Zoom lens and imaging apparatus

Abstract

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

Description

Technical Field

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

Background Art

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

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

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

[0005] In recent years, digital still cameras and the like that perform imaging using live view images have become widespread. During live view imaging, focusing on a subject is performed by an image plane phase difference AF method or a contrast AF method. In particular, in the contrast AF method, the focus group is constantly moved while focusing on the subject. Furthermore, in recent years, digital still cameras and the like that employ tracking AF have also become widely popular. Tracking AF refers to an autofocus function that, after once focusing on a subject to be imaged, continuously focuses on the subject while moving the focus group in accordance with the movement of the subject.

[0006] When performing video imaging or the like using contrast AF or tracking AF in this way, there is a phenomenon in which the size of the subject on the imaging surface changes as the focus group moves. When the change in image magnification due to such movement of the focus group is large, it will cause a sense of discomfort to the imaging person observing the live view image. It is known that this change in image magnification becomes larger as the focus group is arranged closer to the object side, that is, in front of the optical system, in the optical system. Therefore, it is necessary to appropriately set the arrangement of the focus group.

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

[0008] Patent Document 2 discloses a bright zoom lens with an F number of about F2.8, which includes a lens group having refractive powers of positive, negative, positive, negative, and positive in order from the object side. However, in this zoom lens, the second lens group on the object side of the aperture is used as the focus group. That is, since the focus group is arranged in front of the entire system, there is a problem that the change in image magnification is large, 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 in this zoom lens due to the weight of the focus group.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0010] An object of the present invention has been made in view of the above problems, and it is to provide a zoom lens having a large aperture ratio, being overall small in size, and having excellent optical performance, and an imaging device having the zoom lens.

Means for Solving the Problems

[0011] In order to solve the above problems, the zoom lens according to the present invention includes, in order from the object side, a first lens group with a positive refractive power, a second lens group with a negative refractive power, one or more lens groups, and an intermediate group M having a positive refractive power as a whole, a lens group F with a negative refractive power, and a rear group R having one or more lens groups. The intermediate group M includes, in order from the object side, a first positive subgroup Mp1 composed of one or two positive lenses, a first negative subgroup Mn1 composed of only one cemented lens obtained by cementing two or more lenses, a second negative subgroup Mn2 having a negative lens with a concave surface facing the object side, and a second positive subgroup Mp2 having one or two positive lenses. The lens closest to the image side in the second positive subgroup Mp2 is a positive lens. All the lenses and cemented lenses constituting the second negative subgroup Mn2 are lenses having a negative refractive power. When the second negative subgroup Mn2 has the cemented lens, the cemented lens is a cemented lens obtained by cementing two lenses having refractive powers of different signs. All the lenses and cemented lenses constituting the second positive subgroup Mp2 are lenses having a positive refractive power. When the second positive subgroup Mp2 has the cemented lens, the cemented lens is a cemented lens obtained by cementing two lenses having refractive powers of different signs. During zooming, the interval between adjacent lens groups changes, and during focusing, the lens group F moves on the optical axis, and it is characterized by satisfying the following conditional expression. 0.3 ≦ BFw / Y ≦ 1.5 ···(6) However, BFw: The back focus of the zoom lens at the wide-angle end, which is the value when the cover glass thickness is converted to air Y: The maximum image height of the zoom lens

[0012] In addition, in order to solve the above problems, the imaging device according to the present invention is characterized by including the above zoom lens and an imaging element that converts the 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, being overall small-sized, and having excellent optical performance, and an imaging device having the zoom lens.

Brief Description of the Drawings

[0014]

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Modes for Carrying Out the Invention

[0015] Hereinafter, embodiments 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 the present embodiment includes, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, an intermediate group M having one or more lens groups and having a positive refractive power as a whole, a lens group F having a negative refractive power, and a rear group R having one or more lens groups. Hereinafter, the optical configuration of the zoom lens will be described.

[0017] (1) First lens group As long as the first lens group has a positive refractive power as a whole, its specific lens configuration is not particularly limited. For example, if it is configured to include two positive lenses, a strong positive refractive power can be arranged in the first lens group. In that case, while achieving a high magnification ratio, the telephoto tendency can be strengthened at the telephoto end, and it becomes easy to reduce the size of the entire system. Note that a strong telephoto tendency means that the value of the telephoto ratio shows a smaller value. Also, if it is configured to include at least one negative lens, correction of spherical aberration, chromatic aberration, etc. becomes easy, so it is more preferable for realizing a zoom lens having excellent optical performance.

[0018] (2) Second lens group As long as the second lens group has a negative refractive power as a whole, its specific lens configuration is not particularly limited. For example, if it 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 magnification ratio of the second lens group, and it becomes easy to achieve a high magnification ratio and realize excellent optical performance. Also, it is preferable that the lens surface of the second lens group closest to the object side is convex on the object side. Thereby, it becomes easy to favorably 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. In this zoom lens, the intermediate group M includes, in order from the object side, a first positive subgroup Mp1 composed of one or two positive lenses, a first negative subgroup Mn1 composed of only one cemented lens in which two or more lenses are cemented, a second negative subgroup Mn2 having a negative lens with a concave surface facing the object side, and a second positive subgroup Mp2 having one or two positive lenses. Further, the intermediate group M is composed of one or more lens groups arranged between the second lens group and the lens group F. In the present invention, the lens groups are divided with the variable interval during zooming as a boundary. When the intermediate group M is composed of one lens group, the interval between adjacent subgroups is a fixed interval without change even during zooming. When the intermediate group M is composed of two or more lens groups, among these subgroups, the interval between some subgroups may be a variable interval during zooming, or a variable interval may be included within some subgroups.

[0020] By arranging the first positive subgroup Mp1 on the most object side of the intermediate group M, it becomes easy to miniaturize the entire zoom lens system. Further, by arranging the second positive subgroup Mp2 on the most image side, it becomes easy to ensure a bright F-number in the entire zoom lens system. In addition, in order to realize a zoom lens with a large aperture ratio and small size, it is preferable to arrange a strong positive refractive power in the intermediate group M to converge the light beam. When a strong positive refractive power is arranged in the intermediate group M, it is necessary to correct the spherical aberration and field curvature in the under direction generated in the intermediate group M by a strong diverging action. Therefore, in this zoom lens, by arranging the first negative subgroup Mn1 and the second negative subgroup Mn2 in the intermediate group M, while arranging a relatively strong positive refractive power in the intermediate group M by the first positive subgroup Mp1 and the second positive subgroup Mp2, the spherical aberration and field curvature in the above under direction can be corrected well by a strong diverging action, and a zoom lens with a large aperture ratio, small overall size, and excellent optical performance is realized.

[0021] Hereinafter, the preferable configurations of each subgroup will be described. The first positive subgroup Mp1 is a subgroup with positive refractive power. As long as the first positive subgroup Mp1 is composed of one or two positive lenses, its specific lens configuration is not particularly limited. The lens on the object side of the first positive subgroup Mp1 is preferably a positive meniscus lens with its convex surface facing the object side. By configuring it in this way, it becomes easier to further reduce the diameter of the intermediate group M.

[0022] The first negative subgroup Mn1 is a subgroup with negative refractive power. The first negative subgroup Mn1 only needs to be composed of only one of the cemented lenses formed by cementing two or more lenses, and other aspects are not particularly limited. For example, it is preferable that the cemented lens has at least one cemented surface with its convex surface facing the object side. If the first negative subgroup Mn1 is constituted by a cemented lens having a cemented surface with its convex surface facing the object side, it becomes easier to correct the field curvature well in the entire zoom range.

[0023] The second negative subgroup Mn2 is a subgroup with negative refractive power. The second negative subgroup Mn2 has a negative lens with its concave surface facing the object side. As long as the second negative subgroup Mn2 has this negative lens, its other specific configurations are not particularly limited. It may include other negative lenses in addition to the negative lens, or may include positive lenses as long as the whole shows negative refractive power. Also, the object side surface of the negative lens preferably has a stronger curvature than the image side surface. Thereby, spherical aberration can be corrected better.

[0024] The second positive subgroup Mp2 is a subgroup with positive refractive power. The second positive subgroup Mp2 has at least one or two positive lenses, and as long as the lens on the most image side is a positive lens, its other specific configurations are not particularly limited. The image side surface of the positive lens on the most image side of the second positive subgroup Mp2 is preferably convex on the image side. Thereby, it becomes easy to ensure a bright F-number in the entire zoom lens system.

[0025] The intermediate group M preferably has at least one air lens having a negative refractive power. This makes it easier to ensure the above-mentioned diverging action in the intermediate group M, and it becomes easier to correct spherical aberration and field curvature better. Note that the refractive power of the air lens generates a negative refractive power or a positive refractive power depending on the shape between lens surfaces that are adjacently arranged with an air gap therebetween. Since the zoom lens has an air lens having a negative refractive power, the air lens exhibits the same shape as a positive lens having a biconvex shape, a plano-convex shape, or a positive meniscus shape.

[0026] Further, when the intermediate group M is composed of two or more lens groups, it becomes easy to suppress aberration variation by changing the interval on the optical axis between adjacent lens groups during zooming, so that a zoom lens with higher optical performance can be obtained. However, when the number of lens groups constituting the intermediate group M increases, it becomes difficult to obtain a small-sized zoom lens. Therefore, in order to obtain a small-sized zoom lens, the number of lens groups constituting the intermediate group M is preferably 3 or less.

[0027] Regarding the cemented lens included in the intermediate group M, when the lenses constituting each cemented lens are lenses LCn (n = 1, 2, 3,...), the refractive power φLCn of each lens LCn preferably satisfies φLCn ≧ 0.005. With this configuration, it becomes easy to strengthen the diverging action of the cemented surface of the cemented lens. The refractive power φLCn is defined by the following formula. Let "n" represent the arrangement order from the object side of each lens LCn in the intermediate group M. φLCn = |(NLCn - 1)(1 / LCnR1 - 1 / LCnR2)| NLCn: Refractive index of the material of the lens LCn at the d-line LCnR1: Curvature radius of the object side surface of the lens LCn LCnR2: Curvature radius of the image side surface of the lens LCn However, when the center of curvature of the lens surface is on the image side of the lens surface, the sign of the curvature radius is positive, and when the center of curvature of the lens surface is on the object side of the lens surface, the sign of the curvature radius is negative. Also, the sign of the curvature radius is the same for other conditional expressions.

[0028] (4) Lens group F The lens group F is a focus group that moves on the optical axis during focusing. Since the converged light beam by the intermediate group M is incident on the lens group F disposed on the image side of the intermediate group M, it is easy to make the lens diameter small and the configuration lightweight. Therefore, by using the lens group F as the focus group, high-speed autofocus can be realized, and it is also easy to reduce the load on the focus drive system. As long as the lens group F has a negative refractive power as a whole, the specific lens configuration is not particularly limited, but more preferably, it is preferably composed of only a cemented lens in which one negative lens and one positive lens are cemented. With such a configuration, it becomes easy to realize high-speed autofocus due to the weight reduction 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.

[0029] (5) Rear group R The rear group R has one or more lens groups. The rear group R is composed of lens groups disposed between the lens group F and the image plane. The rear group R preferably has at least one lens group with a negative refractive power, and preferably has a 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 overall optical length at the telephoto end. The rear group R may be provided with two or more lens groups, but as the number of lens groups constituting the zoom lens increases, it becomes difficult to achieve miniaturization.

[0030] (6) Aperture stop The aperture stop is preferably disposed on the object side of the intermediate group M or within the intermediate group M. In particular, by disposing it adjacent to the object side of the intermediate group M, that is, the object side of the first positive subgroup Mp1, it becomes easy to reduce the effective diameter of the first lens group at the wide-angle end.

[0031] 1-2. Operation (1) Zooming When the zoom lens changes its magnification by changing the distance between adjacent lens groups on the optical axis during zooming. Each lens group only needs to change the distance between their optical axes during zooming. All lens groups may move along the optical axis, or some lens groups may be fixed in the optical axis direction.

[0032] The presence or absence of movement of each lens group is not particularly limited. However, the first lens group, at least one lens group among the lens groups constituting the intermediate group M, and the lens group F preferably move toward the object side respectively when zooming from the wide-angle end to the telephoto end. By moving these lens groups in this way, it is less likely that the magnification effect of each lens group after the second lens group will be difficult, and a configuration that easily achieves both high magnification and high performance is obtained.

[0033] When zooming from the wide-angle end to the telephoto end, the second lens group preferably moves toward the image side. By moving the second lens group toward the image side, it becomes easy to suppress the outer diameter of the lens of the intermediate group M at the telephoto end, and it becomes easy to reduce the diameter of the aperture unit and to make the zoom lens smaller and lighter.

[0034] When the rear group R includes a lens group with negative refractive power, when zooming from the wide-angle end to the telephoto end, the lens group with negative refractive power preferably moves toward the object side. By making the movement during zooming like this, the magnification effect of the rear group R can be increased. Therefore, the movement amount of each lens group can be reduced, and it becomes easy to obtain a smaller and higher magnification zoom lens.

[0035] When the rear group R includes two or more lens groups, in order to avoid complicating the cam structure of the lens barrel, the lens group arranged closest to the image side of the rear group R is preferably fixed on the optical axis during zooming.

[0036] (2) Focusing When the zoom lens focuses from infinity to a close distance, it is performed by moving the lens group F along the optical axis toward the image side. The lens group F is located on the image side of the intermediate group M, that is, it is arranged rearward in 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 accompanying the movement of the focus group. Therefore, not only when adopting the contrast AF method, but also when adopting the phase difference AF method on the image plane, it is possible to obtain a zoom lens suitable for video imaging using the tracking AF function and the like.

[0037] 1-3. Conditional expression It is desirable that the zoom lens adopts the above-described configuration and satisfies at least one or more of the conditional expressions described below.

[0038] -1.30 ≦ fM / fMn1 < 0 ···(1) However, fMn1: Focal length of the first negative partial group Mn1 fM: Composite focal length of the intermediate group M

[0039] The conditional expression (1) is a conditional expression for appropriately setting the ratio between the focal length of the intermediate group M and the focal length of the first negative partial group Mn1. By satisfying the conditional expression (1), it is possible to satisfactorily correct spherical aberration and field curvature in the entire zoom range. Therefore, even when a strong positive refractive power is arranged in the intermediate group M, these aberrations can be satisfactorily corrected, and it is possible to realize a small-sized zoom lens with high optical performance while increasing the aperture ratio.

[0040] On the other hand, when the numerical value of the conditional expression (1) is less than the lower limit value, the negative divergence action by the first negative partial group Mn1 becomes too strong, and it becomes difficult to satisfactorily correct spherical aberration and field curvature in a well-balanced manner. On the other hand, when the numerical value of the conditional expression (1) exceeds the upper limit value, the negative divergence action by the first negative partial group Mn1 becomes small. When a strong positive refractive power is arranged in the intermediate group M, it becomes difficult to satisfactorily correct the spherical aberration and field curvature that tend to be under.

[0041] In order to obtain the above effects, the value of conditional expression (1) is required to be negative, and the upper limit value of conditional expression (1) is preferably -0.02, more preferably -0.05. Also, the lower limit value of conditional expression (1) is preferably -1.20, more preferably -1.10.

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

[0043] Conditional expression (2) is a conditional expression for appropriately setting the ratio of the radius of curvature of the lens surface on the object side of the intermediate group M closest to the object to the focal length of the zoom lens at the telephoto end. When conditional expression (2) is satisfied, the lens surface on the object side of the intermediate group M is convex on the object side. By satisfying conditional expression (2), it becomes easy to balance the miniaturization of the overall length and the optical performance. Note that the lens surface on the object side of the intermediate group M means the lens surface on the object side of the first positive subgroup Mp1.

[0044] On the other hand, when the numerical value of conditional expression (2) is less than the lower limit value, it becomes easy to miniaturize the overall length, but the spherical aberration and field curvature generated on the lens surface on the object side of the intermediate group M tend to be strongly under, and it becomes difficult to correct them well. On the other hand, when the numerical value of conditional expression (2) exceeds the upper limit value, in order to obtain a small zoom lens while increasing the aperture ratio, it is necessary to strongly converge the light beam in the intermediate group M. Therefore, the number of positive refractive power lenses arranged in the intermediate group M increases, and it becomes difficult to miniaturize the overall length.

[0045] In order to obtain the above effects, the upper limit value of conditional expression (2) is preferably 0.65, more preferably 0.6, and even more preferably 0.55. Also, the lower limit value of conditional expression (2) is preferably 0.20, more preferably 0.25.

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

[0047] Conditional Expression (3) is a conditional expression for appropriately setting the ratio between the radius of curvature of the most image-side lens surface of the intermediate group M and the focal length of the zoom lens at the telephoto end. When Conditional Expression (3) is satisfied, the most image-side lens surface of the intermediate group M is convex on the image side. By satisfying Conditional Expression (3), it becomes easy to ensure the desired brightness of the zoom lens while reducing the overall length. Note that the most image-side lens surface of the intermediate group M means the most image-side lens surface of the second positive subgroup Mp2.

[0048] On the other hand, when the numerical value of Conditional Expression (3) is less than the lower limit value, it becomes difficult to ensure the brightness from the first lens group to the intermediate group M. On the other hand, when the numerical value of Conditional Expression (3) exceeds the upper limit value, it becomes easy to reduce the overall length, but the curvature of the most image-side lens surface of the intermediate group M becomes too strong, making it difficult to correct spherical aberration and field curvature well.

[0049] In order to obtain the above effects, the upper limit value of Conditional Expression (3) is preferably -0.20, and more preferably -0.25. Also, the lower limit value of Conditional Expression (3) is preferably -0.75, more preferably -0.70, and even more preferably -0.65.

[0050] 1-3-4. Conditional Expression (4) and Conditional Expression (5) The intermediate group M has a positive lens P on the most object side, that is, on the most object side of the first positive subgroup Mp1, and it is preferable that this positive lens P simultaneously satisfies the following Conditional Expression (4) and Conditional Expression (5). 0.01≦θgF-(-1.618×10 -3 ×νd+0.6415)≦0.06···(4) 10 ≦ νd ≦ 35 ···(5) However, When the refractive indices of the positive lens P with respect to the d-line, F-line, C-line, and g-line are nd, nF, nC, and ng, respectively, θgF: The partial dispersion ratio θgF of the positive lens P is θgF = (ng - nF) / (nF - nC) νd: The Abbe number νd of the positive lens P with respect to the d-line is νd = (nd - 1) / (nF - nC)

[0051] The conditional expression (4) is a conditional expression for defining the anomalous dispersion property of the material of the positive lens P. The conditional expression (5) is a conditional expression for defining the Abbe number of the material of the positive lens P with respect to the d-line. By arranging the positive lens P that simultaneously satisfies the conditional expression (4) and the conditional expression (5) on the most object side of the intermediate group M, axial chromatic aberration can be corrected well in the entire zoom region. Generally, a positive lens included in a lens group with positive refractive power corrects chromatic aberration by using a material on the low-dispersion side. However, in the intermediate group M of the zoom lens, the diverging action due to the diverging surface is large, and the axial chromatic aberration on the short-wavelength side tends to be excessive. Therefore, by using the positive lens P as a glass material on the high-dispersion side, good chromatic aberration correction becomes easy.

[0052] On the contrary, when the numerical value of the conditional expression (4) is less than the lower limit or the numerical value of the conditional expression (5) exceeds the upper limit, the axial chromatic aberration on the short-wavelength side such as the F-line and g-line tends to be excessive, making correction difficult. On the other hand, when the numerical value of the conditional expression (4) exceeds the upper limit value or the numerical value of the conditional expression (5) is less than the lower limit, the axial chromatic aberration on the short-wavelength side such as the F-line and g-line tends to be insufficient, making correction difficult.

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

[0054] 1-3-5. Conditional Expression (6) 0.3 ≦ BFw / Y ≦ 1.5 ···(6) However, BFw: The back focus of the zoom lens at the wide-angle end, which is the value when the cover glass thickness is converted to air. Y: The maximum image height of the zoom lens

[0055] The conditional expression (6) 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 the conditional expression (6), the back focus of the zoom lens at the wide-angle end can be shortened, and the overall length can be reduced.

[0056] When the numerical value of the conditional expression (6) is less than the lower limit value, 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, when the numerical value of the conditional expression (6) exceeds the upper limit value, the back focus of the zoom lens at the wide-angle end becomes too long, making it difficult to reduce the overall length of the zoom lens.

[0057] In order to obtain the above effects, the upper limit value of the conditional expression (6) is preferably 1.3, more preferably 1.2, and even more preferably 1.1. Also, the lower limit value of the conditional expression (6) is preferably 0.4, more preferably 0.5, and even more preferably 0.6.

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

[0059] In particular, according to the above zoom lens, it has a large aperture ratio, is overall small in size, and has excellent optical performance. Further, the above zoom lens can suppress fluctuations in the angle of view accompanying the movement of the focus group, and is suitable for video imaging using the tracking AF function not only when adopting the contrast AF method, but also when adopting the phase difference AF method on the image plane. Therefore, by adopting the said zoom lens, an imaging device suitable for video imaging having a tracking AF function can be obtained.

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

Examples

[0061] (1) Optical configuration FIG. 1 is a cross-sectional view at infinity focus at the wide-angle end of the zoom lens according to Example 1 of the present invention. The zoom lens of Example 1 is composed of 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, in order from the object side. The third lens group G3 corresponds to the intermediate group M. The fourth lens group G4 corresponds to the lens group F. The fifth lens group G5 corresponds to the rear group R.

[0062] When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves 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 infinite object to a close object is performed by moving the fourth lens group G4 (lens group F) toward the image side. The aperture stop S is arranged adjacent to the object side of the third lens group G3.

[0063] Hereinafter, the configuration of each lens group will be described. The first lens group G1 is composed of, in order from the object side, a cemented lens formed by cementing a negative meniscus lens L1 with a convex surface facing the object side and a biconvex lens L2, and a positive meniscus lens L3 with a convex surface facing the object side.

[0064] 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.

[0065] 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, namely a negative meniscus lens L12 with a convex surface facing the object side, a biconvex lens L13, and a biconcave lens L14, a negative meniscus lens L15 with a concave surface facing the object side, and a biconvex lens L16. The negative meniscus lens L15 is a glass-molded aspherical lens with an aspherical object-side surface. The biconvex lens L16 is a glass-molded aspherical lens with aspherical surfaces on both sides. A first positive subgroup Mp1 is formed by the positive meniscus lens L10 and the positive meniscus lens L11. The positive meniscus lens L10 is a positive lens P, and its object-side surface is convex toward the object side. A first negative subgroup Mn1 is formed by the cemented lens formed by cementing the three lenses, namely the negative meniscus lens L12, the biconvex lens L13, and the biconcave lens L14. The cemented surface between the negative meniscus lens L12 and the biconvex lens L13 faces the object side with a convex surface. A second negative subgroup Mn2 is formed by the negative meniscus lens L15. A second positive subgroup Mp2 is formed by the biconvex lens L16. The image-side surface of the biconvex lens L16 is convex toward the image side. Also, between the biconcave lens L14 and the negative meniscus lens L15, there is an air lens with a biconvex shape, which has a negative refractive power.

[0066] The fourth lens group G4 is composed of a cemented lens formed by cementing a biconvex lens L17 and a biconcave lens L18.

[0067] The fifth lens group G5 is composed of, in order from the object side, a cemented lens formed by cementing a negative meniscus lens L19 with its convex surface facing the object side and a biconvex lens L20, and a negative meniscus lens L21 with its concave surface facing the object side. The negative meniscus lens L21 is a glass-molded aspherical lens with both surfaces being aspherical.

[0068] In FIG. 1, "IP" is the image plane, specifically, the imaging plane of an imaging device such as a CCD sensor or a CMOS sensor, or the film plane of a silver halide film, etc. Also, on the object side of the image plane IP, a parallel plate having substantially no refractive power such as a cover glass CG is provided. Since these points are the same in each lens cross-sectional view shown in other embodiments, the description thereof will be omitted hereinafter.

[0069] (2) Numerical examples Next, numerical examples applying the specific numerical values of the zoom lens will be described. Hereinafter, "lens data", "specifications table", "variable interval", "lens group data", and "aspherical coefficient" are shown. Also, the values of each conditional expression (1) to conditional expression (7) (Table 1), the values used to obtain each conditional expression, and the values of φLCn of each example (Table 2) are shown together after Example 6.

[0070] In the "lens data", "surface number" is the order of the lens surfaces counted from the object side, "r" is the radius of curvature of the lens surface, "d" is the lens thickness or air interval on the optical axis, "nd" is the refractive index at the d-line (wavelength λ = 587.56 nm), and "νd" is the Abbe number at the d-line. Also, "ASPH" attached after the surface number in the "surface number" column indicates that the lens surface is aspherical, and "S" indicates that the surface is the aperture stop. In the "d" column, the notations such as "d(0)", "d(5)", etc. mean that the interval on the optical axis of the lens surface is a variable interval that changes during zooming. Also, "∞" in the column of the radius of curvature means infinity, which means that the lens surface is a plane. The unit of all lengths in the table is "mm", and the unit of all angular fields of view is "°", which is the same in other tables.

[0071] In the "specification table", "f" represents the focal length of the zoom lens, "FNo." represents the F-number, "ω" represents the half field angle, and "Y" represents the image height. The values at the wide-angle end, intermediate focal length, and telephoto end are shown respectively.

[0072] In the "variable interval", the values at the wide-angle end, intermediate focal length, and telephoto end when focusing at infinity and when focusing on a close object are shown respectively.

[0073] [Lens group data] shows the focal length of each lens group.

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

[0075] [Number]

[0076] Since the matters in each of these tables are the same as those in the tables shown in other embodiments, the description will be omitted below.

[0077] Also, FIGS. 2, 3, and 4 show longitudinal aberration diagrams when the zoom lens is focused at infinity at its wide-angle end, intermediate focal length, and telephoto end. The longitudinal aberration diagrams shown in each figure are, in order from the left side toward the drawing, spherical aberration (mm), coma aberration (mm), and distortion (%) respectively. In the spherical aberration diagram, the solid line indicates the spherical aberration at the d line (wavelength 587.56 nm), the dashed line indicates the spherical aberration at the C line (wavelength 656.28 nm), and the one-dot chain line indicates the spherical aberration at the g line (wavelength 435.84 nm). In the coma aberration diagram, the vertical axis is the semi-field angle (ω), the horizontal axis is defocus, the solid line indicates the sagittal image plane (ds) of the d line, and the dashed line indicates the meridional image plane (dm) of the d line respectively. In the distortion diagram, the vertical axis is the semi-field angle (ω), and the horizontal axis is distortion. Since these matters are the same for each aberration diagram shown in other embodiments, the description thereof will be omitted below.

[0078] [Lens Data] Surface No. r d nd νd Object Plane ∞ d(0) 1 192.4282 1.5000 1.91082 35.25 2 100.0065 10.0532 1.49700 81.61 3 -252.2417 0.2000 4 71.5654 6.5650 1.49700 81.61 5 192.2789 d(5) 6 83.7631 1.5000 1.87070 40.73 7 28.8102 8.6177 8 520.2462 4.1099 1.80518 25.46 9 -79.0552 0.4606 10 -180.0295 1.2000 1.87070 40.73 11 128.0584 4.0554 12 -37.2450 1.2000 1.59282 68.62 13 46.6295 5.0613 1.91082 35.25 14 -120.2559 1.9148 15 -42.1599 1.2000 1.72916 54.67 16 -83.9970 d(16) 17S ∞ 1.2000 18 38.6389 5.2507 1.92286 20.88 19 120.0000 0.1500 20 35.4374 5.0901 1.59282 68.62 21 97.2289 0.4000 22 96.5811 1.3000 1.84666 23.78 23 19.5924 13.1150 1.61800 63.39 24 -28.9537 1.3000 1.90366 31.31 25 150.9663 2.2521 26ASPH -112.3666 1.5000 1.80625 40.91 27 -14100.5277 0.2067 28ASPH 40.3440 7.2282 1.77377 47.17 29ASPH -38.9138 d(29) 30 105.0374 3.0753 1.92286 20.88 31 -93.2811 0.9000 1.80100 34.97 32 27.9385 d(32) 33 55.5333 1.2000 1.91082 35.25 34 18.9288 9.5794 1.59270 35.31 35 -48.7564 6.1999 36ASPH -23.1657 1.8000 1.69350 53.18 37ASPH -77.5216 d(37) 38 ∞ 2.5000 1.51680 64.20 39 ∞ 1.0000 Image plane ∞

[0079] ["Specification Table"] Wide-angle end, Middle, Telephoto end f 36.0267 74.9717 145.5296 FNo. 2.0604 2.6090 2.9089 ω 30.9716 15.3720 8.0578 Y 21.6330 21.6330 21.6330

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

[0081] ["Lens Group Data"] Group number, Focal length G1 142.9320 G2 -30.6227 G3 32.3890 G4 -55.4052 G5 -136.9750

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

Example

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

[0084] When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves 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 infinite object to a close object 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.

[0085] Hereinafter, the configuration of each lens group will be described. The first lens group G1 is composed of, in order from the object side, a cemented lens formed by cementing a negative meniscus lens L1 with a convex surface facing the object side and a biconvex lens L2, and a positive meniscus lens L3 with a convex surface facing the object side.

[0086] 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 molded aspherical lens with a composite resin film molded into an aspherical shape attached to the object side surface.

[0087] The third lens group G3 is composed of, in order from the object side, a positive meniscus lens L8 with a convex surface facing the object side, a biconvex lens L9, a cemented lens formed by cementing a biconcave lens L10 and a positive meniscus lens L11 with a convex surface facing the object side, a cemented lens formed by cementing a biconcave lens L12 and a biconvex lens L13, a biconvex lens L14, and a positive meniscus lens L15 with a convex surface facing the object side. The biconvex lens L9 is a glass molded aspherical lens with both surfaces being aspherical. The biconvex lens L14 is a glass molded aspherical lens with both surfaces being aspherical. A first positive subgroup Mp1 is formed by the positive meniscus lens L8 and the biconvex lens L9. The positive meniscus lens L8 is a positive lens P, and the object side surface is convex toward the object side. A first negative subgroup Mn1 is formed by the cemented lens formed by cementing the biconcave lens L10 and the positive meniscus lens L11. The cemented surface of the cemented lens faces the object side with a convex surface. A second negative subgroup Mn2 is formed from the cemented lens formed by cementing the biconcave lens L12 and the biconvex lens L13. A second positive subgroup Mp2 is formed by the biconvex lens L14 and the positive meniscus lens L15. Also, between the positive meniscus lens L11 and the biconcave lens L12, there is an air lens with a biconvex shape, which has a negative refractive power.

[0088] The fourth lens group G4 is composed of a cemented lens formed by cementing a biconvex lens L16 and a biconcave lens L17.

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

[0090] (2) Numerical Examples Next, numerical examples applying the specific numerical values of the zoom lens will be described. The following shows "lens data", "specification table", "variable interval", "lens group data", and "aspherical coefficient". Also, FIGS. 6 to 8 show longitudinal aberration diagrams at infinity focus for the wide-angle end, intermediate focal length, and telephoto end of the zoom lens.

[0091] [Lens Data] Surface No. r d nd νd Object surface ∞ 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) 6 ASPH 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) 14 S ∞ 1.2000 15 43.5524 4.5077 1.92286 20.88 16 144.9998 0.3619 17ASPH 33.9965 7.4165 1.69350 53.18 18ASPH -124.7641 0.2000 19 -700.0000 1.2000 1.84666 23.78 20 21.7021 6.9802 1.49700 81.61 21 303.0657 2.4810 22 -50.7442 1.2000 1.90366 31.31 23 49.9653 4.7458 1.49700 81.61 24 -107.3634 0.2000 25 37.9205 7.2355 1.63930 44.87 26 -48.1484 0.2000 27ASPH 48.6112 2.2908 1.85135 40.10 28ASPH 109.5210 d(28) 29 67.5033 2.6442 1.92286 20.88 30 -1897.7939 0.9000 1.83481 42.72 31 23.7581 d(31) 32 111.0428 1.2000 1.90366 31.31 33 22.3542 8.0792 1.63980 34.47 34 -47.3375 6.1126 35ASPH -22.3258 1.8000 1.69350 53.18 36ASPH -59.5481 d(36) 37 ∞ 2.5000 1.51680 64.20 38 ∞ 1.0000 Image plane ∞

[0092] [Specification Table] Wide-angle end Middle Telephoto end f 36.0230 74.9830 145.6157 FNo. 2.0602 2.5529 2.9033 ω 30.9602 15.3672 8.0607 Y 21.6330 21.6330 21.6330

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

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

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

Example

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

[0097] When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves 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 infinitely distant object to a close-distance object 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.

[0098] Hereinafter, the configurations of the respective lens groups will be described. The first lens group G1 is composed of, in order from the object side, a cemented lens formed by cementing 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.

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

[0100] The third lens group G3 is composed of, in order from the object side, a positive meniscus lens L8 with a convex surface facing the object side, a biconvex lens L9, a cemented lens formed by cementing a negative meniscus lens L10 with a convex surface facing the object side and a positive meniscus lens L11 with a convex surface facing the object side, a cemented lens formed by cementing a biconvex lens L12 and a negative meniscus lens L13 with a concave surface facing the object side, and a negative meniscus lens L14 with a concave surface facing the object side. The negative meniscus lens L14 is a glass-molded aspherical lens with both surfaces being aspherical. A first positive subgroup Mp1 is composed of the positive meniscus lens L8 and the biconvex lens L9. The positive meniscus lens L8 is a positive lens P, and the object side surface is convex toward the object side. A first negative subgroup Mn1 is composed of the cemented lens formed by cementing the negative meniscus lens L10 and the positive meniscus lens L11. The cemented surface with the said cemented lens faces convex toward the object side. A second negative subgroup Mn2 is composed of the cemented lens formed by cementing the biconvex lens L12 and the negative meniscus lens L13 and the negative meniscus lens L14. Also, between the positive meniscus lens L11 and the biconvex lens L12, there is a positive meniscus-shaped air lens with a convex surface facing the object side. Similarly, between the negative meniscus lens L13 and the negative meniscus lens L14, there is a positive meniscus-shaped air lens with a concave surface facing the object side. All of these air lenses have negative refractive power.

[0101] 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 aspherical lens with both surfaces being aspherical. A second positive subgroup Mp2 is formed by the said fourth lens group. Also, the image side surface of the biconvex lens L17 is convex toward the image side.

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

[0103] 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 both surfaces being aspherical.

[0104] (2) Numerical Examples Next, numerical examples applying the specific numerical values of the zoom lens will be described. The following shows "lens data", "specification table", "variable interval", "lens group data", and "aspherical coefficient". Also, FIGS. 10 to 12 show longitudinal aberration diagrams at infinity focus for the wide-angle end, intermediate focal length, and telephoto end of the zoom lens.

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

[0106] [Specification Table] Wide-angle end Middle Telephoto end f 36.0059 74.9901 145.7846 FNo. 2.9006 2.8998 2.8998 ω 31.1279 15.6292 8.1277 Y 21.6330 21.6330 21.6330

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

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

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

Example

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

[0111] When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves 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 infinite object to a close object 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.

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

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

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

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

[0116] The fifth lens group G5 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 its concave surface facing the object side, and a biconvex lens L17. The biconvex lens L17 is a glass molded aspherical lens with aspherical shapes on both surfaces. The fifth lens group G5 forms a second positive subgroup Mp2. The image side surface of the biconvex lens L17 is convex toward the image side.

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

[0118] 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 aspherical lens with both surfaces being aspherical.

[0119] (2) Numerical Examples Next, numerical examples applying the specific numerical values of the zoom lens will be described. The following shows "lens data", "specification tables", "variable intervals", "lens group data", and "aspherical coefficients". Also, FIGS. 14 to 16 show longitudinal aberration diagrams at infinity focus for the wide-angle end, intermediate focal length, and telephoto end of the zoom lens.

[0120] [Lens Data] Surface No. r d nd νd Object surface ∞ d(0) 1 139.2743 1.5000 1.83400 37.34 2 80.8526 8.8653 1.49700 81.61 3 803.6530 0.2000 4 81.1675 7.9247 1.49700 81.61 5 583.4053 d(5) 6 87.4206 1.1000 1.83481 42.72 7 25.7644 7.8524 8 -119.3781 0.8000 1.74320 49.34 9 67.2695 0.2000 10 51.6133 7.0019 1.85478 24.80 11 -115.7829 6.8773 12 -39.5414 0.9000 1.69350 53.18 13ASPH -141.6106 d(13) 14S ∞ 1.2000 15 61.7151 3.2551 1.92286 20.88 16 416.2702 0.2000 17 34.7681 4.9378 1.69680 55.46 18 276.0065 0.2000 19 44.9113 0.9000 1.90366 31.31 20 19.2137 6.2102 1.49700 81.61 21 94.1309 4.8400 22ASPH -30.3282 1.0000 1.88202 37.22 23 -93.5565 d(23) 24 -1065.8143 2.4898 1.61800 63.39 25 -80.2742 1.0000 1.80000 29.84 26 103.2242 d(26) 27 29.4295 7.8340 1.61800 63.39 28 -43.6080 1.0000 1.92286 20.88 29 -68.8061 0.2000 30ASPH 42.2696 4.0064 1.69350 53.18 31ASPH -77.3433 d(31) 32 57.6851 0.9000 1.80100 34.97 33 21.1862 d(33) 34 199.3862 5.2186 1.92286 20.88 35 -38.7197 0.2000 36 -55.4247 0.9000 1.78800 47.37 37 108.8800 5.6525 38ASPH -30.2311 1.5000 1.69350 53.18 39ASPH -105.6295 d(39) 40 ∞ 2.5000 1.51680 64.20 41 ∞ 1.0000 像面 ∞

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

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

[0123] [Lens Group Data] Group Number, Focal Length G1 155.0100 G2 -32.1233 G3 71.8735 G4 -94.1760 G5 20.7231 G6 -42.2663 G7 -124.0100

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

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

[0126] 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 infinite object to a close object is performed by moving the fourth lens group G4 (lens group F) toward the image side. The aperture stop S is arranged adjacent to the object side of the third lens group G3.

[0127] Hereinafter, the configurations of the respective lens groups will be described. The first lens group G1 is composed of, in order from the object side, a cemented lens formed by cementing a negative meniscus lens L1 with a convex surface facing the object side and a biconvex lens L2, and a positive meniscus lens L3 with a convex surface facing the object side.

[0128] 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 L7 is a glass-molded aspherical lens having an aspherical shape on the image side surface.

[0129] 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 consisting of three lenses: a biconvex lens L11 and a biconcave lens L12, a negative meniscus lens L13 with a concave surface facing the object side, a biconvex lens L14, and a biconvex lens L15. The negative meniscus lens L13 is a glass-molded aspherical lens with aspherical surfaces on both sides. The biconvex lens L15 is a glass-molded aspherical lens with aspherical surfaces on both sides. The positive meniscus lens L8 and the positive meniscus lens L9 form a first positive subgroup Mp1. The positive meniscus lens L8 is a positive lens P, and the object-side surface is convex toward the object side. The first negative subgroup Mn1 is composed of a cemented lens formed by cementing together three lenses: a negative meniscus lens L10, a biconvex lens L11, and a biconcave lens L12. The cemented surface between the negative meniscus lens L10 and the biconvex lens L11 has a convex surface facing the object side. The second negative subgroup Mn2 is composed of the negative meniscus lens L13. The second positive subgroup Mp2 is composed of the biconvex lens L14 and the biconvex lens L15. The image side surface of the biconvex lens L15 is convex toward the image side. In addition, a biconvex air lens is formed between the biconcave lens L12 and the negative meniscus lens L13, and has negative refractive power.

[0130] 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.

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

[0132] (2) Numerical examples Next, a numerical example applying the specific numerical values of the zoom lens will be described. The following shows "lens data", "specification table", "variable interval", "lens group data", and "aspherical coefficient". Also, FIGS. 18 to 20 show longitudinal aberration diagrams at infinity focus for the wide-angle end, intermediate focal length, and telephoto end of the zoom lens.

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

[0134] [Specifications table] Wide-angle end 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

[0135] 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

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

[0137] [Aspherical coefficient] Surface number k A4 A6 A8 A10 A12 12 0.0000 -3.71224E-06 -7.54248E-10 -8.10446E-12 1.58508E-14 0.00000E+00 22 8.7544 -3.73634E-06 -9.94629E-08 2.10401E-10 2.38821E-13 5.85973E-16 23 0.0000 2.23671E-05 -1.20692E-07 7.69895E-11 5.84925E-13 0.00000E+00 26 0.0000 2.26546E-05 -9.98620E-08 2.72553E-10 -2.12889E-12 5.61288E-15 27 0.0000 1.70547E-05 -3.84960E-08 3.62167E-10 -2.64544E-12 6.48480E-15 34 0.0000 2.24163E-06 9.38154E-08 -2.94316E-10 1.98794E-13 0.00000E+00 35 0.0000 -1.23427E-05 6.39381E-08 -2.28462E-10 1.27360E-13 0.00000E+00

Example

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

[0139] When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object 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 infinite object to a close object is performed by moving the fourth lens group G4 (lens group F) toward the image side. The aperture stop S is arranged adjacent to the object side of the third lens group G3.

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

[0141] 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 having an aspherical shape on the object side surface. The negative meniscus lens L7 is a glass-molded aspherical lens having an aspherical shape on the image side surface.

[0142] 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 including a biconvex lens L11 and a biconcave lens L12, a biconcave lens L13, a biconvex lens L14, and a biconvex lens L15. The biconcave lens L13 is a glass-molded aspherical lens having aspherical shapes on both surfaces. The biconvex lens L15 is a glass-molded aspherical lens having aspherical shapes on both surfaces. A first positive subgroup Mp1 is formed by the positive meniscus lens L8 and the positive meniscus lens L9. The positive meniscus lens L8 is a positive lens P, and the object side surface is convex on the object side. A first negative subgroup Mn1 is formed by the cemented lens formed by cementing three lenses including the negative meniscus lens L10, the biconvex lens L11, and the biconcave lens L12. The cemented surface between the negative meniscus lens L10 and the biconvex lens L11 faces the object side with a convex surface. A second negative subgroup Mn2 is formed by the biconcave lens L13. A second positive subgroup Mp2 is formed by the biconvex lens L14 and the biconvex lens L15. The image side surface of the biconvex lens L15 is convex on the image side. Also, between the biconcave lens L12 and the biconcave lens L13, there is an air lens having a biconvex shape and having a negative refractive power.

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

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

[0145] The sixth lens group G6 is composed of only a biconvex lens L20.

[0146] (2) Numerical Examples Next, numerical examples applying the specific numerical values of the zoom lens will be described. The following shows "lens data", "specification table", "variable interval", "lens group data", and "aspherical coefficient". Also, FIGS. 22 to 24 show longitudinal aberration diagrams at infinity focus for the wide-angle end, intermediate focal length, and telephoto end of the zoom lens.

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

[0148] [Specifications Table] Wide-angle end Middle Telephoto end f 36.0110 74.9870 145.7999 FNo. 2.0606 2.5369 2.9024 ω 31.0557 15.3703 8.1006 Y 21.6330 21.6330 21.6330

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

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

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

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

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

[0154] (Addendum) In this specification, the following technology is disclosed in one aspect.

[0155] (Technology 1) It is composed of, in order from the object side, a first lens group with a positive refractive power, a second lens group with a negative refractive power, an intermediate group M having one or more lens groups and having an overall positive refractive power, a lens group F with a negative refractive power, and a rear group R having one or more lens groups. The intermediate group M is composed of, in order from the object side, a first positive subgroup Mp1 consisting of one or two positive lenses, a first negative subgroup Mn1 consisting of only one cemented lens formed by cementing two or more lenses, a second negative subgroup Mn2 having a negative lens with a concave surface facing the object side, and a second positive subgroup Mp2 having one or two positive lenses. The cemented lens constituting the first negative subgroup Mn1 has at least one cemented surface with a convex surface facing the object side. The most image-side lens of the second positive subgroup Mp2 is a positive lens. During zooming, the distance between adjacent lens groups changes. During focusing, the lens group F moves on the optical axis. A zoom lens characterized by satisfying the following conditional expressions. -1.30 ≦ fM / fMn1 < 0 ···(1) However, fMn1: The focal length of the first negative subgroup Mn1 fM: The combined focal length of the intermediate group M

[0156] (Technology 2) The zoom lens according to Technology 1, wherein the rear group R has an overall negative refractive power.

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

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

[0159] (Technique 5) A zoom lens according to any one of Techniques 1 to 4 that satisfies the following conditional expression. 0.15 ≦ Rmf / ft ≦ 0.70 ···(2) However, Rmf: The radius of curvature of the lens surface closest to the object side of the intermediate group M ft: The focal length of the zoom lens at the telephoto end

[0160] (Technique 6) A zoom lens according to any one of Techniques 1 to 5 that satisfies the following conditional expression. -0.80 ≦ Rmb / ft ≦ -0.15 ···(3) However, Rmb: The radius of curvature of the lens surface closest to the image side of the intermediate group M ft: The focal length of the zoom lens at the telephoto end

[0161] (Technique 7) A zoom lens according to any one of Techniques 1 to 6, wherein the lens surface closest to the object side of the second lens group is convex toward the object side.

[0162] (Technique 8) A zoom lens according to any one of Techniques 1 to 7, wherein the intermediate group M has at least one air lens having a negative refractive power.

[0163] (Technique 9) The intermediate group M has a positive lens P closest to the object side, and the positive lens P satisfies the following conditional expressions (4) and (5) simultaneously in a zoom lens according to any one of Techniques 1 to 8. 0.01≦θgF-(-1.618×10-3×νd+0.6415)≦0.06···(4) 10 ≦ νd ≦ 35 ···(5) However, θgF: Partial dispersion ratio of g-line and F-line of the material of the positive lens P νd: Abbe number with respect to d-line of the material of the positive lens P

[0164] (Technology 10) A zoom lens according to any one of Technologies 1 to 9 that satisfies the following conditional expression 0.3 ≦ BFw / Y ≦ 1.5 ···(6) However BFw: Back focus of the zoom lens at the wide-angle end, which is the value when the cover glass thickness is converted to air Y: Maximum image height of the zoom lens

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

Industrial Applicability

[0166] According to the present invention, it is possible to provide a zoom lens having a large aperture ratio, being overall small, and having excellent optical performance, and an imaging device having the zoom lens

Explanation of Signs

[0167] G1 ··· First lens group G2 ··· Second lens group G3 ··· Third lens group G4 ··· Fourth lens group G5 ··· Fifth lens group G6 ··· Sixth lens group G7 ··· Seventh lens group M ··· Intermediate group F ··· Focus group (lens group) R ··· Rear group S ··· Aperture stop CG ··· Cover glass IP ··· Image plane

Claims

1. Comprising, in order from the object side, a first lens group with positive refractive power, a second lens group with negative refractive power, an intermediate group M having one or more lens groups and having positive refractive power as a whole, a lens group F with negative refractive power, and a rear group R having one or more lens groups, The intermediate group M comprises, in order from the object side, a first positive subgroup Mp1 consisting of one or two positive lenses, a first negative subgroup Mn1 consisting of only one cemented lens formed by cementing two or more lenses, a second negative subgroup Mn2 having a negative lens with its concave surface facing the object side, and a second positive subgroup Mp2 having one or two positive lenses, The lens on the image side of the second positive subgroup Mp2 is a positive lens, All the lenses and cemented lenses constituting the second negative subgroup Mn2 are lenses with negative refractive power. When the second negative subgroup Mn2 has the cemented lens, the cemented lens is a cemented lens formed by cementing two lenses with refractive powers of different signs, All the lenses and cemented lenses constituting the second positive subgroup Mp2 are lenses with positive refractive power. When the second positive subgroup Mp2 has the cemented lens, the cemented lens is a cemented lens formed by cementing two lenses with refractive powers of different signs, During zooming, the distance between adjacent lens groups changes, During focusing, the lens group F moves on the optical axis, A zoom lens characterized by satisfying the following conditional expression. 0.3 ≤ BFw / Y ≤ 1.5... (6) However, BFw: The back focus of the zoom lens at the wide-angle end, which is the value when the cover glass thickness is converted to air Y: The maximum image height of the zoom lens

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

3. The zoom lens according to claim 1 or claim 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.

4. The zoom lens according to any one of claims 1 to 3, wherein the first lens group moves toward the object side during zooming from the wide-angle end to the telephoto end.

5. The zoom lens according to any one of claims 1 to 4, which satisfies the following conditional expression. 0.15 ≤ Rmf / ft ≤ 0.70... (2) However, Rmf: The radius of curvature of the lens surface on the object side of the intermediate group M ft: Focal length of the zoom lens at the telephoto end

6. The zoom lens according to any one of Claims 1 to 5, satisfying the following conditional expression: -0.80 ≦ Rmb / ft ≦ -0.15... (3) However, Rmb: Curvature radius of the most image-side lens surface of the intermediate group M ft: Focal length of the zoom lens at the telephoto end

7. The zoom lens according to any one of Claims 1 to 6, wherein the most object-side lens surface of the second lens group is convex on the object side.

8. The zoom lens according to any one of Claims 1 to 7, wherein the intermediate group M has at least one air lens having a negative refractive power.

9. The intermediate group M has a positive lens P on the most object side, The zoom lens according to any one of Claims 1 to 8, wherein the positive lens P simultaneously satisfies the following conditional expressions (4) and (5). 0.01 ≤ θgF - (-1.618×10 －３ ×νd + 0.6415) ≤ 0.06...(4) 10 ≦ νd ≦ 35... (5) However, θgF: Partial dispersion ratio of the g-line and F-line of the material of the positive lens P νd: Abbe number with respect to the d-line of the material of the positive lens P

10. An imaging device comprising the zoom lens according to any one of Claims 1 to 9, and an image sensor that converts an optical image formed by the zoom lens into an electrical signal on the image side of the zoom lens.

Images