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, a lens surface, closest to the object side, of the second lens group is convex toward the object side, 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, 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 in widespread use. There are various types of such imaging devices, such as digital still cameras, digital video cameras, broadcast cameras, surveillance cameras, and vehicle-mounted cameras. In any imaging device, there is a strong market demand for zoom lenses with a large aperture ratio and high optical performance.

[0003] As an optical configuration of a zoom lens, for example, a positive lead type configuration is known, 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 from the object side, and a large magnification change load is placed on the second lens group, making it easy to realize a high magnification change. In such a positive lead type zoom lens, the tendency for telephoto is strong, so the total optical length can be shortened compared to the focal length.

[0004] Here, in order to obtain a zoom lens with a small F-number and high optical performance, it is necessary to satisfactorily correct various aberrations that occur due to a large aperture ratio. Therefore, in a zoom lens with a small F-number, it is difficult to arrange a strong refractive power in each lens group compared to a zoom lens with a large F-number, and the entire system is likely to become large. In addition, in order to obtain a zoom lens with a small F-number, it is preferable to arrange a lens group with a strong positive refractive power on the image side, that is, at the rear of the entire system. However, if a lens group with a strong positive refractive power is arranged at the rear of the entire system, it becomes difficult to obtain a zoom lens with a strong telephoto tendency, and it becomes difficult to shorten the total optical length. Thus, in order to realize a zoom lens that has a large aperture ratio, high optical performance, and is compact, it is necessary to appropriately set the power arrangement, imaging magnification, lens configuration, etc. of each lens group.

[0005] In recent years, digital still cameras and the like that capture images using live view images have become widespread. When capturing images using live view, the image plane phase difference AF method or the contrast AF method is used to focus on the subject. In particular, in the contrast AF method, the focus group is constantly moved to focus on the subject. Furthermore, in recent years, digital still cameras and the like that employ tracking AF have also become widespread. Tracking AF refers to an autofocus function that, after focusing on the subject to be captured once, keeps the subject in focus at all times by moving the focus group in response to the movement of the subject.

[0006] When using contrast AF or tracking AF to capture video or the like, there is a phenomenon in which the size of the subject on the imaging surface changes with the movement of the focus group. If the change in image magnification caused by the movement of the focus group is large, it will cause discomfort to the photographer observing the live view image. It is known that the change in image magnification becomes larger the closer the focus group is to the object side, that is, the further forward the focus group is located in the optical system. Therefore, it is necessary to appropriately set the location of the focus group.

[0007] Currently, the following zoom lenses are known. For example, Patent Document 1 discloses a bright zoom lens having an F-number of about 1.9 to F2.8, which includes, in order from the object side, lens groups with positive, negative, positive, negative, 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 disposed at the rear of the entire system.

[0008] Patent Document 2 discloses a bright zoom lens with a aperture of about F2.8, which includes lens groups with the following refractive powers in order from the object side: positive, negative, positive, negative, positive. However, in this zoom lens, the second lens group on the object side of the aperture is used as a focus group. In other words, since the focus group is located in front of the entire system, there is a problem that the image magnification changes greatly, which is not preferable for tracking AF or contrast AF. In addition, the second lens group is relatively heavy, and when contrast AF is adopted, it is difficult to perform rapid focusing with this zoom lens due to the weight of the focus group. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] WO2017 / 99243 publication [Patent Document 2] JP 2020-197600 A 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 an object of the present invention is to provide a zoom lens that has a large aperture ratio, yet is small 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, a lens surface of the second lens group closest to the object side is convex toward the object side, the middle group M includes at least two lens surfaces Si which are cemented surfaces and are diverging surfaces, a distance between adjacent lens groups changes during zooming, and the lens group F moves on the optical axis during focusing, and the zoom lens is characterized in that the following conditional expressions are satisfied: 0.85 ≦ Fnom ≦ 1.40 (2) 0.3 ≦ BFw / Y ≦ 1.5 (7) however, Fnom: F-number from the first lens group to the intermediate group M, the minimum value in the entire zoom range 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

[0012] In order to solve the above problem, an imaging device according to the present invention is characterized by including the above zoom lens and an imaging element that converts an optical image formed by the zoom lens into an electrical signal. Effect of the Invention

[0013] According to the present invention, it is possible to provide a zoom lens having a large aperture ratio, yet being small overall, and having excellent optical performance, and an imaging device having the zoom lens. [Brief description of the drawings]

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

[0015] Hereinafter, an embodiment of the zoom lens and the imaging device according to the present invention will be described. However, the zoom lens and the imaging device described below are one aspect of the zoom lens and the imaging device according to the present invention, and the zoom lens and the 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 the zoom lens will be described below.

[0017] (1) First lens group As long as the first lens group has a positive refractive power as a whole, the specific lens configuration is not particularly limited. For example, if the first lens group is configured to include two positive lenses, a strong positive refractive power can be arranged in the first lens group. In this case, it is possible to strengthen the telephoto tendency at the telephoto end while achieving a high zoom ratio, and it becomes easy to achieve a compact overall system. Note that a strong telephoto tendency means that the telephoto ratio value is smaller. In addition, if the first lens group is configured to include at least one negative lens, it becomes easier to correct spherical aberration, chromatic aberration, and the like, and is therefore more preferable in terms of realizing a zoom lens with excellent optical performance.

[0018] (2) Second lens group As long as the second lens group has a negative refractive power as a whole, the specific lens configuration is not particularly limited. 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 arranged in the second lens group. In that case, it becomes easy to increase the zoom ratio of the second lens group, and it becomes easy to realize excellent optical performance while achieving a high zoom ratio. 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 satisfactorily correct the 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 as a whole. The intermediate group M is composed of one or more lens groups arranged between the second lens group and the lens group F. In order to realize a zoom lens with a large aperture ratio and a small size, it is preferable to arrange a strong positive refractive power in the intermediate group M to converge the light beam. When 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 direction that occur in the intermediate group M by a strong diverging action. Therefore, in the zoom lens, by arranging at least two or more lens surfaces Si that are cemented surfaces and diverging surfaces in the intermediate group M, the spherical aberration and curvature of field in the under direction can be well corrected by a strong diverging action while arranging a relatively strong positive refractive power in the intermediate group M, and a zoom lens that is small overall and has excellent optical performance while having a large aperture ratio is realized. The diverging action may be obtained by the lens surface of a negative single lens in the intermediate group M, but in that case, high-order aberrations are likely to occur and the sensitivity to decentering between the lenses becomes high. 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, at least one surface is preferably convex toward the object side. With this configuration, it becomes easy to effectively correct the field curvature in the entire zoom range. Moreover, 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 may include 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 is not particularly limited.

[0021] When the lenses constituting each lens surface Si are lenses LCn (n=1, 2, 3,...), it is preferable that the refractive power φLCn of each lens LCn satisfies φLCn≧0.005. This configuration makes it easy to strengthen the divergence effect of the lens surface Si. The refractive power φLCn is defined by the following formula. φLCn=|(NLCn-1)(1 / LCnR1-1 / LCnR2)| NLCn: Refractive index at d-line of lens LCn material 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 signs of the radii of curvature in the other conditional expressions.

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

[0023] It is preferable to place a positive lens closest to the object in the intermediate group M. This configuration makes it easy to reduce the size of the entire system. It is more preferable that the positive lens is a positive meniscus lens with a 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 is convex toward the image side, which makes it easy 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 action in the intermediate group M, and makes it easier to correct spherical aberration and curvature of field more satisfactorily. The refractive power of the air lens is negative or positive depending on the shape between the lens surfaces adjacently arranged with an air gap between them. Since the 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 shape, a plano-convex shape, or a positive meniscus shape.

[0026] Furthermore, when 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 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 on the optical axis during focusing. The lens group F arranged on the image side of the intermediate group M receives the light beam converged by the intermediate group M, so it is easy to make the lens diameter small and lightweight. Therefore, by making the lens group F a focus group, high-speed autofocusing can be realized and the load on the focus drive system can be easily reduced. As long as the lens group F has negative refractive power as a whole, the specific lens configuration is not particularly limited, but it is more preferable that the lens group F is composed of only a cemented lens in which one negative lens and one positive lens are cemented together. With such a configuration, it is easy to realize high-speed autofocusing by reducing the weight of the focus group and to obtain a high-performance zoom lens in which various aberrations such as spherical aberration and chromatic aberration are well corrected over the entire object distance.

[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. With such a configuration, it becomes easy to obtain a zoom lens with a stronger telephoto tendency at the telephoto end, and it becomes easy to shorten the total optical length at the telephoto end. The rear group R may have two or more lens groups, but if the number of lens groups constituting the zoom lens increases, it becomes difficult to achieve a compact size.

[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 changes 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 in the optical axis direction as long as the distance between the adjacent lens groups on the optical axis changes during zooming.

[0031] Although 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 makes it less likely that the magnification change action of each lens group after the second lens group will be strained, resulting in a configuration that makes it easier to achieve both high magnification 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, making it easier to reduce the diameter of the aperture unit and the size and weight of the zoom lens.

[0033] When the rear group R includes a lens group with negative refractive power, it is preferable that the lens group with negative refractive power move toward the object side during zooming from the wide-angle end to the telephoto end. By moving in this way during zooming, the magnification change effect of the rear group R can be improved. This makes it possible to reduce the amount of movement of each lens group, making it easier to obtain a compact zoom lens with a high zoom ratio.

[0034] When 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 In this zoom lens, focusing from infinity to a close distance is performed by moving the lens group F toward the image side along the optical axis. The lens group F is disposed on the image side of the intermediate group M, that is, at the rear of the zoom lens. Therefore, by using the lens group F as the focus group, it is possible to suppress fluctuations in the angle of view that accompany the movement of the focus group. Therefore, it is possible to obtain a zoom lens that is suitable for video shooting using a tracking AF function not only when the contrast AF method is adopted but also when the image plane phase difference AF method is adopted.

[0036] 1-3.Conditional Expressions It is desirable for the zoom lens to employ the above-mentioned configuration and to 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: the 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 above-mentioned divergence action of the lens surfaces Si can satisfactorily correct spherical aberration and field curvature throughout the entire zoom range. Therefore, even when a strong positive refractive power is disposed in the intermediate group M, these aberrations can be satisfactorily corrected, and a zoom lens that is compact and has high optical performance while achieving a large aperture ratio can be realized.

[0039] On the other hand, when the value of conditional expression (1) is below the lower limit, the divergence effect of the lens surface Si becomes small. When a strong positive refractive power is placed in the middle group M, it becomes difficult to satisfactorily correct spherical aberration and curvature of field, which tend to cause under-focusing. This makes it difficult to obtain a zoom lens that is small in size and has high optical performance while achieving a large aperture ratio. On the other hand, when the value of conditional expression (1) is equal to or exceeds the upper limit, it becomes difficult to achieve a balanced correction of spherical aberration and curvature of field.

[0040] In order to obtain the above effects, the upper limit value of conditional formula (1) is preferably 1.40, and more preferably 1.30, and the lower limit value of conditional formula (1) is preferably 0.55, and 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 value of the F-number from the first lens group to the middle group M in the entire zoom range. By satisfying conditional expression (2), it becomes easy to ensure the desired brightness of the zoom lens. In addition, 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 formula (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 satisfactorily correct various aberrations. On the other hand, if the value of conditional formula (2) exceeds the upper limit, it becomes difficult to ensure the desired brightness of the zoom lens. In this case, in order to obtain the desired brightness, it is necessary to impart a strong positive refractive power to the rear group R, which weakens the telephoto tendency, making it difficult to shorten the overall length.

[0044] In order to obtain the above-mentioned effects, the upper limit value of conditional formula (2) should preferably be 1.35, and more preferably be 1.30, and the lower limit value of conditional formula (2) should preferably be 0.90, and more preferably be 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 formula (3) is a conditional formula for appropriately setting the ratio between the radius of curvature of the lens surface closest to the object in intermediate group M and the focal length of the zoom lens at the telephoto end. When conditional formula (3) is satisfied, the lens surface closest to the object in intermediate group M is convex toward the object side. Satisfying conditional formula (3) makes it easy to achieve a balance between a reduction in overall length and optical performance.

[0047] On the other hand, when the value of conditional formula (3) is below the lower limit, it is easy to reduce the overall length, but the spherical aberration and curvature of field occurring 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, when the value of conditional formula (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 requires a large number of lenses with positive refractive power to be disposed in the intermediate group M, making it difficult to reduce the overall length.

[0048] In order to obtain the above-mentioned effects, the upper limit of condition (3) is preferably 0.65, more preferably 0.6, and even more preferably 0.55, and the lower limit of condition (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 side 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 middle 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 middle group M becomes convex toward the image side. By satisfying conditional expression (4), it becomes easy to reduce the overall length of the zoom lens while ensuring the desired brightness.

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

[0052] In order to obtain the above-mentioned effects, the upper limit value of conditional formula (4) is preferably -0.20, and more preferably -0.25, and the lower limit value of conditional formula (4) is preferably -0.75, and more preferably -0.70, and even more preferably -0.65.

[0053] 1-3-5. Conditional formula (5) and conditional formula (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, Let the refractive indices of the material of the positive lens P for the d-line, F-line, C-line, and g-line be nd, nF, nC, and ng, respectively. θgF: The partial dispersion ratio θgF = (ng-nF) / (nF-nC) of the material of the positive lens P to the g-line and F-line νd: Abbe number for the d-line of the material of the positive lens P, νd=(nd-1) / (nF-nC)

[0054] Conditional formula (5) is a conditional formula for defining the anomalous dispersion of the material of the positive lens P. Conditional formula (6) is a conditional formula for defining the Abbe number for the d-line of the material of the positive lens P. By arranging the positive lens P that satisfies both conditional formulas (5) and (6) closest to the object in the middle group M, it is possible to correct axial chromatic aberration well in the entire zoom range. In general, a positive lens included in a lens group with positive refractive power corrects chromatic aberration by using a material on the low dispersion side, but the middle group M of this zoom lens has a large diverging effect due to the diverging surface, and the axial chromatic aberration on the short wavelength side tends to be over. Therefore, by using a material on the high dispersion side for the positive lens P, it becomes easy to correct chromatic aberration well.

[0055] In contrast, when the value of conditional formula (5) is less than the lower limit or when 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 over-corrected, making correction difficult. On the other hand, when the value of conditional formula (5) exceeds the upper limit or when 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 under-corrected, making correction difficult.

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

[0057] 1-3-6. Conditional expression (7) 0.3 ≦ BFw / Y ≦ 1.5 (7) however, BFw: The back focus of the zoom lens at the wide-angle end, expressed as the air equivalent value of the cover glass thickness. Y: Maximum image height of the zoom lens

[0058] Conditional expression (7) is a conditional expression for defining the ratio between the back focus 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 focus 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 focus of the zoom lens at the wide-angle end becomes too short, and the inclination angle of the incident light 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 focus 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] In order to obtain the above-mentioned effects, the upper limit of condition (7) should preferably be 1.3, more preferably 1.2, and even more preferably 1.1, while the lower limit of condition (7) should preferably be 0.4, more preferably 0.5, and even more preferably 0.6.

[0061] 2. Imaging device Next, an imaging device according to the present invention will be described. The imaging device according to the present invention is characterized by including the zoom lens according to the present invention 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. A CCD (Charge Coupled Device) sensor or a CMOS (Complementary Metal Oxide Semiconductor) sensor can be suitably used as the imaging element.

[0062] In particular, the zoom lens has a large aperture ratio, yet is small overall and has excellent optical performance. The zoom lens can suppress fluctuations in the angle of view caused by the movement of the focus group, and is suitable for video capture using a tracking AF function, not only when a contrast AF method is adopted, but also when an image plane phase difference AF method is adopted. Therefore, by adopting the zoom lens, an imaging device suitable for video capture with a tracking AF function can be obtained.

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

[0064] (1) Optical configuration 1 is a cross-sectional view of a zoom lens according to a first embodiment of the present invention at the wide-angle end when focusing on infinity. The zoom lens according to the first embodiment 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 group M. The fourth lens group G4 corresponds to the lens group F. The fifth lens group G5 corresponds to the rear 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 now be described. 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 biconvex lens L2, and a positive meniscus lens L3 having 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 a convex surface facing the object side, a biconvex lens L5, a biconcave lens L6, a cemented lens formed by cementing a biconcave lens L7 and a biconvex lens L8, and a negative meniscus lens L9 with a 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 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 whose object side surface is aspherical. The biconvex lens L16 is a glass molded aspherical lens whose both surfaces are aspherical. The cemented surface 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 a diverging surface, and these cemented surfaces are the lens surfaces Si(S1, S2) referred to in the present invention. In addition, between the biconcave lens L14 and the negative meniscus lens L15, there is a biconvex air lens having negative refractive power. In addition, the lens surface closest to the object side 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.

[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 having a convex surface facing the object side and a biconvex lens L20, and a negative meniscus lens L21 having a concave surface facing the object side. The negative meniscus lens L21 is a glass molded aspheric lens having aspheric shapes on both sides.

[0071] In Fig. 1, "IP" denotes an image plane, specifically, an imaging surface of an imaging element such as a CCD sensor or a CMOS sensor, or a film surface of a silver halide film. A parallel plate having 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 the other embodiments, so further explanation will be omitted.

[0072] (2) Numerical examples Next, numerical examples to which specific numerical values ​​of the zoom lens are applied will be described. The "lens data", "specification table", "variable interval", "lens group data", and "aspheric coefficients" are shown below. In addition, 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 shown 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 space 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 aspheric, 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 a variable spacing that changes when the magnification is changed. In the "radius of curvature" column, "∞" indicates infinity, and that the lens surface is flat. All lengths in the table are in "mm", and all angles of view are in "°", which is the same as in other tables.

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

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

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

[0077] "Aspherical coefficient" indicates the aspherical coefficient when the aspherical shape is defined as follows. Here, 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 a direction perpendicular to the optical axis, k is the conical coefficient, and An is the n-th order aspherical coefficient. In the "Aspherical coefficient" 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 the other embodiments, so the explanation will be omitted below.

[0080] 2, 3, and 4 show longitudinal aberration diagrams of the zoom lens at the wide-angle end, the intermediate focal length, and the telephoto end when focusing on infinity. The longitudinal aberration diagrams shown in each diagram are, from the left side of the drawing, spherical aberration (mm), astigmatism (mm), and distortion (%), respectively. In the spherical aberration diagrams, the solid line shows the spherical aberration at the d-line (wavelength 587.56 nm), the dashed line shows the spherical aberration at the C-line (wavelength 656.28 nm), and the dashed line shows the spherical aberration at the g-line (wavelength 435.84 nm). In the astigmatism diagrams, the vertical axis shows the half angle of view (ω) and the horizontal axis shows the defocus, the solid line shows the sagittal image plane (ds) of the d-line, and the dashed line shows the meridional image plane (dm) of the d-line. In the distortion diagrams, the vertical axis shows the half angle of view (ω) and the horizontal axis shows the distortion aberration. These matters are the same in the aberration diagrams shown in the other embodiments, 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 -77.5216d(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 EXAMPLES

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

[0087] 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.

[0088] The configuration of each lens group will now be described. 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 biconvex lens L2, and a positive meniscus lens L3 having 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 a convex surface facing the object side, a cemented lens formed by cementing a biconcave lens L5 and a biconvex lens L6, and a negative meniscus lens L7 with a concave surface facing the object side. The negative meniscus lens L4 is a composite resin type aspherical lens with a composite resin film molded into an aspherical shape attached to the 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 aspheric lens with both surfaces aspheric. The biconvex lens L14 is a glass molded aspheric lens with both surfaces aspheric. The cemented surface 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 the lens surfaces Si(S1, S2) referred to in the present invention. In addition, between the positive meniscus lens L11 and the biconcave lens L12, there is a biconvex air lens having negative refractive power. In addition, 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, from the object side, a cemented lens formed by cementing together a negative meniscus lens L18 having a convex surface facing the object side and a biconvex lens L19, and a negative meniscus lens L20 having a concave surface facing the object side. The negative meniscus lens L20 is a glass molded aspherical lens having aspherical shapes on both sides.

[0093] (2) Numerical examples Next, a numerical example in which specific numerical values ​​of the zoom lens are applied will be described. The "lens data", "specification table", "variable interval", "lens group data", and "aspheric coefficient" are shown below. Also, Figs. 6 to 8 show longitudinal aberration diagrams of the 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 109.5210d(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 -59.5481d(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 EXAMPLES

[0099] (1) Optical configuration 9 is a cross-sectional view of a zoom lens according to a third embodiment of the present invention at the wide-angle end when focusing on infinity. The zoom lens according to the third embodiment is composed of, in order from the object side, a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, a fourth lens group G4 with positive refractive power, a fifth lens group G5 with negative refractive power, and a sixth lens group G6 with negative refractive power. The middle 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 now be described. 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 aspheric lens whose image side surface is aspheric.

[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 aspheric lens having aspheric shapes 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 a diverging surface, and these cemented surfaces are the lens surfaces Si(S1, S2) referred to in the present invention. Furthermore, between the positive meniscus lens L11 and the biconvex lens L12, there is an air lens of a positive meniscus shape with a convex surface facing the object side. Similarly, between the negative meniscus lens L13 and the negative meniscus lens L14, there is an air lens of a positive meniscus shape with a 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, in order from the object side, a cemented lens formed by cementing a biconvex lens L15 and a negative meniscus lens L16 with a concave surface facing the object side, and a biconvex lens L17. The biconvex lens L17 is a glass molded aspheric lens having aspheric shapes 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 the lens surface Si(S3) referred to 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 shapes on both sides.

[0107] (2) Numerical examples Next, a numerical example in which specific numerical values ​​of the zoom lens are applied will be described. The "lens data", "specification table", "variable interval", "lens group data", and "aspheric coefficient" are shown below. Also, Figs. 10 to 12 show longitudinal aberration diagrams of the 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 -134.4780d(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 F No. 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 EXAMPLES

[0113] (1) Optical configuration 13 is a cross-sectional view of a zoom lens according to a fourth embodiment of the present invention at the wide-angle end when focusing on infinity. The zoom lens according to the fourth embodiment 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 now be described. 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 aspheric lens whose image side surface is aspheric.

[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 aspheric lens having an aspheric 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 the lens surface Si(S1) referred to in the present invention. In addition, between the positive meniscus lens L11 and the negative meniscus lens L12, a biconvex air lens is formed, which has negative refractive power. In addition, the lens surface closest to the object side of the third lens group (middle group M) is convex to 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, which is the lens surface Si(S2) of the present invention.

[0119] The fifth lens group G5 is composed of, in order from the object side, a cemented lens formed by cementing a biconvex lens L15 and a negative meniscus lens L16 with a concave surface facing the object side, and a biconvex lens L17. The biconvex lens L17 is a glass molded aspheric lens having aspheric shapes 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 the lens surface Si(S3) of 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, in order from the object side, a biconvex lens L19, a biconcave lens L20, and a negative meniscus lens L21 with its concave surface facing the object side. The negative meniscus lens L21 is a glass molded aspheric lens with aspheric shapes on both sides.

[0122] (2) Numerical examples Next, a description will be given of numerical examples to which specific numerical values ​​of the zoom lens are applied. The "lens data", "specification table", "variable interval", "lens group data", and "aspheric coefficient" are shown below. Also, Figs. 14 to 16 show longitudinal aberration diagrams of the 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 -141.6106d(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 -77.3433d(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 -105.6295d(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 F No. 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 EXAMPLES

[0128] (1) Optical configuration 17 is a cross-sectional view of a zoom lens according to a fifth embodiment of the present invention at the wide-angle end when focusing on infinity. The zoom lens according to the fifth embodiment 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 group M. The fourth lens group G4 corresponds to the lens group F. The fifth lens group G5 corresponds to the rear 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 now be described. 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 biconvex lens L2, and a positive meniscus lens L3 having a convex surface facing the object side.

[0131] The second lens group G2 is composed of, from the object side, a negative meniscus lens L4 with a convex surface facing the object side, a cemented lens formed by cementing a biconcave lens L5 and 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 aspheric lens whose image side surface is aspheric.

[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 cemented lens formed by cementing three lenses, a negative meniscus lens L10 with a convex surface facing the object side, 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 aspheric lens having aspheric shapes on both sides. The biconvex lens L15 is a glass molded aspheric lens having aspheric shapes on both sides. The cemented surface 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 a diverging surface, and these cemented surfaces are the lens surfaces Si(S1, S2) referred to in the present invention. In addition, between the biconcave lens L12 and the negative meniscus lens L13, there is a biconvex air lens having negative refractive power. In addition, the lens surface closest to the object side 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.

[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, from the object side, a cemented lens formed by cementing together a negative meniscus lens L18 having a convex surface facing the object side and a biconvex lens L19, and a negative meniscus lens L20 having a concave surface facing the object side. The negative meniscus lens L20 is a glass molded aspherical lens having aspherical shapes on both sides.

[0135] (2) Numerical examples Next, a numerical example in which specific numerical values ​​of the zoom lens are applied will be described. The "lens data", "specification table", "variable interval", "lens group data", and "aspheric coefficient" are shown below. Also, Figs. 18 to 20 show longitudinal aberration diagrams of the 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 -73.0620d(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 Element] 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 EXAMPLES

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

[0142] 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 is fixed with respect 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 now be described. 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 a convex surface facing the object side, a cemented lens formed by cementing a biconcave lens L5 and a biconvex lens L6, and a negative meniscus lens L7 with a 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 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 aspheric lens having aspheric surfaces on both sides. The biconvex lens L15 is a glass molded aspheric lens having aspheric surfaces on both sides. The cemented surface 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 a diverging surface, and these cemented surfaces are the lens surfaces Si(S1, S2) referred to in the present invention. In addition, between the biconcave lens L12 and the biconcave lens L13, there is a biconvex air lens having negative refractive power. In addition, the lens surface closest to the object side 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, from the object side, a positive meniscus lens L18 with a concave surface facing the object side, and a negative meniscus lens L19 with a concave surface facing the object side. The negative meniscus lens L19 is a glass molded aspherical lens with aspherical shapes on both sides.

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

[0149] (2) Numerical examples Next, a numerical example in which specific numerical values ​​of the zoom lens are applied will be described. The "lens data", "specification table", "variable interval", "lens group data", and "aspheric coefficient" are shown below. Also, Figs. 22 to 24 show longitudinal aberration diagrams of the 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 F No. 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 F-number from the first lens group to the intermediate group M that is the smallest 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 group M at the position where Fnom is the 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] (Additional Note) In one aspect, the present specification discloses the following technology.

[0159] (Technology 1) The optical system 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, 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 intermediate group M includes at least two lens surfaces Si which are cemented surfaces and diverging surfaces, When zooming, the spacing between adjacent lens groups changes. During focusing, the lens group F moves along the optical axis, A zoom lens characterized by satisfying the following conditional expressions: 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, the refractive indices of the medium in front of and behind each lens surface Si at the d-line are Nfi and Nbi, and the radius of curvature of each lens surface Si is Ri. Then, the refractive power of each lens surface Si is φi=|(Nfi-Nbi) / Ri|(i=1, 2, . . .), φm: the 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: F-number from the first lens group to the intermediate group M, the minimum value in the entire zoom range

[0160] (Technology 2) The zoom lens according to claim 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, during zooming from the wide-angle end to the telephoto end, the first lens group moves toward the object side.

[0163] (Technology 5) The zoom lens according to any one of the first to fourth aspects, wherein 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 Technical 1 to Technical 5, which satisfies the following conditional expression: 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

[0165] (Technology 7) The zoom lens according to any one of Technical 1 to Technical 6, which satisfies the following conditional expression: -0.80 ≦ Rmb / ft ≦ -0.15 (4) however, Rmb: radius of curvature of the lens surface closest to the image side of the intermediate group M ft: focal length of the zoom lens at the telephoto end

[0166] (Technology 8) The zoom lens according to any one of Techniques 1 to 7, 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 has at least one air lens having negative refractive power.

[0168] (Technology 10) a positive lens P is disposed closest to the object side of the intermediate lens group M; The zoom lens according to any one of Technical 1 to Technical 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 of the material of the positive lens P between the g-line and the F-line νd: Abbe number for the d line of the material of the positive lens P

[0169] (Technology 11) The zoom lens according to any one of Technical 1 to Technical 10, which satisfies the following conditional expression: 0.3 ≦ BFw / Y ≦ 1.5 (7) however, 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

[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, yet is small overall, and has excellent optical performance, and an imaging device having 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 optical system 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, 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 first lens group includes two positive lenses, the lens surface of the second lens group closest to the object side is convex toward the object side, the intermediate lens group M includes at least two lens surfaces Si which are cemented surfaces and diverging surfaces, When zooming, the spacing between adjacent lens groups changes. During focusing, the lens group F moves along the optical axis, A zoom lens characterized by satisfying the following conditional expressions: 0.85≦Fnom≦1.40 (2) 0.3 ≦ BFw / Y ≦ 1.5 (7) however, Fnom: F-number from the first lens group to the intermediate group M, which is the minimum value in the entire zoom range BFw: Back focus of the zoom lens at the wide-angle end, which is the value when the cover glass thickness is converted into air thickness Y: Maximum image height of the zoom lens

2. 2. The zoom lens according to claim 1, wherein the rear lens unit R has a negative refractive power as a whole.

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

4. 4. 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.

5. 5. The zoom lens according to claim 1, wherein at least one of the lens surfaces Si is convex toward the object side.

6. 6. The zoom lens according to claim 1, which satisfies the following condition: 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

7. 7. The zoom lens according to claim 1, which satisfies the following condition: -0.80 ≦ Rmb / ft ≦ -0.15 ... (4) however, 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

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

9. 9. The zoom lens according to claim 1, wherein the intermediate group M has at least one air lens having negative refractive power.

10. a positive lens P located closest to the object side of the intermediate lens unit M; 10. The zoom lens according to claim 1, 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 of the material of the positive lens P between the g-line and the F-line νd: Abbe number for the d line of the material of the positive lens P

11. 11. An imaging apparatus comprising: the zoom lens according to claim 1; and an image sensor on an image side of the zoom lens for converting an optical image formed by the zoom lens into an electrical signal.

Images