JP2020204684A - Zoom lens - Google Patents

Abstract

To provide a compact zoom lens which has a high zoom ratio, suppresses variation in magnification chromatic aberration associated with zooming in particular, and offers high optical performance over an entire focus range.SOLUTION: A zoom lens of the present invention consists of a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, an aperture stop S, a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, and a fifth lens group G5 having positive refractive power, in order from the object side, and is configured such that, when zooming from the wide-angle end to the telephoto end, an air gap distance between the first lens group G1 and the second lens group G2 increases, an air gap distance between the second lens group G2 and the third lens group G3 decreases, an air gap distance between the third lens group G3 and the fourth lens group G4 is fixed or changes, and an air gap distance between the fourth lens group G4 and the fifth lens group G5 changes. The zoom lens satisfies specific conditional expressions.SELECTED DRAWING: Figure 4

Description

The present invention relates to a zoom lens and an image pickup device having the same, and more particularly to a zoom lens used in an image pickup device such as a digital camera, a video camera, and a film camera.

In recent years, solid-state image sensors used in image pickup devices such as digital cameras have been increasing in pixel count and definition year by year, and an optical system having higher image quality is required. Furthermore, in order to meet the diverse needs of users, smaller and lighter zoom lenses are required.

Among the zoom lenses, a so-called positive lead type zoom lens in which a lens group having a positive refractive power is arranged on the most object side and is composed of four or more lens groups as a whole is known.

Japanese Patent No. 6377319 Japanese Patent No. 6344964

Positive lead type zoom lenses are said to be relatively easy to achieve high zoom ratio and miniaturization. However, when the zoom ratio is high, the amount of movement of each lens group becomes large, and in particular, the zoom fluctuation of the chromatic aberration of magnification increases, making it difficult to achieve both a high zoom ratio and high performance.

Although the zoom lens disclosed in Patent Document 1 realizes small size and light weight while shortening the back focus, it has a small image height and insufficient suppression of fluctuations due to zooming of magnification chromatic aberration, so that it has optical performance. The problem remains.

The zoom lens disclosed in Patent Document 2 attempts to suppress fluctuations in chromatic aberration of magnification by changing the height of the main ray while keeping the height of the ray on the paraxial axis constant during zooming. However, the total optical length is long, and it has not been possible to achieve both compactness and weight reduction.

The present invention has been made in view of such a situation, and provides a zoom lens that is compact, has a high zoom ratio, suppresses fluctuations in chromatic aberration of magnification due to zooming, and obtains high optical performance over the entire focal range. The purpose is to do.

In order to achieve the above object, the first invention in which the present invention is carried out is a first lens group G1 having a positive refractive force, a second lens group G2 having a negative refractive force, and an aperture aperture in order from the object side. It consists of S, a third lens group G3 having a positive refractive power, a fourth lens group G4 having a negative refractive power, and a fifth lens group G5 having a positive refractive power, and the magnification is variable from the wide-angle end to the telescopic end. At that time, the air gap between the first lens group G1 and the second lens group G2 increases, the air gap between the second lens group G2 and the third lens group G3 decreases, and the third lens group G3 The air spacing between the lens group G3 and the fourth lens group G4 changes, the air spacing between the fourth lens group G4 and the fifth lens group G5 changes, and the following conditional expression is satisfied. A featured zoom lens.
(1) (1 / (1 / fW_34 + 1 / DsW) -EW) / √ (fW × fT)> 0
(2) (1 / (1 / fT_34 + 1 / DsT) -ET) / √ (fW × fT) <0
However,
fW: Focus distance of the whole system at infinity focusing at the wide-angle end fT: Focus distance of the whole system at infinity focusing at the telephoto end fW_34: The third lens group G3 and the fourth lens group at the wide-angle end Combined focal point of G4 fT_34: Combined focal point of the third lens group G3 and the fourth lens group G4 at the telephoto end DsW: From the aperture aperture S at the wide-angle end, the third lens group G3 and the fourth lens group Distance to the front principal point of the composite system of the lens group G4 DsT: Distance from the aperture aperture S at the telephoto end to the front principal point of the composite system of the third lens group G3 and the fourth lens group G4 EW: Distance from the rear principal point of the composite system of the third lens group G3 and the fourth lens group G4 at the wide-angle end to the front principal point of the fifth lens group G5 ET: The third lens at the telephoto end Distance from the rear principal point of the composite system of the group G3 and the fourth lens group G4 to the front principal point of the fifth lens group G5 Here, the distance is positive in the direction from the object side to the image side. It shall be measured on the optical axis.

The zoom lens according to the first invention, wherein the second invention according to the present invention is characterized in that the fourth lens group G4 moves toward the image side when focusing from infinity to a short distance.

The third invention for carrying out the present invention is the first invention or the second invention, wherein the fourth lens group G4 is composed of two lenses, a positive lens and a negative lens. The zoom lens described in either.

The fourth invention for carrying out the present invention is the zoom lens according to any one of the first to third inventions, wherein the fifth lens group G5 satisfies the following conditional expression.
(3) 2 <f5 / √ (fW × fT) <10
(4) 0.5 <B_5 <1
However,
f5: Focal length of the fifth lens group G5 fW: Focal length of the entire system at the infinity focusing at the wide-angle end fT: Focal length of the entire system at the infinity focusing at the telephoto end B_5: The fifth lens group Magnification at infinity focus at the wide-angle end of G5

A fifth invention for carrying out the present invention is characterized in that the fifth lens group G5 has a positive lens A and a negative lens B on the most object side, and satisfies the following conditional expression. The zoom lens according to any one of the inventions 1 to 4.
(5) V_5A <50
(6) V_5B> 50
(7) ΔPgF_5B> 0
However,
V_5A: Abbe number of the positive lens A V_5B: Abbe number of the negative lens B ΔPgF_5B: Anomalous dispersibility of the negative lens B

Further, the sixth invention for carrying out the present invention is the first to fifth inventions, wherein the second lens group G2 has a negative lens most satisfying the following conditional expression on the object side. The zoom lens described in either.
(8) V_21> 55
(9) ΔPgF_21> 0
However,
V_21: Abbe number of the negative lens on the most object side of the second lens group G2 ΔPgF_21: Anomalous dispersibility of the negative lens on the most object side of the second lens group G2

According to the present invention, it is possible to provide a zoom lens which is compact and has a high zoom ratio, particularly suppresses fluctuations in chromatic aberration of magnification due to zooming, and obtains high optical performance over the entire focal range.

Schematic diagram of the configuration of the fifth lens group of the first embodiment of the zoom lens of the present invention and the position of each principal point. A reference diagram schematically showing the principle of correcting chromatic aberration of magnification of the zoom lens of the present invention. Schematic diagram illustrating various quantities used in the conditional equations (1) and (2) of the zoom lens of the present invention. Lens configuration diagram at the wide-angle end of the zoom lens according to the first embodiment of the present invention when in focus at infinity. FIG. 6 is a longitudinal aberration diagram at (a) wide-angle end, (b) intermediate zoom position, and (c) telephoto end when the zoom lens according to the first embodiment of the present invention is in focus at infinity. FIG. 6 is a lateral aberration diagram at (a) wide-angle end, (b) intermediate zoom position, and (c) telephoto end when the zoom lens according to the first embodiment of the present invention is in focus at infinity. Lens configuration diagram at the wide-angle end of the zoom lens according to the second embodiment of the present invention when in focus at infinity. Schematic diagram of (a) wide-angle end, (b) intermediate zoom position, and (c) telephoto end of the zoom lens according to the second embodiment of the present invention when in focus at infinity. FIG. 6 is a lateral aberration diagram at (a) wide-angle end, (b) intermediate zoom position, and (c) telephoto end when the zoom lens according to the second embodiment of the present invention is in focus at infinity. The lens configuration diagram at the wide-angle end of the zoom lens according to the third embodiment of the present invention when the zoom lens is in focus at infinity. Schematic diagram of (a) wide-angle end, (b) intermediate zoom position, and (c) telephoto end of the zoom lens according to Example 3 of the present invention when in focus at infinity. FIG. 6 is a lateral aberration diagram at (a) wide-angle end, (b) intermediate zoom position, and (c) telephoto end when the zoom lens according to the third embodiment of the present invention is in focus at infinity. Lens configuration diagram at the wide-angle end of the zoom lens according to the fourth embodiment of the present invention when in focus at infinity. FIG. 6 is a longitudinal aberration diagram at (a) wide-angle end, (b) intermediate zoom position, and (c) telephoto end when the zoom lens according to the fourth embodiment of the present invention is in focus at infinity. FIG. 6 is a lateral aberration diagram at (a) wide-angle end, (b) intermediate zoom position, and (c) telephoto end when the zoom lens according to the fourth embodiment of the present invention is in focus at infinity.

Hereinafter, embodiments of the present invention will be described. The refractive indexes for g-line (wavelength 435.8 nm), F-line (wavelength 486.1 nm), d-line (wavelength 587.6 nm), and C-line (wavelength 656.3 nm) are ng, nF, nd, respectively. When nC, the Abbe number Vd, the partial dispersion ratio PgF, and the anomalous dispersion ΔPgF are expressed by the following equations.
Vd = (nd-1) / (nF-nC)
PgF = (ng-nF) / (nF-nC)
ΔPgF = PgF + 0.0018 × Vd-0.6483

As can be seen from the lens configuration diagrams shown in FIGS. 4, 7, 10 and 13, the zoom lens of the present invention has a first lens group G1 having a positive refractive force and a second lens group having a negative refractive force in order from the object side. It consists of a lens group G2, an aperture aperture S, a third lens group G3 having a positive refractive power, a fourth lens group G4 having a negative refractive power, and a fifth lens group G5 having a positive refractive power, and is telescopic from the wide-angle end. At the time of scaling to the edge, the air gap between the first lens group G1 and the second lens group G2 increases, and the air gap between the second lens group G2 and the third lens group G3 increases. The air spacing between the third lens group G3 and the fourth lens group G4 changes, and the air spacing between the fourth lens group G4 and the fifth lens group G5 changes. It is characterized by satisfying the formula.
(1) (1 / (1 / fW_34 + 1 / DsW) -EW) / √ (fW × fT)> 0
(2) (1 / (1 / fT_34 + 1 / DsT) -ET) / √ (fW × fT) <0
However,
fW: Focus distance of the whole system at infinity focusing at the wide-angle end fT: Focus distance of the whole system at infinity focusing at the telephoto end fW_34: The third lens group G3 and the fourth lens group at the wide-angle end Combined focal point of G4 fT_34: Combined focal point of the third lens group G3 and the fourth lens group G4 at the telephoto end DsW: From the aperture aperture S at the wide-angle end, the third lens group G3 and the fourth lens group Distance to the front principal point of the composite system of the lens group G4 DsT: Distance from the aperture aperture S at the telephoto end to the front principal point of the composite system of the third lens group G3 and the fourth lens group G4 EW: Distance from the rear principal point of the composite system of the third lens group G3 and the fourth lens group G4 at the wide-angle end to the front principal point of the fifth lens group G5 ET: The third lens at the telephoto end Distance from the rear principal point of the composite system of the group G3 and the fourth lens group G4 to the front principal point of the fifth lens group G5 Here, the distance is positive in the direction from the object side to the image side. It shall be measured on the optical axis.

The zoom lens of the present application has a positive lead type configuration having a positive lens group on the most object side. This makes it possible to achieve a high zoom ratio and miniaturization.

Next, the structural features of the present application will be described in detail.
In general, a zoom lens changes the composite focal length of the entire system by changing the distance between each group. Therefore, when analyzing the aberration of a zoom lens, it is important to consider each group as one thin-walled lens system and consider the aberration correction sharing of each group.

In addition, since each group moves greatly with zooming from the wide-angle end to the telephoto end, the aberration changes greatly for each zoom position. Therefore, in the design of the zoom lens, it is important to consider the aberration inherent in each group and the role in the zoom position separately. The contribution of chromatic aberration of magnification in the thin-walled lens system is given by Reference Equation 1 as the sum of each group.
(Reference formula 1) Σ (h ・ hb ・ φ / V)
However,
h: Paraxial main ray height hb: Paraxial main ray height φ: Refractive power V: Abbe number

In a zoom lens, h and hb fluctuate during zooming from the wide-angle end to the telephoto end, so that the aberration correction share of each group changes. In particular, in the conventional positive lead type zoom lens, the distance between the first lens group G1 and the second lens group G2 changes significantly when the magnification is changed, so that h in the first lens group G1 and hb in the second lens group G2 fluctuate. large. Since it is difficult to compensate for the fluctuation of the aberration due to this in the third lens group G3 and later, it becomes difficult to suppress the chromatic aberration of magnification over the entire focal range.

The zoom lens of the present application uses an aberration correction method different from that of the conventional zoom lens. FIG. 1 shows the principal point position (main surface) of the fifth lens group G5 of the first embodiment of the zoom lens of the present application. By making the fifth lens group G5 a telephoto type, the principal point is largely located on the object side.

When the light ray passing through the center of the entrance pupil is taken as the main light ray, it can be considered that the main light ray incident on the fifth lens group G5 is apparently emitted from the image of the aperture seen from the fifth lens group G5. .. Therefore, the height of the principal ray at the front principal point of the fifth lens group G5 is the image of the aperture stop S by the combined system of the third lens group G3 and the fourth lens group G4 and the position of the front principal point of the fifth lens group G5. Is determined by.

Although the fifth lens group G5 is mechanically located on the image side of the fourth lens group G4, the fourth lens group G4 and the fifth lens group are located on the object side because the principal point of the fifth lens group G5 is large. The distance between the principal points of G5 has a negative value. If the principal point is located closer to the object than the image of the aperture diaphragm S seen from the fifth lens group G5 at the wide-angle end, the height of the principal ray incident on the fifth lens group G5 may take a negative value. it can. On the other hand, at the telephoto end, the height of the main ray can take a positive value by locating the principal point on the image side of the image position of the aperture diaphragm S.

In this way, by appropriately defining the position of the fifth lens group G5 during zooming from the wide-angle end to the telephoto end, hb can be set to a negative value at the wide-angle end and hb can be set to a positive value at the telephoto end. it can. This means that, as shown in Reference Equation 1, the contribution of chromatic aberration of magnification is negative at the wide-angle end and positive at the telephoto end. That is, the contribution to the chromatic aberration of magnification due to zooming can be flexibly changed including the sign, and the optimum aberration correction can be performed at each zoom position.

The optical system of the present application is characterized by satisfying the following conditional expression.
(1) (1 / (1 / fW_34 + 1 / DsW) -EW) / √ (fW × fT)> 0
(2) (1 / (1 / fT_34 + 1 / DsT) -ET) / √ (fW × fT) <0
However,
fW: Focus distance of the whole system at infinity focusing at the wide-angle end fT: Focus distance of the whole system at infinity focusing at the telephoto end fW_34: The third lens group G3 and the fourth lens group at the wide-angle end Combined focal point of G4 fT_34: Combined focal point of the third lens group G3 and the fourth lens group G4 at the telephoto end DsW: From the aperture aperture S at the wide-angle end, the third lens group G3 and the fourth lens group Distance to the front principal point of the composite system of the lens group G4 DsT: Distance from the aperture aperture S at the telephoto end to the front principal point of the composite system of the third lens group G3 and the fourth lens group G4 EW: Distance from the rear principal point of the composite system of the third lens group G3 and the fourth lens group G4 at the wide-angle end to the front principal point of the fifth lens group G5 ET: The third lens at the telephoto end Distance from the rear principal point of the composite system of the group G3 and the fourth lens group G4 to the front principal point of the fifth lens group G5 Here, the distance is positive in the direction from the object side to the image side. It shall be measured on the optical axis.

The conditional equations (1) and (2) are related to the height of the paraxial main ray passing through the main plane of the fifth lens group G5 at the wide-angle end and the telephoto end, respectively, and define the conditions to be satisfied by each group. By satisfying the conditional equations (1) and (2), the role of the above-mentioned chromatic aberration of magnification correction can be changed between the wide-angle end and the telephoto end, and the fluctuation can be satisfactorily suppressed.

Next, the physical meanings of the conditional expressions (1) and (2) will be described.

As described above, the height of the main ray at the front principal point of the fifth lens group G5 is the image of the aperture stop S by the combined system of the third lens group G3 and the fourth lens group G4 and the front side of the fifth lens group G5. Determined by the principal point position.

FIG. 3 schematically shows the aperture diaphragm S to the fifth lens group. Note that FIG. 3 schematically shows general quantities used for paraxial ray tracing, and does not match the numerical values of the examples.

The distance Ds'from the rear principal point of the composite system of the third lens group G3 and the fourth lens group G4 to the image of the aperture by the group is derived as follows using the so-called Gauss's equation.
(Reference formula 2) 1 / DsW'-1 / DsW = 1 / fW_34
1 / DsW'= 1 / fW_34 + 1 / DsW
DsW'= 1 / (1 / fW_34 + 1 / DsW)

In order for the height of the main ray passing through the front principal point of the fifth lens group G5 to be a negative value, it is sufficient that the principal point is on the object side of the image of the aperture.
(Reference formula 3) Dsw'> Ew
Should be satisfied.
Therefore, the following equation is derived.
1 / (1 / fW_34 + 1 / DsW)> EW
1 / (1 / fW_34 + 1 / DsW) -EW> 0

Here, since the concept of the present application is similarly established even if the optical system is proportionally expanded or contracted, it can be normalized as follows.
(1 / (1 / fW_34 + 1 / DsW) -EW) / √ (fW × fT)> 0
The same derivation is possible at the telephoto end, and as a condition that the height of the main ray becomes a positive value at the telephoto end.
(1 / (1 / fT_34 + 1 / DsT) -ET) / √ (fW × fT) <0
Is obtained.

If the upper limit of the conditional expression (1) is exceeded and hb becomes positive at the wide-angle end, the chromatic aberration of magnification at the wide-angle end deteriorates, which is not preferable. If the lower limit of the conditional expression (2) is exceeded and hb becomes negative at the telephoto end, the chromatic aberration of magnification at the telephoto end deteriorates, which is not preferable.

More preferably, the range of the conditional expressions (1) and (2) should be defined as follows.
(1-2) (1 / (1 / fW_34 + 1 / DsW) -EW) / √ (fW × fT)> 0.025
(2-2) (1 / (1 / fT_34 + 1 / DsT) -ET) / √ (fW × fT) <-0.1

The zoom lens of the present application is characterized in that the fourth lens group G4 moves to the image side when focusing from infinity to a short distance.

By focusing with the fourth lens group G4 having a low light beam height, the focus group can be made lighter and can be operated at high speed. Further, since the positive third lens group G3 is located immediately on the object side of the fourth lens group G4, the image of the aperture stop S seen from the fourth lens group G4 can be made far away, and the image when the focus group is driven can be obtained. It is possible to suppress fluctuations in magnification.

The fourth lens group is characterized in that it is composed of two positive and negative lenses. By erasing with a positive lens and a negative lens, it is possible to suppress fluctuations in axial chromatic aberration and lateral chromatic aberration due to focusing. Further, by configuring with the minimum number of sheets for achromaticity, it is possible to achieve both weight reduction of the focus group and aberration correction.

The fifth lens group G5 satisfies the following conditional expression.
(3) 2 <f5 / √ (fW × fT) <10
(4) 0.5 <B_5 <1
However,
f5: Focal length of the fifth lens group G5 fW: Focal length of the entire system at the infinity focusing at the wide-angle end fT: Focal length of the entire system at the infinity focusing at the telephoto end B_5: The fifth lens group Magnification at infinity focus at the wide-angle end of G5

Conditional expression (3) defines the focal length of the fifth lens group G5 with respect to the geometric mean of the focal lengths of the entire system at the wide-angle end and the telephoto end. When the focal length of the fifth lens group G5 becomes longer than the upper limit of the conditional expression (3), the combined focal length from the first lens group G1 to the fourth lens group G4 is increased in combination with the conditional expression (4). It becomes difficult to shorten it, which leads to an increase in the size of the entire system, which is not preferable. When the focal length of the fifth lens group G5 becomes shorter than the lower limit of the conditional expression (3), the distance between the fourth lens group G4 and the fifth lens group G5 becomes too short, and the actuator for driving the focus group and other elements are used. It is not preferable because there is not enough space to mount the mechanism.

The conditional expression (4) defines the magnification of the fifth lens group G5. When the absolute value of the magnification of the fifth lens group G5 becomes larger than the upper limit of the conditional expression (4), the aberration generated in the first lens group G1 to the fourth lens group G4 is enlarged, and the residual aberration as a whole is increased. It is not preferable because it becomes large. If the magnification of the fifth lens group becomes smaller than the lower limit of the conditional expression (4), it becomes difficult to secure the back focus, which is not preferable.

More preferably, the range of the conditional expressions (3) and (4) should be defined as follows.
(3-2) 2.8 <f5 / √ (fW × fT) <8.5
(4-2) 0.7 <B_5 <0.9

The fifth lens group G5 has a positive lens A on the most object side and includes a negative lens B. By arranging the positive lens on the most object side, the telephoto type can be obtained, and the principal point of the fifth lens group G5 can be positioned on the object side. The fifth lens group G5 satisfies the following conditional expression.
(5) V_5A <50
(6) V_5B> 50
(7) ΔPgF_5B> 0
However,
V_5A: Abbe number of the positive lens A V_5B: Abbe number of the negative lens B ΔPgF_5B: Anomalous dispersibility of the negative lens B

The conditional expression (5) defines the glass material of the positive lens A, and the conditional expressions (6) and (7) define the glass material of the negative lens B of the fifth lens group G5. In order to satisfy the conditional expression (3) and secure the contribution of the chromatic aberration of magnification, it is necessary to reduce the Abbe number of the fifth lens group G5 as a whole. Therefore, it is desirable to use a glass material having a small Abbe number for the positive lens and a glass material having a large Abbe number for the negative lens to reduce the Abbe number of the fifth lens group G5 as a whole.

If the Abbe number of the positive lens A exceeds the upper limit of the conditional expression (5), the contribution of the fifth lens group G5 to the chromatic aberration of magnification becomes too small, which is not preferable. Further, when the Abbe number of the negative lens B becomes smaller than the lower limit of the conditional equation (6), the contribution of the fifth lens group G5 as a whole to the chromatic aberration of magnification is reduced, and the chromatic aberration of magnification at the telephoto end is particularly deteriorated, which is preferable. Absent. If the anomalous dispersibility of the negative lens B becomes smaller than the lower limit of the conditional expression (7), the ability to correct the secondary spectrum of the chromatic aberration of magnification is reduced, which is not preferable.

More preferably, the range of the conditional expressions (5), (6) and (7) should be defined as follows.
(5-2) V_5A <45
(6-2) V_5B> 65
(7-2) ΔPgF_5B> 0.01

The second lens group G2 of the zoom lens of the present application has friends on the most object side that satisfy the following conditional expression.
(8) V_21> 55
(9) ΔPgF_21> 0
However,
V_21: Abbe number of the negative lens on the most object side of the second lens group G2 ΔPgF_21: Anomalous dispersibility of the negative lens on the most object side of the second lens group G2

As shown in Reference Equation 1, the contribution of the lens group having a high paraxial main ray height is large for the chromatic aberration of magnification. Since the second lens group has large fluctuations in the paraxial main ray and strong power, it also has a great influence on fluctuations in chromatic aberration of magnification. If the Abbe number of the glass material of the lens closest to the object side of the second lens group exceeds the lower limit of the conditional expression (8), the chromatic aberration of magnification generated by the lens increases, which is not preferable. If the anomalous dispersibility becomes too small beyond the lower limit of the conditional expression (9), the secondary spectrum of the chromatic aberration of magnification deteriorates, which is not preferable.

More preferably, the range of the conditional expressions (8) and (9) should be defined as follows.
(8-2) V_21> 60
(9-2) ΔPgF_21> 0.008

Next, the lens configuration of the embodiment according to the imaging optical system of the present invention will be described. In the following description, the lens configuration will be described in order from the object side to the image side.

In [surface data], the surface number is the number of the lens surface or aperture diaphragm S counted from the object side, r is the radius of curvature of each surface, d is the distance between each surface, and nd is the d line (wavelength λ = 587.56 nm). Refractive index with respect to, νd is the Abbe number with respect to the d line, and PgF is the partial dispersion ratio between the g line and the F line. BF represents back focus.

The plane numbered (opening diaphragm) is written with a radius of curvature ∞ (infinity) with respect to a flat surface or an aperture diaphragm S.

[Aspherical surface data] shows each coefficient value that gives the aspherical shape of the lens surface marked with * in [Surface data]. The shape of the aspherical surface is y for the displacement in the direction orthogonal to the optical axis, z for the displacement (sag amount) in the optical axis direction from the intersection of the aspherical surface and the optical axis, and K, 4, 6, 8 for the conic coefficient. When the 10th and 12th order aspherical coefficients are set as A4, A6, A8, A10, and A12, respectively, the coordinates of the aspherical surface shall be expressed by the following equation.

[Various data] shows values such as focal length.

[Variable interval data] shows the values of the variable interval and the BF (back focus) in each shooting distance state.

[Lens group data] shows the surface number on the most object side constituting each lens group and the combined focal distance of the entire group.

In all the following specification values, the units of the focal length f, the radius of curvature r, the lens surface spacing d, and other lengths described are mm (mm) unless otherwise specified, but optics. The system is not limited to this because the same optical performance can be obtained in both proportional expansion and proportional reduction.

Further, in the aberration diagram corresponding to each embodiment, d, g, and C represent the d-line, g-line, and C-line, respectively, and ΔS and ΔM represent the sagittal image plane and the meridional image plane, respectively.

Further, in the lens configuration diagrams shown in FIGS. 4, 7, 10 and 13, S is the aperture diaphragm, I is the image plane, F is the optical filter, and the alternate long and short dash line passing through the center is the optical axis.

FIG. 4 is a lens configuration diagram at infinity focusing at the wide-angle end of the zoom lens according to the first embodiment of the present invention. The zoom lens of the first embodiment has a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, an aperture aperture S, and positive refraction in this order from the object side to the image side. It is composed of a third lens group G3 having a force, a fourth lens group G4 having a negative refractive power, and a fifth lens group G5 having a positive refractive power.

The first lens group G1 is composed of a concave meniscus lens having a convex surface facing the object side, a junction lens of a biconvex lens, and a convex meniscus lens having a convex surface facing the object side in order from the object side to the image side.

The second lens group G2 includes a concave meniscus lens, a biconcave lens, a biconvex lens, a concave meniscus lens having a concave surface facing the object side, and a biconvex lens in order from the object side to the image side. Consists of.

The third lens group G3 includes a convex meniscus lens having a convex surface facing the object side and aspherical surfaces on both sides, a biconvex lens, a bonded lens in which a biconcave lens and a convex meniscus lens are joined, and an aspherical surface on both sides, in order from the object side to the image side. Consists of a biconvex lens, which has.

The fourth lens group G4 is composed of a convex meniscus lens having a concave surface facing the object side and a bonded lens in which both concave lenses are joined in this order from the object side to the image side. When focusing from infinity to close range, the fourth lens group G4 moves toward the image plane.

The fifth lens group G5 is composed of a biconvex lens, a concave meniscus lens having a convex surface facing the object side, and a concave meniscus lens having a concave surface facing the object side in order from the object side to the image side.

Subsequently, the specification values of the zoom lens according to the first embodiment are shown below.
Numerical Example 1
Unit: mm
[Surface data]
Surface number rd nd vd PgF
Physical surface ∞ (d0)
1 136.6048 1.5000 1.73800 32.33 0.59
2 82.7730 7.3116 1.43700 95.10 0.53
3 -890.8231 0.1500
4 65.1502 6.5077 1.49700 81.61 0.54
5 298.0140 (d5)
6 * 800.0000 1.5000 1.59201 67.02 0.54
7 * 20.0000 6.7341
8-43.9481 1.5000 1.59282 68.63 0.54
9 40.7553 1.0794
10 92.1584 4.0133 1.67270 32.17 0.60
11 -32.2836 1.1407
12 -21.5281 1.5000 1.83481 42.72 0.56
13 -103.2905 0.1500
14 85.6118 2.5374 1.80000 29.84 0.60
15 -156.5329 (d15)
16 (Aperture) ∞ 0.1500
17 * 20.1681 5.0000 1.49710 81.56 0.54
18 * 74.9041 0.9689
19 30.5286 6.8337 1.65844 50.88 0.56
20 -42.6511 1.2415
21 -47.0757 1.5000 1.88300 40.80 0.57
22 14.0650 4.4991 1.43700 95.10 0.53
23 176.7012 0.1500
24 * 24.1208 5.5093 1.55332 71.68 0.54
25 * -27.7300 (d25)
26 -119.0554 2.5365 1.77250 49.62 0.55
27 -37.1153 1.5000 1.59410 60.47 0.55
28 26.2360 (d28)
29 223.8293 4.1850 1.65412 39.68 0.57
30 -57.1332 0.1500
31 63.5639 1.5000 1.49700 81.61 0.54
32 34.5938 5.7722
33 -51.7248 1.5000 1.49700 81.61 0.54
34 -197.3965 (d34)
35 ∞ 2.5000 1.51680 64.20 0.53
36 ∞ (BF)
Image plane ∞

[Aspherical data]
6 sides 7 sides 17 sides 18 sides
K 0.00000 0.00000 -0.37567 0.00000
A4 4.63367E-06 -3.90581E-06 6.77578E-07 8.88294E-06
A6 1.68379E-08 2.00349E-08 6.56792E-09 5.11459E-08
A8 1.46028E-10 2.83537E-10 2.37069E-10 1.45832E-10
A10 -7.21741E-13 1.15068E-12 -1.79088E-12 -1.74255E-12
A12 1.06723E-15 0.00000E + 00 0.00000E + 00 0.00000E + 00

24 sides 25 sides
K 0.54217 1.57994
A4 -2.95890E-05 1.34949E-05
A6 2.28153E-08 -2.05420E-08
A8 -9.49428E-11 1.87128E-10
A10 -5.21936E-13 -2.17746E-12
A12 0.00000E + 00 0.00000E + 00

[Various data]
Zoom ratio 7.14
Wide-angle medium telephoto focal length 27.99 71.70 199.93
F number 3.37 4.67 5.60
Full angle of view 2ω 78.26 32.06 11.77
Image height Y 21.63 21.63 21.63
Total lens length 144.99 161.09 220.98

[Variable interval data]
Wide-angle intermediate telephoto
d0 ∞ ∞ ∞
d5 1.0000 20.2505 63.5398
d15 30.7294 6.2894 1.5000
d25 1.3636 7.4560 0.1000
d28 10.7867 23.0664 36.4234
d34 18.9926 21.9098 37.2953
BF 1.0000 1.0000 1.0000

[Lens group data]
Focal length
G1 1 121.73
G2 6 -22.10
G3 17 26.16
G4 26 -40.77
G5 29 630.50

FIG. 7 is a lens configuration diagram at infinity focusing at the wide-angle end of the zoom lens according to the second embodiment of the present invention. In the zoom lens of the first embodiment, in order from the object side to the image side, a first lens group G1 having a positive refractive force, a second lens group G2 having a negative refractive force, an aperture aperture S, and positive refraction It is composed of a third lens group G3 having a force, a fourth lens group G4 having a negative refractive force, and a fifth lens group G5 having a positive refractive force.

The first lens group G1 is composed of a concave meniscus lens having a convex surface facing the object side, a junction lens of a biconvex lens, and a convex meniscus lens having a convex surface facing the object side in order from the object side to the image side.

The second lens group G2 includes a concave meniscus lens, a biconcave lens, a biconvex lens, a concave meniscus lens having a concave surface facing the object side, and a biconvex lens in order from the object side to the image side. Consists of.

The third lens group G3 includes a convex meniscus lens having a convex surface facing the object side and aspherical surfaces on both sides, a junction lens in which a biconvex lens, a biconcave lens, and a convex meniscus lens are joined, and non-both sides in order from the object side to the image side. It is composed of a biconvex lens having a spherical surface.

The fourth lens group G4 is composed of a convex meniscus lens having a concave surface facing the object side and a bonded lens in which both concave lenses are joined in this order from the object side to the image side. When focusing from infinity to close range, the fourth lens group G4 moves toward the image plane.

The fifth lens group G5 is composed of a biconvex lens and a concave meniscus lens having a convex surface facing the object side in this order from the object side to the image side.

Subsequently, the specification values of the zoom lens according to the second embodiment are shown below.
Numerical Example 2
Unit: mm
[Surface data]
Surface number rd nd vd PgF
Physical surface ∞ (d0)
1 125.2573 1.5000 1.74950 35.33 0.58
2 70.8781 6.9294 1.43700 95.10 0.53
3 -1063.3192 0.1500
4 49.8767 6.5701 1.49700 81.61 0.54
5 177.5426 (d5)
6 * 367.6915 1.8000 1.59201 67.02 0.54
7 * 19.3986 6.0248
8 -74.1540 1.5000 1.59282 68.63 0.54
9 36.0441 1.1037
10 102.0889 2.4560 1.85883 30.00 0.60
11 -91.4849 2.0615
12 -19.5761 1.0000 1.77250 49.60 0.55
13 -49.0447 0.1500
14 77.6596 2.0258 1.92119 23.96 0.62
15 -8388.6479 (d15)
16 (Aperture) ∞ 1.2000
17 * 17.7791 5.1059 1.55332 71.68 0.54
18 * 155.9550 1.6189
19 27.9962 3.6876 1.72047 34.71 0.58
20 -59.9631 1.5254 1.90366 31.31 0.59
21 16.3759 3.2384 1.43700 95.10 0.53
22 79.1950 0.2033
23 * 38.6427 3.1473 1.55332 71.68 0.54
24 * -32.2859 (d24)
25 -487.6476 2.2077 1.84666 23.78 0.62
26 -49.6745 0.9176 1.83481 42.72 0.56
27 36.0285 (d27)
28 53.9659 4.9366 1.61340 44.27 0.56
29 -104.0372 0.1500
30 768.7535 1.5000 1.59282 68.63 0.54
31 35.2733 (d31)
32 ∞ 2.5000 1.51680 64.20 0.53
33 ∞ (BF)
Image plane ∞

[Aspherical data]
6 sides 7 sides 17 sides 18 sides
K 0.00000 0.00000 0.00000 0.00000
A4 3.09759E-05 2.97220E-05 -1.23282E-06 1.79331E-05
A6 -1.93921E-07 -1.16817E-07 1.33952E-07 1.85028E-07
A8 1.11693E-09 9.21344E-10 -7.92739E-10 -1.21537E-09
A10 -2.91406E-12 -2.18366E-12 6.03063E-12 6.41296E-12
A12 3.04472E-15 4.07747E-14 0.00000E + 00 0.00000E + 00

23 sides 24 sides
K 0.00000 0.00000
A4 -5.99698E-06 3.42247E-05
A6 2.31109E-07 2.58417E-07
A8 2.81967E-09 3.33545E-09
A10 -2.69163E-11 -1.30629E-11
A12 0.00000E + 00 -6.16690E-15

[Various data]
Zoom ratio 6.73
Wide-angle medium telephoto focal length 28.84 71.72 194.00
F number 3.45 5.01 6.31
Full angle of view 2ω 76.58 32.05 12.21
Image height Y 21.63 21.63 21.63
Total lens length 126.14 141.54 202.14

[Variable interval data]
Wide-angle intermediate telephoto
d0 ∞ ∞ ∞
d5 1.0000 16.3995 51.5407
d15 24.1361 5.0128 1.5000
d24 4.1015 11.1152 1.5000
d27 8.7731 22.0121 37.2428
d31 21.9152 20.7922 44.1426
BF 1.0000 1.0000 1.0000

[Lens group data]
Focal length
G1 1 108.47
G2 6 -20.07
G3 17 23.32
G4 25 -40.43
G5 28 525.69

FIG. 10 is a lens configuration diagram when the zoom lens of the third embodiment of the present invention is in focus at infinity at the wide-angle end. The zoom lens of the first embodiment has a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, an aperture aperture S, and positive refraction in this order from the object side to the image side. It is composed of a third lens group G3 having a force, a fourth lens group G4 having a negative refractive power, and a fifth lens group G5 having a positive refractive power.

The first lens group G1 is composed of a concave meniscus lens having a convex surface facing the object side, a junction lens of a convex meniscus lens, and a convex meniscus lens having a convex surface facing the object side in order from the object side to the image side.

The second lens group G2 includes a concave meniscus lens, a biconcave lens, a biconvex lens, a concave meniscus lens having a concave surface facing the object side, and a biconvex lens in order from the object side to the image side. Consists of.

The third lens group G3 includes a biconvex lens having aspherical surfaces on both sides, a junction lens in which a biconvex lens and a biconcave lens are joined, a concave meniscus lens having a convex surface facing the object side, and a convex surface toward the object side, in order from the object side to the image side. It is composed of a bonded lens in which a convex meniscus lens is joined, and a biconvex lens having aspherical surfaces on both sides.

The fourth lens group G4 is composed of a convex meniscus lens having a concave surface facing the object side and a bonded lens in which both concave lenses are joined in this order from the object side to the image side. When focusing from infinity to close range, the fourth lens group G4 moves toward the image plane.

The fifth lens group G5 is composed of a biconvex lens, a concave meniscus lens having a convex surface facing the object side, and a concave meniscus lens having a concave surface facing the object side in order from the object side to the image side.

Subsequently, the specification values of the zoom lens according to the third embodiment are shown below.
Numerical Example 3
Unit: mm
[Surface data]
Surface number rd nd vd PgF
Physical surface ∞ (d0)
1 124.7962 1.5000 1.88300 40.80 0.57
2 61.0332 9.5554 1.43700 95.10 0.53
3 3125.8033 0.1500
4 58.3037 8.7719 1.59282 68.63 0.54
5 474.2550 (d5)
6 * 634.5967 1.5000 1.55332 71.68 0.54
7 * 16.4360 6.5403
8 -53.7393 1.5000 1.59282 68.63 0.54
9 95.5021 0.7885
10 1329.0836 3.0266 1.74950 35.33 0.58
11 -38.7901 1.4131
12 -21.6919 1.5000 1.77250 49.60 0.55
13 -84.0642 0.1500
14 79.1816 2.1888 1.84666 23.78 0.62
15 -1245.4880 (d15)
16 (Aperture) ∞ 0.1500
17 * 22.6489 5.0000 1.59201 67.02 0.54
18 * -300.7147 4.4559
19 64.7742 2.8318 1.43700 95.10 0.53
20 -77.5083 1.5000 1.90043 37.37 0.58
21 187.3137 0.1500
22 27.6628 1.5000 1.88300 40.80 0.57
23 12.8319 3.7302 1.43700 95.10 0.53
24 32.6366 1.5239
25 * 19.5919 5.5754 1.49710 81.56 0.54
26 * -28.0237 (d26)
27 -63.3925 2.1800 1.85883 30.00 0.60
28 -34.5730 1.5000 1.61881 63.85 0.54
29 * 25.0535 (d29)
30 81.1179 6.2019 1.61340 44.27 0.56
31 -41.5248 0.1831
32 82.7302 1.5000 1.43700 95.10 0.53
33 32.6457 8.1321
34 -24.7842 1.5000 2.00100 29.13 0.60
35 -35.6811 (d35)
36 ∞ 2.5000 1.51680 64.20 0.53
37 ∞ (BF)
Image plane ∞

[Aspherical data]
6 sides 7 sides 17 sides 18 sides
K 0.00000 0.00000 0.00000 0.00000
A4 -7.29012E-06 -2.23365E-05 -1.72441E-05 -1.47764E-05
A6 6.74847E-08 1.67744E-08 2.93810E-09 5.35459E-08
A8 -2.41692E-11 4.42883E-10 -4.57932E-10 -5.52245E-10
A10 -3.09660E-13 -3.10103E-12 2.32772E-12 2.84238E-12
A12 5.65804E-16 2.44274E-14 0.00000E + 00 0.00000E + 00

25 faces 26 faces 29 faces
K 0.00000 0.00000 0.00000
A4 -3.93437E-05 -1.95645E-06 -5.68913E-06
A6 5.93652E-09 -6.93549E-08 -7.94734E-09
A8 -2.94161E-10 -2.75618E-10 5.34648E-11
A10 2.80170E-13 -1.53027E-12 0.00000E + 00
A12 0.00000E + 00 0.00000E + 00 0.00000E + 00

[Various data]
Zoom ratio 6.73
Wide-angle medium telephoto focal length 28.84 71.88 194.00
F number 3.51 5.02 5.59
Full angle of view 2ω 76.58 31.98 12.12
Image height Y 21.63 21.63 21.63
Total lens length 144.99 155.48 218.59

[Variable interval data]
Wide-angle intermediate telephoto
d0 ∞ ∞ ∞
d5 1.0000 16.3693 59.9657
d15 28.8163 4.2426 1.5000
d26 1.5000 8.4013 1.5087
d29 4.5155 10.1341 32.2630
d35 19.4623 26.6306 33.6537
BF 1.0000 1.0000 1.0000

[Lens group data]
Focal length
G1 1 116.05
G2 6 -21.58
G3 17 25.32
G4 27 -31.51
G5 30 212.32

FIG. 13 is a lens configuration diagram when the zoom lens of the fourth embodiment of the present invention is in focus at infinity at the wide-angle end. The zoom lens of the first embodiment has a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, an aperture aperture S, and positive refraction in this order from the object side to the image side. It is composed of a third lens group G3 having a force, a fourth lens group G4 having a negative refractive power, and a fifth lens group G5 having a positive refractive power.

The first lens group G1 is composed of a junction lens of a biconcave lens and a biconvex lens, a convex meniscus lens having a convex surface facing the object side, and a convex meniscus lens having a convex surface facing the object side in order from the object side to the image side. Will be done.

The second lens group G2 has a concave meniscus lens having an aspherical surface on both sides, a concave meniscus lens having a convex surface facing the object side, and a concave surface facing the object side in order from the object side to the image side. It consists of a concave meniscus lens and a biconvex lens.

The third lens group G3 is a convex meniscus lens with a convex surface facing the object side, a junction lens in which a concave meniscus lens with a convex surface facing the object side and a biconvex lens are joined in this order from the object side to the image side, and both concave lenses and the object side. It is composed of a junction lens in which a convex meniscus lens with a convex surface facing is joined, and a biconvex lens having aspherical surfaces on both sides.

The fourth lens group G4 is composed of a convex meniscus lens having a convex surface facing the object side and a junction lens in which both concave lenses having an aspherical surface on the image side surface are joined in this order from the object side to the image side. When focusing from infinity to close range, the fourth lens group G4 moves toward the image plane.

The fifth lens group G5 is composed of a biconvex lens, a concave meniscus lens having a convex surface facing the object side, and a concave meniscus lens having a concave surface facing the object side in order from the object side to the image side.

Subsequently, the specification values of the zoom lens according to the fourth embodiment are shown below.
Numerical Example 4
Unit: mm
[Surface data]
Surface number rd nd vd PgF
Physical surface ∞ (d0)
1 -866.0679 1.5000 1.80610 40.73 0.57
2 271.9885 5.3933 1.49700 81.61 0.54
3 -253.3488 0.1500
4 110.6280 5.6295 1.43700 95.10 0.53
5 1157.4646 0.1500
6 66.0486 5.9884 1.43700 95.10 0.53
7 164.6645 (d7)
8 * 406.3632 1.5000 1.59201 67.02 0.54
9 * 17.5260 5.5160
10 462.8091 1.5000 1.43700 95.10 0.53
11 49.2457 7.4592
12 -16.9824 1.5000 1.43700 95.10 0.53
13 -62.0018 0.1500
14 204.9091 2.2197 2.00100 29.13 0.60
15 -105.6434 (d15)
16 (Aperture) ∞ 0.1500
17 21.1771 3.2531 1.73800 32.26 0.59
18 50.6255 0.3338
19 16.9406 1.5000 1.88300 40.80 0.57
20 11.1027 8.4294 1.49700 81.61 0.54
21 -33.4882 0.2952 0.57
23 14.8605 3.7791 1.49700 81.61 0.54
24 217.8918 0.1500
25 * 24.2110 4.5792 1.59201 67.02 0.54
26 * -24.4188 (d26)
27 -294.3073 2.1302 1.64769 33.84 0.59
28 -55.8455 1.5000 1.80610 40.73 0.57
29 * 35.6472 (d29)
30 119.0218 4.6054 1.72047 34.71 0.58
31 -36.0640 0.1500
32 94.4168 1.5000 1.61997 63.88 0.54
33 41.7736 5.0158
34 -22.1641 1.5000 1.49700 81.61 0.54
35 -71.7260 (d35)
36 ∞ 2.5000 1.51680 64.20 0.53
37 ∞ (BF)
Image plane ∞

[Aspherical data]
8 sides 9 sides 25 sides 26 sides
K 0.00000 0.00000 0.00000 0.00000
A4 7.67405E-06 -2.50629E-06 -4.12445E-05 5.56873E-06
A6 -1.27470E-08 -1.52577E-08 1.69944E-08 -8.36308E-08
A8 1.22873E-10 1.14418E-10 -5.75485E-10 -3.98087E-10
A10 -3.53622E-13 5.80270E-13 4.44158E-12 0.00000E + 00
A12 4.13882E-16 0.00000E + 00 0.00000E + 00 0.00000E + 00

29 pages
K 0.00000
A4 -1.84083E-06
A6 2.44537E-09
A8 -1.66588E-11
A10 0.00000E + 00
A12 0.00000E + 00

[Various data]
Zoom ratio 6.73
Wide-angle medium telephoto focal length 28.84 72.00 194.00
F number 3.50 4.56 5.71
Full angle of view 2ω 75.57 31.93 12.24
Image height Y 21.63 21.63 21.63
Total lens length 139.12 160.81 224.81

[Variable interval data]
Wide-angle intermediate telephoto
d0 ∞ ∞ ∞
d7 1.0000 26.4004 69.3389
d15 24.9357 4.1011 0.1500
d26 1.7991 8.2240 1.2259
d29 4.0000 6.6813 17.5647
d35 24.1346 32.1457 53.2770
BF 1.0000 1.0000 1.0000

[Lens group data]
Focal length
G1 1 132.25
G2 8 -21.80
G3 17 25.68
G4 27 -35.95
G5 30 211.51

The conditional expression corresponding values corresponding to each of the above examples are shown below.
[Conditional expression correspondence value]
Conditional expression Example 1 Example 2 Example 3 Example 4
(1) * 1 0.17 0.03 0.03 0.03
(2) * 2 -0.16 -0.34 -0.34 -0.15
(3) f5 / √ (fW × fT) 8.43 7.03 2.84 2.83
(4) B_5 0.89 0.90 0.73 0.73
(5) V_5A 39.68 44.27 44.27 34.71
(6) V_5B 81.60 68.63 95.10 81.61
(7) ΔPgF_5B 0.04 0.02 0.05 0.04
(8) V_21 67.02 67.02 71.68 67.02
(9) ΔPgF_21 0.01 0.01 0.02 0.01

* 1 (1 / (1 / fW_34 + 1 / DsW) -EW) / √ (fW x fT)
* 2 (1 / (1 / fT_34 + 1 / DsT) -ET) / √ (fW x fT)

G1 1st lens group G2 2nd lens group G3 3rd lens group G4 4th lens group G5 5th lens group S Aperture aperture F Filter I Image plane

Claims (6)

From the object side, the first lens group G1 having a positive refractive power, the second lens group G2 having a negative refractive power, the aperture aperture S, the third lens group G3 having a positive refractive power, and the negative refractive power. It consists of a fourth lens group G4 having a positive refractive power and a fifth lens group G5 having a positive refractive power.
When scaling from the wide-angle end to the telephoto end, the air gap between the first lens group G1 and the second lens group G2 increases, and between the second lens group G2 and the third lens group G3. The air spacing between the third lens group G3 and the fourth lens group G4 changes, and the air spacing between the fourth lens group G4 and the fifth lens group G5 changes. ,
A zoom lens characterized by satisfying the following conditional expression.
(1) (1 / (1 / fW_34 + 1 / DsW) -EW) / √ (fW × fT)> 0
(2) (1 / (1 / fT_34 + 1 / DsT) -ET) / √ (fW × fT) <0
However,
fW: Focus distance of the whole system at infinity focusing at the wide-angle end fT: Focus distance of the whole system at infinity focusing at the telephoto end fW_34: The third lens group G3 and the fourth lens group at the wide-angle end Combined focal point of G4 fT_34: Combined focal point of the third lens group G3 and the fourth lens group G4 at the telephoto end DsW: From the aperture aperture S at the wide-angle end, the third lens group G3 and the fourth lens group Distance to the front principal point of the composite system of the lens group G4 DsT: Distance from the aperture aperture S at the telephoto end to the front principal point of the composite system of the third lens group G3 and the fourth lens group G4 EW: Distance from the rear principal point of the composite system of the third lens group G3 and the fourth lens group G4 at the wide-angle end to the front principal point of the fifth lens group G5 ET: The third lens at the telephoto end Distance from the rear principal point of the composite system of the group G3 and the fourth lens group G4 to the front principal point of the fifth lens group G5 Here, the distance is positive in the direction from the object side to the image side. It shall be measured on the optical axis.
The zoom lens according to claim 1, wherein the fourth lens group G4 moves to the image side when focusing from infinity to a short distance.
The zoom lens according to claim 1 or 2, wherein the fourth lens group G4 is composed of two lenses, a positive lens and a negative lens.
The zoom lens according to any one of claims 1 to 3, wherein the fifth lens group G5 satisfies the following conditional expression.
(3) 2 <f5 / √ (fW × fT) <10
(4) 0.5 <B_5 <1
However,
f5: Focal length of the fifth lens group G5 fW: Focal length of the entire system at the infinity focusing at the wide-angle end fT: Focal length of the entire system at the infinity focusing at the telephoto end B_5: The fifth lens group Magnification at infinity focus at the wide-angle end of G5
The zoom lens according to any one of claims 1 to 4, wherein the fifth lens group G5 has a positive lens A on the most object side, a negative lens B, and satisfies the following conditional expression.
(5) V_5A <50
(6) V_5B> 50
(7) ΔPgF_5B> 0
However,
V_5A: Abbe number of the positive lens A V_5B: Abbe number of the negative lens B ΔPgF_5B: Anomalous dispersibility of the negative lens B
The zoom lens (8) V_21> 55 according to any one of claims 1 to 5, wherein the second lens group G2 has a negative lens most satisfying the following conditional expression on the object side.
(9) ΔPgF_21> 0
However,
V_21: Abbe number of the negative lens on the most object side of the second lens group G2 ΔPgF_21: Anomalous dispersibility of the negative lens on the most object side of the second lens group G2

Images