the overall system tends to become larger. Furthermore, to achieve a zoom lens with a small F-number, it is preferable to position a lens group with strong positive refractive power toward the image side, i.e., at the rear of the overall system. However, if a lens group with strong positive refractive power is positioned at the rear of the overall system, it becomes difficult to achieve a zoom lens with strong telephoto characteristics and to shorten the overall optical length. Thus, to achieve a zoom lens with a large aperture ratio, high optical performance, and a compact size, it is necessary to appropriately design the power distribution, imaging magnification, lens configuration, etc. of each lens group.

[0005] In recent years, digital still cameras and other devices that capture images using live view have become popular. When capturing images using live view, the subject is focused using either the image plane phase difference AF method or the contrast AF method. In particular, the contrast AF method focuses on the subject by constantly moving the focus group. Furthermore, in recent years, digital still cameras and other devices that employ tracking AF have also become widely used. Tracking AF is an autofocus function that, after focusing on the subject to be captured once, continuously 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 to capture video or other images, the size of the subject on the imaging surface changes as the focus group moves. If the change in image magnification caused by the movement of the focus group is significant, it can be unnatural for the photographer observing the live view image. It is known that the change in image magnification increases the closer the focus group is to the object, i.e., the further forward the focus group is positioned in the optical system. Therefore, it is necessary to appropriately position the focus group.

[0007] Currently, the following zoom lenses are known. For example, Patent Document 1 discloses a bright zoom lens with an F-number of approximately 1.9 to 2.8, which includes, in order from the object side, lens groups with positive, negative, positive, negative, and positive refractive powers. However, this zoom lens does not achieve sufficient size reduction because the combined refractive power of the first to third lens groups is weak and a lens group with strong positive refractive power is located at the rear of the entire system.

[0008] Patent Document 2 discloses a bright zoom lens with an aperture of approximately F2.8, which includes, in order from the object side, lens groups with positive, negative, positive, negative, positive refractive powers. However, in this zoom lens, the second lens group, which is closer to the object side than the aperture, is used as a focus group. In other words, since the focus group is located at the front of the entire system, there is a problem that the image magnification changes significantly, making it unsuitable for tracking AF or contrast AF. In addition, the second lens group is relatively heavy, and when contrast AF is used, the weight of the focus group makes it difficult to achieve rapid focusing with this zoom lens. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] WO2017 / 99243 publication [Patent Document 2] Japanese Patent Application Publication No. 2020-197600 Summary of the Invention [Problem to be solved by the invention]

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

[0011] In order to achieve the above object, a zoom lens according to the present invention comprises, in order from the object side, a first lens group with positive refractive power, a second lens group with negative refractive power, a middle 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 first lens group includes two positive lenses, the middle group M includes at least two lens surfaces Si that are cemented surfaces and diverging surfaces, the spacing between adjacent lens groups changes during zooming, at least one lens group of the middle group M moves toward the object side during zooming from the wide-angle end to the telephoto end, and the lens group F moves on the optical axis during focusing, and wherein the following conditional expressions are satisfied: 0.50 ≦ Σφi / φm ≦ 1.50 ···(1) 0.3 ≦ BFw / Y ≦ 1.5 (7) however, Σφi: the sum of the refractive powers of the lens surfaces Si included in the intermediate group M Here, for each lens surface Si (i=1, 2, . . .) included in the intermediate group M, when the refractive indices of the media before and after each lens surface Si at the d-line are Nfi and Nbi, and the radius of curvature of each lens surface Si is Ri, the refractive power of each lens surface Si is φi=|(Nfi-Nbi) / Ri|(i=1, 2, . . .), φm: composite refractive power of the intermediate group M at the telephoto end, which is calculated by φm=1 / fm fm: composite focal length of the intermediate group M at the telephoto end BFw: Back focal length of the zoom lens at the wide-angle end, calculated by converting the cover glass thickness into air. Y: Maximum image height of the zoom lens

[0012] In order to solve the above problem, the imaging device according to the present invention is characterized by including the zoom lens and an imaging element that converts an 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 compact overall, and has excellent optical performance, and an imaging device that includes the zoom lens. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a lens cross-sectional view of a zoom lens of Example 1 at a wide-angle end. [Figure 2] 3A to 3C are diagrams illustrating spherical aberration, astigmatism, and distortion of the zoom lens of Example 1 at the wide-angle end when focused on infinity. [Figure 3] 3A to 3C are diagrams illustrating spherical aberration, astigmatism, and distortion of the zoom lens of Example 1 when focused on infinity at an intermediate focal length. [Figure 4] 3A to 3C are diagrams illustrating spherical aberration, astigmatism, and distortion of the zoom lens of Example 1 at the telephoto end when focused on infinity. [Figure 5] FIG. 10 is a cross-sectional view of a zoom lens according to a second embodiment at the wide-angle end. [Figure 6] 10A to 10C are diagrams illustrating spherical aberration, astigmatism, and distortion of the zoom lens of Example 2 when focused on infinity at the wide-angle end. [Figure 7] 10A to 10C are diagrams illustrating spherical aberration, astigmatism, and distortion of the zoom lens of Example 2 when focused on infinity at an intermediate focal length. [Figure 8] 10A to 10C are diagrams illustrating spherical aberration, astigmatism, and distortion of the zoom lens of Example 2 when focused on infinity at the telephoto end. [Figure 9] FIG. 10 is a lens cross-sectional view of a zoom lens of Example 3 at the wide-angle end. [Figure 10] 10A to 10C are diagrams illustrating spherical aberration, astigmatism, and distortion of the zoom lens of Example 3 when focused on infinity at the wide-angle end. [Figure 11] 10A to 10C are diagrams illustrating spherical aberration, astigmatism, and distortion of the zoom lens of Example 3 when focused on infinity at an intermediate focal length. [Figure 12] 10A to 10C are diagrams illustrating spherical aberration, astigmatism, and distortion of the zoom lens of Example 3 when focused on infinity at the telephoto end. [Figure 13]FIG. 10 is a lens cross-sectional view of a zoom lens of Example 4 at the wide-angle end. [Figure 14] 10A to 10C are diagrams illustrating spherical aberration, astigmatism, and distortion of the zoom lens of Example 4 when focused on infinity at the wide-angle end. [Figure 15] 10A to 10C are diagrams illustrating spherical aberration, astigmatism, and distortion of the zoom lens of Example 4 when focused on infinity at an intermediate focal length. [Figure 16] 10A to 10C are diagrams illustrating spherical aberration, astigmatism, and distortion of the zoom lens of Example 4 when focused on infinity at the telephoto end. [Figure 17] FIG. 10 is a lens cross-sectional view of a zoom lens of Example 5 at the wide-angle end. [Figure 18] 10A to 10C are diagrams illustrating spherical aberration, astigmatism, and distortion of the zoom lens of Example 5 when focused on infinity at the wide-angle end. [Figure 19] 10A to 10C are diagrams illustrating spherical aberration, astigmatism, and distortion of the zoom lens of Example 5 when focused on infinity at an intermediate focal length. [Figure 20] 10A to 10C are diagrams illustrating spherical aberration, astigmatism, and distortion of the zoom lens of Example 5 when focused on infinity at the telephoto end. [Figure 21] FIG. 13 is a lens cross-sectional view of a zoom lens of Example 6 at the wide-angle end. [Figure 22] 13A to 13C are diagrams illustrating spherical aberration, astigmatism, and distortion of the zoom lens of Example 6 when focused on infinity at the wide-angle end. [Figure 23] 13A to 13C are diagrams illustrating spherical aberration, astigmatism, and distortion of the zoom lens of Example 6 when focused on infinity at an intermediate focal length. [Figure 24] 13A to 13C are diagrams illustrating spherical aberration, astigmatism, and distortion of the zoom lens of Example 6 when focused on infinity at the telephoto end. DETAILED DESCRIPTION OF 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 merely one aspect 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 aspects.

[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, a middle group M having one or more lens groups and having positive refractive power as a whole, a lens group F having 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 The specific lens configuration of the first lens group is not particularly limited as long as it has positive refractive power as a whole. For example, if the first lens group is configured to include two positive lenses, a strong positive refractive power can be provided in the first lens group. In this case, a high zoom ratio can be achieved while the telephoto tendency can be strengthened at the telephoto end, making it easier to reduce the size of the entire system. Note that a strong telephoto tendency means a smaller telephoto ratio. Furthermore, if the first lens group is configured to include at least one negative lens, correction of spherical aberration, chromatic aberration, etc. becomes easier, making it more preferable for realizing a zoom lens with excellent optical performance.

[0018] (2) Second lens group The specific lens configuration of the second lens group is not particularly limited, as long as it has negative refractive power as a whole. For example, if the second lens group is configured to include two or more negative lenses and one or more positive lenses, a strong negative refractive power can be provided in the second lens group. In this case, it becomes easy to increase the zoom ratio of the second lens group, and it becomes easy to achieve a high zoom ratio while also realizing excellent optical performance. In addition, it is preferable that the lens surface of the second lens group closest to the object side is convex toward the object side. This makes it easy to effectively correct field curvature at the wide-angle end.

[0019] (3) Intermediate group M The intermediate group M is composed of one or more lens groups and has a positive refractive power overall. The intermediate group M is composed of one or more lens groups located between the second lens group and the lens group F. To achieve a zoom lens with a large aperture ratio and a small size, it is preferable to provide the intermediate group M with a strong positive refractive power to converge light beams. If the intermediate group M has a strong positive refractive power, it is necessary to correct the spherical aberration and curvature of field in the under-focus direction that occur in the intermediate group M with a strong diverging effect. Therefore, in this zoom lens, the intermediate group M is provided with at least two lens surfaces Si that are cemented surfaces and diverging surfaces. This enables the intermediate group M to have a relatively strong positive refractive power while effectively correcting the spherical aberration and curvature of field in the under-focus direction with a strong diverging effect, thereby achieving a zoom lens with a large aperture ratio, a small size overall, and excellent optical performance. While the diverging effect can be achieved by a negative single lens surface in the intermediate group M, this tends to generate high-order aberrations and increases the sensitivity to decentering between the lenses. Therefore, by providing the above-mentioned diverging effect to the cemented surface of a cemented lens formed by cementing two or more lenses together, it becomes easy to achieve both compactness and excellent optical performance.

[0020] Of the two or more lens surfaces Si arranged in the intermediate group M, it is preferable that at least one surface be convex toward the object side. This configuration makes it easy to effectively correct field curvature throughout the entire zoom range. Furthermore, this lens surface Si may be a cemented surface, and may be a diverging surface. The intermediate group M may include two or more cemented lenses each including one lens surface Si, or one or more cemented lenses each including two lens surfaces Si. As long as the intermediate group M includes two or more lens surfaces Si, the specific configuration thereof is not particularly limited.

[0021] When the lenses constituting each lens surface Si are lenses LCn (n=1, 2, 3, etc.), 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 lens surface Si. The refractive power φLCn is defined by the following formula: φLCn=|(NLCn-1)(1 / LCnR1-1 / LCnR2)| NLCn: Refractive index of lens LCn material at d line LCnR1: Radius of curvature of the object-side surface of lens LCn LCnR2: Radius of curvature of the image side of lens LCn However, if the center of curvature of the lens surface is closer to the image side than the lens surface, the sign of the radius of curvature is positive, and if the center of curvature of the lens surface is closer to the object side than the lens surface, the sign of the radius of curvature is negative. The same applies to the other conditional expressions.

[0022] The lens surfaces Si have an index of i=1, 2,..., where "i" represents the arrangement, from the object side, of the lens surfaces Si in the intermediate group M. The lenses LCn have an index of n=1, 2, 3,..., where "i" represents the arrangement, from the object side, of each lens LCn constituting each lens surface Si.

[0023] It is preferable to position a positive lens closest to the object in the intermediate group M. This configuration makes it easier to reduce the size of the entire system. It is more preferable that this positive lens be a positive meniscus lens with its convex surface facing the object side. This configuration makes it even easier to reduce the diameter of the intermediate group M.

[0024] It is preferable to place a positive lens closest to the image side in the intermediate group M. In this case, it is preferable that the image side surface of the positive lens be convex toward the image side, which makes it easier to ensure a bright F-number for the entire zoom lens system.

[0025] It is preferable that the intermediate group M has at least one air lens having negative refractive power. This makes it easier to ensure the divergence effect of the intermediate group M and to more effectively correct spherical aberration and curvature of field. The refractive power of the air lens can be negative or positive depending on the shape between adjacent lens surfaces arranged with an air gap between them. Since this zoom lens has an air lens having negative refractive power, the air lens has a shape similar to that of a positive lens having a biconvex, plano-convex, or positive meniscus shape.

[0026] Furthermore, if the intermediate group M is composed of two or more lens groups, it is possible to easily suppress aberration fluctuations by changing the axial spacing between adjacent lens groups during zooming, resulting in a zoom lens with even higher optical performance. However, if the number of lens groups constituting the intermediate group M is large, 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 is three or less.

[0027] (4) Lens group F The lens group F is a focus group that moves along the optical axis during focusing. The lens group F, located on the image side of the intermediate group M, receives a light beam converged by the intermediate group M, making it easy to achieve a small lens diameter and a lightweight configuration. Therefore, using the lens group F as a focus group makes it possible to achieve high-speed autofocusing and also to reduce the load on the focus drive system. While the specific lens configuration of the lens group F is not particularly limited as long as it has negative refractive power overall, it is more preferable for the lens group F to be composed solely of a cemented lens formed by cementing one negative lens and one positive lens. This configuration facilitates high-speed autofocusing due to the lightweight focus group and a high-performance zoom lens in which various aberrations, such as spherical aberration and chromatic aberration, are well corrected over the entire object distance range.

[0028] (5) Rear group R The rear group R has at least one lens group. The rear group R is composed of lens groups arranged between the lens group F and the image plane. It is preferable that the rear group R has at least one lens group with negative refractive power, and it is preferable that the rear group R has negative refractive power as a whole. This configuration makes it easier to achieve a zoom lens with a stronger telephoto tendency at the telephoto end and to shorten the overall optical length at the telephoto end. The rear group R may have two or more lens groups, but increasing the number of lens groups constituting the zoom lens makes it difficult to achieve compactness.

[0029] (6) Aperture diaphragm It is preferable to place the aperture stop on the object side of the intermediate group M, or within the intermediate group M. In particular, by placing the aperture stop adjacent to the object side of the intermediate group M, it becomes easy to reduce the effective diameter of the first lens group at the wide-angle end.

[0030] 1-2.Operation (1) Zooming The zoom lens varies the magnification by changing the distance between adjacent lens groups on the optical axis during zooming. All of the lens groups may move along the optical axis, or some of the lens groups may be fixed along the optical axis, as long as the distance between the adjacent lens groups on the optical axis changes during zooming.

[0031] While there are no particular limitations on whether 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 side during zooming from the wide-angle end to the telephoto end. Moving these lens groups in this manner reduces the strain on the zooming action of each lens group from the second lens group onwards, resulting in a configuration that makes it easier to achieve both high zoom ratios and high performance.

[0032] It is preferable that the second lens group move toward the image side during zooming from the wide-angle end to the telephoto end. By moving the second lens group toward the image side, it becomes easier to reduce the outer diameter of the middle group M at the telephoto end, which makes it easier to reduce the diameter of the aperture unit and make the zoom lens smaller and lighter.

[0033] If the rear lens unit R includes a lens unit with negative refractive power, it is preferable that the lens unit with negative refractive power move toward the object during zooming from the wide-angle end to the telephoto end. By moving in this manner during zooming, the magnification effect of the rear lens unit R can be improved. This allows the amount of movement of each lens unit to be reduced, making it easier to achieve a more compact zoom lens with a high zoom ratio.

[0034] If the rear group R includes two or more lens groups, it is preferable that the lens group located closest to the image side of the rear group R be fixed on the optical axis during zooming, in order to avoid complicating the cam structure of the lens barrel.

[0035] (2) Focusing This zoom lens performs focusing from infinity to a close distance by moving lens group F toward the image along the optical axis. Lens group F is located on the image side of intermediate group M, i.e., at the rear of the zoom lens. Therefore, by using lens group F as the focus group, fluctuations in the angle of view that accompany movement of the focus group can be suppressed. As a result, a zoom lens suitable for video capture using a tracking AF function can be obtained not only when a contrast AF system is used, but also when an image plane phase-difference AF system is used.

[0036] 1-3.Conditional Expressions It is desirable that the zoom lens employ the above-described configuration and satisfy at least one of the following conditional expressions.

[0037] 0.50 ≦ Σφi / φm ≦ 1.50 ···(1) however, Σφi: the sum of the refractive powers of the lens surfaces Si included in the intermediate group M Here, for each lens surface Si (i=1, 2, . . .) included in the intermediate group M, let Nfi and Nbi be the refractive indices of the media in front of and behind each lens surface Si at the d-line, and let Ri be the radius of curvature of each lens surface Si. Then, let φi = |(Nfi-Nbi) / Ri| (i=1, 2, . . .) φm: composite refractive power of the intermediate group M at the telephoto end, calculated by φm=1 / fm fm: composite focal length of the middle group M at the telephoto end

[0038] Conditional formula (1) is a conditional formula for appropriately setting the sum of the refractive powers of the lens surfaces Si included in the intermediate group M. By satisfying conditional formula (1), the divergence effect of the lens surfaces Si can be used to effectively correct spherical aberration and curvature of field throughout the entire zoom range. Therefore, even when a strong positive refractive power is disposed in the intermediate group M, these aberrations can be effectively corrected, making it possible to achieve a compact zoom lens with high optical performance while achieving a large aperture ratio.

[0039] On the other hand, if the value of conditional expression (1) is below the lower limit, the divergence effect of lens surface Si becomes small. If a strong positive refractive power is placed in the middle group M, it becomes difficult to effectively correct spherical aberration and curvature of field, which tend to cause under-correction. This makes it difficult to achieve a compact zoom lens with high optical performance while achieving a large aperture ratio. On the other hand, if the value of conditional expression (1) is above the upper limit, it becomes difficult to effectively correct spherical aberration and curvature of field.

[0040] To obtain the above effects, the upper limit of conditional expression (1) is preferably 1.40, more preferably 1.30, and the lower limit of conditional expression (1) is preferably 0.55, more preferably 0.60.

[0041] 1-3-2. Conditional Expression (2) 0.85 ≦ Fnom ≦ 1.40 (2) however, Fnom: The F-number from the first lens group to the intermediate group M, which is the minimum value in the entire zoom range

[0042] Conditional expression (2) is a conditional expression for appropriately setting the minimum F-number across the entire zoom range from the first lens group through the middle group M. By satisfying conditional expression (2), it becomes easy to ensure the desired brightness of the zoom lens. Furthermore, the divergence effect of the lens surface Si included in the middle group M can be maximized.

[0043] On the other hand, if the value of conditional expression (2) is below the lower limit, the F-number from the first lens group to the intermediate group M becomes too small, making it difficult to effectively correct various aberrations. On the other hand, if the value of conditional expression (2) exceeds the upper limit, it becomes difficult to ensure the desired brightness of the zoom lens. In this case, to achieve the desired brightness, it is necessary to impart strong positive refractive power to the rear group R, which weakens the telephoto tendency and makes it difficult to shorten the overall length.

[0044] To obtain the above effects, the upper limit of conditional expression (2) is preferably 1.35, and more preferably 1.30, and the lower limit of conditional expression (2) is preferably 0.90, and more preferably 0.95.

[0045] 1-3-3. Conditional Expression (3) 0.15 ≦ Rmf / ft ≦ 0.70 (3) 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

[0046] Conditional expression (3) is a conditional expression for appropriately setting the ratio between the radius of curvature of the lens surface in the intermediate group M closest to the object and the focal length of the zoom lens at the telephoto end. When conditional expression (3) is satisfied, the lens surface in the intermediate group M closest to the object will be convex toward the object. Satisfying conditional expression (3) makes it easy to balance the reduction in overall length and optical performance.

[0047] On the other hand, if the value of conditional expression (3) is below the lower limit, it becomes easy to reduce the overall length, but the spherical aberration and curvature of field that occur at the lens surface closest to the object in the intermediate group M tend to be strongly under-corrected, making it difficult to satisfactorily correct these.On the other hand, if the value of conditional expression (3) exceeds the upper limit, in order to obtain a compact zoom lens while achieving a large aperture ratio, it becomes necessary to strongly converge the light beam in the intermediate group M, which increases the number of lenses with positive refractive power disposed in the intermediate group M, making it difficult to reduce the overall length.

[0048] To obtain the above effect, the upper limit of conditional expression (3) is preferably 0.65, more preferably 0.6, and even more preferably 0.55, and the lower limit of conditional expression (3) is preferably 0.20, and even more preferably 0.25.

[0049] 1-3-4.Conditional Expression (4) -0.80 ≦ Rmb / ft ≦ -0.15 (4) however, Rmb: Radius of curvature of the lens surface closest to the image in the intermediate group M ft: focal length of the zoom lens at the telephoto end

[0050] Conditional expression (4) is a conditional expression for appropriately setting the ratio between the radius of curvature of the lens surface closest to the image in the intermediate group M and the focal length of the zoom lens at the telephoto end. When conditional expression (4) is satisfied, the lens surface closest to the image in the intermediate group M will be convex toward the image side. Satisfying conditional expression (4) makes it easy to reduce the overall length of the zoom lens while ensuring the desired brightness.

[0051] On the other hand, if the value of conditional expression (4) is below the lower limit, it becomes difficult to ensure brightness from the first lens group to the intermediate group M. On the other hand, if the value of conditional expression (4) exceeds the upper limit, it becomes easy to reduce the overall length, but the curvature of the lens surface of the intermediate group M closest to the image becomes too strong, making it difficult to effectively correct spherical aberration and curvature of field.

[0052] To obtain the above effect, the upper limit of conditional expression (4) is preferably −0.20, and more preferably −0.25, and the lower limit of conditional expression (4) is preferably −0.75, and more preferably −0.70, and even more preferably −0.65.

[0053] 1-3-5. Conditional Expressions (5) and (6) It is preferable that the intermediate group M has a positive lens P closest to the object side, and that this positive lens P simultaneously satisfies the following conditional expressions (5) and (6). 0.01≦θgF-(-1.618×10 -3 ×νd+0.6415)≦0.06 (5) 10 ≦ νd ≦ 35 (6) however, When the refractive indices of the material of the positive lens P for the d-line, F-line, C-line, and g-line are nd, nF, nC, and ng, respectively, θgF: The partial dispersion ratio of the material of the positive lens P to the g-line and F-line θgF = (ng-nF) / (nF-nC) νd: Abbe number for the d-line of the material of the positive lens P, νd=(nd-1) / (nF-nC)

[0054] Conditional formula (5) defines the anomalous dispersion of the material of the positive lens P. Conditional formula (6) defines the Abbe number for the d-line of the material of the positive lens P. By positioning the positive lens P that satisfies both conditional formulas (5) and (6) closest to the object in the intermediate group M, axial chromatic aberration can be effectively corrected throughout the entire zoom range. Generally, a positive lens included in a lens group with positive refractive power is corrected for chromatic aberration by using a material on the low-dispersion side. However, the intermediate group M of this zoom lens has a large diverging effect due to the diverging surface, and axial chromatic aberration at short wavelengths tends to be excessive. Therefore, by using a material on the high-dispersion side for the positive lens P, effective chromatic aberration correction becomes easier.

[0055] On the other hand, if the value of conditional formula (5) is less than the lower limit or the value of conditional formula (6) exceeds the upper limit, axial chromatic aberration on the short wavelength side, such as the F-line and g-line, tends to be overcorrected, making correction difficult.On the other hand, if the value of conditional formula (5) exceeds the upper limit or the value of conditional formula (6) is less than the lower limit, axial chromatic aberration on the short wavelength side, such as the F-line and g-line, tends to be undercorrected, making correction difficult.

[0056] In order to obtain the above effect, the upper limit of conditional expression (5) is preferably 0.05, and the lower limit of conditional expression (5) is preferably 0.02, and more preferably 0.03. In order to obtain the above-mentioned effects, the upper limit of conditional expression (6) is preferably 30, more preferably 25, and even more preferably 23. The lower limit of conditional expression (6) is preferably 15, and more preferably 18.

[0057] 1-3-6. Conditional Expression (7) 0.3 ≦ BFw / Y ≦ 1.5 (7) however, BFw: Back focal length of the zoom lens at the wide-angle end, calculated by converting the cover glass thickness into air. Y: Maximum image height of the zoom lens

[0058] Conditional expression (7) defines the ratio between the back focal length of the zoom lens at the wide-angle end and the maximum image height of the zoom lens. By satisfying conditional expression (7), the back focal length of the zoom lens at the wide-angle end can be shortened, and the overall length can be reduced.

[0059] If the value of conditional expression (7) is less than the lower limit, the back focal length of the zoom lens at the wide-angle end becomes too short, and the inclination angle of light incident on the imaging surface with respect to the optical axis becomes too large.On the other hand, if the value of conditional expression (7) is more than the upper limit, the back focal length of the zoom lens at the wide-angle end becomes too long, and it becomes difficult to reduce the overall length of the zoom lens.

[0060] To obtain the above effect, the upper limit of conditional expression (7) is preferably 1.3, more preferably 1.2, and even more preferably 1.1, and the lower limit of conditional expression (7) is preferably 0.4, more preferably 0.5, and even more preferably 0.6.

[0061] 2. Imaging device Next, we will explain the imaging device of the present invention. The imaging device of the present invention is characterized by including the zoom lens of the present invention described above and an imaging element that converts an optical image formed by the zoom lens into an electrical signal. The imaging element is preferably provided on the image side of the zoom lens. As the imaging element, a CCD (Charge Coupled Device) sensor or a CMOS (Complementary Metal Oxide Semiconductor) sensor can be suitably used.

[0062] In particular, the zoom lens has a large aperture ratio, yet is compact overall and offers excellent optical performance. Furthermore, the zoom lens can suppress fluctuations in the angle of view that accompany movement of the focus group, making it suitable for video capture using a tracking AF function, not only when a contrast AF system is used, but also when an image plane phase difference AF system is used. Therefore, by employing this zoom lens, an imaging device with a tracking AF function suitable for video capture can be created.

[0063] Next, the present invention will be specifically described with reference to examples, but the present invention is not limited to the following examples. [Example]

[0064] (1) Optical configuration 1 is a cross-sectional view of a zoom lens according to Example 1 of the present invention at the wide-angle end when focusing at infinity. The zoom lens of Example 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 middle lens group M. The fourth lens group G4 corresponds to the lens group F. The fifth lens group G5 corresponds to the rear lens group R.

[0065] When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side, the second lens group G2 moves toward the image side, the third lens group G3 moves toward the object side, the fourth lens group G4 moves toward the object side, and the fifth lens group G5 moves toward the object side. Focusing from an object at infinity to an object at a close distance is performed by moving the fourth lens group G4 (lens group F) toward the image side. The aperture stop S is disposed adjacent to the object side of the third lens group G3.

[0066] The configuration of each lens group will be described below. The first lens group G1 is composed of, in order from the object side, a cemented lens formed by cementing together a negative meniscus lens L1 with a convex surface facing the object side and a biconvex lens L2, and a positive meniscus lens L3 with a convex surface facing the object side.

[0067] The second lens group G2 is composed of, in order from the object side, a negative meniscus lens L4 with its convex surface facing the object side, a biconvex lens L5, a biconcave lens L6, a cemented lens formed by cementing together a biconcave lens L7 and a biconvex lens L8, and a negative meniscus lens L9 with its concave surface facing the object side.

[0068] The third lens group G3 is composed of, in order from the object side, a positive meniscus lens L10 with a convex surface facing the object side, a positive meniscus lens L11 with a convex surface facing the object side, a cemented lens formed by cementing together three lenses: a negative meniscus lens L12 with a convex surface facing the object side, a biconvex lens L13, and a biconcave lens L14, a negative meniscus lens L15 with a concave surface facing the object side, and a biconvex lens L16. The negative meniscus lens L15 is a glass-molded aspherical lens with an aspherical surface on the object side. The biconvex lens L16 is a glass-molded aspherical lens with aspherical surfaces on both sides. The cemented surfaces between the negative meniscus lens L12 and the biconvex lens L13 and the cemented surface between the biconvex lens L13 and the biconcave lens L14 are each diverging surfaces, and these cemented surfaces are referred to as lens surfaces Si(S1, S2) in this invention. Between the biconcave lens L14 and the negative meniscus lens L15 is a biconvex air lens having negative refractive power. The lens surface closest to the object in the third lens group is convex toward the object, and the lens surface closest to the image is convex toward the image.

[0069] The fourth lens group G4 is composed of a cemented lens in which a biconvex lens L17 and a biconcave lens L18 are cemented together.

[0070] The fifth lens group G5 is composed of, in order from the object side, a cemented lens formed by cementing together a negative meniscus lens L19 with its convex surface facing the object side and a biconvex 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 surfaces on both sides.

[0071] In Figure 1, "IP" denotes an image plane, specifically the imaging surface of an imaging element such as a CCD sensor or CMOS sensor, or the film surface of a silver halide film. A parallel plate with no substantial refractive power, such as a cover glass CG, is provided on the object side of the image plane IP. These points are the same in the lens cross-sectional views shown in other embodiments, and therefore will not be described further below.

[0072] (2) Numerical examples Next, we will explain numerical examples to which specific numerical values of the zoom lens are applied. The following shows "lens data," "specification table," "variable spacing," "lens group data," and "aspherical coefficients." The values of conditional expressions (1) to (7) (Table 1), the values used to determine each conditional expression, and the values of φLCn for each example (Table 2) are listed after Example 6.

[0073] In the "Lens Data" section, "Surface Number" indicates the order of the lens surface counted from the object side, "r" indicates the radius of curvature of the lens surface, "d" indicates the lens thickness or air gap on the optical axis, "nd" indicates the refractive index at the d-line (wavelength λ=587.56 nm), and "νd" indicates the Abbe number at the d-line. In the "Surface Number" column, "ASPH" next to the surface number indicates that the lens surface is aspherical, and "S" indicates that the surface is an aperture stop. In the "d" column, "d(0)," "d(5)," etc. indicate that the spacing on the optical axis of the lens surface is variable, changing with magnification. In the "Radius of Curvature" column, "∞" indicates infinity, meaning that the lens surface is flat. All lengths in the table are in millimeters, and all angles of view are in degrees, as in other tables.

[0074] In the "Specifications Table," "f" indicates the focal length of the zoom lens, "FNo." indicates the F-number, "ω" indicates the half angle of view, and "Y" indicates the image height. The values shown are for the wide-angle end, mid-range focal length, and telephoto end, respectively.

[0075] In the "variable distance" column, values at the wide-angle end, at the intermediate focal length, and at the telephoto end when focusing on an object at infinity and when focusing on a close object are shown.

[0076] [Lens Group Data] shows the focal length of each lens group.

[0077] "Aspherical coefficients" indicate aspherical coefficients when the aspherical shape is defined as follows: where x is the amount of displacement from the reference surface in the optical axis direction, r is the paraxial radius of curvature, H is the height from the optical axis in the direction perpendicular to the optical axis, k is the conical coefficient, and An is the n-th order aspherical coefficient. In the "Aspherical coefficients" table, "E±XX" represents exponential notation, and "×10 ±XX " means.

[0078]

number

[0079] The items in these tables are the same as those in the tables shown in other embodiments, and therefore will not be described below.

[0080] 2, 3, and 4 show longitudinal aberration diagrams of the zoom lens at the wide-angle end, mid-focal length, and telephoto end when focused on infinity. The longitudinal aberration diagrams shown in each diagram, from left to right, represent spherical aberration (mm), astigmatism (mm), and distortion (%), respectively. In the spherical aberration diagrams, the solid line represents spherical aberration at the d-line (wavelength 587.56 nm), the dashed line represents spherical aberration at the C-line (wavelength 656.28 nm), and the dash-dotted line represents spherical aberration at the g-line (wavelength 435.84 nm). In the astigmatism diagrams, the vertical axis represents half angle of view (ω) and the horizontal axis represents defocus. The solid line represents the sagittal image plane (ds) for the d-line, and the dashed line represents the meridional image plane (dm) for the d-line. In the distortion diagrams, the vertical axis represents half angle of view (ω) and the horizontal axis represents distortion. These matters are the same in the aberration diagrams shown in the other examples, and therefore will not be described below.

[0081] [Lens data] Surface 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 55.5333 1.2000 1.91082 35.25 34 18.9288 9.5794 1.59270 35.31 35 -48.7564 6.1999 36ASPH -23.1657 1.8000 1.69350 53.18 37ASPH -77.5216 d(37) 38 ∞ 2.5000 1.51680 64.20 39∞1.0000 Image plane ∞

[0082] [Specifications table] Wide-angle end Mid-range Telephoto end f 36.0267 74.9717 145.5296 F No. 2.0604 2.6090 2.9089 ω 30.9716 15.3720 8.0578 Y 21.6330 21.6330 21.6330

[0083] Variable Spacing Wide-angle end Mid-range Telephoto end Wide-angle end Mid-range 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

[0084] [Lens group data] Group number Focal length G1 142.9320 G2 -30.6227 G3 32.3890 G4 -55.4052 G5 -136.9750

[0085] [Aspheric coefficients] 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 [Example]

[0086] (1) Optical configuration 5 is a cross-sectional view of a zoom lens according to Example 2 of the present invention at the wide-angle end when focusing at infinity. The zoom lens of Example 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 middle lens group M. The fourth lens group G4 corresponds to the lens group F. The fifth lens group G5 corresponds to the rear lens group R.

[0087] During zooming from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side, the second lens group G2 moves toward the image side, the third lens group G3 moves toward the object side, the fourth lens group G4 moves toward the object side, and the fifth lens group G5 moves toward the object side. Focusing from an object at infinity to an object at a close distance is performed by moving the fourth lens group G4 (lens group F) toward the image side. The aperture stop S is disposed adjacent to the object side of the third lens group G3.

[0088] The configuration of each lens group will be described below. The first lens group G1 is composed of, in order from the object side, a cemented lens formed by cementing together a negative meniscus lens L1 with a convex surface facing the object side and a biconvex lens L2, and a positive meniscus lens L3 with a convex surface facing the object side.

[0089] The second lens group G2 is composed of, in order from the object side, a negative meniscus lens L4 with its convex surface facing the object side, a cemented lens formed by cementing together a biconcave lens L5 and a biconvex lens L6, and a negative meniscus lens L7 with its concave surface facing the object side. The negative meniscus lens L4 is a composite resin aspherical lens with a composite resin film molded into an aspherical shape attached to its object-side surface.

[0090] The third lens group G3 is composed of, in order from the object side, a positive meniscus lens L8 with a convex surface facing the object side, a biconvex lens L9, a cemented lens formed by cementing a biconcave lens L10 and a positive meniscus lens L11 with a convex surface facing the object side, a cemented lens formed by cementing a biconcave lens L12 and a biconvex lens L13, a biconvex lens L14, and a positive meniscus lens L15 with a convex surface facing the object side. The biconvex lens L9 is a glass-molded aspherical lens with aspherical surfaces on both sides. The biconvex lens L14 is a glass-molded aspherical lens with aspherical surfaces on both sides. The cemented surfaces between the biconcave lens L10 and the positive meniscus lens L11 and the cemented surface between the biconcave lens L12 and the biconvex lens L13 are diverging surfaces, and these cemented surfaces are referred to as lens surfaces Si(S1, S2) in this invention. Between the positive meniscus lens L11 and the biconcave lens L12 is a biconvex air lens having negative refractive power. The lens surface of the third lens group closest to the object side is convex toward the object side.

[0091] The fourth lens group G4 is composed of a cemented lens in which a biconvex lens L16 and a biconcave lens L17 are cemented together.

[0092] The fifth lens group G5 is composed of, in order from the object side, a cemented lens formed by cementing together a negative meniscus lens L18 with its convex surface facing the object side and a biconvex lens L19, 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 surfaces on both sides.

[0093] (2) Numerical examples Next, we will explain numerical examples that apply specific numerical values of this zoom lens. The following shows "lens data," "specification table," "variable spacing," "lens group data," and "aspherical coefficients." Also, Figures 6 to 8 show longitudinal aberration diagrams of this zoom lens at the wide-angle end, intermediate focal length, and telephoto end when focusing on infinity.

[0094] [Lens data] Surface 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 ∞

[0095] [Specifications table] Wide-angle end Mid-range Telephoto end f 36.0230 74.9830 145.6157 F No. 2.0602 2.5529 2.9033 ω 30.9602 15.3672 8.0607 Y 21.6330 21.6330 21.6330

[0096] Variable Spacing Wide-angle end Mid-range Telephoto end Wide-angle end Mid-range 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

[0097] [Lens group data] Group number Focal length G1 140.4610 G2 -30.5472 G3 31.5372 G4 -48.7235 G5 -122.8010

[0098] [Aspheric coefficients] 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 [Example]

[0099] (1) Optical configuration 9 is a cross-sectional view of a zoom lens according to Example 3 of the present invention at the wide-angle end when focusing at infinity. The zoom lens according to Example 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. An intermediate group M is composed of the third lens group G3 and the fourth lens group G4. The fifth lens group G5 corresponds to the lens group F. The sixth lens group G6 corresponds to the rear group R.

[0100] When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side, the second lens group G2 moves toward the image side, the third lens group G3 moves toward the object side, the fourth lens group G4 moves toward the object side, the fifth lens group G5 moves toward the object side, and the sixth lens group G6 moves toward the object side. Focusing from an object at infinity to an object at a close distance is performed by moving the fifth lens group G5 (lens group F) toward the image side. The aperture stop S is disposed adjacent to the object side of the third lens group G3.

[0101] The configuration of each lens group will be described below. The first lens group G1 is composed of, in order from the object side, a cemented lens formed by cementing together a negative meniscus lens L1 having a convex surface facing the object side and a positive meniscus lens L2 having a convex surface facing the object side, and a positive meniscus lens L3 having a convex surface facing the object side.

[0102] The second lens group G2 is composed of, in order from the object side, a negative meniscus lens L4 with a convex surface facing the object side, a biconcave lens L5, a biconvex lens L6, and a negative meniscus lens L7 with a concave surface facing the object side. The negative meniscus lens L7 is a glass-molded aspherical lens with an aspherical surface on the image side.

[0103] The third lens group G3 is composed of, in order from the object side, a positive meniscus lens L8 with a convex surface facing the object side, a biconvex lens L9, a cemented lens formed by cementing a negative meniscus lens L10 with a convex surface facing the object side and a positive meniscus lens L11 with a convex surface facing the object side, a cemented lens formed by cementing a biconvex lens L12 and a negative meniscus lens L13 with a concave surface facing the object side, and a negative meniscus lens L14 with a concave surface facing the object side. The negative meniscus lens L14 is a glass-molded aspherical lens with aspherical surfaces on both sides. The cemented surface between the negative meniscus lens L10 and the positive meniscus lens L11 and the cemented surface between the biconvex lens L12 and the negative meniscus lens L13 are each diverging surfaces, and these cemented surfaces are referred to as lens surfaces Si(S1, S2) in this invention. Furthermore, between the positive meniscus lens L11 and the biconvex lens L12 there is an air lens with a positive meniscus shape with its convex surface facing the object side. Similarly, between the negative meniscus lens L13 and the negative meniscus lens L14 there is an air lens with a positive meniscus shape with its concave surface facing the object side. All of these air lenses have negative refractive power. Furthermore, the lens surface closest to the object side of the third lens group (middle group M) is convex toward the object side.

[0104] The fourth lens group G4 is composed of, from the object side, a cemented lens formed by cementing 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 surfaces on both sides. The cemented surface between the biconvex lens L15 and the negative meniscus lens L16 is a diverging surface, and this cemented surface is also referred to as the lens surface Si(S3) in the present invention. In addition, the lens surface closest to the image side of the fourth lens group (middle group M) is convex toward the image side.

[0105] The fifth lens group G5 is composed of a negative meniscus lens L18 with its convex surface facing the object side.

[0106] The sixth lens group G6 is composed of, in order from the object side, a biconvex lens L19, a negative meniscus lens L20 with its concave surface facing the object side, 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 surfaces on both sides.

[0107] (2) Numerical examples Next, we will explain numerical examples that apply specific numerical values of this zoom lens. The following shows "lens data," "specification table," "variable spacing," "lens group data," and "aspherical coefficients." Also, Figures 10 to 12 show longitudinal aberration diagrams of this zoom lens at the wide-angle end, intermediate focal length, and telephoto end when focusing on infinity.

[0108] [Lens data] Surface 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 ∞

[0109] [Specifications table] Wide-angle end Mid-range 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

[0110] Variable Spacing Wide-angle end Mid-range Telephoto end Wide-angle end Mid-range 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

[0111] [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

[0112] [Aspheric coefficients] 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 [Example]

[0113] (1) Optical configuration 13 is a cross-sectional view of a zoom lens according to Example 4 of the present invention at the wide-angle end when focusing at infinity. The zoom lens according to Example 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 middle 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 the lens group F. The seventh lens group G7 corresponds to the rear group R.

[0114] When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side, the second lens group G2 moves toward the image side, the third lens group G3 moves toward the object side, the fourth lens group G4 moves toward the object side, the fifth lens group G5 moves toward the object side, the sixth lens group G6 moves toward the object side, and the seventh lens group G7 moves toward the object side. Focusing from an object at infinity to an object at a close distance is performed by moving the sixth lens group G6 (lens group F) toward the image side. The aperture stop S is disposed adjacent to the object side of the third lens group G3.

[0115] The configuration of each lens group will be described below. The first lens group G1 is composed of, in order from the object side, a cemented lens formed by cementing together a negative meniscus lens L1 having a convex surface facing the object side and a positive meniscus lens L2 having a convex surface facing the object side, and a positive meniscus lens L3 having a convex surface facing the object side.

[0116] The second lens group G2 is composed of, in order from the object side, a negative meniscus lens L4 with a convex surface facing the object side, a biconcave lens L5, a biconvex lens L6, and a negative meniscus lens L7 with a concave surface facing the object side. The negative meniscus lens L7 is a glass-molded aspherical lens with an aspherical surface on the image side.

[0117] The third lens group G3 is composed of, in order from the object side, a positive meniscus lens L8 with a convex surface facing the object side, a positive meniscus lens L9 with a convex surface facing the object side, a cemented lens formed by cementing a negative meniscus lens L10 with a convex surface facing the object side and a positive meniscus lens L11 with a convex surface facing the object side, and a negative meniscus lens L12 with a concave surface facing the object side. The negative meniscus lens L12 is a glass-molded aspherical lens with an aspherical surface on the object side. The cemented surface between the negative meniscus lens L10 and the positive meniscus lens L11 is a diverging surface, which is referred to as the lens surface Si(S1) in the present invention. Between the positive meniscus lens L11 and the negative meniscus lens L12 is a biconvex air lens with negative refractive power. The lens surface closest to the object side of the third lens group (middle group M) is convex on the object side.

[0118] The fourth lens group G4 is composed of, in order from the object side, a cemented lens formed by cementing together a positive meniscus lens L13 with its concave surface facing the object side and a biconcave lens L14. The cemented surface of this cemented lens is also a diverging surface, and is referred to as the lens surface Si(S2) in the present invention.

[0119] The fifth lens group G5 is composed of, from the object side, a cemented lens formed by cementing 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 surfaces on both sides. The cemented surface between the biconvex lens L15 and the negative meniscus lens L16 is a diverging surface, and this cemented surface is also referred to as the lens surface Si(S3) in the present invention. In addition, the lens surface closest to the image side of the fifth lens group (middle group M) is convex toward the image side.

[0120] The sixth lens group G6 is composed of a negative meniscus lens L18 with its convex surface facing the object side.

[0121] The seventh lens group G7 is composed of, 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 surfaces on both sides.

[0122] (2) Numerical examples Next, we will explain numerical examples that apply specific numerical values of this zoom lens. The following shows "lens data," "specification table," "variable spacing," "lens group data," and "aspherical coefficients." Also, Figures 14 to 16 show longitudinal aberration diagrams of this zoom lens at the wide-angle end, intermediate focal length, and telephoto end when focusing on infinity.

[0123] [Lens data] Surface 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 -30.2311 1.5000 1.69350 53.18 39ASPH -105.6295 d(39) 40 ∞ 2.5000 1.51680 64.20 41∞1.0000 Image plane ∞

[0124] [Specifications table] Wide-angle end Mid-range 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

[0125] Variable Spacing Wide-angle end Mid-range Telephoto end Wide-angle end Mid-range 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

[0126] [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

[0127] [Aspheric coefficients] 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 [Example]

[0128] (1) Optical configuration 17 is a cross-sectional view of a zoom lens according to Example 5 of the present invention at the wide-angle end when focusing on infinity. The zoom lens of Example 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 middle lens group M. The fourth lens group G4 corresponds to the lens group F. The fifth lens group G5 corresponds to the rear lens group R.

[0129] When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side, the second lens group G2 moves toward the image side, the third lens group G3 moves toward the object side, the fourth lens group G4 moves toward the object side, and the fifth lens group G5 moves toward the object side. Focusing from an object at infinity to an object at a close distance is performed by moving the fourth lens group G4 (lens group F) toward the image side. The aperture stop S is disposed adjacent to the object side of the third lens group G3.

[0130] The configuration of each lens group will be described below. The first lens group G1 is composed of, in order from the object side, a cemented lens formed by cementing together a negative meniscus lens L1 with a convex surface facing the object side and a biconvex lens L2, and a positive meniscus lens L3 with a convex surface facing the object side.

[0131] The second lens group G2 is composed of, in order from the object side, a negative meniscus lens L4 with its convex surface facing the object side, a cemented lens formed by cementing together a biconcave lens L5 and a biconvex lens L6, and a negative meniscus lens L7 with its concave surface facing the object side. The negative meniscus lens L7 is a glass-molded aspherical lens with an aspherical surface on the image side.

[0132] The third lens group G3 is composed of, in order from the object side, a positive meniscus lens L8 with a convex surface facing the object side, a positive meniscus lens L9 with a convex surface facing the object side, a negative meniscus lens L10 with a convex surface facing the object side, a cemented lens formed by cementing together three lenses: a biconvex lens L11 and a biconcave lens L12; a negative meniscus lens L13 with a concave surface facing the object side, a biconvex lens L14, and a biconvex lens L15. The negative meniscus lens L13 is a glass-molded aspherical lens with aspherical surfaces on both sides. The biconvex lens L15 is a glass-molded aspherical lens with aspherical surfaces on both sides. The cemented surfaces between the negative meniscus lens L10 and the biconvex lens L11 and the cemented surface between the biconvex lens L11 and the biconcave lens L12 are each diverging surfaces, and these cemented surfaces are referred to as lens surfaces Si(S1, S2) in the present invention. Between the biconcave lens L12 and the negative meniscus lens L13 is a biconvex air lens having negative refractive power. The lens surface closest to the object in the third lens group is convex toward the object, and the lens surface closest to the image is convex toward the image.

[0133] The fourth lens group G4 is composed of a cemented lens in which a biconvex lens L16 and a biconcave lens L17 are cemented together.

[0134] The fifth lens group G5 is composed of, in order from the object side, a cemented lens formed by cementing together a negative meniscus lens L18 with its convex surface facing the object side and a biconvex lens L19, 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 surfaces on both sides.

[0135] (2) Numerical examples Next, we will explain numerical examples that apply specific numerical values of this zoom lens. The following shows "lens data," "specification table," "variable spacing," "lens group data," and "aspherical coefficients." Also, Figures 18 to 20 show longitudinal aberration diagrams of this zoom lens at the wide-angle end, intermediate focal length, and telephoto end when focusing on infinity.

[0136] [Lens data] Surface 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∞

[0137] [Table of Elements] Wide-angle end Mid-range Telephoto end f 28.8086 49.9831 101.8857 F No. 2.9114 2.9094 2.9097 ω 38.4220 22.4917 11.4289 Y 21.6330 21.6330 21.6330

[0138] Variable Spacing Wide-angle end Mid-range Telephoto end Wide-angle end Mid-range 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

[0139] [Lens group data] Group number Focal length G1 133.6850 G2 -24.0282 G3 29.3072 G4 -36.5784 G5 1654.2900

[0140] [Aspheric coefficients] 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 23 0.0000 2.23671E-05 -1.20692E-07 7.69895E-11 5.84925E-13 0.00000E+00 26 0.0000 2.26546E-05 -9.98620E-08 2.72553E-10 -2.12889E-12 5.61288E-15 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 [Example]

[0141] (1) Optical configuration 21 is a cross-sectional view of a zoom lens according to Example 6 of the present invention at the wide-angle end when focusing at infinity. The zoom lens of Example 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 middle lens group M. The fourth lens group G4 corresponds to the lens group F. The rear lens group R is composed of the fifth lens group G5 and the sixth lens group G6.

[0142] During zooming from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side, the second lens group G2 moves toward the image side, the third lens group G3 moves toward the object side, the fourth lens group G4 moves toward the object side, the fifth lens group G5 moves toward the object side, and the sixth lens group G6 is fixed relative to the optical axis. Focusing from an object at infinity to an object at a close distance is performed by moving the fourth lens group G4 (lens group F) toward the image side. The aperture stop S is disposed adjacent to the object side of the third lens group G3.

[0143] The configuration of each lens group will be described below. The first lens group G1 is composed of, in order from the object side, a cemented lens formed by cementing together a negative meniscus lens L1 having a convex surface facing the object side and a positive meniscus lens L2 having a convex surface facing the object side, and a positive meniscus lens L3 having a convex surface facing the object side.

[0144] The second lens group G2 is composed of, in order from the object side, a negative meniscus lens L4 with its convex surface facing the object side, a cemented lens formed by cementing together a biconcave lens L5 and a biconvex lens L6, and a negative meniscus lens L7 with its concave surface facing the object side. The negative meniscus lens L4 is a glass-molded aspherical lens with an aspherical surface on the object side. The negative meniscus lens L7 is a glass-molded aspherical lens with an aspherical surface on the image side.

[0145] The third lens group G3 is composed of, in order from the object side, a positive meniscus lens L8 with a convex surface facing the object side, a positive meniscus lens L9 with a convex surface facing the object side, a negative meniscus lens L10 with a convex surface facing the object side, a cemented lens formed by cementing together 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 surfaces on both sides. The biconvex lens L15 is a glass-molded aspherical lens with aspherical surfaces on both sides. The cemented surfaces between the negative meniscus lens L10 and the biconvex lens L11 and the cemented surface between the biconvex lens L11 and the biconcave lens L12 are each diverging surfaces, and these cemented surfaces are referred to as lens surfaces Si(S1, S2) in the present invention. Furthermore, a biconvex air lens is provided between the biconcave lens L12 and the biconcave lens L13, and has negative refractive power. In addition, the lens surface closest to the object in the third lens group is convex toward the object side, and the lens surface closest to the image side is convex toward the image side.

[0146] The fourth lens group G4 is composed of a cemented lens formed by cementing together a positive meniscus lens L16 having a convex surface facing the object side and a negative meniscus lens L17 having a convex surface facing the object side.

[0147] The fifth lens group G5 is composed 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 surfaces on both sides.

[0148] The sixth lens group G6 is composed solely of a biconvex lens L20.

[0149] (2) Numerical examples Next, we will explain numerical examples that apply specific numerical values of this zoom lens. The following shows "lens data," "specification table," "variable spacing," "lens group data," and "aspherical coefficients." Also, Figures 22 to 24 show longitudinal aberration diagrams of this zoom lens at the wide-angle end, intermediate focal length, and telephoto end when focusing on infinity.

[0150] [Lens data] Surface 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 ∞

[0151] [Specifications table] Wide-angle end Mid-range 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

[0152] Variable Spacing Wide-angle end Mid-range Telephoto end Wide-angle end Mid-range 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

[0153] [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

[0154] [Aspheric coefficients] 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

[0155] [Table 1] Example 1 2 3 4 5 6 (1)Σφi / φm 0.698 0.765 1.266 0.926 0.529 0.724 (2)Fnom 1.141 1.067 1.122 1.085 1.328 1.073 (3)Rmf / ft 0.266 0.299 0.434 0.423 0.623 0.283 (4)Rmb / ft -0.267 0.752 -0.537 -0.531 -0.766 -0.588 (5)θgF-(-1.618×10 -3 ×νd+0.6415) 0.0313 0.0313 0.0313 0.0313 0.0313 0.0313 (6)νd 20.88 20.88 20.88 20.88 20.88 20.88 (7)BFw / Y 0.746 0.746 0.746 0.746 0.746 0.746

[0156] [Table 2] Example 1 2 3 4 5 6 Σφi 0.0215 0.0243 0.0397 0.0304 0.0181 0.0234 φm 0.0309 0.0317 0.0313 0.0328 0.0341 0.0324 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 f1m 19.953 18.655 56.424 52.727 46.493 18.758 D 17.486 17.485 50.273 48.598 35.015 17.476 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 - -

[0157] In Table 1, Fnom indicates the smallest F-number from the first lens group to the intermediate group M in the entire zoom range, and when expressed as Fnom=f1m / D, f1m is the composite focal length from the first lens group to the middle lens group M at the position where Fnom is at its minimum value in the entire zoom range. D denotes the entrance pupil diameter at the position where Fnom is minimum over the entire zoom range.

[0158] (Addendum) In one aspect, the present specification discloses the following technology.

[0159] (Technology 1) The lens is composed of, in order from the object side, a first lens group having positive refractive power, a second lens group having 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 having negative refractive power, and a rear group R having one or more lens groups, the intermediate lens group M includes at least two lens surfaces Si that are cemented surfaces and diverging surfaces, The spacing between adjacent lens groups changes during zooming, During focusing, the lens group F moves along the optical axis, A zoom lens characterized by satisfying the following conditional expression: 0.50 ≦ Σφi / φm ≦ 1.50 ···(1) 0.85 ≦ Fnom ≦ 1.40 (2) however, Σφi: the sum of the refractive powers of the lens surfaces Si included in the intermediate group M Here, for each lens surface Si (i=1, 2, . . .) included in the intermediate group M, when the refractive indices of the media before and after each lens surface Si at the d-line are Nfi and Nbi, and the radius of curvature of each lens surface Si is Ri, the refractive power of each lens surface Si is φi=|(Nfi-Nbi) / Ri|(i=1, 2, . . .), φm: composite refractive power of the intermediate group M at the telephoto end, which is calculated by φm=1 / fm fm: composite focal length of the intermediate group M at the telephoto end Fnom: the F-number from the first lens group to the intermediate group M, which is the minimum value in the entire zoom range

[0160] (Technology 2) The zoom lens according to Art. 1, wherein the rear group R has a negative refractive power as a whole.

[0161] (Technology 3) The zoom lens according to Art 1 or Art 2, wherein the rear group R has at least one lens group with negative refractive power, and during zooming from the wide-angle end to the telephoto end, the lens group with negative refractive power moves toward the object side.

[0162] (Technology 4) The zoom lens according to any one of Techniques 1 to 3, characterized in that the first lens group moves toward the object side during zooming from the wide-angle end to the telephoto end.

[0163] (Technology 5) The zoom lens according to any one of the first to fourth aspects of the present invention is characterized in that at least one of the lens surfaces Si is convex toward the object side.

[0164] (Technology 6) The zoom lens according to any one of the first to fifth aspects of the present invention satisfies the following conditional expression: 0.15 ≦ Rmf / ft ≦ 0.70 (3) however, Rmf: radius of curvature of the lens surface in the intermediate group M closest to the object ft: focal length of the zoom lens at the telephoto end

[0165] (Technology 7) The zoom lens according to any one of the first to sixth aspects of the present invention satisfies the following conditional expression: -0.80 ≦ Rmb / ft ≦ -0.15 (4) however, Rmb: radius of curvature of the lens surface in the intermediate group M closest to the image side ft: focal length of the zoom lens at the telephoto end

[0166] (Technology 8) The zoom lens according to any one of the first to seventh aspects of the present invention, wherein the lens surface of the second lens group closest to the object side is convex toward the object side.

[0167] (Technology 9) The zoom lens according to any one of the first to eighth aspects of the present invention, wherein the intermediate group M includes at least one air lens having negative refractive power.

[0168] (Technology 10) a positive lens P located closest to the object side of the intermediate group M; The zoom lens according to any one of Technical Examples 1 to 9, wherein the positive lens P simultaneously satisfies the following conditional expressions (5) and (6): 0.01≦θgF-(-1.618×10 -3 ×νd+0.6415)≦0.06 (5) 10 ≦ νd ≦ 35 (6) however, θgF: partial dispersion ratio between the g-line and the 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

[0169] (Technology 11) The zoom lens according to any one of the first to tenth aspects satisfies the following conditional expression: 0.3 ≦ BFw / Y ≦ 1.5 (7) however, BFw: Back focal length of the zoom lens at the wide-angle end, calculated by converting the cover glass thickness into air. Y: Maximum image height of the zoom lens

[0170] (Technology 12) An imaging device comprising: the zoom lens according to any one of Technology 1 to Technology 11; and an imaging element on the image side of the zoom lens that converts an optical image formed by the zoom lens into an electrical signal. [Industrial Applicability]

[0171] According to the present invention, it is possible to provide a zoom lens that has a large aperture ratio, is compact overall, and has excellent optical performance, and an imaging device that includes the zoom lens. [Explanation of symbols]

[0172] G1: First lens group G2: Second lens group G3: Third lens group G4: Fourth lens group G5: Fifth lens group G6: 6th lens group G7: 7th lens group M...middle group F: Focus group (lens group) R...Rear group S Aperture CG ···Cover glass IP...Image plane

Claims

1. The lens is composed of, in order from the object side, a first lens group having positive refractive power, a second lens group having 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 having negative refractive power, and a rear group R having one or more lens groups, the first lens group includes two positive lenses, the intermediate lens unit M includes at least two lens surfaces Si that are cemented surfaces and diverging surfaces, and at least one air lens having negative refractive power; The spacing between adjacent lens groups changes during zooming, During zooming from the wide-angle end to the telephoto end, at least one of the lens groups constituting the intermediate group M moves toward the object side, During focusing, the lens group F moves along the optical axis, The intermediate lens unit M has a positive lens P located closest to the object side and satisfying the following conditional expressions (5) and (6) simultaneously: 0.01≦θgF−(−1.618×10−3×νd+0.6415)≦0.06... ・（５） 10≦νd≦35...(6) A zoom lens characterized by satisfying the following conditional expression: 0.50 ≦ Σφi / φm ≦ 1.50 ... (1) 0.3 ≦ BFw / Y ≦ 1.5 (7) however, Σφi: the sum of the refractive powers of the lens surfaces Si included in the intermediate group M Here, for each lens surface Si (i=1, 2, . . .) included in the intermediate group M, when the refractive indices of the media before and after each lens surface Si at the d-line are Nfi and Nbi, and the radius of curvature of each lens surface Si is Ri, the refractive power of each lens surface Si is defined as φi=|(Nfi-Nbi) / Ri| (i=1, 2, . . . ). φm: composite refractive power of the intermediate group M at the telephoto end, which is calculated by φm=1 / fm fm: composite focal length of the intermediate group M at the telephoto end BFw: Back focus of the zoom lens at the wide-angle end, calculated by converting the cover glass thickness into air Y: Maximum image height of the zoom lens θgF: partial dispersion ratio of the material of the positive lens P between the g-line and the F-line νd: Abbe number of the material of the positive lens P with respect to the d line

2. The lens is composed of, in order from the object side, a first lens group having positive refractive power, a second lens group having 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 having negative refractive power, and a rear group R having one or more lens groups, the first lens group includes two positive lenses, the intermediate lens unit M includes at least two lens surfaces Si that are cemented surfaces and diverging surfaces, The spacing between adjacent lens groups changes during zooming, During zooming from the wide-angle end to the telephoto end, at least one of the lens groups constituting the intermediate group M moves toward the object side, During focusing, the lens group F moves along the optical axis, The intermediate lens unit M has a positive lens P located closest to the object side and satisfying the following conditional expressions (5) and (6) simultaneously: 0.01≦θgF−(−1.618×10−3×νd+0.6415)≦0.06... ・（５） 10≦νd≦35...(6) A zoom lens characterized by satisfying the following conditional expression: 0.50 ≦ Σφi / φm ≦ 1.50 ... (1) 0.3 ≦ BFw / Y ≦ 1.5 (7) -0.65 ≦ Rmb / ft ≦ -0.15 ... (4-1) however, Σφi: the sum of the refractive powers of the lens surfaces Si included in the intermediate group M Here, for each lens surface Si (i=1, 2, . . .) included in the intermediate group M, when the refractive indices of the media before and after each lens surface Si at the d-line are Nfi and Nbi, and the radius of curvature of each lens surface Si is Ri, the refractive power of each lens surface Si is defined as φi=|(Nfi-Nbi) / Ri| (i=1, 2, . . . ). φm: composite refractive power of the intermediate group M at the telephoto end, which is calculated by φm=1 / fm fm: composite focal length of the intermediate group M at the telephoto end BFw: Back focus of the zoom lens at the wide-angle end, calculated by converting the cover glass thickness into air Y: Maximum image height of the zoom lens Rmb: radius of curvature of the lens surface of the intermediate group M closest to the image side ft: focal length of the zoom lens at the telephoto end θgF: partial dispersion ratio of the material of the positive lens P between the g-line and the F-line νd: Abbe number of the material of the positive lens P with respect to the d line

3. The lens is composed of, in order from the object side, a first lens group having positive refractive power, a second lens group having 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 having negative refractive power, and a rear group R having one or more lens groups, the first lens group includes two positive lenses, the intermediate lens unit M includes at least two lens surfaces Si that are cemented surfaces and diverging surfaces, the rear group R has a negative refractive power as a whole, The spacing between adjacent lens groups changes during zooming, During zooming from the wide-angle end to the telephoto end, at least one of the lens groups constituting the intermediate group M moves toward the object side, During focusing, the lens group F moves along the optical axis, A zoom lens characterized by satisfying the following conditional expression: 0.50 ≦ Σφi / φm ≦ 1.50 ... (1) 0.3 ≦ BFw / Y ≦ 1.5 (7) -0.80 ≦ Rmb / ft ≦ -0.15 (4) however, Σφi: the sum of the refractive powers of the lens surfaces Si included in the intermediate group M Here, for each lens surface Si (i=1, 2, . . .) included in the intermediate group M, when the refractive indices of the media before and after each lens surface Si at the d-line are Nfi and Nbi, and the radius of curvature of each lens surface Si is Ri, the refractive power of each lens surface Si is defined as φi=|(Nfi-Nbi) / Ri| (i=1, 2, . . . ). φm: composite refractive power of the intermediate group M at the telephoto end, which is calculated by φm=1 / fm fm: composite focal length of the intermediate group M at the telephoto end BFw: Back focus of the zoom lens at the wide-angle end, calculated by converting the cover glass thickness into air Y: Maximum image height of the zoom lens Rmb: radius of curvature of the lens surface of the intermediate group M closest to the image side ft: focal length of the zoom lens at the telephoto end

4. The lens is composed of, in order from the object side, a first lens group having positive refractive power, a second lens group having 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 having negative refractive power, and a rear group R having one or more lens groups, the first lens group includes two positive lenses, the intermediate lens unit M includes at least two lens surfaces Si that are cemented surfaces and diverging surfaces, and at least one air lens having negative refractive power; the rear group R is composed of one lens group, The spacing between adjacent lens groups changes during zooming, During zooming from the wide-angle end to the telephoto end, at least one of the lens groups constituting the intermediate group M moves toward the object side, During focusing, the lens group F moves along the optical axis, A zoom lens characterized by satisfying the following conditional expression: 0.698 ≦ Σφi / φm ≦ 1.50 ... (1-1) 0.3 ≦ BFw / Y ≦ 1.5 (7) however, Σφi: the sum of the refractive powers of the lens surfaces Si included in the intermediate group M Here, for each lens surface Si (i=1, 2, . . .) included in the intermediate group M, when the refractive indices of the media before and after each lens surface Si at the d-line are Nfi and Nbi, and the radius of curvature of each lens surface Si is Ri, the refractive power of each lens surface Si is defined as φi=|(Nfi-Nbi) / Ri| (i=1, 2, . . . ). φm: composite refractive power of the intermediate group M at the telephoto end, which is calculated by φm=1 / fm fm: composite focal length of the intermediate group M at the telephoto end BFw: Back focus of the zoom lens at the wide-angle end, calculated by converting the cover glass thickness into air Y: Maximum image height of the zoom lens

5. The lens is composed of, in order from the object side, a first lens group having positive refractive power, a second lens group having 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 having negative refractive power, and a rear group R having one or more lens groups, the first lens group includes two positive lenses, the intermediate lens unit M includes at least two lens surfaces Si that are cemented surfaces and diverging surfaces, and at least one air lens having negative refractive power; The spacing between adjacent lens groups changes during zooming, During zooming from the wide-angle end to the telephoto end, at least one of the lens groups constituting the intermediate group M moves toward the object side, During focusing, the lens group F moves along the optical axis, the lens element of the intermediate group M closest to the image side is a positive lens element convex toward the image side, A zoom lens characterized by satisfying the following conditional expression: 0.50 ≦ Σφi / φm ≦ 1.50 ... (1) 0.3 ≦ BFw / Y ≦ 1.5 (7) -0.588 ≦ Rmb / ft ≦ -0.15 ... (4-2) however, Σφi: the sum of the refractive powers of the lens surfaces Si included in the intermediate group M Here, for each lens surface Si (i=1, 2, . . .) included in the intermediate group M, when the refractive indices of the media before and after each lens surface Si at the d-line are Nfi and Nbi, and the radius of curvature of each lens surface Si is Ri, the refractive power of each lens surface Si is defined as φi=|(Nfi-Nbi) / Ri| (i=1, 2, . . . ). φm: composite refractive power of the intermediate group M at the telephoto end, which is calculated by φm=1 / fm fm: composite focal length of the intermediate group M at the telephoto end BFw: Back focus of the zoom lens at the wide-angle end, calculated by converting the cover glass thickness into air Y: Maximum image height of the zoom lens Rmb: radius of curvature of the lens surface of the intermediate group M closest to the image side ft: focal length of the zoom lens at the telephoto end

6. The lens is composed of, in order from the object side, a first lens group having positive refractive power, a second lens group having 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 having negative refractive power, and a rear group R having one or more lens groups, the first lens group includes two positive lenses, the intermediate lens unit M includes at least two lens surfaces Si that are cemented surfaces and diverging surfaces, and at least one air lens having negative refractive power; the rear group R is composed of one lens group, At least one of the lens surfaces Si is convex toward the object side, The spacing between adjacent lens groups changes during zooming, During zooming from the wide-angle end to the telephoto end, at least one of the lens groups constituting the intermediate group M moves toward the object side, During focusing, the lens group F moves along the optical axis, A zoom lens characterized by satisfying the following conditional expression: 0.50 ≦ Σφi / φm ≦ 1.50 ... (1) 0.3 ≦ BFw / Y ≦ 1.5 (7) however, Σφi: the sum of the refractive powers of the lens surfaces Si included in the intermediate group M Here, for each lens surface Si (i=1, 2, . . .) included in the intermediate group M, when the refractive indices of the media before and after each lens surface Si at the d-line are Nfi and Nbi, and the radius of curvature of each lens surface Si is Ri, the refractive power of each lens surface Si is defined as φi=|(Nfi-Nbi) / Ri| (i=1, 2, . . . ). φm: composite refractive power of the intermediate group M at the telephoto end, which is calculated by φm=1 / fm fm: composite focal length of the intermediate group M at the telephoto end BFw: Back focus of the zoom lens at the wide-angle end, calculated by converting the cover glass thickness into air Y: Maximum image height of the zoom lens

7. 7. The zoom lens according to claim 1, wherein the rear group R includes at least one lens group with negative refractive power, and during zooming from the wide-angle end to the telephoto end, the lens group with negative refractive power moves toward the object side.

8. 8. The zoom lens according to claim 1, wherein the first lens group moves toward the object side during zooming from the wide-angle end to the telephoto end.

9. 9. The zoom lens according to claim 1, wherein the following condition is satisfied: 0.15 ≦ Rmf / ft ≦ 0.70 (3) however, Rmf: radius of curvature of the lens surface of the intermediate group M closest to the object ft: focal length of the zoom lens at the telephoto end

10. 10. The zoom lens according to claim 1, wherein the lens surface of the second lens group closest to the object side is convex toward the object side.

11. 11. An imaging device comprising: the zoom lens according to claim 1; and an imaging element on the image side of the zoom lens that converts an optical image formed by the zoom lens into an electrical signal.

Images