JP2022126042A - Zoom lens and imaging device - Google Patents

Abstract

Kind Code: A1 A compact zoom lens and an imaging device having high optical performance are provided. Kind Code: A1 A first lens group having negative refractive power, an intermediate group consisting of one or more lens groups and having positive refractive power as a whole, and a negative refractive power, in order from the object side. The zoom lens is composed of a lens group Ln and a final lens group having a negative refractive power, and the distance between adjacent lens groups changes during zooming or focusing and satisfies a predetermined conditional expression. Also, an imaging apparatus is provided with this zoom lens. [Selection drawing] Fig. 1

Description

The present invention relates to a zoom lens and an imaging device, and more particularly to a zoom lens and an imaging device suitable for a compact imaging device using a solid-state imaging device or the like.

2. Description of the Related Art In recent years, imaging apparatuses using solid-state imaging devices, such as digital still cameras and digital video cameras, have become widespread. Accompanying this, optical systems are becoming more sophisticated and smaller, and compact image pickup systems are rapidly becoming popular. However, for surveillance cameras, video cameras, digital still cameras, single-lens reflex cameras, mirrorless single-lens cameras, etc., where a compact optical system with a short overall length is desired, the zoom lens has a compact optical system while maintaining high optical performance. it was difficult to

Therefore, in Patent Document 1, in order from the object side, a first lens group having negative refractive power, a second lens group having positive refractive power, a third lens group having negative refractive power, and a negative refractive power proposes a zoom lens with a fourth lens group with power.

Patent No. 6040890

However, in the zoom lens having the negative-positive-negative-negative refractive power arrangement of Patent Document 1, the negative refractive power of the first lens group is weaker than the positive refractive power of the second lens group. A lens with a large lens diameter must be arranged on the side closest to the object, and there is a problem that the miniaturization of the optical system in the radial direction is insufficient.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a zoom lens and an imaging device that are smaller and have higher optical performance.

In order to solve the above-described problems, as a result of intensive research, the following invention was conceived.

A zoom lens according to the present invention comprises, in order from the object side, a first lens group having negative refractive power, an intermediate group consisting of one or more lens groups and having positive refractive power as a whole, and a lens group having negative refractive power. and a final lens group having negative refractive power, said intermediate group including a lens group LpMax, said lens group LpMax being the strongest of the lens groups included in said intermediate group A zoom lens that has a positive refractive power, performs zooming or focusing by changing the distance between adjacent lens groups, and is characterized by satisfying the following conditional expression.
0.05≦|f1|/|fpMax|≦0.80 (1)
however,
f1: focal length of the first lens group fpMax: focal length of the lens group LpMax

A zoom lens according to the present invention comprises, in order from the object side, a first lens group having negative refractive power, an intermediate group consisting of one or more lens groups and having positive refractive power as a whole, and a lens group having negative refractive power. and a final lens group having negative refractive power, said intermediate group including a lens group LpMax, said lens group LpMax being the strongest of the lens groups included in said intermediate group A zoom lens that has a positive refractive power, performs zooming or focusing by changing the distance between adjacent lens groups, and is characterized by satisfying the following conditional expression.
βpw≦−0.58 (2)
however,
βpw: Composite lateral magnification of the intermediate group when focusing on infinity at the wide-angle end

Further, in order to solve the above-described problems, an image pickup apparatus according to the present invention includes the above-described zoom lens, and an image sensor that converts an optical image formed by the zoom lens on the image side of the zoom lens into an electrical signal. characterized by comprising

According to the present invention, it is possible to provide a zoom lens and an imaging device that are more compact and have high optical performance over the entire zoom range.

FIG. 2 shows a cross-sectional view of the zoom lens according to the first embodiment of the present invention at the wide-angle end and the telephoto end when focusing on infinity. FIG. 4 shows longitudinal aberration diagrams at the wide-angle end of the zoom lens of the first embodiment when focusing on infinity. FIG. 4 shows longitudinal aberration diagrams of the zoom lens of the first embodiment in an intermediate focal length state when focusing on infinity. FIG. 4 shows longitudinal aberration diagrams of the zoom lens of the first embodiment at the telephoto end when focusing on infinity. FIG. 10 is a cross-sectional view of the zoom lens of the second embodiment of the present invention when focusing on infinity at the wide-angle end and the telephoto end; FIG. 10 is a longitudinal aberration diagram at the wide-angle end of the zoom lens of the second embodiment when focusing on infinity. FIG. 10 is a longitudinal aberration diagram of the zoom lens of the second embodiment when focusing on infinity in an intermediate focal length state; FIG. 10 is a longitudinal aberration diagram at the telephoto end of the zoom lens of the second embodiment when focusing on infinity. FIG. 10 is a cross-sectional view of the zoom lens of the third embodiment of the present invention when focusing on infinity at the wide-angle end and the telephoto end; FIG. 10 is a longitudinal aberration diagram at the wide-angle end of the zoom lens of the third embodiment when focusing on infinity. FIG. 11 shows longitudinal aberration diagrams of the zoom lens of the third embodiment when focusing on infinity in an intermediate focal length state. FIG. 10 is a longitudinal aberration diagram at the telephoto end of the zoom lens of the third embodiment when focusing on infinity. FIG. 10 is a cross-sectional view of the zoom lens of the fourth embodiment of the present invention when focusing on infinity at the wide-angle end and the telephoto end; FIG. 10 is a longitudinal aberration diagram at the wide-angle end of the zoom lens of the fourth embodiment when focusing on infinity. FIG. 11 shows longitudinal aberration diagrams of the zoom lens of the fourth embodiment in an intermediate focal length state when focusing on infinity. FIG. 10 is a longitudinal aberration diagram at the telephoto end of the zoom lens of the fourth embodiment when focusing on infinity. FIG. 10 is a cross-sectional view of the zoom lens of the fifth embodiment of the present invention when focusing on infinity at the wide-angle end and the telephoto end; FIG. 10 is a longitudinal aberration diagram at the wide-angle end of the zoom lens of the fifth embodiment when focusing on infinity. FIG. 11 shows longitudinal aberration diagrams of the zoom lens of the fifth embodiment in an intermediate focal length state when focusing on infinity. FIG. 12 is a longitudinal aberration diagram at the telephoto end of the zoom lens of the fifth embodiment when focusing on infinity.

Embodiments of a zoom lens and an imaging device according to the present invention will be described below. However, the zoom lens and imaging device described below are aspects of the zoom lens and imaging device according to the present invention, and the zoom lens and imaging device according to the present invention are not limited to the following aspects. do not have.

1. Zoom lens 1-1. Optical Configuration of Zoom Lens The zoom lens of this embodiment comprises, in order from the object side, a first lens group having negative refractive power, and an intermediate group consisting of one or more lens groups and having positive refractive power as a whole. , a lens group Ln having negative refractive power and a final lens group having negative refractive power. The intermediate group includes a lens group LpMax, and the lens group LpMax has the strongest positive refractive power among the lens groups included in the intermediate group. The zoom lens is configured to perform zooming or focusing by changing the distance between adjacent lens groups.

The zoom lens has a negative refractive power in the first lens group and a positive refractive power in the intermediate group, so that the object side has a light ray divergence effect and the image side has a light ray convergence effect. ing. By adopting a so-called retrofocus configuration for the optical configuration of the zoom lens in this way, the angle of view at the wide-angle end can be widened without increasing the size of the zoom lens. That is, the zoom lens has a power (refractive power) arrangement suitable for a wide-angle zoom lens.

Further, in order to shorten the total optical length of the zoom lens of the present embodiment, it is preferable to employ a so-called telephoto type refractive power arrangement. That is, it is preferable to arrange a lens group having a positive refractive power on the object side and arrange a lens group having a negative refractive power on the image side. In this zoom lens, on the image side of the first lens group, in order from the object side, an intermediate group having positive refractive power as a whole, a lens group Ln having negative refractive power, and a final lens group Ln having negative refractive power. and a lens group. By adopting such a refractive power arrangement, it is possible to achieve a power arrangement with a strong telephoto tendency on the image side of the first lens group. That is, the zoom lens can shorten the length on the optical axis from the intermediate group to the final lens group compared to the combined focal length from the intermediate group to the final lens group, and the optical system of the entire zoom lens can be shortened. The overall length can be shortened.

The optical configuration and the like of each lens group will be described below.

(1) First lens group As described above, the first lens group is arranged closest to the object side of the plurality of lens groups that make up the zoom lens, and as long as it has negative refractive power, the specific lens configuration is: It is not particularly limited. Also, the first lens group preferably has a lens L1p having a positive refractive power on the most image side in the group. This is because, if this lens L1p or its image-side lens surface satisfies a predetermined conditional expression to be described later, the lens diameter of the lens arranged closest to the object side in the group can be further reduced. .

(2) Intermediate Group The intermediate group is arranged closer to the image side than the first lens group described above, consists of one or more lens groups, and has a positive refractive power as a whole. The configuration of the lenses in the group is not particularly limited. The intermediate group may include at least one lens group having positive refractive power, may have two or more lens groups having positive refractive power, or may have positive refractive power. One or more lens groups each having negative refractive power may be provided. In the present invention, the lens group having the strongest positive refractive power among the lens groups included in the intermediate group is referred to as the lens group LpMax.

(3) Lens group Ln
The lens group Ln is arranged closer to the image side than the intermediate group described above, and its specific lens configuration is not particularly limited as long as it has negative refractive power. Further, it is preferable that the lens group Ln is a single lens having negative refractive power in order to operate the lens group Ln at high speed. In terms of correction of curvature of field, it is preferable that the lens closest to the image side in the group be a meniscus lens.

(4) Final lens group The final lens group is arranged closest to the image side among the plurality of lens groups that make up the zoom lens, and as long as it has negative refractive power, its specific lens configuration is not particularly limited. do not have. In order to reduce the size of the optical system, it is preferable that the final lens group consists of two lenses, one having a positive refractive power and the other having a negative refractive power, in order from the object side.

(5) Focus group In the zoom lens, presence or absence of the focus group is not particularly limited. When the zoom lens is provided with a focus group, at least one of the constituent lenses can be used as the focus group, and the focus group can be moved in the optical axis direction during focusing to focus on the subject. In the zoom lens, the position and refractive power of the lens used as the focus group are not particularly limited.

(6) Anti-Vibration Group In the zoom lens, presence or absence of an anti-vibration group is not particularly limited. When the zoom lens is provided with an anti-vibration group, at least one lens among the lenses constituting the zoom lens is used as the anti-vibration group, and the image is shifted by moving the anti-vibration group in a direction substantially perpendicular to the optical axis. When (so-called camera shake correction) is performed, it is possible to reduce the size of the entire zoom lens unit including the lens barrel, which is preferable for reducing the size of the optical system. In addition to the zoom lens, the zoom lens unit includes a drive mechanism (zoom drive mechanism) for moving each lens group relative to each other during zooming, and a drive mechanism for moving the focus group along the optical axis during focusing. In addition to the drive mechanism (focus drive mechanism), the lens barrel and the like for accommodating these are included.

(7) Aperture Stop In the zoom lens, the position of the aperture stop is not particularly limited. However, the aperture stop here means the aperture stop that defines the diameter of the light beam of the zoom lens, that is, the aperture stop that defines the F-number of the zoom lens.

In the zoom lens, it is preferable to arrange the aperture diaphragm closer to the image side than the first lens group in order to reduce the size of the diaphragm unit, and it is more preferable to arrange it in the intermediate group in order to further reduce the size. .

(8) Lens Group Configuration Although the number of lens groups that make up the zoom lens is not particularly limited, for example, a first lens group having negative refractive power and a second lens group having positive refractive power. and a third lens group having positive refractive power, a lens group Ln consisting of a fourth lens group having negative refractive power, and a final lens group consisting of a fifth lens group having negative refractive power. A zoom lens composed of five groups, a first lens group having negative refractive power, a second lens group having positive refractive power, a third lens group having negative refractive power, and a fourth lens group having positive refractive power A six-group configuration consisting of a middle group having positive refractive power as a whole, a lens group Ln consisting of a fifth lens group having negative refractive power, and a final lens group consisting of a sixth lens group having negative refractive power. A variety of lens group configurations can be employed, such as a zoom lens. That is, in order from the object side, a first lens group having negative refractive power, an intermediate group having positive refractive power, a lens group Ln having negative refractive power, and a final lens group having negative refractive power. A specific lens group configuration of the zoom lens is not particularly limited as long as it has a configuration including

1-2. Operation (1) Operation during zooming In the zoom lens, the distance between adjacent lens groups changes during zooming from the wide-angle end to the telephoto end.

In the zoom lens, it is sufficient that the air gap between adjacent lens groups changes when zooming from the wide-angle end to the telephoto end, and the increase or decrease in the air gap between the lens groups is not particularly limited. Also, when changing the magnification, all the lens groups constituting the zoom lens may be moved in the optical axis direction, or some lens groups may be fixed in the optical axis direction and the remaining lens groups may be moved in the optical axis direction. The presence or absence of movement of each lens group and the direction of movement are not particularly limited.

(2) Operation during focusing When a focus group is provided in the zoom lens, the position, refractive power, movement direction, etc. of the focus group are not particularly limited. When focusing on a close object, it is preferable to move the lens unit Ln toward the image side for focusing. This is because the lens group Ln is arranged closer to the image side than the intermediate group, and the variation in the angle of incidence of light rays is small, so that the variation in the angle of view during focusing can be suppressed.

1-3. Conditional Expression It is preferable that the zoom lens of the present invention employs the configuration described above and satisfies either conditional expression (1) or conditional expression (2) described below.

1-3-1. Conditional expression (1)
0.05≦|f1|/|fpMax|≦0.80 (1)
however,
f1: focal length of the first lens group fpMax: focal length of the lens group LpMax

Conditional expression (1) above defines the ratio between the focal length of the first lens group and the focal length of the lens group LpMax having the strongest positive refractive power among the lens groups included in the intermediate group. is the formula. By satisfying conditional expression (1), the angle of view can be widened at the wide-angle end, and aberration fluctuations during zooming can be suppressed. That is, by satisfying conditional expression (1) above, it is possible to realize a zoom lens with a wide angle of view at the wide-angle end and high optical performance.

On the other hand, if the numerical value of conditional expression (1) is less than the lower limit, the power of the first lens group becomes too strong relative to the power of the intermediate group, making it difficult to correct coma and distortion. It is not preferable because it becomes difficult to realize a zoom lens with high optical performance. On the other hand, if the numerical value of conditional expression (1) exceeds the upper limit, the power of the first lens group becomes too weak relative to the power of the intermediate group, which is undesirable. That is, in order to achieve a wide angle of view at the wide-angle end, it becomes necessary to dispose a lens having a large lens diameter closest to the object side among the lenses constituting the first lens group, which makes it possible to reduce the size in the radial direction. Unfavorable because it becomes difficult.

To obtain these effects, the lower limit of conditional expression (1) is more preferably 0.10, even more preferably 0.15, and even more preferably 0.20. The upper limit of conditional expression (1) is more preferably 0.75, even more preferably 0.70, and even more preferably 0.65.

1-3-2. Conditional expression (2)
βpw≦−0.58 (2)
however,
βpw: Composite lateral magnification of middle group when focusing on infinity at wide-angle end

The above conditional expression (2) is an expression for defining the composite lateral magnification of the intermediate group when focusing on infinity at the wide-angle end. By satisfying conditional expression (2), the power of the first lens group can be increased, and the angle of view can be widened at the wide-angle end while the first lens group is made compact in the radial direction. Therefore, aberration fluctuations during zooming can be suppressed. That is, it is possible to realize a compact zoom lens with a wide angle of view at the wide-angle end and high optical performance.

On the other hand, if the numerical value of conditional expression (2) exceeds the upper limit, the power of the first lens group cannot be increased. It is necessary to dispose a lens having a large lens diameter closest to the object side of the lenses constituting the .

In order to obtain these effects, the upper limit of conditional expression (2) is more preferably -0.60, more preferably -0.62, even more preferably -0.64, -0.66 is even more preferred.

The zoom lens of the present invention preferably satisfies either conditional expression (1) or conditional expression (2) described above, and at least one or more of conditional expressions described below.

1-3-3. Conditional expression (3)
−1.50≦f1/fw≦−0.05 (3)
however,
f1: Focal length of the first lens group fw: Focal length of the zoom lens when focusing on infinity at the wide-angle end

The above conditional expression (3) is an expression for defining the focal length of the first lens group. By satisfying conditional expression (3), the angle of view can be widened at the wide-angle end, and aberration fluctuations during zooming can be suppressed. That is, it is possible to realize a zoom lens with a wide angle of view at the wide-angle end and high optical performance.

On the other hand, if the numerical value of conditional expression (3) is less than the lower limit, it is necessary to have the largest lens diameter on the object side among the lenses constituting the first lens group in order to achieve a wide angle of view at the wide-angle end. A lens must be arranged, which makes it difficult to reduce the size in the radial direction. On the other hand, if the numerical value of conditional expression (3) exceeds the upper limit, the power of the first lens group becomes too strong, making it difficult to correct coma and distortion, thereby realizing a zoom lens with high optical performance. becomes difficult.

In order to obtain these effects, the lower limit of conditional expression (3) is more preferably −1.45, more preferably −1.40, even more preferably −1.35, -1.30 is even more preferred, and -1.25 is even more preferred. The upper limit of conditional expression (3) is more preferably -0.10, more preferably -0.15, and even more preferably -0.20.

1-3-4. Conditional expression (4)
−4.0≦fn/fpMax≦−1.5 (4)
however,
fn: focal length of lens group Ln fpMax: focal length of lens group LpMax

The above conditional expression (4) is an expression for defining the ratio between the focal length of the lens group Ln and the focal length of the lens group LpMax. By satisfying conditional expression (4), it is possible to achieve a high degree of telephoto effect in the optical system (the optical system consisting of the intermediate group, the lens group Ln, and the final lens group) located closer to the image side than the first lens group. Shortening can be realized.

On the other hand, if the numerical value of conditional expression (4) is less than the lower limit, the power of the lens group Ln becomes too strong, making it difficult to correct distortion and coma, which is not preferable. Further, if the power of the lens group Ln becomes too strong, the height of the peripheral ray passing through the final lens group arranged closer to the image side than the lens group Ln becomes higher, and the last lens group closest to the image side. A lens with a large lens diameter needs to be arranged at the center of the lens, making it difficult to reduce the size in the radial direction, which is not preferable. On the other hand, if the numerical value of conditional expression (4) exceeds the upper limit, the total length of the optical system becomes long, which is not preferable because the size of the zoom lens cannot be reduced.

In order to obtain these effects, the lower limit of conditional expression (4) is more preferably −3.9, more preferably −3.8, even more preferably −3.7, -3.6 is even more preferred. The upper limit of conditional expression (4) is more preferably −1.6, even more preferably −1.7, and even more preferably −1.8.

1-3-5. Conditional expression (5)
0.05≦frt/ft≦1.50 (5)
however,
frt: Composite focal length from the middle group to the final lens group when focusing on infinity at the telephoto end ft: Focal length of the zoom lens when focusing on infinity at the telephoto end

The above conditional expression (5) is an expression for defining the synthetic focal length from the intermediate group to the final lens group when focusing on infinity at the telephoto end. By satisfying the conditional expression (5), it is possible to achieve both miniaturization and high optical performance of the zoom lens.

On the other hand, if the numerical value of conditional expression (5) is less than the lower limit, correction of distortion, coma, and spherical aberration becomes difficult, which is not preferable. On the other hand, if the numerical value of conditional expression (5) exceeds the upper limit, it becomes necessary to increase the diameter of the lens closest to the object side in the first lens group, which is not preferable because the size of the zoom lens cannot be reduced.

To obtain these effects, the lower limit of conditional expression (5) is more preferably 0.10, even more preferably 0.15, and even more preferably 0.20. The upper limit of conditional expression (5) is more preferably 1.45, even more preferably 1.40, and even more preferably 1.35.

1-3-6. Conditional expression (6)
1.00≦βn1≦5.00 (6)
however,
βn1: Lateral magnification of the lens group Ln when focusing on infinity at the wide-angle end

The above-mentioned conditional expression (6) is an expression for defining the lateral magnification of the lens group Ln when focusing on infinity at the wide-angle end. By satisfying the conditional expression (6), it is possible to improve the optical performance over the entire zoom range and shorten the overall optical length.

On the other hand, if the numerical value of conditional expression (6) is less than the lower limit, the amount of movement of the lens units Ln during zooming from the wide-angle end to the telephoto end becomes too large, resulting in an increase in the total length of the optical system. , the size of the zoom lens cannot be reduced, which is not preferable. On the other hand, if the numerical value of conditional expression (6) exceeds the upper limit, the lateral magnification of the lens group Ln becomes too high, which makes it difficult to correct distortion and curvature of field, which is undesirable.

To obtain these effects, the lower limit of conditional expression (6) is more preferably 1.10, even more preferably 1.20, and even more preferably 1.30. The upper limit of conditional expression (6) is more preferably 4.90, even more preferably 4.80, and even more preferably 4.70.

1-3-7. Conditional expression (7)
1.00≦βn12≦5.00 (7)
however,
βn12: Combined lateral magnification of the lens group Ln and the final lens group when focusing on infinity at the wide-angle end

The above conditional expression (7) is an expression for defining the combined lateral magnification of the lens group Ln and the final lens group when focusing on infinity at the wide-angle end. By satisfying the conditional expression (7), it is possible to improve the optical performance over the entire zoom range and shorten the overall optical length.

On the other hand, if the numerical value of conditional expression (7) is less than the lower limit, the amount of movement of the lens group Ln and the final lens group during zooming from the wide-angle end to the telephoto end becomes too large. becomes long, and the size of the zoom lens cannot be reduced, which is not preferable. On the other hand, if the numerical value of conditional expression (7) exceeds the upper limit, the combined lateral magnification of the lens group Ln and the final lens group becomes too high, making it difficult to correct distortion and curvature of field, which is undesirable.

To obtain these effects, the lower limit of conditional expression (7) is more preferably 1.10, even more preferably 1.20, and even more preferably 1.30. The upper limit of conditional expression (7) is more preferably 4.90, even more preferably 4.80, and even more preferably 4.70.

1-3-8. Conditional expression (8)
When focusing on a close object from infinity by moving the lens unit Ln in the optical axis direction, it is preferable to satisfy the following conditional expression.
0.60≦|{1−(βn1×βn1)}×(βn2×βn2)|≦15.0 (8)
however,
βn1: Lateral magnification of the lens group Ln when focusing on infinity at the wide-angle end βn2: Lateral magnification of the last lens group when focusing on infinity at the wide-angle end

The above-described conditional expression (8) is an expression for defining the absolute value of the focus sensitivity of the lens unit Ln that moves on the optical axis during focusing, that is, the amount of image plane movement when the lens unit Ln moves by a unit amount. is. By satisfying conditional expression (8), it is possible to shorten the amount of movement of the focus group (lens group Ln) when focusing from infinity to the closest distance (near object), realizing a zoom lens with a short overall optical length. can do.

On the other hand, if the numerical value of conditional expression (8) is less than the lower limit, the amount of movement of the lens unit Ln during focusing from an infinite object to a close object becomes large, making it difficult to reduce the overall optical length. I don't like it because On the other hand, if the numerical value of conditional expression (8) exceeds the upper limit, the amount of movement of the lens unit Ln for correcting the positional deviation of the focus position becomes too small, which is not preferable because high-precision control is required.

To obtain these effects, the lower limit of conditional expression (8) is more preferably 0.65, and even more preferably 0.70. The upper limit of conditional expression (8) is more preferably 14.0, even more preferably 13.0, and even more preferably 12.0.

1-3-9. Conditional expression (9)
1.00≦|CrG1r/fw| (9)
however,
CrG1r: Radius of curvature of the lens surface closest to the image side in the first lens group fw: Focal length of the zoom lens when focused on infinity at the wide-angle end

The above conditional expression (9) is an expression for defining the radius of curvature of the lens surface closest to the image side in the first lens group. By satisfying conditional expression (9), spherical aberration and curvature of field can be easily corrected, and miniaturization can be achieved while achieving high performance.

On the other hand, if the numerical value of conditional expression (9) is less than the lower limit, the curvature of field will be overcorrected, and it will be necessary to increase the diameter of the lens closest to the object side in the first lens group. It is not preferable because the size cannot be reduced.

In order to obtain these effects, the lower limit of conditional expression (9) is preferably 1.50, more preferably 2.00, even more preferably 2.50, and even more preferably 3.00. Preferably, 3.50 is even more preferable.

1-3-10. Conditional expression (10)
0.65≦(fw×tanω)/BFw≦2.30 (10)
however,
fw: focal length of the zoom lens when focused on infinity at the wide-angle end ω: half angle of view of the zoom lens when focused on infinity at the wide-angle end BFw: length of the zoom lens when focused on infinity at the wide-angle end Distance on the optical axis between the lens surface closest to the image and the image surface

The above conditional expression (10) is an expression for defining the ratio between the angle of view at the wide-angle end and the distance between the lens surface closest to the image side and the image plane of the zoom lens at the wide-angle end (back focus of the optical system). is. By satisfying the conditional expression (10), it is possible to improve the optical performance over the entire zoom range and shorten the overall optical length.

If the numerical value of conditional expression (10) is less than the lower limit, it is not preferable because it is necessary to increase the angle of incidence of off-axis rays on the image plane. That is, it becomes necessary to reduce the focal length of the final lens group, which makes it difficult to correct coma and distortion, which is not preferable. Alternatively, it is necessary to increase the lens diameter of the final lens group, which is not preferable because the size of the zoom lens cannot be reduced. If the numerical value of conditional expression (10) exceeds the upper limit, the total length of the optical system becomes long, which is not preferable because the size of the zoom lens cannot be reduced.

In order to obtain these effects, the lower limit of conditional expression (10) is more preferably 0.70, more preferably 0.75, even more preferably 0.80, and even more preferably 0.85. and even more preferably 0.90. In addition, the upper limit of conditional expression (10) is more preferably 2.20, more preferably 2.10, even more preferably 2.00, and even more preferably 1.90. Preferably, it is even more preferably 1.80.

1-3-11. Conditional expression (11)
The zoom lens of the present invention preferably has at least one lens LpMp having positive refractive power in the lens group LpMax and satisfies the following conditional expression.
45.0≦νdLpMp≦98.0 (11)
however,
νdLpMp: Abbe number at d-line of lens LpMp

The above conditional expression (11) is an expression for defining the Abbe number at the d-line of the lens LpMp included in the lens unit LpMax. By satisfying the conditional expression (11), axial chromatic aberration and spherical aberration can be easily corrected, and miniaturization can be achieved while achieving high performance.

If the numerical value of conditional expression (11) is less than the lower limit, correction of axial chromatic aberration becomes difficult, which is not preferable. If the numerical value of conditional expression (11) exceeds the upper limit, the lens becomes expensive, which is not preferable in terms of cost reduction.

To obtain these effects, the lower limit of conditional expression (11) is more preferably 50.0, even more preferably 55.0, and even more preferably 60.0. The upper limit of conditional expression (11) is more preferably 95.0, even more preferably 90.0, and even more preferably 85.0.

1-3-12. Conditional expression (12)
The zoom lens of the present invention preferably has at least one lens L1p having positive refractive power in the first lens group and satisfies the following conditional expression.
20.0≦νdL1p≦50.0 (12)
however,
νdL1p: Abbe number at the d-line of lens L1p

The above conditional expression (12) is an expression for defining the Abbe number at the d-line of the lens L1p having positive refractive power and included in the first lens group. In lens groups with negative refractive power, it is common to use high-dispersion glass for lenses with positive refractive power and low-dispersion glass for lenses with negative refractive power to correct lateral chromatic aberration. target. However, high-dispersion glass in which the numerical value of conditional expression (12) is less than the lower limit is expensive, and is not preferable in terms of cost reduction. If the numerical value of conditional expression (12) exceeds the upper limit, correction of chromatic aberration of magnification becomes difficult even if low-dispersion glass is used for the lens having negative refractive power, which is not preferable. That is, when the structure of the zoom lens satisfies the conditional expression (12), cost reduction can be achieved while ensuring good image plane properties.

To obtain these effects, the lower limit of conditional expression (12) is more preferably 22.0, even more preferably 24.0, and even more preferably 26.0. The upper limit of conditional expression (12) is more preferably 47.0, even more preferably 44.0, and even more preferably 41.0.

1-3-13. Conditional expression (13)
The zoom lens of the present invention preferably has at least one lens L1p having positive refractive power in the first lens group and satisfies the following conditional expression.
1.70≦NdL1p≦2.20 (13)
however,
NdL1p: Refractive index for d-line of lens L1p

The above conditional expression (13) is an expression for defining the refractive index for the d-line of the lens L1p having positive refractive power and included in the first lens group. In the lens group with negative refractive power, the Petzval sum is corrected by using high refractive index glass for the lens with positive refractive power and using low refractive index glass for the lens with negative refractive power. is common. Here, if the numerical value of the above conditional expression (13) is less than the lower limit, correction of the image plane property becomes difficult, which is not preferable. Further, high refractive index glass having a refractive index that exceeds the upper limit of the numerical value of conditional expression (13) is expensive, which is not preferable in terms of cost reduction. That is, by satisfying conditional expression (13), cost reduction can be achieved while ensuring good image plane properties.

To obtain these effects, the lower limit of conditional expression (13) is more preferably 1.75, even more preferably 1.80, and even more preferably 1.85. The upper limit of conditional expression (13) is more preferably 2.15, even more preferably 2.10, and even more preferably 2.05.

1-3-14. Conditional expression (14)
|BFt−BFw|/TLw≦0.30 (14)
however,
BFt: Distance on the optical axis between the lens surface of the zoom lens closest to the image side and the image plane when focusing on infinity at the telephoto end BFw: Distance closest to the image side of the zoom lens when focusing on infinity at the wide-angle end Distance on the optical axis between the lens surface and the image surface TLw: Optical total length of the zoom lens when focusing on infinity at the wide-angle end

The above conditional expression (14) is an expression for defining the amount of movement of the final lens group toward the object side when zooming from the wide-angle end to the telephoto end. By satisfying conditional expression (14), the refractive power of the final lens group is appropriate, and the amount of movement during zooming is within an appropriate range. Therefore, it is possible to shorten the total optical length at the telephoto end while ensuring a predetermined variable magnification.

On the other hand, if the numerical value of conditional expression (14) exceeds the upper limit, the amount of movement of the final lens group during zooming (toward the object side of the final lens group during zooming from the wide-angle end to the telephoto end) movement amount) increases. In this case, when the lens barrel has a nested structure in which the inner barrel is accommodated in the outer barrel, if the length of the barrel is designed according to the total optical length at the wide-angle end, the inner barrel is doubled and the outer barrel is It is not preferable because the structure of the lens barrel becomes complicated, such as the need to store it in a separate part, and the outer diameter of the lens barrel increases (the product becomes large).

In order to obtain these effects, the upper limit of conditional expression (14) is more preferably 0.27, more preferably 0.24, even more preferably 0.21, and even more preferably 0.18. is even more preferable.

2. Imaging Apparatus Next, an imaging apparatus according to the present invention will be described. An imaging device according to the present invention comprises the above-described zoom lens according to the present invention, and an image pickup device that converts an optical image formed by the zoom lens into an electrical signal on the image side of the zoom lens. Characterized by

Here, the imaging element or the like is not particularly limited, and a solid-state imaging element such as a CCD (Charge Coupled Device) sensor or a CMOS (Complementary Metal Oxide Semiconductor) sensor can also be used. The imaging device according to the present invention is suitable for imaging devices using these solid-state imaging devices, such as digital cameras and video cameras. Further, the imaging device may be a lens-fixed imaging device in which a lens is fixed to a housing, or may be a lens-exchangeable imaging device such as a single-lens reflex camera or a mirrorless single-lens camera. is of course.

The imaging apparatus includes an image processing unit that electrically processes captured image data acquired by the imaging device to change the shape of the captured image, and image correction data that is used to process the captured image data in the image processing unit. , and an image correction data holding section for holding an image correction program and the like. When the size of the zoom lens is reduced, distortion is likely to occur in the captured image shape formed on the imaging plane. In this case, the distortion correction data for correcting the distortion of the captured image shape is held in advance in the image correction data holding unit, and the distortion correction data held in the image correction data holding unit is used in the above-described image processing unit. It is preferable to correct the distortion of the captured image shape. With such an imaging device, the negative refractive power of the lens closest to the image side in the zoom lens can be increased, so the diameter of the lens closest to the image side of the zoom lens can be reduced. can be That is, according to the image pickup apparatus, it is possible to further reduce the size of the zoom lens, obtain an excellent captured image, and reduce the size of the entire image pickup apparatus.

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

(1) Optical Configuration of Zoom Lens FIG. 1 is a cross-sectional view showing the lens configuration of the zoom lens of Example 1 according to the present invention when focusing on infinity at the wide-angle end and the telephoto end. Note that "IP" shown in FIG. 1 is an imaging plane (image plane), and specifically represents an imaging plane of a solid-state imaging device such as a CCD sensor or a CMOS sensor, or a film plane of a silver halide film. Further, a parallel flat plate having no substantial refractive power, such as a cover glass "CG", is provided on the object side of the imaging plane IP. Since these points are the same in each lens cross-sectional view shown in other examples, description thereof will be omitted below.

The zoom lens of Example 1 comprises, in order from the object side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, and a third lens group G3 having positive refractive power. , a fourth lens group G4 having negative refractive power, and a fifth lens group G5 having negative refractive power. The aperture stop S is arranged adjacent to the object side of the third lens group G3. In this embodiment, the intermediate group is composed of the second lens group G2 and the third lens group G3, and the lens group Ln corresponds to the fourth lens group G4.

The configuration of each lens group will be described below. The first lens group G1 comprises, in order from the object side, an object-side convex negative meniscus lens L101, an object-side convex negative meniscus lens L102, a biconcave lens L103, and an object-side convex positive meniscus lens L104. Configured. Note that each lens surface on the image side of the lens L102 and the lens L104 is
It is a so-called compound aspherical surface in which an aspherical film is attached to the glass surface. Further, the lens L104 corresponds to the lens "L1p" according to the present invention, and the image-side lens surface of the lens L104 corresponds to the lens surface "CrG1r" according to the present invention.

The second lens group G2 is composed of a cemented lens in which an object-side convex negative meniscus lens L105 and a biconvex lens L106 are cemented together.

The third lens group G3 includes, in order from the object side, an aperture stop S, a cemented lens in which a biconvex lens L107 and a biconcave lens L108 are cemented together, a negative meniscus lens L109 convex on the object side, and a positive meniscus convex on the object side. It is composed of a cemented lens to which the lens L110 is cemented and a biconvex lens L111. Both surfaces of the lens L111 are aspherical. The third lens group G3 corresponds to the lens group "LpMax" according to the present invention, and the lens L111 corresponds to the lens "LpMp" according to the present invention.

The fourth lens group G4 is composed of an object-side convex negative meniscus lens L112.

The fifth lens group G5 is composed of, in order from the object side, a biconvex lens L113 and a biconcave lens L114. Both surfaces of the lens L113 are aspherical.

In the zoom lens of Example 1, during zooming from the wide-angle end to the telephoto end, the first lens group G1 moves toward the image side and then toward the object side with respect to the image plane, and the second lens group G2 moves toward the object 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.

In the zoom lens, the fourth lens group G4 moves from the object side to the image side along the optical axis when focusing from an infinite object to a close object.

The zoom lens can correct camera shake by using the lens L111 included in the third lens group G3 as an anti-vibration group and moving the anti-vibration group in a direction perpendicular to the optical axis.

(2) Numerical Examples Next, numerical examples to which specific numerical values of the zoom lens are applied will be described. In the tables below, all units of length are "mm", and all units of angle of view are "°". Table 1 shows surface data of the zoom lens. In Table 1, "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 distance between the lens surfaces on the optical axis, and "Nd" is the d-line (wavelength λ=587.6 nm), and “ABV” indicates the Abbe number for the d-line. "ASP" displayed in the column next to the surface number indicates that the lens surface is aspherical, and "S" indicates the aperture stop. Furthermore, "D(10)", "D(13)", etc. are indicated in the column of the distance between the lens surfaces on the optical axis because the distance between the lens surfaces on the optical axis is changed during zooming or focusing. It is meant to be a variable interval that changes. Also, the radius of curvature "∞ (infinity)" means a plane. The 29th and 30th surfaces in Table 1 are the surface data of the cover glass (CG).

Table 2 is a specification table of the zoom lens. In the specification table, the focal length "f", F number "Fno.", half angle of view "ω", image height "Y", total optical length "TL", variable Fig. 3 shows the variable spacing on the optical axis of the zoom lens at magnification and in focus; However, Table 2 shows respective values at the wide-angle end, the intermediate focal length state, and the telephoto end in order from the left.

Table 3 shows the lens surface number of each lens group constituting the zoom lens and the focal length of each lens group.

Table 4 shows the aspheric coefficients of each aspheric surface. The aspheric coefficient is a value when each aspheric shape is defined by the following formula.

X(Y)=CY ² /[1+{1-(1+K).C ² Y ² } ^1/2 ]+A ^4.Y ₄ +A _6.Y ⁶ +A _8.Y ⁸ +A ^10.Y ₁₀

However, in Table 4, "Ea" indicates "×10 ^-a ". In the above formula, "X" is the amount of displacement from the reference plane in the direction of the optical axis, "C" is the curvature at the surface vertex, "Y" is the height from the optical axis in the direction perpendicular to the optical axis, Let “K” be the conic coefficient and “A _n ” be the n-th order aspheric coefficient.

Table 21 shows the values of conditional expressions (1) to (14) and the values used in the calculations of conditional expressions (1) to (14).

Since the matters related to the tables described above are the same for each table shown in other embodiments, description thereof will be omitted below.

[Table 1]
Face number RD Nd ABV
Object plane ∞ ∞
1 51.4464 2.0000 1.89085 36.41
2 20.0000 5.7196
3 47.2371 1.5000 1.72916 54.67
4 23.5686 0.2000 1.53610 41.21
5 ASP 19.7552 6.4678
6 -206.9428 1.5000 1.72916 54.67
7 23.0858 1.9587
8 26.8465 4.0557 1.85764 22.33
9 121.5647 0.2000 1.53610 41.21
10 ASP 105.4586 D(10)
11 29.2922 1.0000 1.92108 22.20
12 16.8467 4.9210 1.64109 33.36
13-216.9562D(13)
14S ∞ 2.0000
15 59.2608 4.0417 1.54697 68.55
16 -17.6603 1.0000 1.71375 55.52
17 69.4793 0.1016
18 20.2723 1.0000 1.80899 42.96
19 13.2943 3.8193 1.51650 70.18
20 51.7432 4.1444
21 ASP 34.3114 6.1621 1.48556 80.01
22 ASP -18.9780 D(22)
23 32.3936 1.0000 1.68811 57.08
24 19.0779 D(24)
25 ASP 23.9793 8.9358 1.49700 81.61
26 ASPs -18.9694 0.1000
27 -34.6849 1.2000 1.73979 49.98
28 22.9171 D(28)
29 ∞ 2.5000 1.51680 64.20
30 ∞ 1.0000

[Table 2]
Wide-angle end Intermediate focal length Telephoto end
f 15.45 21.84 29.11
2.88 3.60 4.12
ω 56.70 45.52 36.98
Y 19.97 20.64 21.23
TL 120.00 117.10 119.65
D(10) 10.1655 5.7974 3.1563
D(13) 16.3597 7.5636 2.1111
D(22) 6.1150 3.5611 2.4945
D(24) 3.4600 6.0138 7.0805
D(28) 17.3722 27.6314 38.2786

[Table 3]
Group surface number Focal length
G1 1-10 -16.25
G2 11-13 55.96
G3 14-22 28.71
G4 23-24 -69.58
G5 25-28 -400.00

[Table 4]
Surface number K A4 A6 A8 A10
5 0.00000E+00 -2.23462E-05 -4.09357E-08 -8.91357E-11 0.00000E+00
10 0.00000E+00 4.48229E-06 6.87070E-09 -5.54223E-11 0.00000E+00
21 0.00000E+00 -2.17920E-05 -5.42256E-09 1.86040E-10 0.00000E+00
22 0.00000E+00 3.69697E-05 -7.19257E-08 2.55987E-10 0.00000E+00
25 0.00000E+00 1.97160E-05 -5.15489E-08 3.03503E-10 -5.84468E-13
26 0.00000E+00 5.13298E-05 -3.64861E-08 2.43868E-10 -2.67122E-13

2 to 4 show longitudinal aberration diagrams of the zoom lens of Example 1 at the wide-angle end, the intermediate focal length state, and the telephoto end when focusing on infinity. The longitudinal aberration diagrams shown in each figure are spherical aberration (mm), astigmatism (mm), and distortion (%) in order from the left side of the drawing. In the graph showing spherical aberration, the vertical axis is the ratio to the maximum F value, and the horizontal axis is defocus. , the dotted line indicates the spherical aberration at the C line (wavelength λ=656.3 nm). In the diagram showing astigmatism, the vertical axis represents the half angle of view and the horizontal axis represents defocus. . In the diagrams representing distortion, the vertical axis represents the half angle of view and the horizontal axis represents %. Matters relating to these longitudinal aberration diagrams are the same for the longitudinal aberration diagrams shown in other examples, and therefore description thereof will be omitted below.

(1) Optical Configuration of Zoom Lens FIG. 5 is a cross-sectional view showing the lens configuration of the zoom lens of Example 2 according to the present invention when focusing on infinity at the wide-angle end and the telephoto end. The zoom lens includes, in order from the object side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having positive refractive power, and a negative lens group G3. and a fifth lens group G5 having negative refractive power. The aperture stop S is arranged adjacent to the object side of the third lens group G3. In this embodiment, the intermediate group is composed of the second lens group G2 and the third lens group G3, and the lens group Ln corresponds to the fourth lens group G4.

The configuration of each lens group will be described below. The first lens group G1 includes, in order from the object side, an object-side convex negative meniscus lens L201, an object-side convex negative meniscus lens L202, an object-side convex negative meniscus lens L203, and an object-side convex meniscus lens L203. and a positive meniscus lens L204. Note that each lens surface on the image side of the lens L202 and the lens L204 is a compound aspherical surface. Further, the lens L204 corresponds to the lens "L1p" according to the present invention, and the image-side lens surface of the lens L204 corresponds to the lens surface "CrG1r" according to the present invention.

The second lens group G2 is composed of a cemented lens in which an object-side convex negative meniscus lens L205 and a biconvex lens L206 are cemented together.

The third lens group G3 includes, in order from the object side, an aperture diaphragm S, a cemented lens in which a biconvex lens L207 and a biconcave lens L208 are cemented together, a negative meniscus lens L209 convex on the object side, and a positive meniscus convex on the object side. It is composed of a cemented lens to which a lens L210 is cemented and a biconvex lens L211. Both surfaces of the lens L211 are aspherical. The third lens group G3 corresponds to the lens group "LpMax" according to the present invention, and the lens L211 corresponds to the lens "LpMp" according to the present invention.

The fourth lens group G4 is composed of an object side convex negative meniscus lens L212.

The fifth lens group G5 is composed of, in order from the object side, a biconvex lens L213 and a biconcave lens L214. Both surfaces of the lens L213 are aspherical.

In the zoom lens of Example 2, during zooming from the wide-angle end to the telephoto end, the first lens group G1 moves toward the image side and then toward the object side with respect to the image plane, and 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.

In the zoom lens, the fourth lens group G4 moves from the object side to the image side along the optical axis when focusing from an infinity object to a close object.

The zoom lens can correct camera shake by using the lens L211 included in the third lens group G3 as an anti-vibration group and moving the anti-vibration group in a direction perpendicular to the optical axis.

(2) Numerical Examples Next, numerical examples to which specific numerical values of the zoom lens are applied will be described. Table 5 shows surface data of the zoom lens. Table 6 is a specification table of the zoom lens. Table 7 shows the lens surface number of each lens group constituting the zoom lens and the focal length of each lens group. Table 8 shows the aspheric coefficients of each aspheric surface. 6 to 8 show longitudinal aberration diagrams of the zoom lens at the wide-angle end, the intermediate focal length state, and the telephoto end when focusing on infinity. Table 21 shows the values of conditional expressions (1) to (14) and the values used in the calculations of conditional expressions (1) to (14).

[Table 5]
Face number RD Nd ABV
Object plane ∞ ∞
1 49.9199 2.0000 1.78436 45.77
2 20.0000 4.8247
3 36.9299 1.5000 1.72916 54.67
4 17.7030 0.2000 1.53610 41.21
5 ASP 17.1820 6.4517
6 100.7210 1.5000 1.72916 54.67
7 20.4815 2.6125
8 28.3348 4.6408 1.71736 29.50
9 115.4139 0.2000 1.53610 41.21
10 ASP 52.1147 D(10)
11 33.8489 1.0000 1.91970 23.36
12 14.8237 6.1699 1.72405 27.25
13-210.0707D(13)
14S ∞ 2.0000
15 24.3756 4.8951 1.53845 72.92
16 -28.4241 1.0000 1.70018 56.32
17 55.9270 2.7897
18 25.6060 1.0000 1.77131 47.50
19 13.9069 3.6869 1.49700 81.61
20 54.8489 3.2852
21 ASP 26.7652 5.8021 1.49710 81.56
22 ASP -23.9208 D(22)
23 34.3910 1.0000 1.69680 55.46
24 17.8455D(24)
25 ASP 24.0464 8.1846 1.49710 81.56
26 ASPs -19.4330 0.1000
27 -34.7778 1.2000 1.72604 54.84
28 23.4576 D(28)
29 ∞ 2.5000 1.51680 64.20
30 ∞ 1.0000

[Table 6]
Wide-angle end Intermediate focal length Telephoto end
f 15.46 21.85 29.10
2.89 3.61 4.12
ω 56.72 45.30 36.73
Y 19.97 20.64 21.23
TL 120.62 117.02 118.06
D(10) 4.2008 2.8886 2.0000
D(13) 21.2547 9.7141 2.1000
D(22) 5.0787 3.1436 2.4987
D(24) 3.4065 5.3416 5.9865
D(28) 17.1402 26.3913 35.9284

[Table 7]
Group surface number Focal length
G1 1-10 -14.84
G2 11-13 57.53
G3 14-22 26.30
G4 23-24 -54.59
G5 25-28-541.46

[Table 8]
Surface number K A4 A6 A8 A10
5 0.00000E+00 -7.13353E-06 -2.73137E-08 -1.73885E-11 0.00000E+00
10 0.00000E+00 -2.16483E-05 -3.23519E-08 -1.69294E-10 0.00000E+00
21 0.00000E+00 -1.84352E-05 2.43101E-08 8.28668E-11 0.00000E+00
22 0.00000E+00 3.13539E-05 -5.21245E-08 1.08634E-10 0.00000E+00
25 0.00000E+00 1.44636E-05 -3.13467E-08 3.20638E-10 -9.57521E-13
26 0.00000E+00 4.11894E-05 -1.81690E-08 2.54212E-10 -6.03157E-13

(1) Optical Configuration of Zoom Lens FIG. 9 is a cross-sectional view showing the lens configuration of the zoom lens of Example 3 according to the present invention at the wide-angle end and the telephoto end when focusing on infinity. The zoom lens includes, in order from the object side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative refractive power, and a negative refractive power. and a fourth lens group G4 having a refractive power of . An aperture stop S is arranged in the second lens group G2. In this embodiment, the intermediate group corresponds to the second lens group G2, and the lens group Ln corresponds to the third lens group G3.

The configuration of each lens group will be described below. The first lens group G1 is composed of, in order from the object side, an object-side convex negative meniscus lens L301, an object-side convex negative meniscus lens L302, a biconcave lens L303, and a biconvex lens L304. Note that each lens surface on the image side of the lens L302 and the lens L304 is a compound aspherical surface. Further, the lens L304 corresponds to the lens "L1p" according to the present invention, and the image-side lens surface of the lens L304 corresponds to the lens surface "CrG1r" according to the present invention.

The second lens group G2 includes, in order from the object side, a cemented lens obtained by cementing an object-side convex negative meniscus lens L305 and a biconvex lens L306, an aperture diaphragm S, a biconcave lens L307, and a biconvex lens L308. a cemented lens, a positive meniscus lens L309 convex on the object side, and a biconvex lens L310. Both surfaces of the lens L310 are aspherical. Further, the second lens group G2 corresponds to the lens group "LpMax" according to the present invention, and the lens L310 corresponds to the lens "LpMp" according to the present invention.

The third lens group G3 is composed of a negative meniscus lens L311 having a concave shape on the object side.

The fourth lens group G4 is composed of, in order from the object side, a biconvex lens L312 and a biconcave lens L313. Both surfaces of lens L312 are aspherical.

In the zoom lens of Example 3, during zooming from the wide-angle end to the telephoto end, the first lens group G1 moves toward the image side and then toward the object side with respect to the image plane, and the second lens group G2 moves toward the object side. , the third lens group G3 moves toward the object side, and the fourth lens group G4 moves toward the object side.

In the zoom lens, the third lens group G3 moves from the object side to the image side along the optical axis when focusing from an infinity object to a close object.

The zoom lens can correct camera shake by using the lens L310 included in the second lens group G2 as an anti-vibration group and moving the anti-vibration group in a direction perpendicular to the optical axis.

(2) Numerical Examples Next, numerical examples to which specific numerical values of the zoom lens are applied will be described. Table 9 shows surface data of the zoom lens. Table 10 is a specification table of the zoom lens. Table 11 shows the lens surface number of each lens group constituting the zoom lens and the focal length of each lens group. Table 12 shows the aspheric coefficients of each aspheric surface. 10 to 12 show longitudinal aberration diagrams of the zoom lens at the wide-angle end, the intermediate focal length state, and the telephoto end when focusing on infinity. Table 21 shows the values of conditional expressions (1) to (14) and the values used in the calculations of conditional expressions (1) to (14).

[Table 9]
Face number RD Nd ABV
Object plane ∞ ∞
1 45.9665 2.0000 1.91082 35.25
2 20.0000 4.6653
3 35.8656 1.5000 1.72916 54.67
4 19.1538 0.2000 1.53610 41.21
5 ASP 16.9422 7.5065
6 -78.2089 1.5000 1.72916 54.67
7 25.2371 2.0427
8 37.1407 4.9633 1.71736 29.50
9 -62.4250 0.2000 1.53610 41.21
10 ASP -94.7173 D(10)
11 20.0044 1.0000 1.91082 35.25
12 15.5086 4.4513 1.68046 33.39
13 -312.6741 2.1000
14S ∞ 2.5110
15 -63.1697 1.0000 1.91082 35.25
16 11.7699 4.3762 1.63416 61.14
17 629.8056 0.1000
18 22.9325 2.6332 1.49700 81.61
19 78.5401 4.6758
20 ASP 36.8447 4.2746 1.49710 81.56
21 ASP -22.3539 D(21)
22 -65.7587 1.0000 1.72916 54.67
23-672.0766 D(23)
24 ASP 48.6211 5.2314 1.49710 81.56
25 ASP -18.8806 0.1182
26 -44.4585 1.2000 1.72916 54.67
27 30.8496 D(27)
28 ∞ 2.5000 1.51680 64.20
29 ∞ 1.0000

[Table 10]
Wide-angle end Intermediate focal length Telephoto end
f 15.45 21.85 29.11
2.88 3.61 4.12
ω 56.68 43.76 34.79
Y 19.97 20.64 21.23
TL 120.00 115.76 115.50
D(10) 22.4143 10.0680 2.0000
D(21) 3.0925 7.4275 14.3355
D(23) 8.9418 8.9357 6.0656
D(27) 22.8019 26.5746 30.3516

[Table 11]
Group surface number Focal length
G1 1-10 -17.97
G2 11-21 27.92
G4 22-23 -100.04
G5 24-27 -400.00

[Table 12]
Surface number K A4 A6 A8 A10
5 0.00000E+00 -2.38163E-05 -4.78409E-08 -1.47334E-10 0.00000E+00
10 0.00000E+00 -6.06540E-06 6.24989E-10 -1.49920E-10 0.00000E+00
20 0.00000E+00 -3.54582E-05 -1.04141E-07 -7.27066E-11 0.00000E+00
21 0.00000E+00 -5.56397E-06 -1.05803E-07 -4.01537E-10 0.00000E+00
24 0.00000E+00 -3.56136E-05 1.23145E-07 -2.04005E-09 6.67569E-12
25 0.00000E+00 3.07376E-05 1.28930E-07 -1.98340E-09 6.50202E-12

(1) Optical Configuration of Zoom Lens FIG. 13 is a cross-sectional view showing the lens configuration of the zoom lens of Example 4 according to the present invention at the wide-angle end and the telephoto end when focusing on infinity. The zoom lens includes, in order from the object side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having positive refractive power, and a positive lens group G3. a fourth lens group G4 having a refractive power of , a fifth lens group G5 having a negative refractive power, and a sixth lens group G6 having a negative refractive power. The aperture stop S is arranged adjacent to the object side of the third lens group G3. In this embodiment, the intermediate group is composed of the second lens group G2, the third lens group G3 and the fourth lens group G4, and the lens group Ln corresponds to the fifth lens group G5.

The configuration of each lens group will be described below. The first lens group G1 comprises, in order from the object side, an object-side convex negative meniscus lens L401, an object-side convex negative meniscus lens L402, a biconcave lens L403, and an object-side convex positive meniscus lens L404. It is configured. Note that each lens surface on the image side of the lens L402 and the lens L404 is a compound aspherical surface. Further, the lens L404 corresponds to the lens "L1p" according to the present invention, and the image-side lens surface of the lens L404 corresponds to the lens surface "CrG1r" according to the present invention.

The second lens group G2 is composed of a cemented lens in which an object-side convex negative meniscus lens L405 and a biconvex lens L406 are cemented together.

The third lens group G3 includes, in order from the object side, an aperture diaphragm S, a cemented lens in which a biconvex lens L407 and a biconcave lens L408 are cemented together, a negative meniscus lens L409 convex on the object side, and a positive meniscus convex on the object side. It is composed of a cemented lens to which the lens L410 is cemented.

The fourth lens group G4 is composed of a biconvex lens L411. Both surfaces of the lens L411 are aspherical. The fourth lens group G4 corresponds to the lens group "LpMax" according to the present invention, and the lens L411 corresponds to the lens "LpMp" according to the present invention.

The fifth lens group G5 is composed of an object-side convex negative meniscus lens L412.

The sixth lens group G6 is composed of, in order from the object side, a biconvex lens L413 and a biconcave lens L414. Both surfaces of the lens L413 are aspherical.

In the zoom lens of Example 4, during zooming from the wide-angle end to the telephoto end, the first lens group G1 does not move and is fixed with respect to the image plane, the second lens group G2 moves toward the object side, and the second lens group G2 moves toward the object 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.

In the zoom lens, the fifth lens group G5 moves from the object side to the image side along the optical axis when focusing from an infinite object to a close object.

In this zoom lens, camera shake correction can be performed by using L411, which constitutes the fourth lens group G4, as an anti-vibration group and moving the anti-vibration group in a direction perpendicular to the optical axis.

(2) Numerical Examples Next, numerical examples to which specific numerical values of the zoom lens are applied will be described. Table 13 shows surface data of the zoom lens. Table 14 is a specification table of the zoom lens. Table 15 shows the lens surface number of each lens group constituting the zoom lens and the focal length of each lens group. Table 16 shows the aspheric coefficients of each aspheric surface. 14 to 16 show longitudinal aberration diagrams of the zoom lens at the wide-angle end, the intermediate focal length state, and the telephoto end when focusing on infinity. Table 21 shows the values of conditional expressions (1) to (14) and the values used in the calculations of conditional expressions (1) to (14).

[Table 13]
Face number RD Nd ABV
Object plane ∞ ∞
1 42.8582 2.0000 1.91082 35.25
2 20.0000 5.9132
3 57.1247 1.5000 1.73647 53.21
4 24.1922 0.2000 1.53610 41.21
5 ASP 20.5048 6.9517
6 -106.4452 1.5000 1.73014 54.47
7 23.2844 1.9588
8 25.9803 3.7932 1.85056 24.21
9 134.1277 0.2000 1.53610 41.21
10 ASP 123.9146 D(10)
11 27.7803 1.0000 1.91733 25.65
12 16.0429 4.1181 1.64065 33.41
13-950.9894D(13)
14S ∞ 2.8785
15 43.3018 4.0046 1.54824 71.30
16 -20.4613 1.0000 1.71210 53.95
17 42.4758 0.2273
18 23.8726 1.0000 1.80697 38.92
19 15.7558 3.8401 1.51721 76.95
20 355.5760 D(20)
21 ASP 27.4262 7.0734 1.48614 82.92
22 ASP -21.2352 D(22)
23 38.1860 1.0000 1.68905 57.02
24 18.4614 D(24)
25 ASP 25.2455 9.4359 1.50250 76.18
26 ASP -17.1401 0.1150
27 -27.1371 1.2000 1.72791 54.74
28 25.1493 D(28)
29 ∞ 2.5000 1.51680 64.20
30 ∞ 1.0000

[Table 14]
Wide-angle end Intermediate focal length Telephoto end
f 15.45 21.85 29.10
2.88 3.61 4.14
ω 56.69 45.61 36.70
Y 19.97 20.64 21.23
TL 120.00 120.00 120.00
D(10) 9.2631 5.9048 2.3457
D(13) 15.3884 8.8201 4.7874
D(20) 5.8497 4.3952 3.1279
D(22) 4.9839 2.1108 2.7002
D(24) 3.0300 7.0471 5.5293
D(28) 17.0751 27.3122 37.0998

[Table 15]
Group surface number Focal length
G1 1-10 -16.41
G2 11-13 59.86
G3 14-20 401.05
G4 21-22 25.85
G5 23-24 -52.97
G6 25-28 -400.00

[Table 16]
Surface number K A4 A6 A8 A10
5 0.00000E+00 -2.15513E-05 -3.54019E-08 -1.03182E-10 0.00000E+00
10 0.00000E+00 8.64701E-06 6.06914E-09 -3.21414E-12 0.00000E+00
21 0.00000E+00 -1.79955E-05 5.40156E-09 1.53060E-10 0.00000E+00
22 0.00000E+00 4.21377E-05 -8.37172E-08 4.00374E-10 0.00000E+00
25 0.00000E+00 1.97469E-05 -6.09841E-08 3.24007E-10 -1.67902E-13
26 0.00000E+00 5.31544E-05 -1.54076E-08 2.14204E-10 6.55586E-13

(1) Optical Configuration of Zoom Lens FIG. 17 is a cross-sectional view showing the lens configuration of the zoom lens of Example 5 according to the present invention at the wide-angle end and the telephoto end when focusing on infinity. The zoom lens includes, in order from the object side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative refractive power, and a positive lens group G3. a fourth lens group G4 having a refractive power of , a fifth lens group G5 having a negative refractive power, and a sixth lens group G6 having a negative refractive power. The aperture stop S is arranged adjacent to the object side of the third lens group G3. In this embodiment, the intermediate group is composed of the second lens group G2, the third lens group G3 and the fourth lens group G4, and the lens group Ln corresponds to the fifth lens group G5.

The configuration of each lens group will be described below. The first lens group G1 is composed of, in order from the object side, an object-side convex negative meniscus lens L501, an object-side convex negative meniscus lens L502, a biconcave lens L503, and a biconvex lens L504. Note that each lens surface on the image side of the lens L502 and the lens L504 is a compound aspherical surface. Further, the lens L504 corresponds to the lens "L1p" according to the present invention, and the image-side lens surface of the lens L504 corresponds to the lens surface "CrG1r" according to the present invention.

The second lens group G2 is composed of a cemented lens in which an object-side convex negative meniscus lens L505 and a biconvex lens L506 are cemented together.

The third lens group G3 is composed of, in order from the object side, an aperture diaphragm S, an object side concave negative meniscus lens L507, and a cemented lens in which a biconvex lens L508 and a biconcave lens L509 are cemented together.

The fourth lens group G4 is composed of, in order from the object side, a cemented lens in which an object-side convex negative meniscus lens L510 and an object-side convex positive meniscus lens L511 are cemented together, and a biconvex lens L512. Both surfaces of the lens L512 are aspherical. The fourth lens group G4 corresponds to the lens group "LpMax" according to the present invention, and the lens L512 corresponds to the lens "LpMp" according to the present invention.

The fifth lens group G5 is composed of an object-side convex negative meniscus lens L513.

The sixth lens group G6 is composed of, in order from the object side, a biconvex lens L514 and a biconcave lens L515. Both surfaces of lens L515 are aspherical.

In the zoom lens of Example 5, when zooming from the wide-angle end to the telephoto end, the first lens group G1 moves toward the image side and then toward the object side with respect to the image plane, and the second lens group G2 moves toward the object 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. do.

In the zoom lens, the fifth lens group G5 moves from the object side to the image side along the optical axis when focusing from an infinite object to a close object.

The zoom lens can correct camera shake by using the lens L512 included in the fourth lens group G4 as an anti-vibration group and moving the anti-vibration group in a direction perpendicular to the optical axis.

(2) Numerical Examples Next, numerical examples to which specific numerical values of the zoom lens are applied will be described. Table 17 shows surface data of the zoom lens. Table 18 is a specification table of the zoom lens. Table 19 shows the lens surface number of each lens group constituting the zoom lens and the focal length of each lens group. Table 20 shows the aspheric coefficients of each aspheric surface. 18 to 20 show longitudinal aberration diagrams of the zoom lens of Example 5 at the wide-angle end, the intermediate focal length state, and the telephoto end when focusing on infinity. Table 21 shows the values of conditional expressions (1) to (14) and the values used in the calculations of conditional expressions (1) to (14).

[Table 17]
Face number RD Nd ABV
Object plane ∞ ∞
1 64.4935 2.0000 1.80420 46.50
2 20.0000 5.8149
3 44.3380 1.5000 1.72916 54.67
4 21.1456 0.2000 1.53610 41.21
5 ASP 19.2295 7.5156
6 -150.7078 1.5000 1.72916 54.67
7 30.8746 2.0751
8 39.1591 4.7734 1.85883 30.00
9 -122.1827 0.2000 1.53610 41.21
10 ASP -337.0680 D(10)
11 25.7483 1.0000 1.91082 35.25
12 16.7808 3.8598 1.63680 49.15
13-108.4616D(13)
14S ∞ 2.7762
15 -36.6701 1.0000 1.82332 36.47
16 -663.6925 0.1000
17 24.1845 3.9673 1.54571 51.63
18 -33.7101 1.0000 1.72916 54.67
19 119.1041 D(19)
20 29.2776 1.0000 1.83338 40.48
21 13.7692 4.4721 1.49700 81.61
22 158.7714 2.5000
23 ASPs 30.8545 5.1765 1.49710 81.56
24 ASP -33.1652 D(24)
25 29.6714 1.0000 1.73357 53.78
26 20.5408 D(26)
27 21.5900 8.4030 1.53350 56.48
28 -29.7187 0.1000
29 ASP -57.0454 1.2000 1.76029 49.12
30 ASP 20.4524 D(30)
31 ∞ 2.5000 1.51680 64.20
32 ∞ 1.0000

[Table 18]
Wide-angle end Intermediate focal length Telephoto end
f 15.45 21.85 29.10
2.88 3.60 4.12
ω 56.68 44.98 36.07
Y 19.97 20.64 21.23
TL 120.00 116.50 117.59
D(10) 20.3946 9.6191 2.0000
D(13) 4.3222 5.1184 5.3378
D(19) 5.4505 3.2882 2.5000
D(24) 2.0059 2.0030 4.6652
D(26) 3.4503 4.3535 6.1135
D(30) 17.7429 25.4839 30.3398

[Table 19]
Group surface number Focal length
G1 1-10 -20.57
G2 11-13 40.26
G3 14-19 -100.00
G4 20-24 32.69
G5 25-26-95.42
G6 27-30 -400.00

[Table 20]
Surface number K A4 A6 A8 A10
5 0.00000E+00 -1.33896E-05 -4.03264E-08 -4.74820E-12 0.00000E+00
10 0.00000E+00 -7.18688E-06 -4.32457E-09 -4.62078E-11 0.00000E+00
23 0.00000E+00 -1.87086E-05 4.43421E-08 1.89540E-10 0.00000E+00
24 0.00000E+00 9.14539E-06 9.72993E-09 4.52486E-11 0.00000E+00
29 0.00000E+00 -1.25529E-05 3.09804E-08 -3.76634E-10 0.00000E+00
30 0.00000E+00 3.30936E-06 4.84433E-08 -5.50774E-10 0.00000E+00

[Table 21]
Example 1 Example 2 Example 3 Example 4 Example 5
Conditional expression (1) |f1| / |fpMax| 0.57 0.56 0.64 0.63 0.63
Conditional expression (2) βpw -0.63 -0.70 -0.61 -0.62 -0.61
Conditional expression (3) f1/fw -1.23 -0.96 -1.16 -1.06 -1.33
Conditional expression (4) fn/fpMax -2.70 -2.08 -3.58 -2.05 -2.92
Conditional expression (5) frt / ft 1.02 0.96 1.03 0.95 0.98
Conditional expression (6) βn1 1.39 1.65 1.41 1.69 1.38
Conditional expression (7) βn12 1.29 1.49 1.42 1.52 1.24
Conditional expression (8) |{1-(βn1×βn1)}×(βn2×βn2)|
0.80 1.40 1.00 1.50 0.73
Conditional expression (9) | CrG1r / fw | 1981.08 3.37 6.13 8.02 21.82
Conditional expression (10) (fw×tanω) / BFw 1.19 1.19 0.92 1.19 1.15
Conditional expression (11) νdLpMp 80.01 81.56 81.56 82.92 81.56
Conditional expression (12) νdL1p 22.33 29.50 29.50 24.21 30.00
Conditional expression (13) NdL1p 1.86 1.72 1.72 1.85 1.86
Conditional expression (14) |BFt - BFw| / TLw 0.16 0.16 0.06 0.17 0.10
frt 29.55 27.94 30.01 27.54 28.62
BFw 19.80 19.80 25.46 19.74 20.40
BFt 39.65 38.59 33.01 39.76 33.00

According to the present invention, it is possible to provide a compact zoom lens and an imaging device with high optical performance.

G1 First lens group G2 Second lens group G3 Third lens group G4 Fourth lens group G5 Fifth lens group G6 Sixth lens group CG Cover glass IP Imaging plane (image plane)
S aperture diaphragm W wide-angle end T telephoto end FNo. F number ω Half angle of view

Claims (15)

In order from the object side, a first lens group having negative refractive power, an intermediate group consisting of one or more lens groups and having positive refractive power as a whole, a lens group Ln having negative refractive power, and a negative and a final lens group having refractive power,
The intermediate group includes a lens group LpMax,
The lens group LpMax has the strongest positive refractive power among the lens groups included in the intermediate group,
A zoom lens that performs zooming or focusing by changing the distance between adjacent lens groups,
A zoom lens that satisfies the following conditional expression.
0.05≦|f1|/|fpMax|≦0.80 (1)
however,
f1: focal length of the first lens group fpMax: focal length of the lens group LpMax In order from the object side, a first lens group having negative refractive power, an intermediate group consisting of one or more lens groups and having positive refractive power as a whole, a lens group Ln having negative refractive power, and a negative and a final lens group having refractive power,
The intermediate group includes a lens group LpMax,
The lens group LpMax has the strongest positive refractive power among the lens groups included in the intermediate group,
A zoom lens that performs zooming or focusing by changing the distance between adjacent lens groups,
A zoom lens that satisfies the following conditional expression.
βpw≦−0.58 (2)
however,
βpw: Composite lateral magnification of the intermediate group when focusing on infinity at the wide-angle end 3. The zoom lens according to claim 1, which satisfies the following conditional expression.
−1.50≦f1/fw≦−0.05 (3)
however,
f1: focal length of the first lens group fw: focal length of the zoom lens when focusing on infinity at the wide-angle end 4. The zoom lens according to any one of claims 1 to 3, which satisfies the following conditional expressions.
−4.0≦fn/fpMax≦−1.5 (4)
however,
fn: focal length of the lens group Ln fpMax: focal length of the lens group LpMax The zoom lens according to any one of claims 1 to 4, which satisfies the following conditional expressions.
0.05≦frt/ft≦1.50 (5)
however,
frt: Composite focal length from the intermediate group to the final lens group when focusing on infinity at the telephoto end ft: Focal length of the zoom lens when focusing on infinity at the telephoto end 6. The zoom lens according to any one of claims 1 to 5, which satisfies the following conditional expressions.
1.00≦βn1≦5.00 (6)
however,
βn1: Lateral magnification of the lens unit Ln when focusing on infinity at the wide-angle end 7. The zoom lens according to any one of claims 1 to 6, which satisfies the following conditional expressions.
1.00≦βn12≦5.00 (7)
however,
βn12: Synthetic lateral magnification of the lens group Ln and the final lens group when focusing on infinity at the wide-angle end The zoom lens according to any one of claims 1 to 7, wherein the lens group Ln moves along the optical axis when focusing on a near object from infinity, satisfying the following conditional expression.
0.6≦|{1−(βn1×βn1)}×(βn2×βn2)|≦15.0 (8)
however,
βn1: Lateral magnification of the lens group Ln when focusing on infinity at the wide-angle end βn2: Lateral magnification of the last lens group when focusing on infinity at the wide-angle end 9. The zoom lens according to any one of claims 1 to 8, which satisfies the following conditional expressions.
1.00≦|CrG1r/fw| (9)
however,
CrG1r: Radius of curvature of the lens surface closest to the image side in the first lens group fw: Focal length of the zoom lens when focusing on infinity at the wide-angle end 10. The zoom lens according to any one of claims 1 to 9, which satisfies the following conditional expressions.
0.65≦(fw×tanω)/BFw≦2.30 (10)
however,
fw: focal length of the zoom lens when focused on infinity at the wide-angle end ω: half angle of view of the zoom lens when focused on infinity at the wide-angle end BFw: length of the zoom lens when focused on infinity at the wide-angle end Distance on the optical axis between the lens surface closest to the image and the image surface 11. The zoom lens according to any one of claims 1 to 10, wherein the lens group LpMax has at least one lens LpMp having a positive refractive power and satisfies the following conditional expression.
45.0≦νdLpMp≦98.0 (11)
however,
νdLpMp: Abbe number at the d-line of the lens LpMp The zoom lens according to any one of claims 1 to 11, wherein the first lens group has at least one lens L1p having a positive refractive power and satisfies the following conditional expression.
20.0≦νdL1p≦50.0 (12)
however,
νdL1p: Abbe number at the d-line of the lens L1p The zoom lens according to any one of claims 1 to 12, wherein the first lens group has at least one lens L1p having a positive refractive power, and satisfies the following conditional expression.
1.70≦NdL1p≦2.20 (13)
however,
NdL1p: Refractive index for the d-line of the lens L1p 14. The zoom lens according to any one of claims 1 to 13, which satisfies the following conditional expressions.
|BFt−BFw|/TLw≦0.30 (14)
however,
BFt: Distance on the optical axis between the lens surface of the zoom lens closest to the image side and the image plane when focused on infinity at the telephoto end BFw: The closest image of the zoom lens when focused on infinity at the wide-angle end Distance on the optical axis between the lens surface on the side and the image surface TLw: The total optical length of the zoom lens when focused on infinity at the wide-angle end A zoom lens according to any one of claims 1 to 14, and an imaging device provided on the image side of the zoom lens for converting an optical image formed by the zoom lens into an electrical signal. An imaging device characterized by:

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