JP6745430B2 - Zoom lens system, imaging device - Google Patents

Description

The present invention provides a small-sized zoom lens system having a zoom ratio of about 10 and high resolution from infinity to a short distance, and an imaging device using the zoom lens system. In addition, a camera provided with the image pickup device is provided.

In a camera having an image pickup device that performs photoelectric conversion, such as a digital still camera or a digital video camera, there is a strong demand for downsizing along with a high zoom ratio. In recent years, particularly in a compact camera with an image pickup device integrated, Higher image quality is required due to larger size. For example, in order from the object side to the image side, a first lens group having positive power, a second lens group having negative power, a third lens group having positive power, and a third lens group having negative power. Various zoom lens systems having a positive, negative, positive, negative, and positive five-group configuration in which four lens groups and a fifth lens group having positive power are arranged have been proposed.

Patent Documents 1 and 2 disclose zoom lens systems that perform zooming by changing the interval between each group in a positive, negative, positive, negative, and positive five-group configuration that can obtain a high zoom ratio.

JP, 2014-178478, A JP, 2014-235238, A

The present disclosure provides a zoom lens system that is small in size, has a variable power ratio of about 10 times, and has high resolution from infinity to a short distance, an imaging device using the zoom lens system, and a camera including the imaging device. The purpose is to

The zoom lens system according to the present invention comprises, in order from the object side to the image side, a first lens group having a positive power, a second lens group having a negative power, and a third lens group having a positive power. , A fourth lens group having a negative power and a fifth lens group having a positive power . The lens units move during zooming from the wide-angle end to the telephoto end, intends row focusing by the fourth lens group moves along the optical axis. Then, the following conditions (1) to ( 4 ) are satisfied.

Σd/(fT×tanωT)<3.5 (1)
LT/fT <1.1 (2)
9.1 <fT/fw... (3)
−3.0<fT/fG4<−2.7 (4)
here,
Σd: total thickness on the optical axis of each lens group,
ωT: Half angle of view at the telephoto end,
fw: focal length at wide angle end,
fT: focal length at telephoto end,
LT: total optical length at the telephoto end,
fG4: focal length of the fourth lens group,
Is.

Further, the zoom lens system according to the present invention includes, in order from the object side to the image side, a first lens group having a positive power, a second lens group having a negative power, and a third lens having a positive power. It includes a group, a fourth lens group having a negative power, and a fifth lens group having a positive power. During zooming from the wide-angle end to the telephoto end, each lens unit moves, and the fourth lens unit moves on the optical axis for focusing. Then, the following conditions (1) to (3) and (5) are satisfied.

Σd / (fT x tanωT) <3.5... (1)
LT/fT <1.1 (2)
9.1 <fT/fw... (3)
1.0 <m4T/m4W <1.3 (5)
here,
Σd: total thickness on the optical axis of each lens group,
ωT: Half angle of view at the telephoto end,
fw: focal length at wide angle end,
fT: focal length at telephoto end,
LT: total optical length at the telephoto end,
m4T: magnification of the fourth lens group at the telephoto end,
m4W: magnification of the fourth lens group at the wide-angle end,
Is.

Further, the zoom lens system according to the present invention includes, in order from the object side to the image side, a first lens group having a positive power, a second lens group having a negative power, and a third lens having a positive power. It includes a group, a fourth lens group having a negative power and consisting of one lens element, and a fifth lens group having a positive power. During zooming from the wide-angle end to the telephoto end, each lens unit moves, and the fourth lens unit moves on the optical axis for focusing. Then, the following conditions (1) to (3) are satisfied.

Σd / (fT x tanωT) <3.5... (1)
LT/fT <1.1 (2)
9.1 <fT/fw... (3)
here,
Σd: total thickness on the optical axis of each lens group,
ωT: Half angle of view at the telephoto end,
fw: focal length at wide angle end,
fT: focal length at telephoto end,
LT: total optical length at the telephoto end,
Is.

Further, the zoom lens system according to the present invention includes, in order from the object side to the image side, a first lens group having a positive power, a second lens group having a negative power, and a third lens having a positive power. And a fourth lens group having a negative power, and a fifth lens group having a positive power and including one lens element. During zooming from the wide-angle end to the telephoto end, each lens unit moves, and the fourth lens unit moves on the optical axis for focusing. Then, the following conditions (1) to (3) are satisfied.

Σd / (fT x tanωT) <3.5... (1)
LT/fT <1.1 (2)
9.1 <fT/fw... (3)
here,
Σd: total thickness on the optical axis of each lens group,
ωT: Half angle of view at the telephoto end,
fw: focal length at wide angle end,
fT: focal length at telephoto end,
LT: total optical length at the telephoto end,
Is.

The present invention also relates to an image pickup apparatus including an image pickup element that converts an optical image formed by the zoom lens system into an electric image signal.

According to the present invention, a compact zoom lens system having a zoom ratio of about 10 times and high resolution from infinity to a short distance, an image pickup apparatus using the zoom lens system, and a camera including the image pickup apparatus are provided. Can be provided.

A lens arrangement diagram showing an infinity in-focus state of the zoom lens system according to Embodiment 1 (Example 1). Vertical aberration diagram of the zoom lens system according to Example 1 in an in-focus state at infinity. Lateral aberration diagrams at the telephoto end of the zoom lens system according to Example 1 in a basic state in which image blur correction is not performed and in an image blur correction state. A lens arrangement diagram showing an infinity in-focus state of a zoom lens system according to Embodiment 2 (Example 2). Vertical aberration diagram of the zoom lens system according to Example 2 in an in-focus state at infinity. Lateral aberration diagrams at the telephoto end of the zoom lens system according to Example 2 in a basic state in which image blur correction has not been performed and in an image blur correction state. A lens arrangement diagram showing an infinity in-focus state of a zoom lens system according to Embodiment 3 (Example 3). A longitudinal aberration diagram of a zoom lens system according to Example 3 in an in-focus state at infinity. Lateral aberration diagrams at the telephoto end of the zoom lens system according to Example 3 in a basic state in which image blur correction is not performed and in an image blur correction state. 1 is a schematic configuration diagram of a digital still camera to which the zoom lens system according to Embodiment 1 is applied.

(Embodiments 1 to 3)
1, 4, and 7 are lens layout diagrams of the zoom lens systems according to Embodiments 1 to 3, respectively, all showing the zoom lens system in the infinity in-focus state.

In FIGS. 1, 4, and 7, (a) is a lens configuration at the wide-angle end (shortest focal length state: focal length fW), and (b) is an intermediate position (intermediate focal length state: focal length fM=√( fW*fT)) and the lens configuration at the telephoto end (longest focal length state: focal length fT) are shown in FIG. In addition, in FIG. 1, FIG. 4, and FIG. 7, the broken line arrows provided between FIG. 1(a) and FIG. 4(b) indicate the lens groups in the wide-angle end, the intermediate position, and the telephoto end in order from the top. It is a straight line obtained by connecting the positions of. The wide-angle end and the intermediate position, and the intermediate position and the telephoto end are simply connected by a straight line, which is different from the actual movement of each lens group.

Further, in FIG. 1, FIG. 4, and FIG. 7, the arrow attached to the lens group represents focusing from the infinity in-focus state to the near-junction focus state. That is, FIGS. 1, 4, and 7 show the direction in which the fourth lens group G4, which will be described later, moves during focusing from the infinity in-focus state to the near-junction focus state. Note that, in FIGS. 1, 4, and 7, the reference numerals of the respective lens groups are shown below the positions of the respective lens groups in FIG. The direction in which each lens group moves during focusing in each zooming state will be specifically described later for each embodiment.

In addition, in FIGS. 1, 4, and 7, an asterisk * attached to a specific surface indicates that the surface is an aspherical surface. Further, in FIGS. 1, 4, and 7, the symbols (+) and (−) attached to the reference numerals of the respective lens groups correspond to the reference numerals of the powers of the respective lens groups. Further, in FIG. 1, FIG. 4, and FIG. 7, the straight line on the rightmost side represents the position of the image surface S (the object side surface of the image sensor).

[Embodiment 1]
FIG. 1 shows a zoom lens system according to the first embodiment. The zoom lens system includes, in order from the object side to the image side, a first lens group G1 having positive power, a second lens group G2 having negative power, and a third lens group G3 having positive power. It is composed of a fourth lens group G4 having negative power, a fifth lens group G5 having positive power, and a parallel plate R.

The first lens group G1 is composed of, in order from the object side to the image side, a first lens element L1 having negative power, a second lens element L2 having positive power, and a third lens element L3 having positive power. To be done. The first lens element L1 and the second lens element L2 are cemented lenses adhered with an adhesive or the like.

The second lens group G2 includes, in order from the object side to the image side, a fourth lens element L4 having negative power, a fifth lens element L5 having negative power, and a sixth lens element L6 having positive power. To be done.

The third lens group G3 includes, in order from the object side to the image side, an aperture diaphragm A, a seventh lens element L7 having positive power, an eighth lens element L8 having positive power, and a ninth lens having negative power. It is composed of an element L9 and a tenth lens element L10 having a positive power. The eighth lens element L8 and the ninth lens element L9 are cemented lenses adhered with an adhesive or the like.

The fourth lens group G4 is a single lens and includes an eleventh lens element L11 having negative power.

The fifth lens group G5 is a single lens and includes a twelfth lens element L12 having positive power.

Each lens element will be described.

The lens elements in the first lens group G1 will be described. The first lens element L1 is a meniscus lens having a convex surface on the object side. The second lens element L2 is a meniscus lens having a convex surface on the object side. The third lens element L3 is a meniscus lens having a convex surface on the object side.

The lens elements in the second lens group G2 will be described. The fourth lens element L4 is a meniscus lens having a convex surface on the object side, and has an aspherical shape on the object side and the image side. The fifth lens element L5 is a biconcave lens. The sixth lens element L6 is a biconvex lens.

The lens elements in the third lens group G3 will be described. The seventh lens element L7 is a meniscus lens having a convex surface on the object side, and has an aspherical shape on the object side and the image side. The eighth lens element L8 is a meniscus lens having a convex surface on the object side. The ninth lens element L9 is a meniscus lens having a convex surface on the object side. The tenth lens element L10 is a biconvex lens and has an aspherical shape on the image side.

The lens elements in the fourth lens group G4 will be described. The eleventh lens element L11 is a meniscus lens having a convex surface on the object side, and has an aspherical shape on the object side and the image side.

The lens elements in the fifth lens group G5 will be described. The twelfth lens element L12 is a biconvex lens and has an aspherical shape on the object side and the image side.

In the zoom lens system according to Embodiment 1, the first lens group G1, the third lens group G3, and the fourth lens group G4 move to the object side during zooming from the wide-angle end to the telephoto end during image pickup, The second lens group G2 moves in a convex locus toward the object side, and the fifth lens group G5 moves toward the image side. That is, during zooming, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 decreases, and the third lens group G3 and the fourth lens group G3 decrease. Each lens group moves along the optical axis so that the distance between the lens group G4 and the distance between the fourth lens group G4 and the fifth lens group G5 increases.

In the zoom lens system according to Embodiment 1, the fourth lens group G4 moves toward the image side along the optical axis during focusing from the infinity in-focus state to the near-junction focus state.

It should be noted that all the lens elements (image blur correction lens elements) in the third lens group G3 move in the direction perpendicular to the optical axis in order to optically correct the image blur. With this image blur correction lens element, the zoom lens system can correct the image point movement due to the vibration of the entire system. That is, the zoom lens system can optically correct image blur due to camera shake, vibration, and the like.

[Second Embodiment]
FIG. 4 shows a zoom lens system according to the second embodiment. The zoom lens system includes, in order from the object side to the image side, a first lens group G1 having positive power, a second lens group G2 having negative power, and a third lens group G3 having positive power. It is composed of a fourth lens group G4 having negative power, a fifth lens group G5 having positive power, and a parallel plate R.

The first lens group G1 is composed of, in order from the object side to the image side, a first lens element L1 having negative power and a second lens element L2 having positive power. The first lens element L1 and the second lens element L2 are cemented lenses adhered with an adhesive or the like.

The second lens group G2 is composed of, in order from the object side to the image side, a third lens element L3 having negative power, a fourth lens element L4 having negative power, and a fifth lens element L5 having positive power. To be done.

The third lens group G3 includes, in order from the object side to the image side, an aperture diaphragm A, a sixth lens element L6 having positive power, a seventh lens element L7 having positive power, and an eighth lens having negative power. It is composed of an element L8 and a ninth lens element L9 having a positive power. The seventh lens element L7 and the eighth lens element L8 are cemented lenses adhered with an adhesive or the like.

The fourth lens group G4 is a single lens and includes a tenth lens element L10 having negative power.

The fifth lens group G5 is a single lens and is composed of an eleventh lens element L11 having positive power.

Each lens element will be described.

The lens elements in the first lens group G1 will be described. The first lens element L1 is a meniscus lens having a convex surface on the object side. The second lens element L2 is a biconvex lens and has an aspherical shape on the image side.

The lens elements in the second lens group G2 will be described. The third lens element L3 is a meniscus lens having a convex surface on the object side, and has an aspherical shape on the object side and the image side. The fourth lens element L4 is a biconcave lens. The fifth lens element L5 is a biconvex lens.

The lens elements in the third lens group G3 will be described. The sixth lens element L6 is a biconvex lens and has an aspherical shape on the object side and the image side. The seventh lens element L7 is a meniscus lens having a convex surface on the object side. The eighth lens element L8 is a meniscus lens having a convex surface on the object side. The ninth lens element L9 is a biconvex lens and has an aspherical shape on the image side.

The lens elements in the fourth lens group G4 will be described. The tenth lens element L10 is a biconcave lens and has an aspherical shape on the object side and the image side.

The lens elements in the fifth lens group G5 will be described. The eleventh lens element L11 is a biconvex lens and has an aspherical shape on the object side and the image side.

In the zoom lens system according to Embodiment 2, during zooming from the wide-angle end to the telephoto end during image pickup, the first lens group G1, the second lens group G2, the third lens group G3, and the fourth lens group G4 are Moving to the object side, the fifth lens group G5 moves to the image side. That is, during zooming, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 decreases, and the third lens group G3 and the fourth lens group G3 decrease. Each lens group moves along the optical axis so that the distance between the group G4 increases and the distance between the fourth lens group G4 and the fifth lens group G5 increases.

In the zoom lens system according to Embodiment 2, the fourth lens group G4 moves toward the image side along the optical axis during focusing from the infinity in-focus state to the near-junction focus state.

It should be noted that all the lens elements (image blur correction lens elements) in the third lens group G3 move in the direction perpendicular to the optical axis in order to optically correct the image blur. With this image blur correction lens element, the zoom lens system can correct the image point movement due to the vibration of the entire system. That is, the zoom lens system can optically correct image blur due to camera shake, vibration, and the like.

[Third Embodiment]
FIG. 7 shows a zoom lens system according to the third embodiment. The zoom lens system includes, in order from the object side to the image side, a first lens group G1 having positive power, a second lens group G2 having negative power, and a third lens group G3 having positive power. It is composed of a fourth lens group G4 having negative power, a fifth lens group G5 having positive power, and a parallel plate R.

The first lens group G1 is composed of, in order from the object side to the image side, a first lens element L1 having negative power and a second lens element L2 having positive power. The first lens element L1 and the second lens element L2 are cemented lenses adhered with an adhesive or the like.

The second lens group G2 is composed of, in order from the object side to the image side, a third lens element L3 having negative power, a fourth lens element L4 having negative power, and a fifth lens element L5 having positive power. To be done.

The third lens group G3 includes, in order from the object side to the image side, an aperture diaphragm A, a sixth lens element L6 having positive power, a seventh lens element L7 having positive power, and an eighth lens having negative power. It is composed of an element L8 and a ninth lens element L9 having a positive power. The seventh lens element L7 and the eighth lens element L8 are cemented lenses adhered with an adhesive or the like.

The fourth lens group G4 is a single lens and includes a tenth lens element L10 having negative power.

The fifth lens group G5 is a single lens and is composed of an eleventh lens element L11 having positive power.

Each lens element will be described.

The lens elements in the first lens group G1 will be described. The first lens element L1 is a meniscus lens having a convex surface on the object side. The second lens element L2 is a biconvex lens and has an aspherical shape on the image side.

The lens elements in the second lens group G2 will be described. The third lens element L3 is a meniscus lens having a convex surface on the object side, and has an aspherical shape on the object side and the image side. The fourth lens element L4 is a biconcave lens. The fifth lens element L5 is a biconvex lens.

The lens elements in the third lens group G3 will be described. The sixth lens element L6 is a meniscus lens having a convex surface on the object side, and has an aspherical shape on the object side and the image side. The seventh lens element L7 is a meniscus lens having a convex surface on the object side. The eighth lens element L8 is a meniscus lens having a convex surface on the object side. The ninth lens element L9 is a biconvex lens.

The lens elements in the fourth lens group G4 will be described. It is a meniscus lens having a convex surface on the object side, and has an aspherical shape on the object side and the image side.

The lens elements in the fifth lens group G5 will be described. It is a biconvex lens and has an aspherical shape on the object side and the image side.

In the zoom lens system according to Embodiment 3, during zooming from the wide-angle end to the telephoto end during image pickup, the first lens group G1, the third lens group G3, and the fourth lens group G4 move to the object side. , The second lens group G2 moves in a convex locus toward the object side, and the fifth lens group G5 moves to the image side. That is, during zooming, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 decreases, and the third lens group G3 and the fourth lens group G3 decrease. Each lens group moves along the optical axis so that the distance between the lens group G4 and the distance between the fourth lens group G4 and the fifth lens group G5 increases.

In the zoom lens system according to Embodiment 3, the fourth lens group G4 moves toward the image side along the optical axis during focusing from the infinity in-focus state to the near-junction focus state.

It should be noted that all the lens elements (image blur correction lens elements) in the third lens group G3 move in the direction perpendicular to the optical axis in order to optically correct the image blur. With this image blur correction lens element, the zoom lens system can correct the image point movement due to the vibration of the entire system. That is, the zoom lens system can optically correct image blur due to camera shake, vibration, and the like.

[Other Embodiments]
As described above, the first to third embodiments have been described as examples of the technique disclosed in the present application. However, the technique in the present disclosure is not limited to this, and is also applicable to the embodiment in which changes, replacements, additions, omissions, etc. are appropriately made.

The number of lens groups and the number of lens elements in the lens group are substantial numbers, and lenses having substantially no power may be added.

Although the image blur correction lens group is configured by using all the lens elements of the third lens group G3 as image blur correction lens elements, it may be configured by a part of the lens elements of the third lens group G3.

Image blur correction The image blur is corrected by moving the lens element in the direction perpendicular to the optical axis, but the movement method can correct the image blur by moving it so that it has a vertical component. is there. For example, if the lens barrel structure is allowed to be complicated, the image blur correction may be performed by rotating the image blur correction lens element so as to have the rotation center on the optical axis.

As an example in which the third lens group G3 has a diaphragm, a mode in which the diaphragm is arranged closest to the object side of the third lens group is shown, but the diaphragm may be arranged closest to the image side of the third lens group. The diaphragm may be provided between any two lens elements of the third lens group. The diaphragm may be located at a position that moves integrally with the third lens group during zooming.

[Conditions and effects]
Hereinafter, for example, conditions that can be satisfied by the zoom lens systems according to Embodiments 1 to 3 will be described. Although a plurality of possible conditions are defined for the zoom lens system according to the first to third embodiments, the configuration of the zoom lens system that satisfies all of these plurality of conditions is most effective. However, by satisfying the individual conditions, it is possible to obtain a zoom lens system having the respective corresponding effects.

The zoom lens systems according to Embodiments 1 to 3 include, in order from the object side to the image side, a first lens group having positive power, a second lens group having negative power, and a second lens group having positive power. It comprises three lens groups, a fourth lens group having a negative power, and a fifth lens group having a positive power.

During zooming operation from the wide-angle end to the telephoto end, each lens group moves along the optical axis during zooming from the wide-angle end to the telephoto end, and the fourth lens group moves on the optical axis for focusing.

The zoom lens system preferably satisfies the following conditions (1) to (3), for example.

Σd/(fT×tanωT)<3.5 (1)
LT/fT <1.1 (2)
9.1 <fT/fw... (3)
here,
Σd: total thickness on the optical axis of each lens group,
ωT: Half angle of view at the telephoto end,
fw: focal length at wide angle end,
fT: focal length at telephoto end,
LT: total optical length at the telephoto end,
Is.

The specific numerical value of the thickness on the optical axis of each lens group corresponds to the lens constituent length shown in Table 3C, Table 6C, and Table 9C of Numerical Examples 1 to 3 described later. Specific numerical values of the half angle of view at the telephoto end, the focal length at the wide-angle end, the focal length at the telephoto end, and the optical total length at the telephoto end are shown in Tables 3A, 6A, and 9A of Numerical Examples 1 to 3 described later. ..

The condition (1) is a condition for defining the total of the thicknesses on the optical axis of each lens group and the ratio of the focal length at the telephoto end to the half field angle. If the upper limit of condition (1) is exceeded, the sum of the on-axis thickness of each lens group with respect to the image height calculated from the focal length at the telephoto end and the half angle of view will become too large. It is difficult to provide the device. The condition (2) is a condition for defining the ratio between the total optical length and the focal length at the telephoto end. When the value exceeds the upper limit of the condition (2), the optical total length with respect to the focal length at the telephoto end becomes too large, which makes it difficult to provide a compact lens barrel or an imaging device. On the other hand, when the value goes below the lower limit of the condition (3), the zoom magnification becomes small, and it becomes impossible to provide a high-magnification zoom lens system.

More preferably, the above effect can be further achieved by satisfying the following condition (1)'.

Σd/(fT×tanωT)<3.2 (1)′
Further, for example, it is desirable to satisfy the following condition (4).

−3.0<fT/fG4<−2.7 (4)
here,
fT: focal length at telephoto end,
fG4: focal length of the fourth lens group,
Is.

Specific numerical values of the focal length of the fourth lens group are shown in Tables 3C, 6C, and 9C of Numerical Examples 1 to 3 described later.

The condition (4) is a condition for defining the focal length of the fourth lens unit that is the focusing lens unit. When the condition (4) is satisfied, it is possible to suppress aberration variation during zooming and achieve high-speed focusing. When the value exceeds the upper limit of the condition (4), variation in aberration between the infinity in-focus state and the near cemented in-focus state, particularly variation in field curvature becomes large, leading to deterioration in image quality. On the other hand, when the value goes below the lower limit of the condition (4), the amount of focus movement increases, and it becomes difficult to achieve high-speed focusing.

Further, for example, it is desirable to satisfy the following condition (5).

1.0 <m4T/m4W <1.3 (5)
here,
m4T: magnification of the fourth lens group at the telephoto end,
m4W: magnification of the fourth lens group at the wide-angle end,
Is.

Specific numerical values of the magnification of the fourth lens group at the telephoto end and the wide-angle end are shown in Tables 3D, 6D, and 9D of Numerical Examples 1 to 3 described later.

The condition (5) is a condition for defining the ratio of the magnification of the fourth lens group at the telephoto end to the magnification of the fourth lens group at the wide-angle end. When the value goes below the lower limit of the condition (5), the magnification of the fourth lens unit at the telephoto end becomes too small, which makes it difficult to correct various aberrations, particularly curvature of field. When the value exceeds the upper limit of the condition (5), the magnification of the fourth lens group at the wide-angle end becomes too small, which makes it difficult to correct various aberrations, particularly curvature of field.

Further, it is desirable that the first lens group be composed of two or three lens elements.

This makes it possible to achieve both correction of various aberrations, particularly chromatic aberration, and reduction of the thickness of the first lens group.

It is desirable that each of the second lens group, the third lens group, the fourth lens group, and the fifth lens group has a lens element having at least one aspherical surface.

As a result, each aberration can be properly corrected, so that the number of lens elements can be reduced and the size can be reduced.

Further, it is desirable that the fourth lens group be composed of one lens element. As a result, the number of required lens elements is reduced, which enables downsizing and cost reduction. Further, since the weight can be reduced, high-speed focusing becomes possible.

Further, it is desirable that the fifth lens group be composed of one lens element. As a result, the number of required lens elements is reduced, which enables downsizing and cost reduction. Further, the weight can be reduced, so that the weight of the lens barrel can be reduced.

The fourth lens group and the fifth lens group are each composed of one lens element, and preferably satisfy the following condition (6), for example.

1.3<|νd2 + νd3|/|νd4 + νd5|<2.0...(6)
here,
νd2: Abbe number of the lens element closest to the object in the second lens group,
νd3: Abbe number of the lens element closest to the object in the third lens group,
νd4: Abbe number of the lens element of the fourth lens group,
νd5: Abbe number of the lens element of the fifth lens group,
Is.

The Abbe number of each lens element is shown in Tables 1, 4, and 7 of Numerical Examples 1 to 3 described later.

The condition (6) is the Abbe number of the most object-side lens element of the second lens group, the most object-side lens element of the third lens group, the fourth lens group single lens element, and the fifth lens group single lens element. Is a condition for prescribing. When the condition (6) is satisfied, it is possible to achieve both correction of chromatic aberration from infinity to short distance at the wide-angle end to the telephoto end and provision of a compact lens barrel, image pickup device, and camera.

More preferably, the above effect can be further achieved by satisfying the following condition (6)'.

1.5<|νd2 + νd3|/|νd4 + νd5|<1.8...(6)′
Further, it is desirable that the whole or a part of the third lens group moves so as to have a component in the direction perpendicular to the optical axis when correcting the image blur.

As a result, the lens diameter can be reduced, and the image blur correction lens group can be reduced in size and weight. Therefore, the image blur correction lens group can be driven by a simple drive mechanism. In particular, when the image blur correction lens group is composed of only one lens element, the drive mechanism of the image blur correction lens group can be further simplified.

Further, it is desirable to have a diaphragm in the third lens group. Thereby, the lens barrel structure can be simplified and the lens barrel can be downsized.

(Schematic configuration of digital camera to which Embodiment 1 is applied)
FIG. 10 is a schematic configuration diagram of a digital camera to which the zoom lens system according to the first embodiment is applied. It is also possible to apply the zoom lens system according to the second and third embodiments.

The digital camera 5 includes a housing 4, an image pickup element 2, a zoom lens system 1, and a monitor 3.

Similar to the first embodiment, the zoom lens system 1 includes actuators and lenses so that all the lens groups from the first lens group G1 to the fifth lens group G5 move along the optical axis during zooming. The frame is configured.

Although the example in which the zoom lens system according to the first embodiment described above is applied to a digital camera has been shown, the zoom lens system may be applied to a smartphone, a lens-interchangeable camera, or the like. The digital camera 5 is an example of an imaging device.

(Numerical example)
Numerical examples that specifically implement the zoom lens systems according to Embodiments 1 to 3 will be described below. In each numerical example, the unit of length in the table is “mm” and the unit of half angle of view is “°”. In each numerical example, r is the radius of curvature, d is the surface spacing, nd is the refractive index for the d line, and vd is the Abbe number for the d line. In each numerical example, the surface marked with * is an aspherical surface, and the aspherical shape is defined by the following equation.

here,
Z: Distance from a point on the aspherical surface whose height from the optical axis is h to the tangent plane of the aspherical surface apex,
h: height from the optical axis,
r: radius of curvature of vertex,
κ: conic constant,
An: an aspherical coefficient of order n,
Is.

2, 5 and 8 are longitudinal aberration diagrams of the zoom lens systems according to Examples 1 to 3 in the in-focus state at infinity, respectively.

In each of the longitudinal aberration diagrams, (a) is the wide-angle end, (b) is the intermediate position, and (c) is the telephoto end. Each longitudinal aberration diagram shows spherical aberration (SA (mm)), astigmatism (AST (mm)), and distortion (DIS (%)) in order from the left side. In the spherical aberration diagram, the vertical axis represents the F number (indicated by F in the figure), the solid line is the d line (d-line), the short dashed line is the F line (F-line), and the long dashed line is the C line (C- line) and the alternate long and short dash line are characteristics of the g line (g-line). In the astigmatism diagram, the vertical axis represents the image height (indicated by H in the figure), the solid line represents the sagittal plane (indicated by s in the figure), and the broken line represents the meridional plane (indicated by m in the figure). is there. In the distortion diagram, the vertical axis represents the image height (indicated by H in the figure).

3, 6, and 9 are lateral aberration diagrams at the telephoto end of the zoom lens systems according to Embodiments 1 to 3, respectively.

In each lateral aberration diagram, the upper three aberration diagrams show the basic state where image blur correction is not performed at the telephoto end, and the lower three aberration diagrams show the image blur compensating lens element or the image blur compensating lens group. This corresponds to the image blur correction state at the telephoto end, which is moved by a predetermined amount in the direction perpendicular to the axis. In each lateral aberration diagram in the basic state, the upper row shows the lateral aberration at the image point of 70% of the maximum image height, the middle row shows the lateral aberration at the axial image point, and the lower row shows the lateral aberration at the image point of −70% of the maximum image height. , Respectively. In each lateral aberration diagram in the image blur correction state, the upper stage shows the lateral aberration at the image point of 70% of the maximum image height, the middle stage shows the lateral aberration at the axial image point, and the lower stage shows the image point of −70% of the maximum image height. Corresponds to lateral aberrations respectively. In each lateral aberration diagram, the horizontal axis represents the distance from the principal ray on the pupil plane, the solid line is the d line (d-line), the short broken line is the F line (F-line), and the long broken line is the C line ( The C-line) and the alternate long and short dash line are characteristics of the g-line. In each lateral aberration diagram, the meridional plane is a plane including the optical axis of the first lens group G1 and the optical axis of the third lens group G3 (Examples 1 to 3).

In the zoom lens system of each example, the amount of movement of the image blur correction lens group in the image blur correction state in the direction perpendicular to the optical axis at the telephoto end is as shown below.

Example 1 0.170 mm
Example 2 0.146 mm
Example 3 0.155 mm
The image decentering amount when the zoom lens system is tilted by a predetermined angle at the telephoto end at the infinity is the image when the image blur compensating lens unit is translated by the above values in the direction perpendicular to the optical axis. Equal to the amount of eccentricity.

As is clear from each lateral aberration diagram, the symmetry of the lateral aberration at the axial image point is good. Further, comparing the lateral aberrations at the +70% image point and the lateral aberrations at the −70% image point in the basic state, both have a small degree of curvature and the inclinations of the aberration curves are almost the same. It can be seen that the aberration is small. This means that sufficient imaging performance is obtained even in the image blur correction state. When the image blur correction angles of the zoom lens system are the same, the parallel movement amount required for image blur correction decreases as the focal length of the entire zoom lens system decreases. Therefore, at any zoom position, it is possible to perform sufficient image blur correction for image blur correction angles up to a predetermined angle without deteriorating the imaging characteristics.

(Numerical Example 1)
The zoom lens system of Numerical Example 1 corresponds to the first embodiment shown in FIG. Table 1 shows surface data of the zoom lens system of Numerical Example 1, Table 2 shows aspherical surface data, and Tables 3A to 3D show various data in the infinity focused state.

(Surface data)

(Aspherical data)

(Various data when focused at infinity)

(Numerical example 2)
The zoom lens system of Numerical Example 2 corresponds to the second embodiment shown in FIG. Table 4 shows surface data of the zoom lens system of Numerical Example 2, Table 5 shows aspherical surface data, and Tables 6A to 6D show various data in the in-focus state at infinity.

(Surface data)

(Aspherical data)

(Various data when focused at infinity)

(Numerical example 3)
The zoom lens system of Numerical Example 3 corresponds to the third embodiment shown in FIG. Table 7 shows surface data of the zoom lens system of Numerical Example 3, Table 8 shows aspherical surface data, and Tables 9A to 9D show various data in the in-focus state at infinity.

(Surface data)

(Aspherical data)

(Various data when focused at infinity)

(Corresponding value of condition)
Table 10 below shows corresponding values for each condition in the zoom lens system of each numerical example.

The zoom lens system according to the present disclosure includes a digital still camera, an interchangeable lens type digital camera, a digital video camera, a camera of a mobile phone device, a PDA (Personal Digital Assistance) camera, a surveillance camera in a surveillance system, a web camera, an in-vehicle camera, and the like. In particular, it is suitable for a photographing optical system that requires high image quality such as a digital still camera system and a digital video camera system.

G1 First lens group G2 Second lens group G3 Third lens group G4 Fourth lens group G5 Fifth lens group L1 First lens element L2 Second lens element L3 Third lens element L4 Fourth lens element L5 Fifth lens element L6 6th lens element L7 7th lens element L8 8th lens element L9 9th lens element L10 10th lens element L11 11th lens element L12 12th lens element A Aperture stop R Parallel plate S Image plane 1 Zoom lens system 2 Imaging Element 3 Monitor 4 Housing 5 Digital camera

Claims (13)

From the object side to the image side,
A first lens group having positive power,
A second lens group having negative power,
A third lens group having positive power,
A fourth lens group having negative power,
A fifth lens group having a positive power,
Consists of
Each lens group moves during zooming from the wide-angle end to the telephoto end,
Focusing is performed by moving the fourth lens group on the optical axis,
Zoom lens system satisfying the following conditions (1) to ( 4 ):
Σd / (fT x tanωT) <3.5... (1)
LT/fT <1.1 (2)
9.1 <fT/fw... (3)
−3.0<fT/fG4<−2.7 (4)
here,
Σd: total thickness on the optical axis of each lens group,
ωT: Half angle of view at the telephoto end,
fw: focal length at wide angle end,
fT: focal length at telephoto end,
LT: total optical length at the telephoto end,
fG4: focal length of the fourth lens group,
Is. From the object side to the image side,
A first lens group having positive power,
A second lens group having negative power,
A third lens group having positive power,
A fourth lens group having negative power,
A fifth lens group having a positive power,
Consists of
Each lens group moves during zooming from the wide-angle end to the telephoto end,
Focusing is performed by moving the fourth lens group on the optical axis,
Zoom lens system satisfying the following conditions (1) to (3) and (5) :
Σd / (fT x tanωT) <3.5... (1)
LT/fT <1.1 (2)
9.1 <fT/fw... (3)
1.0 <m4T/m4W <1.3 (5)
here,
Σd: total thickness on the optical axis of each lens group,
ωT: Half angle of view at the telephoto end,
fw: focal length at wide angle end,
fT: focal length at telephoto end,
LT: total optical length at the telephoto end,
m4T: magnification of the fourth lens group at the telephoto end,
m4W: magnification of the fourth lens group at the wide-angle end,
Is. From the object side to the image side,
A first lens group having positive power,
A second lens group having negative power,
A third lens group having positive power,
Have a negative power, a fourth lens group composed of one lens element,
A fifth lens group having a positive power,
Consists of
Each lens group moves during zooming from the wide-angle end to the telephoto end,
Focusing is performed by moving the fourth lens group on the optical axis,
Zoom lens system satisfying the following conditions (1) to (3):
Σd / (fT x tanωT) <3.5... (1)
LT/fT <1.1 (2)
9.1 <fT/fw... (3)
here,
Σd: total thickness on the optical axis of each lens group,
ωT: Half angle of view at the telephoto end,
fw: focal length at wide angle end,
fT: focal length at telephoto end,
LT: total optical length at the telephoto end,
Is. From the object side to the image side,
A first lens group having positive power,
A second lens group having negative power,
A third lens group having positive power,
A fourth lens group having negative power,
Have a positive power, and a fifth lens group composed of one lens element,
Consists of
Each lens group moves during zooming from the wide-angle end to the telephoto end,
Focusing is performed by moving the fourth lens group on the optical axis,
Zoom lens system satisfying the following conditions (1) to (3):
Σd / (fT x tanωT) <3.5... (1)
LT/fT <1.1 (2)
9.1 <fT/fw... (3)
here,
Σd: total thickness on the optical axis of each lens group,
ωT: Half angle of view at the telephoto end,
fw: focal length at wide angle end,
fT: focal length at telephoto end,
LT: total optical length at the telephoto end,
Is. Satisfies the following condition (4) ,
−3.0<fT/fG4<−2.7 (4)
here,
fT: focal length at telephoto end,
fG4: focal length of the fourth lens group,
It is,
The zoom lens system according to claim 2. Satisfies the following condition (5) ,
1.0 <m4T/m4W <1.3 (5)
here,
m4T: magnification of the fourth lens group at the telephoto end,
m4W: magnification of the fourth lens group at the wide-angle end,
It is,
The zoom lens system according to claim 1, or any one of claims 3 to 4. The first lens group consists of two or three lens elements,
The zoom lens system according to claim 1. Each of the second lens group, the third lens group, the fourth lens group, and the fifth lens group has a lens element having at least one aspherical surface.
The zoom lens system according to claim 1. The fourth lens group includes one lens element,
The zoom lens system according to any one of claims 1 to 5, which does not refer to claim 1 , 2, 4, or claim 3 . The fifth lens group includes one lens element,
The zoom lens system according to any one of claims 5 to 9, which does not cite Claims 1 , 2, 3, or 4 . The whole or a part of the third lens group moves so as to have a component in a direction perpendicular to the optical axis at the time of image blur correction,
The zoom lens system according to claim 1. A diaphragm is provided in the third lens group,
The zoom lens system according to claim 1. The zoom lens system according to claim 1, which forms an optical image of an object,
An image pickup device for converting an optical image formed by the zoom lens system into an electric image signal,
Ru with a,
Imaging device.