CN116360084A - Zoom lens and imaging device - Google Patents

Abstract

The object is to provide an imaging device having a high optical performance, a wide angle, a small size, and a high magnification zoom lens. The solution is that a zoom lens has sequentially from the object side to the image side: a first lens group (G1) with negative refractive power, a second lens group (G2) with positive refractive power, and a second lens group (G2) with negative refractive power. The 3rd lens group (G3) with a refractive power of 1000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000. , at least the second lens group (G2), the third lens group (G3) and the fourth lens group (G4) move along the optical axis, the intervals of the lens groups on the optical axis change, and the zoom lens meets the requirements mathematical formula.

Description

Zoom lens and camera device

Technical Field

The invention relates to a zoom lens and a camera device.

Background Art

In recent years, photographic devices using solid-state imaging elements such as digital cameras have become increasingly popular. Along with this, the performance and miniaturization of zoom lenses have progressed, and small-sized imaging device systems are rapidly becoming popular. In the past, in particular, in surveillance lenses, camera lenses, digital camera lenses, single-lens reflex camera lenses, and mirrorless single-lens camera lenses that expect a short total length and small-sized zoom lens, the problem is that the lens itself is small and lightweight, while having high optical performance and being able to photograph a wide range with one camera (wide field of view), and having a high magnification.

The zoom lens described in Patent Document 1 discloses a zoom lens composed of a first lens group having negative optical power, a second lens group having positive optical power, a third lens group having negative optical power, and a fourth lens group having positive optical power. However, the zoom ratio is about 3 times, and it is difficult to achieve a high magnification with a small size.

The zoom lens described in Patent Document 2 discloses a wide-angle zoom lens that is composed of a first lens group having negative power, a second lens group having positive power, a third lens group having negative power, and a rear group including one or more lens groups on the image side of the third lens group, and is small and high-power, and achieves a wide angle of view at the wide-angle end. However, the positive power of the second lens is weak relative to the negative power of the first lens group, so that it is difficult to achieve high resolution at the wide-angle end to ensure a wide angle of view by generating a large distortion aberration.

The zoom lens described in Patent Document 3 discloses a zoom lens composed of a first lens group having negative optical power, a second lens group having positive optical power, a third lens group having negative optical power, and a fourth lens group having positive optical power. The zoom lens intends to achieve a wide angle by sequentially arranging two negative meniscus lenses with concave surfaces facing the image side in the first lens group from the object side, and to achieve a high zoom ratio by moving at least the first lens group to the third lens group along the optical axis during zooming. However, the zoom ratio is about 6 times, and it is difficult to achieve a high ratio with a small size.

Prior Art Literature

Patent Literature

Patent Document 1: Japanese Patent Application Publication No. 2019-135552

Patent Document 2: Japanese Patent No. 6711436

Patent Document 3: Japanese Patent No. 6543815

Summary of the invention

Problems to be solved by the invention

Therefore, an object of the present invention is to provide a zoom lens having high optical performance, a wide angle, and a small size, and a high magnification.

Means for solving problems

A zoom lens comprises, in order from the object side to the image side, at least: a first lens group with negative optical power, a second lens group with positive optical power, a third lens group with negative optical power, and a fourth lens group with positive optical power. When zooming from a wide-angle end to a telephoto end, the first lens group is fixed, and at least the second lens group, the third lens group, and the fourth lens group move along the optical axis, and the intervals between adjacent lens groups on the optical axis change. The zoom lens satisfies the following formula:

0.1≤β23w/tan(ωw)≤0.5············(1)

1.0≤f2/√(fw×ft)≤3.25············(2)

0.15≤(β23t/β23w)/(ft/fw)≤0.98··(3)

in,

fw: The focal length of the zoom lens when focusing at infinity at the wide-angle end

ft: The focal length of the zoom lens when focusing at infinity at the telephoto end

f2: focal length of the second lens group

ωw: Half-angle of view of the most off-axis ray at the wide-angle end

β23w: The combined lateral magnification of the second lens group and the third lens group when focusing at infinity at the wide-angle end

β23t: The combined lateral magnification of the second lens group and the third lens group when focusing at infinity at the telephoto end

In order to solve the above-mentioned problems, an imaging device according to the present invention includes the above-mentioned zoom lens and an imaging element that converts an optical image formed by the zoom lens into an electrical signal.

Effects of the Invention

According to the present invention, it is possible to provide a compact zoom lens having a high magnification and a wide angle.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a zoom lens according to Example 1. FIG.

FIG. 2 is a diagram showing longitudinal aberrations of the zoom lens according to Example 1 at the wide-angle end.

FIG. 3 is a diagram showing longitudinal aberrations of the zoom lens according to Example 1 at the telephoto end.

FIG. 4 is a cross-sectional view of a zoom lens according to Example 2. FIG.

FIG. 5 is a diagram showing aberrations of the zoom lens according to Example 2 at the wide-angle end.

FIG. 6 is a diagram showing aberrations of the zoom lens according to Example 2 at the telephoto end.

FIG. 7 is a cross-sectional view of a zoom lens according to Example 3. FIG.

FIG. 8 is a diagram showing aberrations of the zoom lens according to Example 3 at the wide-angle end.

FIG. 9 is a diagram showing aberrations of the zoom lens according to Example 3 at the telephoto end.

FIG. 10 is a cross-sectional view of a zoom lens according to Example 4.

FIG. 11 is a diagram showing aberrations of the zoom lens according to Example 4 at the wide-angle end.

FIG. 12 is a diagram showing aberrations of the zoom lens according to Example 4 at the telephoto end.

FIG. 13 is a cross-sectional view of the zoom lens of Example 5.

FIG. 14 is a diagram showing aberrations of the zoom lens according to Example 5 at the wide-angle end.

FIG. 15 is a diagram showing aberrations of the zoom lens according to Example 5 at the telephoto end.

FIG16 is a cross-sectional view of a zoom lens according to Example 6.

FIG. 17 is a diagram showing aberrations of the zoom lens according to Example 6 at the wide-angle end.

FIG. 18 is a diagram showing aberrations of the zoom lens according to Example 6 at the telephoto end.

FIG19 is a cross-sectional view of the zoom lens of Example 7.

FIG. 20 is a diagram showing aberrations of the zoom lens according to Example 7 at the wide-angle end.

FIG. 21 is a diagram showing aberrations of the zoom lens according to Example 7 at the telephoto end.

FIG. 22 is a diagram schematically showing an example of the configuration of an imaging device according to an embodiment of the present invention.

Description of Reference Numerals

S···Aperture Diaphragm

CG, 22···Protective glass

IMG···Image

G1···1st lens group

G2···2nd lens group

G3···The third lens group

G4···The 4th lens group

G5···The 5th lens group

G6···The 6th lens group

G7···The 7th lens group

1. Camera

2. Main body

3. Lens tube

21···CCD sensor

DETAILED DESCRIPTION

The following describes an embodiment of the zoom lens and the imaging device according to the present invention. The zoom lens and the imaging device described below are one embodiment of the zoom lens and the imaging device according to the present invention, and the zoom lens and the imaging device according to the present invention are not limited to the following embodiment.

1. Zoom lens

1-1. Optical structure

The zoom lens of the present invention is composed of at least a first lens group having negative optical power, a second lens group having positive optical power, a third lens group having negative optical power, and a fourth lens group having positive optical power, in order from the object side to the image side. This configuration makes it easy to achieve wide angle and miniaturization. In addition, in order to further improve the performance, it is preferred to have a fifth lens group on the image side of the fourth lens group.

(1) Lens Group 1

The specific structure of the first lens group is not particularly limited as long as it has negative refractive power and is fixed relative to the image plane during zooming. The first lens group is composed of a single meniscus lens, which facilitates wide angle and miniaturization.

Here, a "lens group" is composed of one or multiple adjacent lenses, and the distance between adjacent lens groups along the optical axis changes when changing magnification or focusing. When a lens group is composed of multiple lenses, the distance on the optical axis between the lenses included in the lens group does not change when changing magnification or focusing.

(2) Second lens group

The specific structure of the second lens group is not particularly limited as long as it is a lens group having positive optical power and moving along the optical axis when changing the magnification. In terms of moving on the optical axis at high speed when changing the magnification, the second lens group is preferably composed of two or less positive lenses. In addition, the second lens group preferably has a biconvex lens. With this structure, it is easy to correct aberrations and achieve miniaturization.

(3) Third lens group

The specific structure of the third lens group is not particularly limited as long as it is a lens group having negative optical power and moving along the optical axis when changing the magnification. The third lens group is preferably configured to have less than 2 negative lenses. In addition, the positive lens included in the third lens group is preferably only 1. In addition, the third lens group is preferably composed of a negative lens, a negative lens, and a positive lens from the object side to the image side. Through this structure, it is easy to correct aberrations and achieve miniaturization.

(4) The fourth lens group

The specific structure of the fourth lens group is not particularly limited as long as it has positive optical power and moves along the optical axis when changing the magnification. The fourth lens group preferably has a positive lens on the object side. In addition, the fourth lens group is preferably composed of a positive lens, a negative lens, a positive lens, and a negative lens from the object side to the image side. With this structure, it is easy to correct aberrations and achieve miniaturization.

(5) Fifth lens group

The specific structure of the fifth lens group is not particularly limited as long as it is a lens group having positive or negative optical power and being fixed relative to the image plane when changing the magnification. The fifth lens group is preferably composed of only a negative lens and a positive lens from the object side to the image side. With this structure, it is easy to correct aberrations and achieve miniaturization.

(6) Aperture diaphragm

In this zoom lens, the arrangement of the aperture stop is not particularly limited. By arranging the aperture stop between the third lens group and the fourth lens group, aberrations can be efficiently cancelled before and after the aperture stop, which is preferable in obtaining a zoom lens with high optical performance.

1-2. Action

(1) Zoom

When the zoom lens changes magnification from the wide-angle end to the telephoto end, as long as the first lens group is fixed on the optical axis and the second lens group, the third lens group and the fourth lens group are moved on the optical axis, the specific operation is not particularly limited.

(2) Focus

When the zoom lens is focused from infinity to close distance, as long as the fourth lens group moves on the optical axis, its specific action is not particularly limited. In addition, when focusing from infinity to close distance, it is preferred that the fourth lens group moves toward the object side on the optical axis.

1-3. Mathematical formula

The zoom lens preferably has the above-described configuration and satisfies at least one of the mathematical expressions described below.

1-3-1. Formula (1)

0.1≤β23w/tan(ωw)≤0.5············(1)

in,

β23w: The combined lateral magnification of the second lens group and the third lens group when focusing at infinity at the wide-angle end ωw: The half angle of view of the most off-axis ray at the wide-angle end

Formula (1) is a formula for defining the ratio of the combined lateral magnification of the second lens group and the third lens group at the wide-angle end to the half-angle of view of the most off-axis ray at the wide-angle end. By satisfying Formula (1), it is easy to achieve a high magnification and expand the angle of view at the wide-angle end.

If the value is lower than the lower limit of formula (1), it is easy to expand the field angle at the wide-angle end, but it is difficult to correct the field curvature and distortion at the wide-angle end. On the other hand, if the value is higher than the upper limit of formula (1), it is difficult to expand the field angle while maintaining the zoom ratio at the wide-angle end.

In terms of obtaining the above-mentioned effect, the lower limit of formula (1) is preferably 0.13, and more preferably 0.15. In addition, the upper limit of formula (1) is preferably 0.45, and more preferably 0.40. In addition, when adopting these preferred lower limits or upper limits, the inequality sign (≤) with an equal sign can also be replaced with an inequality sign (<) in formula (1). The same is true for other mathematical formulas as a principle.

1-3-2. Formula (2)

1.0≤f2/√(fw×ft)≤3.25············(2)

in,

fw: Focal length of the zoom lens when focusing at infinity at the wide-angle end

ft: Focal length of the zoom lens when focusing at infinity at the telephoto end

f2: Focal length of the second lens group

Formula (2) is a formula for defining the ratio of the focal length of the second lens group to "the square root of the product of the focal length of the zoom lens when focusing at infinity at the wide-angle end and the focal length of the zoom lens when focusing at infinity at the telephoto end". By satisfying Formula (2), it is possible to appropriately correct the field curvature, distortion, and chromatic aberration occurring in the first lens group, and it is easy to achieve miniaturization.

If the value is lower than the lower limit of formula (2), the focal length of the second lens group is too short, and the field curvature, distortion aberration, and chromatic aberration at the wide-angle end cannot be corrected. The number of lenses required to correct the aberration increases, making it difficult to achieve miniaturization. On the other hand, if the value exceeds the upper limit of formula (2), the focal length of the second lens group becomes longer, and the correction of the field curvature, distortion aberration, and chromatic aberration occurring in the first lens group is insufficient. In addition, the movement amount of the second lens group when changing magnification from the wide-angle end to the telephoto end increases, making it difficult to achieve miniaturization.

In order to obtain the above-mentioned effect, the lower limit value of the formula (2) is preferably 1.10, and more preferably 1.20. In addition, the upper limit value of the formula (2) is preferably 2.80, and more preferably 2.60.

1-3-3. Formula (3)

0.15≤(β23t/β23w)/(ft/fw)≤0.98··(3)

in,

β23t: The combined lateral magnification of the second and third lens groups when focusing at infinity at the telephoto end

Formula (3) is a formula for defining the ratio of the contribution to the zoom magnification of the second lens group and the third lens group. By satisfying formula (3), the ratio of the contribution to the zoom magnification of the second lens group and the third lens group can be appropriate, and high magnification and miniaturization can be easily achieved.

If the value is lower than the lower limit of formula (3), the proportion of the second lens group and the third lens group that contribute to the zoom magnification becomes smaller, so it is difficult to achieve a high magnification. On the other hand, if the value is higher than the upper limit of formula (3), the proportion of the second lens group and the third lens group that contribute to the zoom magnification becomes larger, so the number of lenses required to reduce the amount of aberration when zooming from the wide-angle end to the telephoto end increases, making it difficult to achieve miniaturization.

In order to obtain the above-mentioned effect, the lower limit of the formula (3) is preferably 0.30, and more preferably 0.40. In addition, the upper limit of the formula (3) is preferably 0.97, and more preferably 0.95.

1-3-4. Formula (4)

5.0≤|f1/fw|≤20.0···(4)

in,

f1: Focal length of the first lens group

Formula (4) is a formula for defining the absolute value of the ratio of the focal length of the first lens group to the focal length of the zoom lens when focusing at infinity at the wide-angle end. By satisfying formula (4), it is possible to correct field curvature and distortion at the wide-angle end and expand the field of view, making it easy to achieve miniaturization.

If the value is lower than the lower limit of formula (4), the focal length of the first lens group becomes shorter, the field curvature and distortion aberration occurring in the first lens group increase, and the number of lenses required to correct these aberrations in the group closer to the image side than the first lens increases, making it difficult to achieve miniaturization. On the other hand, if the value exceeds the upper limit of formula (4), the focal length of the first lens group is too long, the field curvature is not sufficiently corrected at the wide-angle end, and it is difficult to obtain good optical performance. In addition, it is difficult to expand the field angle at the wide-angle end.

In order to obtain the above-mentioned effect, the lower limit value of the formula (4) is preferably 5.5, and more preferably 6.0. In addition, the upper limit value of the formula (4) is preferably 18.0, and more preferably 17.0.

1-3-5. Formula (5)

0.5≤|f1/f2|≤4.0···(5)

Formula (5) is a formula for defining the absolute value of the ratio of the focal length of the second lens group to the focal length of the first lens group. By satisfying Formula (5), field curvature and distortion can be properly corrected, and the field angle can be expanded at the wide-angle end, making it easy to obtain high optical performance.

If the value is lower than the lower limit of formula (5), the focal length of the first lens group becomes shorter relative to the focal length of the second lens group, and the field curvature and distortion aberration increase at the wide-angle end, making it difficult to achieve high optical performance. On the other hand, if the value is higher than the upper limit of formula (5), the focal length of the first lens group becomes longer relative to the focal length of the second lens group, and the negative optical power becomes weaker, making it difficult to expand the field of view at the wide-angle end.

In order to obtain the above-mentioned effect, the lower limit value of the formula (5) is preferably 0.70, and more preferably 1.00. In addition, the upper limit value of the formula (5) is preferably 3.70, and more preferably 35.0.

1-3-6. Formula (6)

0.5≤|f12t/ft|≤3.0···(6)

in,

f12t: The combined focal length of the first and second lens groups when focusing at infinity at the telephoto end

Formula (6) is a formula for defining the ratio of the focal length of the zoom lens when focusing at infinity at the telephoto end to the combined focal length of the first lens group and the second lens group at the telephoto end. By satisfying Formula (6), it is easy to appropriately correct spherical aberration, astigmatism, and axial chromatic aberration occurring in the first lens group and the second lens group at the telephoto end, and to obtain high optical performance or achieve miniaturization.

If the value is lower than the lower limit of formula (6), the combined focal length of the first lens group and the second lens group at the telephoto end becomes shorter, spherical aberration, astigmatism, and axial chromatic aberration increase, and it is difficult to obtain high optical performance. On the other hand, if the value is higher than the upper limit of formula (6), the combined focal length of the first lens group and the second lens group at the telephoto end becomes longer, spherical aberration, astigmatism, and axial chromatic aberration are not corrected sufficiently, and it is difficult to achieve miniaturization of the optical system.

In order to obtain the above-mentioned effect, the lower limit value of the formula (6) is preferably 0.55, and more preferably 0.60. In addition, the upper limit value of the formula (6) is preferably 2.70, and more preferably 2.50.

1-3-7. Formula (7)

0.3≤|X3|/√(fw×ft)≤2.0···(7)

in,

X3: Movement amount of the third lens group in the direction of the optical axis when zooming from the wide-angle end to the telephoto end Formula (7) is a formula for defining the ratio of the movement amount of the third lens group when zooming from the wide-angle end to the telephoto end relative to the "square root of the product of the focal length of the zoom lens when focusing at infinity at the wide-angle end and the focal length of the zoom lens when focusing at infinity at the telephoto end". By satisfying Formula (7), the movement amount of the third lens group is appropriately set when zooming from the wide-angle end to the telephoto end, spherical aberration is easily corrected, and high magnification and miniaturization are achieved.

If the value is lower than the lower limit of formula (7), the movement amount of the third lens group becomes shorter when zooming from the wide-angle end to the telephoto end, making it difficult to achieve a high magnification of the optical system. On the other hand, if the value is higher than the upper limit of formula (7), the movement amount of the third lens group becomes longer when zooming from the wide-angle end to the telephoto end, making it difficult to achieve miniaturization.

In order to obtain the above-mentioned effect, the lower limit value of the formula (7) is preferably 0.35, and more preferably 0.40. In addition, the upper limit value of the formula (7) is preferably 1.90, and more preferably 1.80.

1-3-8. Formula (8)

1.5≤|f2/f3|≤6.0···(8)

Formula (8) is a formula for defining the ratio of the focal length of the second lens group to the focal length of the third lens group. By satisfying formula (8), it is easy to well correct the spherical aberration and field curvature occurring in the second lens group and the third lens group when zooming from the wide-angle end to the telephoto end, and obtain high optical performance or achieve miniaturization.

If the value is lower than the lower limit of formula (8), the focal length of the second lens group becomes shorter than the focal length of the third lens group, the spherical aberration is overcorrected from the wide-angle end to the telephoto end, and the field curvature cannot be corrected, making it difficult to obtain high optical performance. On the other hand, if the value is higher than the upper limit of formula (8), the spherical aberration cannot be corrected from the wide-angle end to the telephoto end, making it difficult to achieve miniaturization.

In order to obtain the above-mentioned effect, the lower limit value of the formula (8) is preferably 1.70, and more preferably 2.00. In addition, the upper limit value of the formula (8) is preferably 5.50, and more preferably 5.00.

1-3-9. Formula (9)

ν2p_max≤70···(9)

in,

ν2p_max: Maximum value of the Abbe number of the positive lens in the second lens group

Formula (9) is a formula for defining the Abbe number of the positive lens in the second lens group. By satisfying Formula (9), axial chromatic aberration and lateral chromatic aberration can be corrected from the wide-angle end to the telephoto end, and high optical performance can be easily obtained.

If the upper limit value of the formula (9) is exceeded, axial chromatic aberration and lateral chromatic aberration cannot be corrected from the wide-angle end to the telephoto end, making it difficult to obtain high optical performance.

In order to obtain the above-mentioned effect, the lower limit value of the formula (9) is preferably 40.0, and more preferably 45.0. In addition, the upper limit value of the formula (9) is preferably 68.0, and more preferably 67.0.

2. Camera device

Next, the imaging device of the present invention is described. The imaging device of the present invention is characterized in that it comprises the zoom lens of the present invention and an imaging element that converts an optical image formed by the zoom lens into an electrical signal. In addition, the imaging element is preferably arranged on the image side of the zoom lens.

Here, there is no particular limitation on the imaging element, and solid-state imaging elements such as CCD (Charge Coupled Device) sensors and CMOS (Complementary Metal Oxide Semiconductor) sensors can also be used. The imaging device involved in the present invention is suitable for imaging devices such as digital cameras and video cameras that use these solid-state imaging elements. In addition, the imaging device can be applied to various imaging devices such as single-lens reflex cameras, mirrorless single-lens cameras, digital cameras, surveillance cameras, vehicle-mounted cameras, and drone-mounted cameras. In addition, these imaging devices can be either interchangeable lens-type imaging devices or fixed lens-type imaging devices in which the lens is fixed to the housing. The zoom lens involved in the present invention is particularly suitable as a zoom lens for an imaging device equipped with a large-size imaging element such as a full-size one. The zoom lens is small and lightweight as a whole, and has high optical performance, so high-quality camera images can be obtained when used as a zoom lens for such an imaging device.

Fig. 22 is a diagram schematically showing an example of the configuration of an imaging device according to the present embodiment. As shown in Fig. 21 , a camera 1 includes a main body 2 and a lens barrel 3 that is attachable to and detachable from the main body 2. The camera 1 is one form of an imaging device.

The main body 2 has a CCD sensor 21 as an imaging element and a protective glass 22. The CCD sensor 21 is arranged at a position in the main body 2 where the optical axis of the zoom lens 30 mounted in the lens barrel 3 of the main body 2 becomes its central axis. The main body 2 may have an IR cut filter or the like instead of the protective glass 22.

Next, the present invention will be specifically described with reference to Examples. However, the present invention is not limited to the following Examples.

[Example 1]

(1) Optical structure

Fig. 1 is a cross-sectional view of a zoom lens according to Example 1 of the present invention at a wide angle end and a telephoto end when focusing at infinity. The zoom lens is composed of, 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, a fourth lens group G4 having positive refractive power, and a fifth lens group G5 having negative refractive power.

When zooming from the wide-angle end to the telephoto end, along the optical axis, the second lens group G2 moves toward the object side in a trajectory convex toward the image plane, the third lens group G3 moves from the image side to the object side, and the fourth lens group G4 moves toward the object side in a trajectory convex toward the object side.

When focusing from an object at infinity to an object at a close distance, the fourth lens group G4 moves along the optical axis from the image side to the object side.

The first lens group G1 is composed of a negative meniscus lens with a convex surface on the object side.

The second lens group G2 is composed of a biconvex lens and a biconvex lens in order from the object side.

The third lens group G3 is composed of a biconcave lens, a biconcave lens, and a biconvex lens in order from the object side.

The fourth lens group G4 is composed of, in order from the object side, a biconvex lens, a negative meniscus lens, and a cemented lens in which the biconvex lens and the negative meniscus lens are cemented.

The fifth lens group G5 is composed of a negative meniscus lens and a biconvex lens in order from the object side.

The aperture stop S is located between the third lens group G3 and the fourth lens group G4, and is fixed relative to the image plane IMG when zooming from the wide-angle end to the telephoto end and when focusing from an object at infinity to an object at a close distance.

In FIG. 1 , “IMG” is an image plane, and specifically, represents an image plane of a solid-state image pickup element such as a CCD sensor or a CMOS sensor, or a film surface of a silver halide film, etc. In addition, a protective glass CG is provided on the object side of the image plane IMG. This is also the same in each lens cross-sectional view shown in other embodiments, so the description thereof will be omitted hereinafter.

(2) Numerical Example

Next, numerical examples using specific numerical values for the zoom lens are described. The following represents "lens data", "various specification tables", "variable intervals", "aspheric coefficients", and "focal lengths of each lens group". In addition, the values of various formulas (Table 1) are summarized after Example 7. In addition, in the following numerical examples, the units of the numerical values without length units are all "mm", and the units of the angles are all "°". "INF" means infinity.

In (Lens Data), "Surface NO." indicates the serial number of the lens surface counted from the object side, "r" indicates the radius of curvature of the lens surface, "D" indicates the lens wall thickness or air gap on the optical axis, "Nd" indicates the refractive index at the d-line (wavelength λ=587.56nm), and "vd" indicates the Abbe number at the d-line. In addition, the "*" marked after the number in the "Surface NO." column indicates that the lens surface is an aspherical surface, and "S" indicates that the surface is an aperture stop. In the "D" column, "D(7)", "D(10)", etc. mean that the interval on the optical axis of the lens surface is a variable interval that changes when changing magnification or focusing. In addition, "BF" indicates back focus.

In the (various specification tables), "f" is the focal length of the zoom lens, "Fno." is the F value, "ω" is the half angle of view, "Y" is the image height, and "L" is the total length of the lens. These represent the values when focusing at infinity at the wide-angle end, the middle end, and the telephoto end, respectively.

In (variable interval), the values for focusing at infinity at the wide-angle end, the middle end, and the telephoto end and focusing at a limited distance are shown respectively.

(Aspheric coefficient) indicates the aspheric coefficient when the aspheric shape is defined as follows. Among them, x is the displacement relative to the reference surface in the direction of the optical axis, r is the paraxial curvature radius, H is the height relative to the optical axis in the direction perpendicular to the optical axis, K is the cone coefficient, and An is the n-order aspheric coefficient. In addition, in the table of "Aspheric coefficient", "E±XX" represents the index mark, which means "×10 ^±XX ".

[Formula 1]

The matters in these numerical examples are the same as in other examples, so the description thereof will be omitted below.

In addition, FIG. 2 and FIG. 3 show the longitudinal aberration diagrams when the zoom lens is focused on an infinitely distant object at the wide-angle end and the telephoto end. The longitudinal aberration diagrams shown in each figure are spherical aberration (mm), astigmatism (mm), and distortion aberration (%), starting from the left side of the drawing. In the spherical aberration diagram, the solid line represents the spherical aberration at the d-line (wavelength 587.56nm), the short dashed line represents the spherical aberration at the g-line (wavelength 435.84nm), and the long dashed line represents the spherical aberration at the C-line (wavelength 656.28nm). In the astigmatism diagram, the vertical axis is the half field angle (ω), and the horizontal axis is the defocus. The solid line represents the sagittal image plane of the d-line, and the dotted line represents the meridional image plane of the d-line. In the distortion aberration diagram, the vertical axis is the half field angle (ω), and the horizontal axis is the distortion aberration. These matters are the same in the aberration diagrams shown in other embodiments, so the description will be omitted later.

(Lens data)

Noodles NO. r D Nd vd 1 152.469 1.100 1.79999 29.84 2 25.610 D(2) 3 42.712 4.100 1.60300 65.44 4 -79.438 0.150 5 22.379 4.300 1.61799 63.4 6 -268.591 D(6) 7 -148.152 0.500 1.95375 32.32 8 10.486 2.170 9 -11.948 0.500 1.91082 35.25 10 14.890 0.380 11 17.550 2.401 1.98613 16.48 12 -32.183 D(12) 13S INF D(13) 14* 7.136 3.785 1.55332 71.68 15* -37.444 1.250 16 8.506 0.600 1.79360 37.09 17 5.461 0.762 18 6.519 3.880 1.59282 68.62 19 -5.691 0.500 2.00100 29.13 20 -14.215 D(20) twenty one 359.787 0.500 2.00100 29.13 twenty two 5.905 1.607 twenty three* 21.301 2.226 1.63973 23.53 twenty four* -10.833 3.200 25 INF 0.800 1.51633 64.14 26 INF BF

(Various specifications)

Wide angle middle Telephoto end f 4.465 13.703 44.388 Fno. 1.838 2.507 3.596 ω 41.188 12.783 3.975 Y 3.300 3.300 3.300 L 66.000 66.000 66.000

(Variable interval)

Wide angle middle Telephoto end Photo distance INF INF INF D(2) 6.445 5.956 3.296 D(6) 1.100 12.397 22.578 D(12) 19.328 8.520 1.000 D(13) 2.315 0.759 1.346 D(20) 1.100 2.656 2.069 BF 1.000 1.000 1.000 Wide angle middle Telephoto end Photo distance 0.3m 1.0m 1.2m D(13) 2.290 0.672 0.598 D(20) 1.125 2.743 2.816

(Aspheric coefficient)

Noodles NO. K A4 A6 A8 A10 14 0.0000E+00 -1.6033E-04 -2.5593E-06 8.1019E-09 -2.1009E-09 15 0.0000E+00 2.2852E-04 -5.3631E-07 -9.8586E-08 1.5727E-09 twenty three 0.0000E+00 -6.7519E-05 5.5632E-06 1.3150E-06 -9.7898E-08 twenty four 0.0000E+00 -6.3664E-06 6.4237E-06 -9.8230E-07 1.4817E-08

(Focal length of each lens group)

Group Noodles NO. focal length G1 1-2 -38.625 G2 3-6 20.048 G3 7-12 -7.055 G4 14-20 8.827 G5 21-24 -23.029

[Example 2]

(1) Optical structure

Fig. 4 is a cross-sectional view of the zoom lens of Example 2 involved in the present invention when focusing at infinity. The zoom lens is composed of, 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, a fourth lens group G4 having positive refractive power, and a fifth lens group G5 having negative refractive power.

When zooming from the wide-angle end to the telephoto end, along the optical axis, the second lens group G2 moves toward the object side in a trajectory convex toward the image plane, the third lens group G3 moves from the image side to the object side, and the fourth lens group G4 moves toward the object side in a trajectory convex toward the object side.

When focusing from an object at infinity to an object at a close distance, the fourth lens group G4 moves along the optical axis from the image side to the object side.

The first lens group G1 is composed of a negative meniscus lens with a convex surface on the object side.

The second lens group G2 is composed of a biconvex lens and a biconvex lens in order from the object side.

The third lens group G3 is composed of a biconcave lens, a biconcave lens, and a biconvex lens in order from the object side.

The fourth lens group G4 is composed of, in order from the object side, a biconvex lens, a negative meniscus lens, and a cemented lens in which the biconvex lens and the negative meniscus lens are cemented.

The fifth lens group G5 is composed of a negative meniscus lens and a biconvex lens in order from the object side.

The aperture stop S is located between the third lens group G3 and the fourth lens group G4, and is fixed relative to the image plane IMG when zooming from the wide-angle end to the telephoto end and when focusing from an object at infinity to an object at a close distance.

(2) Numerical Example

Next, numerical examples to which specific numerical values are applied to the zoom lens are shown. In addition, longitudinal aberration diagrams of the zoom lens at the wide-angle end and the telephoto end when focusing at infinity are shown in FIG5 and FIG6 .

(Lens data)

(Various specifications)

Wide angle middle Telephoto end f 4.521 13.698 42.745 Fno. 1.900 2.510 3.630 ω 40.986 12.599 4.080 Y 3.300 3.300 3.300 L 68.000 68.000 68.000

(Variable interval)

Wide angle middle Telephoto end Photo distance INF INF INF D(2) 5.830 4.531 3.087 D(6) 1.321 13.915 24.029 D(12) 20.965 9.670 1.000 D(13) 2.291 1.013 0.987 D(20) 1.099 2.378 2.404 BF 1.000 1.000 1.000 Wide angle middle Telephoto end Photo distance 0.3m 1.0m 1.2m D(13) 2.269 0.940 0.359 D(20) 1.122 2.450 3.032

(Aspheric coefficient)

Noodles NO. K A4 A6 A8 A10 14 0.0000E+00 -1.5721E-04 -2.6048E-06 1.5255E-08 -2.2799E-09 15 0.0000E+00 2.2305E-04 -3.3196E-07 -1.0576E-07 1.6823E-09 twenty three 0.0000E+00 -6.9128E-05 3.0041E-05 2.3662E-06 -2.4054E-07 twenty four 0.0000E+00 2.0961E-04 1.9349E-05 1.6146E-06 -1.7801E-07

(Focal length of each lens group)

Group Noodles NO. focal length G1 1-2 -28.342 G2 3-6 18.284 G3 7-12 -7.731 G4 14-20 8.920 G5 21-24 -34.185

[Example 3]

(1) Optical structure

Fig. 7 is a cross-sectional view showing the zoom lens of Example 3 involved in the present invention when focusing at infinity. The zoom lens is composed of, 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, a fourth lens group G4 having positive refractive power, and a fifth lens group G5 having positive refractive power.

When zooming from the wide-angle end to the telephoto end, along the optical axis, the second lens group G2 moves toward the object side in a trajectory convex toward the image plane, the third lens group G3 moves from the image side to the object side, and the fourth lens group G4 moves toward the object side in a trajectory convex toward the object side.

When focusing from an object at infinity to an object at a close distance, the fourth lens group G4 moves along the optical axis from the image side to the object side.

The first lens group G1 is composed of a negative meniscus lens with a convex surface on the object side.

The second lens group G2 is composed of a biconvex lens and a biconvex lens in order from the object side.

The third lens group G3 is composed of, in order from the object side, a biconcave lens and a cemented lens in which a biconcave lens and a biconvex lens are cemented.

The fourth lens group G4 is composed of, in order from the object side, a biconvex lens, a negative meniscus lens, and a cemented lens in which the biconvex lens and the negative meniscus lens are cemented.

The fifth lens group G5 is composed of a negative meniscus lens and a biconvex lens in order from the object side.

The aperture stop S is located between the third lens group G3 and the fourth lens group G4, and is fixed relative to the image plane IMG when zooming from the wide-angle end to the telephoto end and when focusing from an object at infinity to an object at a close distance.

(2) Numerical Example

Next, numerical examples to which specific numerical values are applied to the zoom lens are shown. In addition, FIG8 and FIG9 show longitudinal aberration diagrams of the zoom lens at the wide-angle end and the telephoto end when focusing at infinity.

(Lens data)

Noodles NO. r D Nd vd 1 49.662 1.100 1.75211 25.05 2 24.365 D(2) 3 52.199 2.817 1.60300 65.44 4 -455.288 0.150 5 22.145 4.502 1.60300 65.44 6 -250.778 D(6) 7 -131.554 0.500 2.00100 29.13 8 10.294 2.316 9 -9.965 0.500 1.91082 35.25 10 13.339 2.626 1.98613 16.48 11 -27.147 D(11) 12S INF D(12) 13* 7.282 3.782 1.55332 71.68 14* -29.011 1.299 15 8.720 0.600 1.79360 37.09 16 5.810 1.435 17 6.829 3.614 1.59282 68.62 18 -6.176 0.500 2.00100 29.13 19 -17.876 D(19) 20 84.650 0.500 2.00100 29.13 twenty one 5.140 2.890 twenty two* 13.941 2.911 1.61608 25.80 twenty three* -7.974 2.207 twenty four INF 0.800 1.51633 64.14 25 INF BF

(Various specifications)

(Variable interval)

Wide angle middle Telephoto end Photo distance INF INF INF D(2) 5.867 8.221 3.613 D(6) 1.100 10.778 20.678 D(11) 18.323 6.292 1.000 D(12) 4.849 2.332 1.589 D(19) 1.150 3.667 4.410 BF 1.000 1.000 1.000 Wide angle middle Telephoto end Photo distance 0.3m 1.0m 1.2m D(12) 4.823 2.229 0.311 D(19) 1.176 3.769 5.687

(Aspheric coefficient)

Noodles NO. K A4 A6 A8 A10 13 0.0000E+00 -1.7913E-04 -2.9441E-06 -1.4515E-09 -1.5791E-09 14 0.0000E+00 2.1837E-04 -1.2362E-06 -7.6305E-08 1.5419E-09 twenty two 0.0000E+00 -1.7083E-04 -3.7080E-05 2.6028E-06 -2.0109E-09 twenty three 0.0000E+00 1.5029E-04 -5.5221E-06 -1.6829E-06 1.1828E-07

(Focal length of each lens group)

Group Noodles NO. focal length G1 1-2 -64.212 G2 3-6 23.976 G3 7-11 -6.492 G4 13-19 9.064 G5 20-23 50.855

[Example 4]

(1) Optical structure

Fig. 10 is a cross-sectional view of the zoom lens of Example 4 according to the present invention when focusing at infinity. The zoom lens is composed of, 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, a fourth lens group G4 having positive refractive power, and a fifth lens group G5 having negative refractive power.

When zooming from the wide-angle end to the telephoto end, along the optical axis, the second lens group G2 moves toward the object side in a trajectory convex toward the image plane, the third lens group G3 moves from the image side to the object side, and the fourth lens group G4 moves toward the object side in a trajectory convex toward the object side.

When focusing from an object at infinity to an object at a close distance, the fourth lens group G4 moves along the optical axis from the image side to the object side.

The first lens group G1 is composed of a negative meniscus lens with a convex surface on the object side.

The second lens group G2 is composed of a biconvex lens and a biconvex lens in order from the object side.

The third lens group G3 is composed of a biconcave lens, a biconcave lens, and a biconvex lens in order from the object side.

The fourth lens group G4 is composed of, in order from the object side, a biconvex lens, a negative meniscus lens, and a cemented lens in which the biconvex lens and the negative meniscus lens are cemented.

The fifth lens group G5 is composed of a negative meniscus lens and a biconvex lens in order from the object side.

The aperture stop S is located between the third lens group G3 and the fourth lens group G4, and is fixed relative to the image plane IMG when zooming from the wide-angle end to the telephoto end and when focusing from an object at infinity to an object at a close distance.

(2) Numerical Example

Next, numerical examples to which specific numerical values are applied to the zoom lens are shown. In addition, FIG11 and FIG12 show longitudinal aberration diagrams of the zoom lens at the wide-angle end and the telephoto end when focusing at infinity.

(Lens data)

(Various specifications)

Wide angle middle Telephoto end f 4.543 13.698 43.216 Fno. 2.000 2.510 3.629 ω 40.827 12.767 4.070 Y 3.300 3.300 3.300 L 66.501 66.501 66.501

(Variable interval)

Wide angle middle Telephoto end Photo distance INF INF INF D(2) 7.471 6.087 3.439 D(6) 1.100 12.759 23.009 D(12) 18.877 8.601 1.000 D(13) 2.051 0.763 1.870 D(20) 1.100 2.388 1.282 BF 1.000 1.000 1.000 Wide angle middle Telephoto end Photo distance 0.3m 1.0m 1.2m D(13) 2.024 0.676 1.080 D(20) 1.127 2.475 2.072

(Aspheric coefficient)

Noodles NO. K A4 A6 A8 A10 14 0.0000E+00 -1.5967E-04 -2.5363E-06 6.3789E-09 -2.2278E-09 15 0.0000E+00 2.3047E-04 -6.1012E-07 -1.0092E-07 1.4691E-09 twenty three 0.0000E+00 -9.2171E-05 4.3552E-06 9.6814E-07 -1.1530E-07 twenty four 0.0000E+00 4.9774E-06 4.9500E-06 -1.2885E-06 -6.5196E-09

(Focal length of each lens group)

Group Noodles NO. focal length G1 1-2 -38.662 G2 3-6 20.084 G3 7-12 -7.414 G4 14-20 8.890 G5 21-24 -24.780

[Example 5]

(1) Optical structure

Fig. 13 is a cross-sectional view of the zoom lens of Example 5 involved in the present invention when focusing at infinity. The zoom lens is composed of, 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, a fourth lens group G4 having positive refractive power, and a fifth lens group G5 having negative refractive power.

When zooming from the wide-angle end to the telephoto end, along the optical axis, the second lens group G2 moves toward the object side in a trajectory convex toward the image plane, the third lens group G3 moves from the image side to the object side, and the fourth lens group G4 moves toward the object side in a trajectory convex toward the object side.

When focusing from an object at infinity to an object at a close distance, the fourth lens group G4 moves along the optical axis from the image side to the object side.

The first lens group G1 is composed of a negative meniscus lens with a convex surface on the object side.

The second lens group G2 is composed of a biconvex lens and a positive meniscus lens in order from the object side.

The third lens group G3 is composed of, in order from the object side, a biconcave lens, a cemented lens in which a negative meniscus lens and a positive meniscus lens are cemented together, and a negative meniscus lens.

The fourth lens group G4 is composed of, in order from the object side, a biconvex lens, a negative meniscus lens, and a cemented lens in which the biconvex lens and the negative meniscus lens are cemented.

The fifth lens group G5 is composed of a negative meniscus lens and a positive meniscus lens in order from the object side.

The aperture stop S is located between the third lens group G3 and the fourth lens group G4, and is fixed relative to the image plane IMG when zooming from the wide-angle end to the telephoto end and when focusing from an object at infinity to an object at a close distance.

(2) Numerical Example

Next, numerical examples to which specific numerical values are applied to the zoom lens are shown. In addition, FIG14 and FIG15 show longitudinal aberration diagrams of the zoom lens at the wide-angle end and the telephoto end when focusing at infinity.

(Lens data)

Noodles NO. r D Nd vd 1 157.165 1.100 1.84666 23.78 2 44.488 D(2) 3 66.576 2.977 1.59349 67.00 4 -106.692 0.150 5 30.559 3.184 1.65844 50.85 6 306.103 D(6) 7 -2515.812 0.500 2.00100 29.13 8 12.800 2.232 9 -8.950 0.500 1.91082 35.25 10 -215.924 3.481 1.94595 17.98 11 -11.344 0.150 12 -14.692 0.600 1.95375 32.32 13 -31.030 D(13) 14S INF D(14) 15* 6.946 3.712 1.55332 71.68 16* -39.702 0.273 17 8.251 0.600 1.64850 53.02 18 5.450 0.927 19 6.856 3.800 1.59282 68.62 20 -5.734 0.500 2.00100 29.13 twenty one -14.292 D(21) twenty two 41.044 0.500 2.00100 29.13 twenty three 4.908 2.933 twenty four* -90.351 2.222 1.63973 23.53 25* -6.610 2.200 26 INF 0.800 1.51633 64.14 27 INF BF

(Various specifications)

(Variable interval)

Wide angle middle Telephoto end Photo distance INF INF INF D(2) 11.859 9.629 2.526 D(6) 1.171 16.301 30.092 D(13) 20.589 7.688 0.999 D(14) 2.444 1.173 0.991 D(21) 1.096 2.368 2.550 BF 1.000 1.000 1.000 Wide angle middle Telephoto end Photo distance 0.3m 1.0m 1.2m D(14) 2.425 1.111 0.376 D(21) 1.116 2.429 3.164

(Aspheric coefficient)

Noodles NO. K A4 A6 A8 A10 15 0.0000E+00 -1.5421E-04 -2.6083E-06 4.3172E-09 -2.3523E-09 16 0.0000E+00 2.6011E-04 -1.4695E-06 -9.9759E-08 1.6512E-09 twenty four 0.0000E+00 -4.4671E-04 2.0712E-06 7.2361E-06 -4.3248E-07 25 0.0000E+00 6.8398E-04 -5.5083E-06 4.4141E-06 -2.4151E-07

(Focal length of each lens group)

Group Noodles NO. focal length G1 1-2 -72.901 G2 3-6 29.672 G3 7-13 -8.369 G4 15-21 8.220 G5 22-25 -59.503

[Example 6]

(1) Optical structure

Fig. 16 is a cross-sectional view of the zoom lens of Example 6 according to the present invention when focusing at infinity. The zoom lens is composed of, 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, a fourth lens group G4 having positive refractive power, and a fifth lens group G5 having positive refractive power.

When zooming from the wide-angle end to the telephoto end, along the optical axis, the second lens group G2 moves toward the object side in a trajectory convex toward the image plane, the third lens group G3 moves from the image side to the object side, and the fourth lens group G4 moves toward the object side in a trajectory convex toward the object side.

When focusing from an object at infinity to an object at a close distance, the fourth lens group G4 moves along the optical axis from the image side to the object side.

The first lens group G1 is composed of a negative meniscus lens with a convex surface on the object side.

The second lens group G2 is composed of a biconvex lens.

The third lens group G3 is composed of, in order from the object side, a biconcave lens and a cemented lens in which a biconcave lens and a positive meniscus lens are cemented.

The fourth lens group G4 is composed of, in order from the object side, a biconvex lens, a cemented lens in which a negative meniscus lens and a biconvex lens are cemented together, and a cemented lens in which a biconvex lens and a biconcave lens are cemented together.

The fifth lens group G5 is composed of a biconvex lens.

The aperture stop S is located between the third lens group G3 and the fourth lens group G4, and is fixed relative to the image plane IMG when zooming from the wide-angle end to the telephoto end and when focusing from an object at infinity to an object at a close distance.

(2) Numerical Example

Next, numerical examples to which specific numerical values are applied to the zoom lens are shown. In addition, FIG17 and FIG18 show longitudinal aberration diagrams of the zoom lens at the wide-angle end and the telephoto end when focusing at infinity.

(Lens data)

(Various specifications)

Wide angle middle Telephoto end f 4.431 13.695 41.809 Fno. 1.854 3.065 3.357 ω 41.211 12.924 4.225 Y 3.300 3.300 3.300 L 63.000 63.000 63.000

(Variable interval)

Wide angle middle Telephoto end Photo distance INF INF INF D(2) 8.327 7.353 1.559 D(4) 1.372 7.719 16.337 D(9) 10.394 5.020 2.197 D(10) 11.714 5.247 0.868 D(18) 2.382 8.850 13.229 BF 0.200 0.200 0.200 Wide angle middle Telephoto end Photo distance 0.3m 1.0m 1.2m D(10) 11.526 6.645 3.385 D(18) 2.570 7.452 10.710

(Aspheric coefficient)

Noodles NO. K A4 A6 A8 A10 11 0.0000E+00 1.8960E-04 5.7996E-06 -7.7026E-09 1.2534E-09 12 0.0000E+00 6.3995E-04 9.5312E-06 1.1571E-07 9.3991E-10 19 0.0000E+00 -3.2148E-04 -1.8335E-06 1.3205E-06 1.3701E-08 20 0.0000E+00 7.1958E-05 6.6237E-06 1.5684E-07 6.2622E-08

(Focal length of each lens group)

[Example 7]

(1) Optical structure

Fig. 19 is a cross-sectional view of the zoom lens of Example 7 of the present invention when focusing at infinity. The zoom lens is composed of, 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 fourth lens group G4 having positive refractive power.

When zooming from the wide-angle end to the telephoto end, along the optical axis, the second lens group G2 moves toward the object side in a trajectory convex toward the image plane, the third lens group G3 moves from the image side to the object side, and the fourth lens group G4 moves toward the object side in a trajectory convex toward the object side.

When focusing from an object at infinity to an object at a close distance, the fourth lens group G4 moves along the optical axis from the image side to the object side.

The first lens group G1 is composed of a negative meniscus lens with a convex surface on the object side.

The second lens group G2 is composed of a biconvex lens and a biconvex lens.

The third lens group G3 is composed of, in order from the object side, a negative meniscus lens and a cemented lens in which a biconcave lens and a biconvex lens are cemented.

The fourth lens group G4 is composed of, in order from the object side, a biconvex lens, a negative meniscus lens, a cemented lens in which a biconvex lens and a negative meniscus lens are cemented, a biconcave lens, and a biconvex lens.

The aperture stop S is located between the third lens group G3 and the fourth lens group G4, and is fixed relative to the image plane IMG when zooming from the wide-angle end to the telephoto end and when focusing from an object at infinity to an object at a close distance.

(2) Numerical Example

Next, numerical examples to which specific numerical values are applied to the zoom lens are shown. In addition, FIG20 and FIG21 show longitudinal aberration diagrams of the zoom lens at the wide-angle end and the telephoto end when focusing at infinity.

(Lens data)

Noodles NO. r D Nd vd 1 160.265 1.100 1.95375 32.32 2 33.798 D(2) 3 91.299 4.469 1.59349 67.00 4 -50.765 0.150 5 23.387 4.500 1.59349 67.00 6 -648.643 D(6) 7 55.085 0.500 2.00100 29.13 8 10.545 2.896 9 -9.384 0.500 1.91082 35.25 10 23.986 2.414 1.98613 16.48 11 -21.800 D(11) 12S INF D(12) 13* 7.101 3.586 1.55332 71.68 14* -58.637 1.148 15 6.868 0.600 1.61799 63.40 16 4.789 0.848 17 6.100 3.634 1.59282 68.62 18 -7.218 0.500 2.00100 29.13 19 -12.615 0.416 20 -33.584 0.500 1.96300 24.11 twenty one 5.235 1.804 twenty two* 7.819 2.306 1.63973 23.53 twenty three* -121.819 D(23) twenty four INF 0.800 1.51633 64.14 25 INF BF

(Various specifications)

Wide angle middle Telephoto end f 4.564 13.487 36.162 Fno. 2.001 2.508 3.628 ω 40.942 13.111 4.954 Y 3.300 3.300 3.300 L 71.500 71.500 71.500

(Variable interval)

(Aspheric coefficient)

Noodles NO. K A4 A6 A8 A10 13 0.0000E+00 -2.1448E-04 -2.4845E-06 -2.1469E-08 -1.9870E-09 14 0.0000E+00 1.2206E-04 8.3942E-07 -8.3526E-08 9.7903E-10 twenty two 0.0000E+00 -6.3481E-04 -1.4507E-05 -5.4029E-06 2.8740E-07 twenty three 0.0000E+00 -5.7961E-04 -2.9081E-05 -4.5313E-06 2.2271E-07

(Focal length of each lens group)

Group Noodles NO. focal length G1 1-2 -48.070 G2 3-6 23.760 G3 7-11 -8.238 G4 13-23 11.255

(Table 1)

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 (1)β23w/tan(ωw) 0.26 0.37 0.16 0.27 0.15 0.31 0.23 (2)f2/√(fw×ft) 1.42 1.32 1.74 1.43 2.16 1.36 1.85 (3)(β23t/β23w)/(ft/fw) 0.74 0.66 0.47 0.94 0.59 0.38 0.75 (4)|f1/fw| 8.59 6.27 14.27 8.51 16.20 9.15 10.53 (5)|f1/f2| 1.92 1.55 2.68 1.93 2.46 2.19 2.02 (6)|f12t/ft| 0.73 0.77 0.81 0.75 1.10 0.77 1.05 (7)|X3|/√(fw×ft) 1.30 1.44 1.26 1.28 1.43 0.60 1.07 (8)|f2/f3| 2.83 2.36 3.69 2.71 3.55 2.34 2.88 (9)ν2p_max 65.44 63.40 65.44 65.44 67.00 40.42 67.00

Industrial Applicability

The zoom lens according to the present invention can be suitably used as a zoom lens for an imaging device such as a surveillance camera, a film camera, a digital still camera, or a digital video camera.

Claims (11)

1. A zoom lens includes, in order from an object side to an image side: a 1 st lens group having negative optical power, a 2 nd lens group having positive optical power, a 3 rd lens group having negative optical power, and a 4 th lens group having positive optical power, the 1 st lens group being fixed at a time of zooming from a wide angle end to a telephoto end, at least the 2 nd lens group, the 3 rd lens group, and the 4 th lens group being moved along an optical axis, an interval between adjacent lens groups being varied on the optical axis, the zoom lens satisfying the following formula:

0.1≤β23w/tan(ωw)≤0.5···········(1)

1.0≤f2/√(fw×ft)≤3.25···········(2)

0.15≤(β23t/β23w)/(ft/fw)≤0.98··(3)

wherein,,

fw: focal length of the zoom lens at the time of infinity focusing at the wide-angle end

And (2) ft: focal length of the zoom lens at infinity focusing at telephoto end

f2: focal length of the 2 nd lens group

ωw: half field angle of outermost ray at wide angle end

Beta 23w: a combined lateral magnification of the 2 nd lens group and the 3 rd lens group at the time of infinity focusing at the wide-angle end

Beta 23t: and a combined lateral magnification of the 2 nd lens group and the 3 rd lens group at the time of infinity focusing at a telephoto end.

2. The zoom lens of claim 1, satisfying the following formula:

5.0≤|f1/fw|≤20.0···(4)

wherein,,

f1: focal length of the 1 st lens group.

3. The zoom lens according to claim 1 or claim 2,

the 2 nd lens group is composed of 2 or less positive lenses.

4. The zoom lens according to any one of claim 1 to 3,

the 1 st lens group is composed of 1 piece of negative lenses.

5. The zoom lens according to any one of claims 1 to 4, satisfying the following formula:

0.5≤|f1/f2|≤4.0···(5)。

6. the zoom lens according to any one of claims 1 to 5, satisfying the following formula:

0.5≤|f12t/ft|≤3.0···(6)

wherein,,

f12t: a combined focal length of the 1 st lens group and the 2 nd lens group at the time of infinity focusing at the telephoto end.

7. The zoom lens according to any one of claims 1 to 6, satisfying the following formula:

0.3≤|X3|/√(fw×ft)≤2.0···(7)

wherein,,

x3: and a movement amount of the 3 rd lens group in the optical axis direction when changing magnification from the wide-angle end to the telephoto end.

8. The zoom lens according to any one of claims 1 to 7, satisfying the following formula:

1.5≤|f2/f3|≤6.0···(8)

f3: focal length of the 3 rd lens group.

9. The zoom lens according to any one of claims 1 to 8, satisfying the following formula:

ν2p＿max≤70···(9)

wherein,,

v 2 p_max: and the maximum value of Abbe numbers of the positive lenses in the 2 nd lens group.

10. The zoom lens according to any one of claim 1 to 9,

an aperture stop is disposed between the 3 rd lens group and the 4 th lens group, and is fixed when zooming from a wide-angle end to a telephoto end and focusing from infinity to a close-range.

11. An image pickup apparatus provided with the zoom lens according to any one of claims 1 to 10, and an image pickup element that converts an optical image formed by the zoom lens into an electric signal on an image side of the optical system.

Images