CN116338920A

CN116338920A - Zoom lens and imaging device

Info

Publication number: CN116338920A
Application number: CN202211638739.6A
Authority: CN
Inventors: 太幡浩文
Original assignee: Tamron Co Ltd
Current assignee: Tamron Co Ltd
Priority date: 2021-12-27
Filing date: 2022-12-20
Publication date: 2023-06-27
Also published as: JP2023096911A

Abstract

The object is to provide an imaging device provided with a compact zoom lens. The solution is that a zoom lens comprises, in order from an object side to an image side: the zoom lens is characterized in that a 1 st lens group (G1) having negative optical power, a 2 nd lens group (G2) having positive optical power, a 3 rd lens group (G3) having negative optical power, a 4 th lens group (G4) having positive optical power, a 5 th lens group (G5) having negative optical power, and a 6 th lens group (G6) having positive optical power are fixed when zooming from a wide-angle end to a telephoto end, at least the 2 nd lens group (G2), the 3 rd lens group (G3), the 4 th lens group (G4) and the 5 th lens group (G5) are moved along an optical axis, and the intervals between adjacent lens groups on the optical axis are changed, and the zoom lens satisfies a prescribed mathematical formula.

Description

Zoom lens and imaging device

Technical Field

The present invention relates to a zoom lens and an imaging apparatus.

Background

In recent years, imaging devices using solid-state imaging elements such as digital cameras have been increasingly popular. With this, the zoom lens has been advanced in high performance and miniaturization, and a small-sized image pickup apparatus system has been rapidly popularized. Among conventional lenses, particularly in a monitoring lens, a camera lens, a digital camera lens, a single lens reflex camera lens, a mirror-less single lens camera lens, and the like, which are required to have a zoom lens of a full length and a small size, there is a problem that the zoom lens has a high optical performance and is made wide-angle and small-sized.

The zoom lens described in patent document 1 discloses an invention of a zoom lens including 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, a 4 th lens group having positive optical power, a 5 th lens group having positive optical power, and a 6 th lens group having positive optical power. However, in the zoom lens described in the embodiment, the overall length is long although the zoom lens is wide-angle and high magnification, which hinders miniaturization.

The zoom lens described in patent document 2 is a zoom lens including 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, a 4 th lens group, and a rear group. However, in the zoom lens described in the embodiment, the magnification is small, and it is difficult to achieve miniaturization and high magnification.

The zoom lens described in patent document 3 is a zoom lens including 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 1 or more rear groups. However, in the zoom lens described in the embodiment, the group constituting the lens is small, and therefore it is difficult to achieve a wide angle, high magnification, and high resolution.

Prior art literature

Patent literature

Patent document 1: japanese patent No. 6840661

Patent document 2: japanese patent application laid-open No. 2020-012922

Patent document 3: japanese patent laid-open publication No. 2019-159746

Disclosure of Invention

Problems to be solved by the invention

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

Means for solving the problems

A zoom lens includes, in order from an object side to an image side: the zoom lens includes 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, a 4 th lens group having positive optical power, a 5 th lens group having negative optical power, and a 6 th lens group having positive optical power, wherein the 1 st lens group is fixed at the time of zooming from a wide angle end to a telephoto end, at least the 2 nd lens group, the 3 rd lens group, the 4 th lens group, and the 5 th lens group are moved along an optical axis, an interval between adjacent lens groups on the optical axis is changed, and the zoom lens satisfies the following formula.

3.0≤f12w/fw≤15.0····(1)

1.2≤|f2/f3|≤8.0·····(2)

vd1≤35················(3)

Wherein,,

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

f12w: synthetic focal length of the 1 st lens group and the 2 nd lens group at infinity focusing at wide-angle end

f2: focal length of the 2 nd lens group

f3: focal length of the 3 rd lens group

vd1: abbe number of negative lens included in 1 st lens group at d-line

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

Effects of the invention

According to the present invention, a zoom lens having high optical performance and wide angle and small size can be provided.

Drawings

Fig. 1 is a sectional view of a zoom lens of embodiment 1.

Fig. 2 is a longitudinal aberration diagram at the wide-angle end of the zoom lens of embodiment 1.

Fig. 3 is a longitudinal aberration diagram at the telephoto end of the zoom lens of embodiment 1.

Fig. 4 is a sectional view of the zoom lens of embodiment 2.

Fig. 5 is an aberration diagram at the wide-angle end of the zoom lens of embodiment 2.

Fig. 6 is an aberration diagram at the telephoto end of the zoom lens of embodiment 2.

Fig. 7 is a sectional view of the zoom lens of embodiment 3.

Fig. 8 is an aberration diagram at the wide-angle end of the zoom lens of embodiment 3.

Fig. 9 is an aberration diagram at the telephoto end of the zoom lens of embodiment 3.

Fig. 10 is a sectional view of the zoom lens of embodiment 4.

Fig. 11 is an aberration diagram at the wide-angle end of the zoom lens of embodiment 4.

Fig. 12 is an aberration diagram at the telephoto end of the zoom lens of embodiment 4.

Fig. 13 is a sectional view of a zoom lens of embodiment 5.

Fig. 14 is an aberration diagram at the wide-angle end of the zoom lens of embodiment 5.

Fig. 15 is an aberration diagram at the telephoto end of the zoom lens of embodiment 5.

Fig. 16 is a sectional view of a zoom lens of embodiment 6.

Fig. 17 is an aberration diagram at the wide-angle end of the zoom lens of embodiment 6.

Fig. 18 is an aberration diagram at the telephoto end of the zoom lens of embodiment 6.

Fig. 19 is a sectional view of a zoom lens of embodiment 7.

Fig. 20 is an aberration diagram at the wide-angle end of the zoom lens of embodiment 7.

Fig. 21 is an aberration diagram at the telephoto end of the zoom lens of embodiment 7.

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 the reference numerals

S.aperture stop

CG. 22. Protective glass

IMG image plane

G1.1 st lens group

G2.2 nd lens group

G3.3 rd lens group

G4.4 th lens group

G5.5 th lens group

G6.6 th lens group

G7.7 th lens group

1- & camera

2. Main body

3.lens barrel

21-CCD sensor for detecting a position of a body

Detailed Description

Embodiments of a zoom lens and an imaging apparatus according to the present invention are described below. The zoom lens and the image pickup apparatus described below are one embodiment of the zoom lens and the image pickup apparatus according to the present invention, and the zoom lens and the image pickup apparatus according to the present invention are not limited to the following embodiments.

1. Zoom lens

1-1 optical constitution

The zoom lens according to the present invention is configured to have, 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, a 4 th lens group having positive optical power, a 5 th lens group having negative optical power, and a 6 th lens group having positive optical power. According to this configuration, the optical performance is high, and the wide angle and the miniaturization are easily achieved. In addition, in terms of further improving performance, it is preferable to have the 7 th lens group on the image side of the 6 th lens group.

(1) 1 st lens group

The 1 st lens group is not particularly limited as long as it has negative optical power and is fixed with respect to the image plane at the time of magnification change. The 1 st lens group is composed of 1 meniscus lens, which facilitates wide angle and miniaturization.

Here, the "lens group" is constituted by 1 lens or a plurality of lenses adjacent to each other, and the interval between the adjacent lens groups along the optical axis varies at the time of magnification change. In the case where one lens group is constituted by a plurality of lenses, it is assumed that the distance on the optical axis between the lenses included in the one lens group does not change at the time of focusing.

(2) Lens group 2

The specific configuration of the 2 nd lens group is not particularly limited as long as it is a lens group having positive optical power and moving along the optical axis at the time of magnification change. In terms of moving on the optical axis at high speed at the time of magnification change, the 2 nd lens group is preferably constituted by 1 lens. In addition, the 2 nd lens group preferably has a biconvex lens. With this configuration, aberration can be easily corrected and miniaturization can be achieved.

(3) 3 rd lens group

The 3 rd lens group is not particularly limited as long as it is a lens group having negative optical power and moving along the optical axis at the time of magnification change. The negative lenses included in the 3 rd lens group are preferably 3 or less. The 3 rd lens group is preferably configured to have only 1 positive lens. The 3 rd lens group is preferably composed of a negative lens, and a positive lens from the object side toward the image side. With this configuration, aberration can be easily corrected and miniaturization can be achieved.

(4) 4 th lens group

The 4 th lens group is not particularly limited as long as it has positive optical power and moves along the optical axis at the time of magnification change. The 4 th lens group preferably has a positive lens on the most object side. The 4 th lens group is preferably composed of a positive lens, a negative lens, and a positive lens from the object side toward the image side. With this configuration, aberration can be easily corrected and miniaturization can be achieved.

(5) 5 th lens group

The 5 th lens group is not particularly limited as long as it has negative optical power and moves along the optical axis at the time of magnification change. The 5 th lens group is preferably composed of a positive lens and a negative lens from the object side toward the image side. With this configuration, aberration can be easily corrected and miniaturization can be achieved.

(6) 6 th lens group

The specific configuration of the 6 th lens group is not particularly limited as long as it has positive optical power. The 6 th lens group is preferably constituted by only positive lenses. The 6 th lens group is preferably fixed with respect to the image plane. With this configuration, aberration can be easily corrected and miniaturization can be achieved.

(7) Aperture diaphragm

In this zoom lens, the arrangement of the aperture stop is not particularly limited. By disposing the aperture stop between the 3 rd lens group and the 4 th lens group, aberrations can be effectively offset in the front-rear direction of the aperture stop, which is preferable in obtaining a zoom lens having high optical performance.

1-2. Action

(1) Zoom ratio

In this zoom lens, the specific operation is not particularly limited as long as the 1 st lens group is fixed on the optical axis and the 2 nd, 3 rd, 4 th and 5 th lens groups are moved on the optical axis when changing magnification from the wide-angle end to the telephoto end.

(2) Focusing

The zoom lens is not limited as long as it moves on the optical axis when focusing from infinity to a close distance. In order to suppress aberration fluctuation, it is preferable that the 3 rd lens group, the 4 th lens group, or the 5 th lens group is moved on the optical axis. In addition, in order to properly suppress aberration fluctuation and obtain higher resolution in focusing from infinity to a close distance, it is preferable that the 5 th lens group is moved on the optical axis to the image side.

1-3. Math

The zoom lens preferably has the above-described configuration, and satisfies at least 1 or more of the following equations.

1-3-1. Formula (1)

3.0≤f12w/fw≤15.0····(1)

Wherein,,

f12w: composite focal length of 1 st lens group and 2 nd lens group at infinity focusing at wide-angle end

Equation (1) is an equation for specifying a ratio of a focal length of the zoom lens at the time of infinity focusing at the wide-angle end to a combined focal length of the 1 st lens group and the 2 nd lens group at the wide-angle end. By satisfying the expression (1), spherical aberration, astigmatism, axial chromatic aberration are well corrected, and miniaturization is easily achieved at the wide-angle end.

If the value is lower than the lower limit value of the formula (1), the combined power of the 1 st lens group and the 2 nd lens group at the wide angle end becomes strong, spherical aberration, astigmatism, and axial chromatic aberration increase, and it is difficult to obtain high optical performance. On the other hand, if the upper limit value of the formula (1) is exceeded, the combined power of the 1 st lens group and the 2 nd lens group at the wide angle end becomes weak, correction of spherical aberration, astigmatism, axial chromatic aberration is insufficient, and miniaturization of the zoom lens is difficult to achieve.

In order to obtain the above-described effect, the lower limit value of the formula (1) is preferably 3.5, more preferably 4.0. The upper limit of the formula (1) is preferably 14.0, more preferably 11.0. In the case where these preferable lower limit or upper limit are used, the inequality sign (. Ltoreq.) with the equal sign may be replaced with the inequality sign (. <) in the formula (1). The same applies to other formulas as the principle.

1-3-2. Formula (2)

1.2≤|f2/f3|≤8.0·····(2)

Wherein,,

f2: focal length of the 2 nd lens group

f3: focal length of 3 rd lens group

Equation (2) is an equation for defining a ratio of the focal length of the 2 nd lens group to the focal length of the 3 rd lens group. By satisfying the expression (2), when the magnification is changed from the wide-angle end to the telephoto end, the spherical aberration and curvature of field that occur can be corrected well, and the wide-angle and miniaturization can be easily achieved.

If the refractive power of the 2 nd lens group is lower than the lower limit value of the formula (2), the spherical aberration from the wide-angle end to the telephoto end is excessively corrected, and the curvature of field cannot be corrected, so that it is difficult to obtain high optical performance. On the other hand, if the upper limit value of the formula (2) is exceeded, the optical power of the 2 nd lens group becomes weak, and it is difficult to correct spherical aberration from the wide-angle end to the telephoto end. In addition, miniaturization is difficult to achieve.

In order to obtain the above-described effect, the lower limit value of the formula (2) is preferably 1.8, more preferably 2.0. The upper limit of the formula (2) is preferably 7.0, more preferably 6.5.

1-3-3. 1 (3)

vd1≤35················(3)

Wherein,,

vd1: abbe number at d-line of negative lens included in 1 st lens group

The expression (3) is an expression for defining the abbe number of the negative lens included in the 1 st lens group at the d-line. By satisfying the expression (3), it is easy to correct axial chromatic aberration from the wide-angle end to the telephoto end, chromatic aberration of magnification, and realize high optical performance.

On the other hand, if the upper limit value of the expression (3) is exceeded, the axial chromatic aberration and chromatic aberration of magnification from the wide-angle end to the telephoto end cannot be corrected, and it is difficult to obtain high optical performance.

In order to obtain the above-described effect, the lower limit value of the formula (3) is preferably 10.0, more preferably 15.0. The upper limit of the formula (3) is preferably 30.0, more preferably 25.0.

1-3-4. 1 (4)

1.2≤|f1/f2|≤6.0·····(4)

Wherein,,

f1: focal length of 1 st lens group

Equation (4) is an equation for defining a ratio of the focal length of the 1 st lens group to the focal length of the 2 nd lens group. By satisfying the expression (4), the curvature of field at the wide-angle end can be corrected appropriately, and a zoom lens having a bright F value can be obtained.

If the refractive power is lower than the lower limit value of expression (4), the optical power of the 1 st lens group becomes strong, and field curvature cannot be corrected at the wide angle end, so that it is difficult to achieve a wide angle and high optical performance. On the other hand, if the upper limit value of the formula (4) is exceeded, the optical power of the 1 st lens group becomes weak, and miniaturization at the wide-angle end is difficult to achieve.

In order to obtain the above-described effect, the lower limit value of the formula (4) is preferably 1.5, more preferably 1.8. The upper limit of the formula (4) is preferably 5.0, more preferably 4.0.

1-3-5. 1. 5)

5.0≤|f1/fw|≤50.0····(5)

Equation (5) is an equation for defining a ratio of a focal length of the zoom lens at the time of infinity focusing at the wide-angle end to a focal length of the 1 st lens group. By satisfying the expression (5), curvature of field can be easily corrected well at the wide-angle end, and miniaturization can be achieved.

If the refractive power is lower than the lower limit value of the formula (5), the optical power of the 1 st lens group becomes strong, the correction of curvature of field becomes excessive, and it is difficult to obtain high optical performance at the wide-angle end. On the other hand, if the upper limit value of the expression (5) is exceeded, the optical power of the 1 st lens group becomes weak, the curvature of field cannot be corrected, and downsizing at the wide-angle end is difficult.

In order to obtain the above-described effect, the lower limit value of the formula (5) is preferably 7.0, more preferably 8.0. The upper limit of the formula (5) is preferably 40.0, more preferably 35.0.

1-3-6. 1 (6)

2.0≤f2/fw≤15.0······(6)

Equation (6) is an equation for defining a ratio of a focal length of the zoom lens at the time of infinity focusing at the wide-angle end to a focal length of the 2 nd lens group. By satisfying the expression (6), field curvature can be easily corrected well at the wide-angle end, and miniaturization can be achieved.

If the value is less than the lower limit value of the formula (6), the optical power of the 2 nd lens group becomes strong, the correction of curvature of field becomes excessive, and it is difficult to obtain high optical performance at the wide-angle end. On the other hand, if the upper limit value of the expression (6) is exceeded, the optical power of the 2 nd lens group becomes weak, the curvature of field cannot be corrected, and downsizing at the wide-angle end is difficult.

In order to obtain the above-described effect, the lower limit value of the formula (6) is preferably 3.0, more preferably 3.5. The upper limit of the formula (6) is preferably 12.0, more preferably 10.0.

1-3-7. Formula (7)

0.5≤|f3/fw|≤5.0·····(7)

Equation (7) is an equation for defining a ratio of a focal length of the zoom lens at the time of infinity focusing at the wide-angle end to a focal length of the 3 rd lens group. By satisfying the expression (7), it is easy to correct spherical aberration, coma, curvature of field, distortion aberration at the wide-angle end well, and realize high optical performance.

If the refractive power of the 3 rd lens group is lower than the lower limit value of the formula (7), the optical power becomes strong, and spherical aberration, coma, curvature of field, and distortion aberration at the wide-angle end cannot be corrected, so that it is difficult to obtain high optical performance. On the other hand, if the upper limit value of expression (7) is exceeded, the optical power of the 3 rd lens group becomes weak, and the amount of movement of the 3 rd lens group is required when changing magnification from the wide-angle end to the telephoto end, making it difficult to achieve miniaturization.

In order to obtain the above-described effect, the lower limit value of the formula (7) is preferably 0.6, more preferably 0.8, still more preferably 1.0, and still more preferably 1.2. The upper limit of the formula (7) is preferably 4.0, more preferably 3.5, still more preferably 3.0, and still more preferably 2.5.

1-3-8. 1 (8)

0.3≤|f3/f4|≤3.0·····(8)

Equation (8) is an equation for defining a ratio of the focal length of the 4 th lens group to the focal length of the 3 rd lens group. By satisfying the expression (8), spherical aberration, coma, curvature of field, and distortion aberration can be easily corrected well, and miniaturization can be achieved.

If the refractive power of the 3 rd lens group is lower than the lower limit value of the formula (8), the refractive power becomes strong, and spherical aberration, coma, curvature of field, and distortion cannot be corrected, so that it is difficult to obtain high optical performance. On the other hand, if the upper limit value of the formula (8) is exceeded, the optical power of the 3 rd lens group becomes weak, and spherical aberration, coma aberration, curvature of field, and distortion aberration cannot be corrected, so that miniaturization is difficult.

In order to obtain the above-described effect, the lower limit value of the formula (8) is preferably 0.4, more preferably 0.5. The upper limit of the formula (8) is preferably 2.0, more preferably 1.5.

1-3-9. 1 (9)

0.3≤f12t/ft≤3.0·····(9)

Wherein,,

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

f12t: composite focal length of 1 st lens group and 2 nd lens group at infinity focusing at telephoto end

Equation (9) is an equation for specifying a ratio of a focal length of the zoom lens at the telephoto end at the time of infinity focusing to a combined focal length of the 1 st lens group and the 2 nd lens group at the telephoto end. By satisfying the expression (9), spherical aberration, astigmatism, axial chromatic aberration are easily corrected well, and miniaturization is achieved.

If the value is lower than the lower limit value of the formula (9), the combined power of the 1 st lens group and the 2 nd lens group at the telephoto end becomes strong, spherical aberration, astigmatism, and axial chromatic aberration increase, and it is difficult to obtain high optical performance. On the other hand, if the upper limit value of the formula (9) is exceeded, the combined power of the 1 st lens group and the 2 nd lens group at the telephoto end becomes weak, the correction of spherical aberration, astigmatism, axial chromatic aberration is insufficient, and it is difficult to achieve miniaturization of the zoom lens.

In order to obtain the above-described effect, the lower limit value of the formula (9) is preferably 0.4, more preferably 0.5. The upper limit of the formula (9) is preferably 2.0, more preferably 1.5.

1-3-10. 1 (10)

10.0≤TL ² /(fw×ft)≤50.0·····(10)

Wherein,,

TL: lens full length from most object side surface to image pickup surface on optical axis

Equation (10) is an equation for specifying the ratio of the product of the focal length of the zoom lens at the time of infinity focusing at the wide-angle end to the focal length of the zoom lens at the time of infinity focusing at the telephoto end to the square of the total length of the zoom lens. Here, the total lens length represents the distance from the object-closest side surface to the image pickup surface on the optical axis, and the object-closest side surface represents the lens tip on the object side on the optical axis. By satisfying the expression (10), the entire length of the zoom lens from the wide-angle end to the telephoto end can be made appropriate, and a compact zoom lens can be obtained.

If the value is lower than the lower limit value of the formula (10), it is difficult to suppress each aberration and obtain high optical performance when zooming from the wide-angle end to the telephoto end. On the other hand, if the upper limit value of the expression (10) is exceeded, it is difficult to suppress each aberration and achieve miniaturization when zooming from the wide-angle end to the telephoto end.

In order to obtain the above-described effect, the lower limit value of the formula (10) is preferably 15.0, more preferably 20.0. The upper limit of the formula (10) is preferably 40.0, more preferably 30.0.

1-3-11. Formula (11)

0.01≤|X3| ² /(fw×ft)≤5.0·····(11)

Wherein,,

x3: shift amount of 3 rd lens group at varying magnification from wide-angle end to telephoto end

Equation (11) is an equation for defining a ratio of a product of a focal length of the zoom lens at the time of infinity focusing at the wide-angle end and a focal length of the zoom lens at the time of infinity focusing at the telephoto end to a square of a moving amount of the 3 rd lens group at the time of zooming from the wide-angle end to the telephoto end. By satisfying the expression (11), correction of each aberration is easy and miniaturization is achieved.

If the amount of movement of the 3 rd lens group is less than the lower limit value of expression (11), the amount of movement is too short when changing magnification from the wide-angle end to the telephoto end, and it is difficult to obtain high magnification optical performance. It is difficult to achieve miniaturization. On the other hand, if the upper limit value of the expression (11) is exceeded, the amount of movement of the 3 rd lens group increases when changing magnification from the wide-angle end to the telephoto end, and it is difficult to achieve miniaturization.

In order to obtain the above-described effect, the lower limit value of the formula (11) is preferably 0.02, more preferably 0.03. The upper limit of the formula (11) is preferably 4.0, more preferably 3.0.

1-3-12. 1 (12)

0.3≤|f1/ft|≤7.0·····(12)

Equation (12) is an equation for defining a ratio of a focal length of the zoom lens at the telephoto end to a focal length of the 1 st lens group at the time of infinity focusing. By satisfying the expression (12), field curvature can be easily corrected well at the telephoto end, and miniaturization can be achieved.

If the refractive power is lower than the lower limit value of the formula (12), the optical power of the 1 st lens group becomes strong, the correction of curvature of field becomes excessive, and it is difficult to obtain high optical performance at the telephoto end. On the other hand, if the upper limit value of the formula (5) is exceeded, the optical power of the 1 st lens group becomes weak, the curvature of field cannot be corrected, and it is difficult to achieve miniaturization of the telephoto end.

In order to obtain the above-described effect, the lower limit value of the formula (12) is preferably 0.5, more preferably 0.7. The upper limit of the formula (12) is preferably 5.0, more preferably 4.0.

1-3-13. Formula (13)

0.1≤f2/ft≤3.0·····(13)

Equation (13) is an equation for specifying a ratio of a focal length of the zoom lens at the telephoto end to a focal length of the 2 nd lens group at the time of infinity focusing. By satisfying the expression (13), correction of each aberration is easy and miniaturization is achieved.

Equation (13) is an equation for specifying a ratio of a focal length of the zoom lens at the telephoto end to a focal length of the 2 nd lens group at the time of infinity focusing. By satisfying the expression (13), field curvature can be easily corrected well at the telephoto end, and miniaturization can be achieved.

If the value is less than the lower limit value of the formula (13), the optical power of the 2 nd lens group becomes strong, the correction of field curvature becomes excessive, and it is difficult to obtain high optical performance at the telephoto end. On the other hand, if the upper limit value of the formula (13) is exceeded, the optical power of the 2 nd lens group becomes weak, the curvature of field cannot be corrected, and it is difficult to achieve miniaturization of the telephoto end.

In order to obtain the above-described effect, the lower limit value of the formula (13) is preferably 0.2, more preferably 0.3. The upper limit of the formula (13) is preferably 2.0, more preferably 1.0.

1-3-14. Formula (14)

0.5≤|f5/fw|≤5.0·····(14)

Wherein,,

f5: focal length of 5 th lens group

Equation (14) is an equation for defining a ratio of a focal length of the zoom lens at the time of infinity focusing at the wide-angle end to a focal length of the 5 th lens group. By satisfying the expression (14), coma aberration and curvature of field can be easily corrected well, and miniaturization can be achieved.

If the refractive power of the 5 th lens group is lower than the lower limit value of expression (14), coma and curvature of field at the wide-angle end cannot be corrected, and it is difficult to obtain high optical performance. On the other hand, if the upper limit value of expression (14) is exceeded, the movement amount of the 5 th lens group is required, and it is difficult to achieve miniaturization.

In order to obtain the above-described effect, the lower limit value of the formula (14) is preferably 1.0, more preferably 1.2. The upper limit of the formula (14) is preferably 4.0, more preferably 3.0.

1-3-15. Formula (15)

2.0≤f6/fw≤30.0·····(15)

Wherein,,

f6: focal length of 6 th lens group

Equation (15) is an equation for defining a ratio of a focal length of the zoom lens at the time of infinity focusing at the wide-angle end to a focal length of the 6 th lens group. By satisfying the expression (15), coma aberration and curvature of field can be easily corrected well, and miniaturization can be achieved.

If the refractive power of the 6 th lens group is lower than the lower limit value of the expression (15), coma aberration and curvature of field at the wide-angle end cannot be corrected, and it is difficult to obtain high optical performance. On the other hand, if the upper limit value of expression (15) is exceeded, the amount of movement is required in other groups, and it is difficult to achieve miniaturization.

In order to obtain the above-described effect, the lower limit value of the formula (15) is preferably 2.5, more preferably 3.0. The upper limit of the formula (15) is preferably 20.0, more preferably 15.0.

2. Image pickup apparatus

Next, an imaging device according to the present invention will be described. An imaging device according to the present invention is characterized by comprising the zoom lens according to the present invention and an imaging element for converting an optical image formed by the zoom lens into an electrical signal. Further, the image pickup element is preferably provided on the image side of the zoom lens.

Here, the image pickup device and the like are not particularly limited, and a solid-state image pickup device and the like such as a CCD (Charge Coupled Device: charge coupled device) sensor, a CMOS (Complementary Metal Oxide Semiconductor: complementary metal oxide semiconductor) sensor and the like can also be used. The imaging device according to the present invention is suitable for imaging devices such as digital cameras and video cameras using these solid-state imaging elements. The imaging device can be applied to various imaging devices such as a single-lens reflex camera, a mirror-less single-lens camera, a digital camera, a monitoring camera, a vehicle-mounted camera, and a unmanned aerial vehicle-mounted camera. The imaging device may be a lens-interchangeable imaging device or a fixed lens type imaging device in which a lens is fixed to a housing. The zoom lens according to the present invention is particularly suitable as a zoom lens for an imaging device mounted with an imaging element having a large size such as a full size. The zoom lens is compact and lightweight as a whole, and has high optical performance, so that a high-quality captured image can be obtained even when the zoom lens is used as a zoom lens for such an imaging device.

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

The main body 2 has a CCD sensor 21 as an image pickup element and a cover glass 22. The CCD sensor 21 is disposed in the body 2 at a position where the optical axis of the zoom lens 30 mounted in the barrel 3 of the body 2 becomes the center thereof. The main body 2 may also have an IR cut filter or the like instead of the cover glass 22.

Next, examples are shown and the present invention is specifically explained. However, the present invention is not limited to the following examples.

Example 1

(1) Optical structure

Fig. 1 is a sectional view of a zoom lens according to embodiment 1 of the present invention at the time of infinity focusing. The zoom lens is composed of, in order from the object side, a 1 st lens group G1 having negative optical power, a 2 nd lens group G2 having positive optical power, a 3 rd lens group G3 having negative optical power, a 4 th lens group G4 having positive optical power, a 5 th lens group G5 having negative optical power, and a 6 th lens group G6 having positive optical power.

When changing magnification from the wide-angle end to the telephoto end, the 2 nd lens group G2 moves from the image side to the object side, the 3 rd lens group G3 moves to the image side, the 4 th lens group G4 moves from the image side to the object side, and the 5 th lens group G5 moves to the object side in a locus convex to the object side along the optical axis.

Upon focusing from an infinitely-distant object to a close-distance object, the 5 th lens group G5 moves along the optical axis from the object side to the image side.

The 1 st lens group G1 is composed of a negative meniscus lens having a convex object side.

The 2 nd lens group G2 is constituted by a biconvex lens.

The 3 rd lens group G3 is composed of a biconcave lens and a cemented lens formed by a biconcave lens and a positive meniscus lens, in order from the object side.

The 4 th lens group G4 is composed of a biconvex lens having aspherical surfaces on both sides, and a cemented lens formed by a negative meniscus lens and a biconvex lens cemented together, in order from the object side.

The 5 th lens group G5 is composed of a cemented lens formed by a positive meniscus lens and a negative meniscus lens cemented in order from the object side.

The 6 th lens group G6 is constituted by a biconvex lens having aspherical surfaces on both sides.

The aperture stop S is located between the 3 rd lens group G3 and the 4 th lens group G4, and is fixed to the image plane IMG when zooming from the wide-angle end to the telephoto end and focusing from an infinitely distant object to a close object.

In fig. 1, "IMG" is an image plane, and specifically, indicates an image pickup plane of a solid-state image pickup device such as a CCD sensor or a CMOS sensor, a film plane of a silver halide film, or the like. In addition, a cover glass CG is provided on the object side of the image plane IMG. This point is also the same in the cross-sectional views of the lenses shown in the other embodiments, and therefore, the description thereof will be omitted.

(2) Numerical examples

Next, a numerical example to which specific numerical values are applied to the zoom lens will be described. The following indicates "lens data", "various specifications", "variable interval", "aspherical coefficient", "focal length of each lens group". The values of the respective formulas (table 1) are summarized in example 7. In the following numerical examples, the units of the numerical values of the length units are not described as "mm" and the units of the angles are all "°. "INF" means infinity.

In (lens data), "surface No." denotes a number of a lens surface counted from the object side, "r" denotes a radius of curvature of the lens surface, "D" denotes a lens wall thickness or an air interval on the optical axis, "Nd" denotes a refractive index at D-line (wavelength λ=587.56 nm), and "vd" denotes an abbe number at D-line. In addition, the column "face No." is followed by a numeral "" indicates that the lens face is aspherical, and "S" indicates that the face is an aperture stop. In the column of "D", the meaning of "D (7)", "D (10)", etc. is that the interval on the optical axis of the lens surface is a variable interval that varies at the time of magnification or at the time of focusing. In addition, "BF" means back focus.

In (various specification tables), "F" is the focal length of the zoom lens, "fno" is the F value, "ω" is the half field angle, "Y" is the image height, and "L" is the total lens length. The values at the time of infinity focusing at the wide-angle end, intermediate end, and telephoto end are shown, respectively.

In (variable interval), values at the wide-angle end, intermediate end, and telephoto end at the time of infinity focusing and at the time of a finite distance are shown, respectively.

The (aspherical surface coefficient) means an aspherical surface coefficient when an aspherical surface shape is defined as follows. Where x is the displacement amount with respect to the reference plane in the optical axis direction, r is the paraxial radius of curvature, H is the height with respect to the optical axis in the direction perpendicular to the optical axis, K is the conic coefficient, and An is the aspherical coefficient n times. In the table of "aspherical coefficients", the "E.+ -. XX" represents an index mark, which means ". Times.10 ^±XX ”。

[ number 1]

The matters in each numerical embodiment are the same as those in other embodiments, and therefore, the explanation thereof will be omitted.

Fig. 2 and 3 show longitudinal aberration diagrams of the zoom lens at the wide-angle end and the telephoto end when an object at infinity is in focus. The longitudinal aberration diagrams shown in the respective figures are spherical aberration (mm), astigmatism (mm), and distortion aberration (%) in order from the left side of the figure. In the spherical aberration diagram, the solid line represents the spherical aberration at the d-line (wavelength 587.56 nm), the short-dashed line represents the spherical aberration at the g-line (wavelength 435.84 nm), and the long-dashed line represents the spherical aberration at the C-line (wavelength 656.28 nm). In the astigmatic diagram, the vertical axis represents the half field angle (ω), the horizontal axis represents defocus, the solid line represents the sagittal image plane of the d-line, and the broken line represents the meridional image plane of the d-line. In the distortion aberration diagram, the vertical axis is a half field angle (ω), and the horizontal axis is distortion aberration. These matters are the same in the aberration diagrams shown in other embodiments, and therefore, description thereof will be omitted later.

(lens data)

Surface NO.	r	D	Nd	vd
					1	27.458	0.800	1.86966	20.01
2	16.805	D(2)
					3	18.388	4.080	1.77250	49.62
4	-132.936	D(4)
					5	-61.341	0.500	1.87071	40.72
6	10.064	2.072
					7	-13.959	0.500	1.69930	51.11
8	13.743	1.513	1.95906	17.47
					9	125.261	D(9)
10S	INF	D(10)
					11*	10.000	3.237	1.61881	63.85
12*	-54.622	0.582
					13	11.522	0.500	1.91082	35.25
14	6.854	4.117	1.43700	95.10
					15	-16.453	D(15)
16	8.422	2.142	1.49700	81.60
					17	21.545	0.500	1.91082	35.25
18	5.263	D(18)
					19*	31.625	2.149	1.53504	55.71
20*	-13.893	4.500
					21	INF	0.800	1.51680	64.19
22	INF	BF
					23	INF	-

(various specification sheets)

	Wide angle end	Intermediate part	Telephoto end
				f	4.428	13.609	41.802
Fno.	1.854	2.615	3.656
				ω	41.244	13.000	4.267
Y	3.300	3.300	3.300
				L	63.000	63.000	63.000

(variable spacing)

	Wide angle end	Intermediate part	Telephoto end
				Photographic distance	INF	INF	INF
D(2)	8.138	5.073	1.457
				D(4)	1.250	9.313	15.690
D(9)	9.959	4.961	2.200
				D(10)	12.243	6.557	0.750
D(15)	0.902	2.506	8.390
				D(18)	2.288	6.371	6.293
BF	0.200	0.200	0.200
					Wide angle end	Intermediate part	Telephoto end
Photographic distance	0.3m	1.0m	1.2m
				D(15)	0.959	2.611	9.252
D(18)	2.231	6.266	5.431

(aspherical coefficient)

Surface NO.	K	A4	A6	A8	A10
						11	0.0000E+00	-1.0953E-04	2.8597E-07	2.2924E-08	-9.9126E-10
12	0.0000E+00	1.6584E-04	2.7412E-07	3.0230E-08	-1.2626E-09
						19	0.0000E+00	-6.0896E-04	2.6000E-05	-3.0000E-06	1.1924E-07
20	0.0000E+00	-4.6032E-04	2.6000E-05	-3.0000E-06	1.1006E-07

(focal Length of each lens group)

Group of	Surface NO.	Focal length
			G1	1-2	-51.415
G2	3-4	21.125
			G3	5-9	-6.735
G4	11-15	10.251
			G5	16-18	-12.734
G6	19-20	18.317

Example 2

(1) Optical structure

Fig. 4 is a sectional view of the zoom lens according to embodiment 2 of the present invention at the time of infinity focusing. The zoom lens is composed of, in order from the object side, a 1 st lens group G1 having negative optical power, a 2 nd lens group G2 having positive optical power, a 3 rd lens group G3 having negative optical power, a 4 th lens group G4 having positive optical power, a 5 th lens group G5 having negative optical power, and a 6 th lens group G6 having positive optical power.

When changing magnification from the wide-angle end to the telephoto end, the 2 nd lens group G2 moves from the image side to the object side, the 3 rd lens group G3 moves to the image side, the 4 th lens group G4 moves from the image side to the object side, and the 5 th lens group G5 moves from the image side to the object side along the optical axis.

The 2 nd lens group G2 is constituted by a biconvex lens.

(2) Numerical examples

Next, a numerical example of the zoom lens to which specific numerical values are applied is shown. Fig. 5 and 6 show longitudinal aberration diagrams of the zoom lens at the time of infinity focusing at the wide-angle end and the telephoto end.

(lens data)

(various specification sheets)

	Wide angle end	Intermediate part	Telephoto end
				f	4.431	13.611	41.797
Fno.	1.855	3.301	4.368
				ω	38.754	13.000	4.271
Y	3.300	3.300	3.300
				L	64.000	64.000	64.000

(variable spacing)

	Wide angle end	Intermediate part	Telephoto end
				Photographic distance	INF	INF	INF
D(2)	9.729	7.196	2.261
				D(4)	1.250	5.766	11.970
D(9)	7.900	5.917	4.648
				D(10)	13.794	5.961	0.750
D(15)	0.894	1.963	4.224
				D(18)	2.296	9.060	12.010
BF	0.200	0.200	0.200
					Wide angle end	Intermediate part	Telephoto end
Photographic distance	0.3m	1.0m	1.2m
				D(15)	0.937	2.026	4.629
D(18)	2.253	8.997	11.607

(aspherical coefficient)

(focal Length of each lens group)

Group of	Surface NO.	Focal length
			G1	1-2	-38.073
G2	3-4	16.360
			G3	5-9	-6.018
G4	11-15	9.887
			G5	16-18	-10.706
G6	19-20	17.859

Example 3

(1) Optical structure

Fig. 7 is a cross-sectional view showing the zoom lens according to embodiment 3 of the present invention in infinity focusing. The zoom lens is composed of, in order from the object side, a 1 st lens group G1 having negative optical power, a 2 nd lens group G2 having positive optical power, a 3 rd lens group G3 having negative optical power, a 4 th lens group G4 having positive optical power, a 5 th lens group G5 having negative optical power, and a 6 th lens group G6 having positive optical power.

When changing magnification from the wide-angle end to the telephoto end, the 2 nd lens group G2 moves toward the object side along the optical axis in a locus convex toward the image side, the 3 rd lens group G3 moves toward the image side, the 4 th lens group G4 moves from the image side to the object side, and the 5 th lens group G5 moves toward the object side in a locus convex toward the object side.

The 2 nd lens group G2 is constituted by a biconvex lens.

(2) Numerical examples

Next, a numerical example of the zoom lens to which specific numerical values are applied is shown. Fig. 8 and 9 show longitudinal aberration diagrams of the zoom lens at the time of infinity focusing at the wide-angle end and the telephoto end.

(lens data)

Surface NO.	r	D	Nd	vd
					1	39.881	0.800	1.86966	20.01
2	23.957	D(2)
					3	26.664	4.353	1.77250	49.62
4	-119.925	D(4)
					5	-60.839	0.500	1.87071	40.72
6	14.473	2.148
					7	-48.037	0.500	1.69930	51.11
8	10.497	1.846	1.95906	17.47
					9	20.819	D(9)
10S	INF	D(10)
					11*	10.000	2.757	1.61881	63.85
12*	-260.853	0.200
					13	10.208	0.500	1.91082	35.25
14	6.800	3.669	1.43700	95.10
					15	-12.670	D(15)
16	7.860	1.657	1.49700	81.60
					17	8.692	0.500	1.91082	35.25
18	4.057	D(18)
					19*	34.372	1.855	1.53504	55.71
20*	-24.203	4.500
					21	INF	0.800	1.51680	64.19
22	INF	BF
					23	INF	-

(various specification sheets)

	Wide angle end	Intermediate part	Telephoto end
				f	4.414	13.624	41.789
Fno.	1.864	2.636	3.449
				ω	40.296	12.986	4.296
Y	3.300	3.300	3.300
				L	64.500	64.500	64.500

(variable spacing)

	Wide angle end	Intermediate part	Telephoto end
				Photographic distance	INF	INF	INF
D(2)	2.887	3.550	1.698
				D(4)	1.250	11.810	20.960
D(9)	20.721	9.499	2.200
				D(10)	9.638	4.576	0.750
D(15)	0.933	1.967	6.151
				D(18)	2.257	6.285	5.927
BF	0.200	0.200	0.200
					Wide angle end	Intermediate part	Telephoto end
Photographic distance	0.3m	1.0m	1.2m
				D(15)	0.972	2.034	6.714
D(18)	2.218	6.218	5.363

(aspherical coefficient)

Surface NO.	K	A4	A6	A8	A10
						11	0.0000E+00	-2.1033E-04	-3.0000E-06	7.6424E-08	-8.4453E-09
12	0.0000E+00	1.0297E-04	-1.0000E-06	-5.8301E-08	-5.4233E-09
						19	0.0000E+00	-4.4131E-04	3.1000E-05	-3.0000E-06	2.1936E-07
20	0.0000E+00	-6.7174E-04	4.5000E-05	-6.0000E-06	3.3540E-07

(focal Length of each lens group)

Group of	Surface NO.	Focal length
			G1	1-2	-70.375
G2	3-4	28.562
			G3	5-9	-8.346
G4	12-16	9.467
			G5	17-19	-10.514
G6	20-21	26.803

Example 4

(1) Optical structure

Fig. 10 is a sectional view of a zoom lens according to embodiment 4 of the present invention at the time of infinity focusing. The zoom lens is composed of, in order from the object side, a 1 st lens group G1 having negative optical power, a 2 nd lens group G2 having positive optical power, a 3 rd lens group G3 having negative optical power, a 4 th lens group G4 having positive optical power, a 5 th lens group G5 having negative optical power, and a 6 th lens group G6 having positive optical power.

The 2 nd lens group G2 is constituted by a biconvex lens.

(2) Numerical examples

Next, a numerical example of the zoom lens to which specific numerical values are applied is shown. Fig. 11 and 12 show longitudinal aberration diagrams of the zoom lens at the time of infinity focusing at the wide-angle end and the telephoto end.

(lens data)

(various specification sheets)

	Wide angle end	Intermediate part	Telephoto end
				f	4.436	13.611	41.796
Fno.	1.960	3.377	4.035
				ω	39.084	12.999	4.249
Y	3.300	3.300	3.300
				L	65.000	65.000	65.000

(variable spacing)

	Wide angle end	Intermediate part	Telephoto end
				Photographic distance	INF	INF	INF
D(2)	9.350	9.848	4.636
				D(4)	1.250	6.012	14.356
D(9)	10.592	5.332	2.200
				D(10)	13.292	5.131	0.750
D(15)	0.873	2.077	4.345
				D(18)	2.317	9.273	11.387
BF	0.200	0.200	0.200
					Wide angle end	Intermediate part	Telephoto end
Photographic distance	0.3m	1.0m	1.2m
				D(15)	0.932	2.165	4.947
D(18)	2.258	9.185	10.783

(aspherical coefficient)

Surface NO.	K	A4	A6	A8	A10
						11	0.0000E+00	-5.4000E-05	-1.0000E-06	2.8219E-08	-1.8839E-09
12	0.0000E+00	1.4341E-04	-2.1532E-07	1.8688E-08	-2.0949E-09
						19	0.0000E+00	-1.8000E-05	1.4000E-05	2.0000E-06	-8.1203E-09
20	0.0000E+00	4.5332E-04	3.0000E-06	1.0000E-06	8.1617E-08

(focal Length of each lens group)

Group of	Surface NO.	Focal length
			G1	1-2	-35.549
G2	3-4	18.008
			G3	5-9	-7.830
G4	11-15	10.729
			G5	16-18	-13.276
G6	19-20	18.289

Example 5

(1) Optical structure

Fig. 13 is a sectional view of a zoom lens according to embodiment 5 of the present invention at the time of infinity focusing. The zoom lens is composed of, in order from the object side, a 1 st lens group G1 having negative optical power, a 2 nd lens group G2 having positive optical power, a 3 rd lens group G3 having negative optical power, a 4 th lens group G4 having positive optical power, a 5 th lens group G5 having negative optical power, and a 6 th lens group G6 having positive optical power.

The 2 nd lens group G2 is constituted by a biconvex lens.

The 3 rd lens group G3 is composed of, in order from the object side, a negative meniscus lens, and a cemented lens formed by a biconcave lens and a positive meniscus lens cemented.

(2) Numerical examples

Next, a numerical example of the zoom lens to which specific numerical values are applied is shown. Fig. 14 and 15 show longitudinal aberration diagrams of the zoom lens at the time of infinity focusing at the wide-angle end and the telephoto end.

(lens data)

Surface NO.	r	D	Nd	vd
					1	26.295	0.800	1.86966	20.01
2	21.470	D(2)
					3	24.971	4.527	1.55032	75.49
4	-153.261	D(4)
					5	64.227	0.500	1.87071	40.72
6	10.481	2.488
					7	-11.952	0.500	1.88300	40.80
8	13.768	1.591	1.95906	17.47
					9	114.143	D(9)
10S	INF	D(10)
					11*	10.971	4.396	1.61881	63.85
12*	-17.327	0.200
					13	10.964	0.500	1.91082	35.25
14	6.800	3.877	1.43700	95.10
					15	-11.465	D(15)
16	34.496	1.337	1.49700	81.60
					17	19.263	0.500	1.91082	35.25
18	4.730	D(18)
					19*	116.563	1.917	1.53504	55.71
20*	-13.171	4.500
					21	INF	0.800	1.51680	64.19
22	INF	BF
					23	INF	-

(various specification sheets)

	Wide angle end	Intermediate part	Telephoto end
				f	4.305	13.616	41.759
Fno.	2.068	3.136	4.138
				ω	42.049	13.128	4.255
Y	3.300	3.300	3.300
				L	69.900	69.900	69.900

(variable spacing)

(aspherical coefficient)

Surface NO.	K	A4	A6	A8	A10
						11	0.0000E+00	-2.9513E-04	-2.0000E-06	2.4331E-08	-4.0129E-09
12	0.0000E+00	1.4831E-04	-1.0000E-06	-9.9081E-08	-7.2693E-10
						19	0.0000E+00	1.8891E-04	4.5000E-05	1.0000E-06	-3.3580E-08
20	0.0000E+00	3.2885E-04	3.6000E-05	1.0000E-06	5.5023E-08

(focal Length of each lens group)

Group of	Surface NO.	Focal length
			G1	1-2	-145.238
G2	3-4	39.331
			G3	5-9	-6.243
G4	11-15	8.308
			G5	16-18	-6.537
G6	19-20	22.201

Example 6

(1) Optical structure

Fig. 16 is a sectional view of the zoom lens according to embodiment 5 of the present invention at the time of infinity focusing. The zoom lens is composed of, in order from the object side, a 1 st lens group G1 having negative optical power, a 2 nd lens group G2 having positive optical power, a 3 rd lens group G3 having negative optical power, a 4 th lens group G4 having positive optical power, a 5 th lens group G5 having negative optical power, and a 6 th lens group G6 having positive optical power.

The 2 nd lens group G2 is constituted by a biconvex lens.

(2) Numerical examples

Next, a numerical example of the zoom lens to which specific numerical values are applied is shown. Fig. 17 and 18 show longitudinal aberration diagrams of the zoom lens at the time of infinity focusing at the wide-angle end and the telephoto end.

(lens data)

Surface NO.	r	D	Nd	vd
					1	45.481	0.800	1.86966	20.01
2	28.104	D(2)
					3	35.936	4.044	1.77250	49.62
4	-97.585	D(4)
					5	-53.838	0.500	1.87071	40.72
6	18.264	2.396
					7	-34.374	0.500	1.69930	51.11
8	14.095	1.863	1.95906	17.47
					9	32.887	D(9)
10S	INF	D(10)
					11*	10.070	3.015	1.61881	63.85
12*	-26.509	0.200
					13	10.575	0.500	1.91082	35.25
14	6.823	3.527	1.43700	95.10
					15	-11.046	D(15)
16	53.781	1.251	1.49700	81.60
					17	17.312	0.500	1.91082	35.25
18	4.844	D(18)
					19*	39.996	2.060	1.53504	55.71
20*	-11.037	4.500
					21	INF	0.800	1.51680	64.19
22	INF	0.200
					23	INF	-

(various specification sheets)

	Wide angle end	Intermediate part	Telephoto end
				f	4.422	14.464	41.800
Fno.	1.954	3.180	3.474
				ω	41.184	12.253	4.257
Y	3.300	3.300	3.300
				L	69.000	69.000	69.000

(variable spacing)

	Wide angle end	Intermediate part	Telephoto end
				Photographic distance	INF	INF	INF
D(2)	4.014	4.500	1.917
				D(4)	1.250	12.165	25.590
D(9)	24.444	13.042	2.200
				D(10)	9.418	1.913	0.750
D(15)	0.911	1.441	3.400
				D(18)	2.279	9.254	8.457
BF	0.200	0.200	0.200
					Wide angle end	Intermediate part	Telephoto end
Photographic distance	0.3m	1.0m	1.2m
				D(15)	0.932	1.473	3.644
D(18)	2.258	9.221	8.214

(aspherical coefficient)

Surface NO.	K	A4	A6	A8	A10
						11	0.0000E+00	-2.8341E-04	-3.0000E-06	6.4816E-08	-1.0224E-08
12	0.0000E+00	1.4091E-04	-1.0000E-06	-1.1196E-07	-4.9978E-09
						19	0.0000E+00	-2.2953E-04	1.2000E-05	1.0000E-06	1.4561E-08
20	0.0000E+00	1.4874E-04	-1.6000E-05	2.0000E-06	1.6496E-09

(focal Length of each lens group)

Group of	Surface NO.	Focal length
			G1	1-2	-86.098
G2	3-4	34.399
			G3	5-9	-9.785
G4	11-15	8.154
			G5	16-18	-6.566
G6	19-20	16.375

Example 7

(1) Optical structure

Fig. 19 is a sectional view of a zoom lens according to embodiment 7 of the present invention at the time of infinity focusing. The zoom lens is composed of, in order from the object side, a 1 st lens group G1 having negative optical power, a 2 nd lens group G2 having positive optical power, a 3 rd lens group G3 having negative optical power, a 4 th lens group G4 having positive optical power, a 5 th lens group G5 having negative optical power, a 6 th lens group G6 having positive optical power, and a 7 th lens group G7 having positive optical power.

When changing magnification from the wide-angle end to the telephoto end, along the optical axis, the 2 nd lens group G2 moves toward the object side in a locus convex toward the image side, the 3 rd lens group G3 moves toward the image side, the 4 th lens group G4 moves toward the object side from the image side, the 5 th lens group G5 moves toward the object side in a locus convex toward the object side, and the 6 th lens group G6 moves toward the object side in a locus convex toward the object side.

The 2 nd lens group G2 is constituted by a biconvex lens.

The 6 th lens group G6 is constituted by a positive lens having aspherical surfaces on both sides.

The 7 th lens group G7 is constituted by a biconvex lens.

(2) Numerical examples

Next, a numerical example of the zoom lens to which specific numerical values are applied is shown. Fig. 20 and 21 show longitudinal aberration diagrams of the zoom lens at the time of infinity focusing at the wide-angle end and the telephoto end.

(lens data)

Surface NO.	r	D	Nd	vd
					1	33.151	0.800	1.84666	23.78
2	17.177	D(2)
					3	18.874	4.473	1.77250	49.62
4	-113.180	D(4)
					5	-55.141	0.500	1.87071	40.72
6	11.408	2.132
					7	-20.584	0.500	1.69930	51.11
8	12.041	1.612	1.95906	17.47
					9	37.860	D(9)
10S	INF	D(10)
					11*	10.152	3.149	1.61881	63.85
12*	-37.811	0.699
					13	10.887	0.500	1.91082	35.25
14	6.800	3.696	1.43700	95.10
					15	-14.565	D(15)
16	16.988	1.617	1.49700	81.60
					17	30.206	0.500	1.91082	35.25
18	5.753	D(18)
					19*	23.340	1.672	1.53504	55.71
20*	113.570	D(20)
					21	38.400	2.195	1.49700	81.60
22	-11.720	4.000
					23	INF	0.800	1.51680	64.19
24	INF	BF
					25	INF	-

(various specification sheets)

	Wide angle end	Intermediate part	Telephoto end
				f	4.429	13.608	41.795
Fno.	1.854	2.503	3.098
				ω	41.242	13.004	4.287
Y	3.300	3.300	3.300
				L	65.300	65.300	65.300

(variable spacing)

(aspherical coefficient)

Surface NO.	K	A4	A6	A8	A10
						11	0.0000E+00	-1.5411E-04	-4.3261E-07	2.0930E-08	-2.4993E-09
12	0.0000E+00	1.4967E-04	5.2679E-09	-5.3179E-09	-2.2562E-09
						19	0.0000E+00	-4.6373E-04	-2.8000E-05	-1.0000E-06	9.4122E-08
20	0.0000E+00	-2.1330E-04	-3.1000E-05	-5.4862E-08	5.5314E-08

(focal Length of each lens group)

Group of	Surface NO.	Focal length
			G1	1-2	-42.955
G2	3-4	21.220
			G3	5-9	-7.133
G4	11-15	9.392
			G5	16-18	-9.153
G6	19-20	54.477
			G7	21-22	18.316

(Table 1)

	Example 1	Example 2	Example 3	Example 4	Example 5	Example 6	Example 7
								(1)f12w/fw	6.46	4.50	10.24	5.33	11.95	12.04	7.40
(2)\|f2/f3\|	3.14	2.72	3.42	2.30	6.30	3.52	2.97
								(3)vd1	20.02	20.02	20.02	20.02	20.02	20.02	23.78
(4)\|f1/f2\|	2.44	2.33	2.46	1.97	3.69	2.50	2.02
								(5)\|f1/fw\|	11.65	8.59	15.94	8.01	33.74	19.47	9.70
(6)f2/fw	4.78	3.69	6.47	4.06	9.14	7.78	4.79
								(7)\|f3/fw\|	1.52	1.36	1.89	1.77	1.45	2.21	1.61
(8)\|f3/f4\|	0.66	0.61	0.88	0.73	0.75	1.20	0.76
								(9)f12t/ft	0.83	0.63	1.11	0.69	1.29	1.32	0.94
(10)TL ² /(fw×ft)	21.43	22.12	22.55	22.79	27.18	25.76	23.04
								(11)\|X3\| ² /(fw×ft)	0.32	0.06	1.86	0.38	1.65	2.68	1.03
(12)\|f1/ft\|	1.23	0.91	1.68	0.85	3.48	2.06	1.03
								(13)f2/ft	0.51	0.39	0.68	0.43	0.94	0.82	0.51
(14)\|f5/fw\|	2.88	2.42	2.38	2.99	1.52	1.48	2.07
								(15)f6/fw	4.14	4.03	6.07	4.12	5.16	3.70	12.30

Industrial applicability

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

Claims

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, a 4 th lens group having positive optical power, a 5 th lens group having negative optical power, and a 6 th lens group having positive optical power,

at the time of changing magnification from the wide-angle end to the telephoto end, the 1 st lens group is fixed, at least the 2 nd lens group, the 3 rd lens group, the 4 th lens group, and the 5 th lens group move along an optical axis, intervals between adjacent lens groups on the optical axis change, and the zoom lens satisfies the following formula:

3.0≤f12w/fw≤15.0····(1)

1.2≤|f2/f3|≤8.0·····(2)

vd1≤35················(3)

Wherein,,

f2: focal length of the 2 nd lens group

f3: focal length of the 3 rd lens group

vd1: the 1 st lens group includes negative lenses having abbe numbers at d-line.

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

1.2≤|f1/f2|≤6.0·····(4)

wherein,,

f1: focal length of the 1 st lens group.

3. The zoom lens according to claim 1 or claim 2, satisfying the following formula:

5.0≤|f1/fw|≤50.0····(5)

f1: focal length of the 1 st lens group.

4. A zoom lens according to any one of claims 1 to 3, satisfying the following formula:

2.0≤f2/fw≤15.0······(6)。

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

0.5≤|f3/fw|≤5.0·····(7)。

6. the zoom lens according to any one of claim 1 to 5,

the 3 rd lens group is sequentially provided with a negative lens, a negative lens and a positive lens from the object side to the image side,

the 4 th lens group has a positive lens on the most object side,

the zoom lens satisfies the following formula:

0.3≤|f3/f4|≤3.0·····(8)

f4: focal length of the 4 th lens group.

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

0.3≤f12t/ft≤3.0·····(9)

wherein,,

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

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.

8. The zoom lens according to any one of claim 1 to 7,

the 1 st lens group is composed of 1 piece of negative concave-convex lens.

9. The zoom lens according to any one of claim 1 to 8,

the 2 nd lens group is composed of 1 positive lens.

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

the 5 th lens group moves on the optical axis upon focusing from infinity to a close distance.

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

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

12. The zoom lens according to any one of claims 1 to 11, satisfying the following formula:

10.0≤TL ² /(fw×ft)≤50.0·····(10)

wherein,,

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

13. The zoom lens according to any one of claims 1 to 12, satisfying the following formula:

0.01≤|X3| ² /(fw×ft)≤5.0·····(11)

Wherein,,

x3: movement amount of the 3 rd lens group when zooming from wide-angle end to telephoto end

14. The zoom lens according to any one of claims 1 to 13, satisfying the following formula:

0.3≤|f1/ft|≤7.0·····(12)

f1: focal length of the 1 st lens group

15. The zoom lens according to any one of claims 1 to 14, satisfying the following formula:

0.1≤f2/ft≤3.0·····(13)

16. The zoom lens according to any one of claims 1 to 15, satisfying the following formula:

0.5≤|f5/fw|≤5.0·····(14)

wherein,,

f5: focal length of the 5 th lens group.

17. The zoom lens according to any one of claims 1 to 16, satisfying the following formula:

2.0≤f6/fw≤30.0·····(15)

wherein,,

f6: focal length of the 6 th lens group.

18. An image pickup apparatus provided with the zoom lens according to any one of claims 1 to 17, 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 zoom lens.