JP2014035404A - Zoom lens, optical device, and zoom lens manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact zoom lens with properly corrected aberrations and high imaging performance, an optical device including the same, and a zoom lens manufacturing method.SOLUTION: A zoom lens includes, from an object side, a first lens group (G1) with negative refractive power and a second lens group (G2) with positive refractive power. In varying magnification from a wide-angle-end state (a) to a telephoto-end state (c), a distance between the first lens group (G1) and the second lens group (G2) is changed. The first lens group (G1) includes, from the object side, a negative meniscus lens (L1) having a concave surface facing an image surface side, a negative lens (L2), and a positive lens (L3) having a convex surface facing the object side. The second lens group (G2) includes, from the object side, a positive lens (L4), a first cemented lens (L56), and a second cemented lens (L78), and satisfies predetermined conditions.

Description

  The present invention relates to a zoom lens suitable for a small camera or the like having a solid-state image sensor, an optical device having the zoom lens, and a method for manufacturing the zoom lens.

  Conventionally, a zoom lens preceding a negative lens suitable for a small camera having a solid-state imaging device has been proposed (see, for example, Patent Document 1).

JP 2001-215407 A

  The negative-positive two-group zoom lens has a simple configuration and is suitable for miniaturization, but in order to further reduce the size, the first lens unit having negative refractive power is reduced to two lenses, a negative lens and a positive lens. In the case where it is configured only with this, it becomes difficult to correct various aberrations satisfactorily. In order to perform aberration correction, it is necessary to sufficiently widen the distance between the two lenses, and as a result, the thickness of the entire first lens group increases, making it difficult to achieve miniaturization. In addition, depending on the configuration of the second lens group, there is a problem that aberration correction is insufficient, or the positional sensitivity of each lens constituting the zoom lens is increased, resulting in a deterioration in manufacturing yield.

  The present invention has been made in view of the above-described problems, and provides a zoom lens having a high imaging performance in which various aberrations are favorably corrected while being small, an optical device having the zoom lens, and a method for manufacturing the zoom lens. To do.

In order to solve the above problems, the present invention provides:
In order from the object side, it has a first lens group with negative refractive power and a second lens group with positive refractive power,
During zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group changes,
The first lens group includes, in order from the object side, a negative meniscus lens having a concave surface facing the image surface side, a negative lens, and a positive lens having a convex surface facing the object side,
The second lens group includes, in order from the object side, a positive lens, a first cemented lens, and a second cemented lens.
A zoom lens characterized by satisfying the following conditions is provided.
1.40 <f2 / fw <1.85
Here, f2 is the focal length of the second lens group, and fw is the focal length of the zoom lens in the wide-angle end state.

  The present invention also provides an optical apparatus comprising the zoom lens.

The present invention also provides:
A method of manufacturing a zoom lens having a first lens unit having a negative refractive power and a second lens group having a positive refractive power in order from the object side,
The first lens group includes, in order from the object side, a negative meniscus lens having a concave surface facing the image surface side, a negative lens, and a positive lens having a convex surface facing the object side.
The second lens group includes, in order from the object side, a positive lens, a first cemented lens, and a second cemented lens;
So that the following conditional expression is satisfied,
A zoom lens manufacturing method is provided, wherein an interval between the first lens group and the second lens group is changed upon zooming from the wide-angle end state to the telephoto end state.
1.40 <f2 / fw <1.85
Here, f2 is the focal length of the second lens group, and fw is the focal length of the zoom lens in the wide-angle end state.

  ADVANTAGE OF THE INVENTION According to this invention, the zoom lens which has the high image formation performance which corrected various aberrations favorably though it is small, an optical apparatus having this, and the manufacturing method of a zoom lens can be provided.

1 is a cross-sectional view illustrating a lens configuration of a zoom lens according to Example 1 of the present application, in which (a) shows a wide-angle end state, (b) shows an intermediate focal length state, and (c) shows a telephoto end state. FIG. 4A illustrates various aberration diagrams of the zoom lens according to Example 1 of the present application when focusing on infinity, where (a) illustrates a wide-angle end state, (b) illustrates an intermediate focal length state, and (c) illustrates a telephoto end state. Each is shown. It is sectional drawing which shows the lens structure of the zoom lens which concerns on 2nd Example of this application, (a) shows a wide angle end state, (b) shows an intermediate focal distance state, (c) shows a telephoto end state, respectively. FIG. 7A shows aberration diagrams of the zoom lens according to Example 2 of the present application at the time of focusing on infinity, (a) shows a wide-angle end state, (b) shows an intermediate focal length state, and (c) shows a telephoto end state. Each is shown. It is sectional drawing which shows the lens structure of the zoom lens which concerns on 3rd Example of this application, (a) shows a wide-angle end state, (b) shows an intermediate focal distance state, (c) shows a telephoto end state, respectively. FIG. 7A shows various aberration diagrams of the zoom lens according to Example 3 of the present application when focusing on infinity, where (a) shows a wide-angle end state, (b) shows an intermediate focal length state, and (c) shows a telephoto end state. Each is shown. It is sectional drawing which shows the lens structure of the zoom lens which concerns on 4th Example of this application, (a) shows a wide angle end state, (b) shows an intermediate focal distance state, (c) shows a telephoto end state, respectively. FIG. 9A shows various aberration diagrams of the zoom lens according to Example 4 of the present application at the time of focusing on infinity, (a) shows a wide-angle end state, (b) shows an intermediate focal length state, and (c) shows a telephoto end state. Each is shown. It is sectional drawing which shows the lens structure of the zoom lens which concerns on 5th Example of this application, (a) shows a wide-angle end state, (b) shows an intermediate focal distance state, (c) shows a telephoto end state, respectively. FIG. 6A shows various aberration diagrams of the zoom lens according to Example 5 of the present application when focusing on infinity, (a) shows a wide-angle end state, (b) shows an intermediate focal length state, and (c) shows a telephoto end state. Each is shown. An example of a camera equipped with the zoom lens of the present application is shown. It is a flowchart which shows the manufacturing method of the zoom lens of this application.

  Hereinafter, a zoom lens according to an embodiment of the present application, an optical device having the zoom lens, and a method for manufacturing the zoom lens will be described. The following embodiments are only for facilitating the understanding of the invention, and excluding additions and substitutions that can be performed by those skilled in the art without departing from the technical idea of the present invention. It is not intended.

  The zoom lens according to the present application includes, in order from the object side, a first lens unit having a negative refractive power and a second lens group having a positive refractive power, and at the time of zooming from the wide-angle end state to the telephoto end state, The distance between the first lens group and the second lens group changes, and the first lens group has a negative meniscus lens having a concave surface facing the image surface side, a negative lens, and a convex surface facing the object side, in order from the object side. The second lens group includes a positive lens, a first cemented lens, and a second cemented lens in order from the object side.

  In the zoom lens according to the present application, the first lens group and the second lens group are configured as described above, so that it is possible to achieve downsizing while favorably correcting aberrations. In addition, each lens group can be configured with a small number of lenses, and deterioration in imaging performance due to position errors during manufacturing can be suppressed.

The zoom lens according to the present application satisfies the following conditional expression (1).
(1) 1.40 <f2 / fw <1.85
Here, f2 is the focal length of the second lens group, and fw is the focal length of the zoom lens in the wide-angle end state.

  Conditional expression (1) is a conditional expression that defines an appropriate range of the focal length of the positive second lens group by the focal length in the wide-angle end state. Satisfying this conditional expression (1) prevents so-called shading, ensures a sufficient zoom ratio, can satisfactorily correct spherical aberration and coma, and achieve high imaging performance. it can.

  Exceeding the upper limit value of conditional expression (1) is not preferable because the amount of movement of the second lens group during zooming increases and the distance between the first lens group and the second lens group cannot be maintained in the telephoto end state. . Alternatively, the total length is too short, and the exit pupil is displaced to the image plane side, causing vignetting of light on the image plane, so-called shading, which is not preferable.

  Exceeding the lower limit value of conditional expression (1) is not preferable because the focal length in the wide-angle end state is too long, and a sufficient zoom ratio cannot be ensured or the lens cannot be widened. Alternatively, the focal length of the second lens group is too small, and it is difficult to sufficiently correct spherical aberration and coma aberration.

  In order to secure the effect of the present application, it is preferable to set the upper limit of conditional expression (1) to 1.75. Furthermore, in order to raise the effect of this application, it is preferable to make an upper limit into 1.65. In order to secure the effect of the present application, it is preferable to set the lower limit of conditional expression (1) to 1.42. Furthermore, in order to raise the effect of this application, it is preferable to make a lower limit into 1.44.

  With the above configuration, according to the present invention, it is possible to realize a zoom lens having high imaging performance in which various aberrations are favorably corrected while being small.

  In the zoom lens of the present application, it is desirable that the first cemented lens has a negative refractive power. Thus, by making the first cemented lens have a negative refractive power, it is possible to satisfactorily correct various aberrations such as spherical aberration and achieve high imaging performance.

  In the zoom lens of the present application, it is desirable that the second cemented lens has a positive refractive power. Thus, by making the second cemented lens have a positive refractive power, it is possible to satisfactorily correct various aberrations such as spherical aberration and achieve high imaging performance.

In addition, it is desirable that the zoom lens of the present application satisfies the following conditional expression (2).
(2) 0.15 <S2 / TLt <0.35
Where S2 is the distance on the optical axis from the most object-side lens surface to the most image-side lens surface of the second lens group, and TLt is the most object-side lens when focused at infinity in the telephoto end state. This is the distance on the optical axis from the surface to the image plane.

  Conditional expression (2) shows the total length in the telephoto end state (distance on the optical axis from the most object-side lens surface to the image plane in the infinite focus state in the telephoto end state) and the thickness of the second lens group (first It defines an appropriate balance of the distance on the optical axis from the lens surface closest to the object side to the lens surface closest to the image plane in the two lens groups. By satisfying this conditional expression (2), the occurrence of so-called shading can be prevented, spherical aberration and coma can be favorably corrected, and high imaging performance can be achieved.

  Exceeding the upper limit value of conditional expression (2) is not preferable because the total length is too short and the exit pupil is displaced to the image plane side, causing light vignetting on the image plane, so-called shading.

  Exceeding the lower limit value of conditional expression (2) is not preferable because the thickness of the second lens group becomes too thin and correction of spherical aberration and coma aberration becomes difficult.

  In order to secure the effect of the present application, it is preferable to set the upper limit of conditional expression (2) to 0.30. Furthermore, in order to ensure the effect of the present application, the upper limit value is preferably set to 0.25. In order to secure the effect of the present application, it is preferable to set the lower limit of conditional expression (2) to 0.17. Furthermore, in order to ensure the effect of the present application, it is preferable to set the lower limit value to 0.19.

  The zoom lens of the present application preferably has an aperture stop, and the aperture stop is preferably arranged on the image plane side with respect to the lens surface closest to the image plane of the first lens group. With such a configuration, the zoom lens of the present application can satisfactorily correct off-axis aberrations such as coma and achieve high imaging performance. It is more desirable to arrange the aperture stop on the object side of the second lens group. Accordingly, the zoom lens of the present application can achieve high imaging performance by better correcting off-axis aberrations such as coma.

Moreover, it is desirable that the zoom lens of the present application satisfies the following conditional expression (3).
(3) 0.65 <SA / r6R ≦ 1.40
Where SA is the distance on the optical axis from the aperture stop to the image surface side lens surface of the first cemented lens, and r6R is the radius of curvature of the image surface side lens surface of the first cemented lens.

  Conditional expression (3) defines a preferable balance between the distance on the optical axis from the aperture stop to the lens surface on the image plane side of the first cemented lens and the radius of curvature of the lens surface on the image plane side of the first cemented lens. It is a thing. Satisfying this conditional expression (3) prevents a decrease in brightness and displacement of the exit pupil toward the image plane, keeps the paraxial ray height low, and corrects off-axis coma well. High imaging performance can be achieved.

  The lens surface on the image surface side of the first cemented lens in the second lens group is preferably shaped so that the concave surface faces the image surface side in order to correct spherical aberration and upper coma aberration in a balanced manner. However, the smaller the radius of curvature of the lens surface, the larger the declination, and the outer frame tendency increases as the distance from the stop to the lens surface increases.

  Exceeding the upper limit of conditional expression (3) is not preferable because the distance between the first cemented lens and the second cemented lens is increased and the brightness is lowered. In addition, the exit pupil is also not preferable because it is displaced to the image plane side.

  Exceeding the lower limit value of conditional expression (3) is not preferable because it is difficult to keep the paraxial ray height low and it is difficult to satisfactorily correct off-axis coma.

  In order to secure the effect of the present application, it is preferable to set the upper limit of conditional expression (3) to 1.30. Furthermore, in order to ensure the effect of the present application, it is preferable to set the upper limit value to 1.20. In order to secure the effect of the present application, it is preferable to set the lower limit of conditional expression (3) to 0.75. Furthermore, in order to ensure the effect of the present application, it is preferable to set the lower limit value to 0.85.

Moreover, it is desirable that the zoom lens of the present application satisfies the following conditional expression (4).
(4) 0.00 ≦ f2 / | fL56 | <0.70
Here, f2 is the focal length of the second lens group, and fL56 is the focal length of the first cemented lens.

  The conditional expression (4) defines an appropriate balance between the focal length of the second lens group and the focal length of the first cemented lens in the second lens group. Satisfying this conditional expression (4) prevents the second lens group from increasing in movement during zooming, suppresses fluctuations in coma due to zooming, and corrects off-axis aberrations, spherical aberration, and coma well. And high imaging performance can be achieved.

  Exceeding the upper limit of conditional expression (4) is not preferable because the amount of movement of the second lens group during zooming increases, and the distance between the first lens group and the second lens group cannot be maintained in the telephoto end state. . Further, it is not preferable because fluctuations in coma due to zooming increase and correction of off-axis aberrations becomes difficult.

Above the lower limit of conditional expression (4), spherical aberration and coma can be corrected well.
In order to secure the effect of the present application, it is preferable to set the upper limit of conditional expression (4) to 0.50. Furthermore, in order to ensure the effect of the present application, the upper limit value is preferably set to 0.30. In order to secure the effect of the present application, it is preferable to set the lower limit of conditional expression (4) to 0.02. Furthermore, in order to ensure the effect of the present application, it is preferable to set the lower limit value to 0.05.

The second lens group preferably includes at least one negative lens that satisfies the following conditional expression (5).
(5) 1.810 <ndLi
Here, ndLi is a refractive index with respect to the d-line (wavelength λ = 587.6 nm) of the negative lens.

  Conditional expression (5) above defines the refractive index with respect to the d-line (λ = 587.6 nm) of a lens having negative refractive power included in at least one of the positive second lens groups. By satisfying this conditional expression (5), an increase in higher-order aberrations can be prevented, the Petzval sum can be corrected well, deterioration of the curvature of field at the wide-angle end state can be suppressed, and high imaging performance can be achieved. be able to.

  Exceeding the lower limit of conditional expression (5) is not preferable because the radius of curvature of the negative lens included in the second lens group becomes too small and higher-order aberrations increase. Further, it is difficult to correct the Petzval sum, and the field curvature in the wide-angle end state is deteriorated, which is not preferable.

  In order to secure the effect of the present application, it is preferable to set the lower limit of conditional expression (5) to 1.840. Furthermore, in order to ensure the effect of the present application, it is preferable to set the lower limit of conditional expression (5) to 1.870.

  In the zoom lens of the present application, it is desirable that the first cemented lens is configured by cementing a positive lens and a negative lens in order from the object side. In this way, by configuring the first cemented lens by cementing the positive lens and the negative lens, it is possible to satisfactorily correct spherical aberration, axial chromatic aberration, and other aberrations, and a small zoom lens having high imaging performance. Can be achieved.

  In the zoom lens of the present application, it is preferable that the second cemented lens is configured by cementing a negative lens and a positive lens in order from the object side. In this way, by constructing the second cemented lens by cementing the negative lens and the positive lens, it is possible to satisfactorily correct aberrations such as spherical aberration and axial chromatic aberration, and a small zoom lens having high imaging performance. Can be achieved.

  In the zoom lens of the present application, it is desirable that the focusing from an object at infinity to an object at a short distance is performed by moving the entire first lens group. Thereby, the zoom lens of this application can achieve size reduction.

  In the zoom lens of the present application, it is desirable to arrange parallel plane glass on the object side of the lens surface closest to the object side of the first lens group. With such a configuration, the lens surface closest to the image plane of the first lens group can be protected from dust and dirt.

  Next, a camera equipped with a zoom lens according to a first embodiment of the present invention to be described later will be described with reference to FIG.

  The camera 1 is a so-called mirrorless camera of an interchangeable lens provided with a zoom lens according to a first embodiment of the present application, which will be described later, as a photographic lens 2 as shown in FIG.

  In the camera 1, light from an object (subject) (not shown) is collected by the taking lens 2 and picked up by the image pickup unit 3 through an LPF (Optical low pass filter) in the taking lens 2. A subject image is formed on the surface. Then, the subject image is photoelectrically converted by the photoelectric conversion element provided in the imaging unit 3 to generate an image of the subject. This image is displayed on an EVF (Electronic view finder) 4 provided in the camera 1. Thus, the photographer can observe the subject via the EVF 4.

  Further, when a release button (not shown) is pressed by the photographer, an image photoelectrically converted by the imaging unit 3 is stored in a memory (not shown). In this way, the photographer can shoot the subject with the camera 1.

  Here, the zoom lens according to the first embodiment of the present application mounted on the camera 1 as the photographing lens 2 is a zoom lens having high imaging performance in which various aberrations are favorably corrected while being small. Therefore, the camera 1 can achieve downsizing and high imaging performance. It should be noted that the same effect as that of the camera 1 can be obtained even if a camera having a zoom lens according to second to fifth embodiments described later is mounted as the photographing lens 2. In this embodiment, an example of a mirrorless camera has been described. However, a zoom lens according to each of the above embodiments is mounted on a single-lens reflex camera that has a quick return mirror in the camera body and observes a subject with a finder optical system. Even in this case, the same effect as the camera 1 can be obtained.

Next, a method for manufacturing the zoom lens of the present application will be described with reference to FIG.
The zoom lens manufacturing method shown in FIG. 12 is a zoom lens manufacturing method including a first lens group having negative refractive power and a second lens group having positive refractive power in order from the object side. S4 is included.

(Step S1)
The first lens group includes, in order from the object side, a negative meniscus lens having a concave surface facing the image surface side, a negative lens, and a positive lens having a convex surface facing the object side.

(Step S2)
The second lens group includes, in order from the object side, a positive lens, a first cemented lens, and a second cemented lens.

(Step S3)
The following conditional expression (1) is satisfied.
(1) 1.40 <f2 / fw <1.85
Here, f2 is the focal length of the second lens group, and fw is the focal length of the zoom lens in the wide-angle end state.

(Step S4)
The first lens group and the second lens group are arranged in order from the object side in the lens barrel, and a known moving mechanism is provided, so that at the time of zooming from the wide-angle end state to the telephoto end state, The distance from the second lens group is changed.

  According to the zoom lens manufacturing method of the present application, it is possible to manufacture a small zoom lens having high imaging performance from the wide-angle end state to the telephoto end state while suppressing aberration fluctuation during zooming.

Hereinafter, zoom lenses according to numerical examples of the present application will be described with reference to the accompanying drawings.
(First embodiment)
FIG. 1 is a cross-sectional view showing a lens configuration of a zoom lens according to Example 1 of the present application, in which (a) shows a wide-angle end state, (b) shows an intermediate focal length state, and (c) shows a telephoto end state. Each is shown.

  The zoom lens according to the present exemplary embodiment includes, in order from the object side, a first lens group G1 having a negative refractive power and a second lens group G2 having a positive refractive power.

  The first lens group G1 includes, in order from the object side, a negative meniscus lens L1 having a convex surface facing the object side, a biconcave negative lens L2, and a positive meniscus lens L3 having a convex surface facing the object side.

  The second lens group G2, in order from the object side, has a biconvex positive lens L4, a negative cemented lens L56 of a biconvex positive lens L5 and a biconcave negative lens L6, and a concave surface on the image side. And a positive cemented lens L78 of a biconvex positive lens L8.

  In the zoom lens according to the present embodiment, an aperture stop S is disposed between the first lens group G1 and the second lens group G2. A low-pass filter LPF is disposed between the second lens group G2 and the image plane I. The low-pass filter LPF is for cutting a spatial frequency higher than the limit resolution of a solid-state imaging device such as a CCD disposed on the image plane I.

  The zoom lens according to the present example moves the first lens group G1 and the second lens group G2 in the optical axis direction so that the air gap between the first lens group G1 and the second lens group G2 changes. Thus, zooming from the wide-angle end state to the telephoto end state is performed. At this time, the aperture stop S moves in the optical axis direction together with the second lens group G2, and the position of the low-pass filter LPF in the optical axis direction is fixed.

  The zoom lens according to the present embodiment performs focusing from an object at infinity to a near object by moving the first lens group G1 as a focusing lens group in the optical axis direction.

  Table 1 below lists values of specifications of the zoom lens according to the present example. In Table 1, f indicates the focal length, and BF indicates the back focus (distance on the optical axis from the lens surface closest to the image plane to the image plane I). In [Surface data], the surface number is the order of the optical surfaces counted from the object side, r is the radius of curvature, d is the surface interval (the interval between the nth surface (n is an integer) and the n + 1th surface), and nd is The refractive index for the d-line (λ = 587.6 nm) and νd indicate the Abbe number for the d-line (λ = 587.6 nm), respectively. In addition, the object plane indicates the object plane, the variable indicates the variable plane spacing, the stop S indicates the aperture stop S, and the image plane indicates the image plane I. The radius of curvature r = ∞ indicates a plane. Further, the aspherical surface is marked with * as the surface number, and the paraxial radius of curvature is shown in the column of the radius of curvature r.

[Aspherical data] shows an aspherical coefficient and a conic constant when the shape of the aspherical surface shown in [Surface data] is expressed by the following equation.
X (y) = y ² / [r · {1+ (1−κ · y ² / r ² ) ^1/2 }]
+ A4 ・ y ⁴ + A6 ・ y ⁶ + A8 ・ y ⁸ + A10 ・ y ¹⁰

Here, y is the height in the direction perpendicular to the optical axis, X (y) is the distance (sag amount) along the optical axis direction from the tangential plane of the apex of the aspheric surface to the aspheric surface at height y, κ Is a conic constant, A4, A6, A8, and A10 are aspheric coefficients, and r is a radius of curvature of the reference sphere (paraxial radius of curvature). “E−n” (n is an integer) indicates “× 10 ⁻ⁿ ”, for example “1.234E-05” indicates “1.234 × 10 ⁻⁵ ”. The secondary aspherical coefficient A2 is 0 and is not shown.

  In [Various data], FNO is the F number, 2ω is the angle of view (unit is “°”), Y is the image height, TL is the total length of the zoom lens (distance on the optical axis from the first surface to the image surface I). , Air conversion TL is an air conversion value of the entire length of the zoom lens, air conversion BF is an air conversion value of the back focus, and dn is a variable interval between the nth surface and the n + 1th surface. W represents the wide-angle end state, M represents the intermediate focal length state, and T represents the telephoto end state.

  Here, the focal length f, the radius of curvature r, and other length units listed in Table 1 are generally “mm”. However, the optical system is not limited to this because an equivalent optical performance can be obtained even when proportionally enlarged or proportionally reduced. In addition, the code | symbol of Table 1 described above shall be similarly used also in the table | surface of each Example mentioned later.

(Table 1) First Example
[Surface data]
Surface number r d nd νd
Object ∞
1 21.1989 1.10 1.85135 40.10
* 2 7.5975 4.41 1.00000
3 -52.6643 0.80 1.49782 82.57
4 42.3237 0.84 1.00000
5 15.6071 1.68 1.84666 23.78
6 32.7790 Variable 1.00000
7 (Aperture S) ∞ 0.65 1.00000
8 37.1408 1.47 1.65844 50.84
9 -29.0801 0.10 1.00000
10 9.6037 2.76 1.59319 67.90
11 -14.5302 3.16 1.74400 44.81
12 9.7023 1.83 1.00000
13 31.5814 0.80 1.90265 35.73
14 9.1997 2.75 1.58913 61.22
15 -15.6188 Variable 1.00000
16 ∞ 2.79 1.51680 63.88
17 ∞ 2.11 1.00000
Image plane ∞

[Aspherical data]
Surface number κ A4 A6 A8 A10
2 0.7566 -3.95310E-07 -6.33270E-08 1.17320E-09 -1.39090E-10

[Various data]
Scaling ratio 2.35

W M T
f 11.35 17.00 26.71
FNO 3.64 4.38 5.77
2ω 73.6 ° 51.2 ° 33.4 °
Y 8.00 8.00 8.00
TL 59.8037 56.6351 59.8037
Air conversion TL 58.8531 55.6845 58.8531
BF 20.0378 25.5878 35.1214
Air conversion BF 19.0872 24.6372 34.1708

W M T
d6 17.4158 8.6974 2.3323
d15 15.1378 20.6878 30.2214

[Lens group data]
Group start surface f
1 1 -17.41
2 8 17.10

[Conditional expression values]
(1) f2 / fw = 1.507
(2) S2 / TLt = 0.215
(3) SA / r6R = 0.973
(4) f2 / | fL56 | = 0.149
(5) ndLi = 1.903 (L7)

  2A and 2B are graphs showing various aberrations of the zoom lens according to the first example of the present application when focused at infinity. FIG. 2A shows a wide-angle end state, FIG. 2B shows an intermediate focal length state, and FIG. 2C shows telephoto. Each end state is shown.

  In each aberration diagram, FNO represents an F number, and Y represents an image height. The spherical aberration diagram shows the F-number corresponding to the maximum aperture, the astigmatism diagram and the distortion diagram show the maximum image height, and the coma diagram shows the value of each image height. d indicates the aberration at the d-line (λ = 587.6 nm), and g indicates the aberration at the g-line (λ = 435.8 nm). In the astigmatism diagram, the solid line indicates the sagittal image plane, and the broken line indicates the meridional image plane. Note that the same reference numerals as in this embodiment are used in the aberration diagrams of each embodiment described later.

  From the respective aberration diagrams, it can be seen that the zoom lens according to the present embodiment has excellent imaging performance with various aberrations corrected well from the wide-angle end state to the telephoto end state.

(Second embodiment)
FIGS. 3A and 3B are sectional views showing the lens configuration of the zoom lens according to Example 2 of the present application, in which FIG. 3A shows the wide-angle end state, FIG. 3B shows the intermediate focal length state, and FIG. 3C shows the telephoto end state. Each is shown.

  The zoom lens according to the present exemplary embodiment includes, in order from the object side, a first lens group G1 having a negative refractive power and a second lens group G2 having a positive refractive power.

  The first lens group G1 includes, in order from the object side, a negative meniscus lens L1 having a convex surface facing the object side, a biconcave negative lens L2, and a positive meniscus lens L3 having a convex surface facing the object side.

  The second lens group G2, in order from the object side, has a biconvex positive lens L4, a negative cemented lens L56 of a biconvex positive lens L5 and a biconcave negative lens L6, and a concave surface on the image side. And a positive cemented lens L78 of a biconvex positive lens L8.

  In the zoom lens according to the present embodiment, an aperture stop S is disposed between the first lens group G1 and the second lens group G2. A low-pass filter LPF is disposed between the second lens group G2 and the image plane I.

  The zoom lens according to the present example moves the first lens group G1 and the second lens group G2 in the optical axis direction so that the air gap between the first lens group G1 and the second lens group G2 changes. Thus, zooming from the wide-angle end state to the telephoto end state is performed. At this time, the aperture stop S moves in the optical axis direction together with the second lens group G2, and the position of the low-pass filter LPF in the optical axis direction is fixed.

  The zoom lens according to the present embodiment performs focusing from an object at infinity to a near object by moving the first lens group G1 as a focusing lens group in the optical axis direction.

Table 2 below lists values of specifications of the zoom lens according to the present example.
(Table 2) Second Example
[Surface data]
Surface number r d nd νd
Object ∞
1 27.6355 1.10 1.85135 40.10
* 2 7.6407 3.86 1.00000
3 -150.2962 1.00 1.59319 67.90
4 31.0526 0.55 1.00000
5 15.2311 1.93 1.78472 25.64
6 55.6807 Variable 1.00000
7 (Aperture S) ∞ 1.00 1.00000
8 27.1591 1.47 1.69680 55.52
9 -42.3201 0.10 1.00000
10 9.7355 4.49 1.59319 67.90
11 -14.9453 1.00 1.79952 42.09
12 9.9794 2.29 1.00000
13 34.1656 1.00 1.95400 33.46
14 9.1459 2.31 1.65844 50.84
15 -16.2105 Variable 1.00000
16 ∞ 2.79 1.51680 63.88
17 ∞ 2.11 1.00000
Image plane ∞

[Aspherical data]
Surface number κ A4 A6 A8 A10
2 0.7876 -2.07080E-05 -6.78850E-07 6.59940E-09 -3.36460E-10

[Various data]
Scaling ratio 2.35

W M T
f 11.35 17.30 26.70
FNO 3.65 4.39 5.77
2ω 75.1 ° 51.6 ° 34.3 °
Y 8.20 8.20 8.20
TL 59.6000 56.3856 59.6000
Air conversion TL 58.6494 55.4350 58.6494
BF 20.2437 26.1597 35.5059
Air conversion BF 19.2931 25.2091 34.5553

W M T
d6 17.2621 8.1318 2.0000
d15 15.3437 21.2597 30.6059

[Lens group data]
Group start surface f
1 1 -17.41
2 8 17.31

[Conditional expression values]
(1) f2 / fw = 1.525
(2) S2 / TLt = 0.212
(3) SA / r6R = 0.964
(4) f2 / | fL56 | = 0.254
(5) ndLi = 1.954 (L7)

  4A and 4B are graphs showing various aberrations of the zoom lens according to the second example of the present application at the time of focusing on infinity. FIG. 4A shows a wide-angle end state, FIG. 4B shows an intermediate focal length state, and FIG. 4C shows telephoto. Each end state is shown.

  From the respective aberration diagrams, it can be seen that the zoom lens according to the present embodiment has excellent imaging performance with various aberrations corrected well from the wide-angle end state to the telephoto end state.

(Third embodiment)
FIGS. 5A and 5B are sectional views showing the lens configuration of the zoom lens according to Example 3 of the present application. FIG. 5A shows the wide-angle end state, FIG. 5B shows the intermediate focal length state, and FIG. 5C shows the telephoto end state. Each is shown.

  The zoom lens according to the present exemplary embodiment includes, in order from the object side, a first lens group G1 having a negative refractive power and a second lens group G2 having a positive refractive power.

  The first lens group G1 includes, in order from the object side, a negative meniscus lens L1 having a convex surface facing the object side, a biconcave negative lens L2, and a positive meniscus lens L3 having a convex surface facing the object side.

  The second lens group G2, in order from the object side, has a biconvex positive lens L4, a negative cemented lens L56 of a biconvex positive lens L5 and a biconcave negative lens L6, and a concave surface on the image side. And a positive cemented lens L78 of a biconvex positive lens L8.

  In the zoom lens according to the present embodiment, an aperture stop S is disposed between the first lens group G1 and the second lens group G2. A low-pass filter LPF is disposed between the second lens group G2 and the image plane I.

  The zoom lens according to the present example moves the first lens group G1 and the second lens group G2 in the optical axis direction so that the air gap between the first lens group G1 and the second lens group G2 changes. Thus, zooming from the wide-angle end state to the telephoto end state is performed. At this time, the aperture stop S moves in the optical axis direction together with the second lens group G2, and the position of the low-pass filter LPF in the optical axis direction is fixed.

  The zoom lens according to the present embodiment performs focusing from an object at infinity to a near object by moving the first lens group G1 as a focusing lens group in the optical axis direction.

Table 3 below provides values of specifications of the zoom lens according to the present example.
(Table 3) Third Example
[Surface data]
Surface number r d nd νd
Object ∞
1 20.9555 1.10 1.85135 40.14
* 2 7.6934 4.31 1.00000
3 -73.1411 0.84 1.49782 82.56
4 25.3734 1.02 1.00000
5 15.7101 1.69 2.00069 25.47
6 31.1165 Variable 1.00000
7 (Aperture S) ∞ 0.65 1.00000
8 40.2590 1.43 1.69680 55.52
9 -31.7401 0.10 1.00000
10 9.8087 3.12 1.59319 67.94
11 -14.5256 2.80 1.74400 44.82
12 10.5639 1.73 1.00000
13 27.6157 1.00 1.95000 29.39
14 8.6732 2.76 1.58267 46.46
15 -15.6920 Variable 1.00000
16 ∞ 2.79 1.51680 63.88
17 ∞ 2.11 1.00000
Image plane ∞

[Aspherical data]
Surface number κ A4 A6 A8 A10
2 0.1520 1.66840E-04 1.76430E-06 -9.16880E-09 3.34540E-10

[Various data]
Scaling ratio 2.35

W M T
f 11.35 17.30 26.70
FNO 3.64 4.57 5.80
2ω 75.0 ° 51.5 ° 34.2 °
Y 8.20 8.20 8.20
TL 59.8881 56.7244 59.8834
Air equivalent TL 58.9375 55.7738 58.9328
BF 19.9000 25.7174 34.9080
Air conversion BF 18.9494 24.7668 33.9574

W M T
d6 17.4426 8.4614 2.4299
d15 15.0000 20.8174 30.0080

[Lens group data]
Group start surface f
1 1 -17.41
2 8 17.02

[Conditional expression values]
(1) f2 / fw = 1.500
(2) S2 / TLt = 0.216
(3) SA / r6R = 1.075
(4) f2 / | fL56 | = 0.084
(5) ndLi = 1.950 (L7)

  6A and 6B show various aberration diagrams of the zoom lens according to the third example of the present application at the time of focusing on infinity. FIG. 6A shows a wide-angle end state, FIG. 6B shows an intermediate focal length state, and FIG. Each end state is shown.

  From the respective aberration diagrams, it can be seen that the zoom lens according to the present embodiment has excellent imaging performance with various aberrations corrected well from the wide-angle end state to the telephoto end state.

(Fourth embodiment)
FIG. 7 is a cross-sectional view showing the lens configuration of a zoom lens according to Example 4 of the present application, in which (a) shows the wide-angle end state, (b) shows the intermediate focal length state, and (c) shows the telephoto end state. Each is shown.

  The zoom lens according to the present exemplary embodiment includes, in order from the object side, a first lens group G1 having a negative refractive power and a second lens group G2 having a positive refractive power.

  The first lens group G1 includes, in order from the object side, a negative meniscus lens L1 having a convex surface facing the object side, a biconcave negative lens L2, and a positive meniscus lens L3 having a convex surface facing the object side.

  The second lens group G2, in order from the object side, has a biconvex positive lens L4, a negative cemented lens L56 of a biconvex positive lens L5 and a biconcave negative lens L6, and a concave surface on the image side. And a positive cemented lens L78 of a biconvex positive lens L8.

  In the zoom lens according to the present embodiment, a plane parallel plate P is disposed on the object side of the first lens group G1. This parallel plane plate P can protect the lens surface closest to the object side in the first lens group G1. An aperture stop S is disposed between the first lens group G1 and the second lens group G2. A low-pass filter LPF is disposed between the second lens group G2 and the image plane I.

  The zoom lens according to the present example moves the first lens group G1 and the second lens group G2 in the optical axis direction so that the air gap between the first lens group G1 and the second lens group G2 changes. Thus, zooming from the wide-angle end state to the telephoto end state is performed. At this time, the plane parallel plate P moves in the optical axis direction together with the first lens group G1, the aperture stop S moves in the optical axis direction together with the second lens group G2, and the low-pass filter LPF has a fixed position in the optical axis direction. is there.

  The zoom lens according to the present embodiment performs focusing from an object at infinity to a near object by moving the first lens group G1 as a focusing lens group in the optical axis direction.

Table 4 below lists values of specifications of the zoom lens according to the present example.
(Table 4) Fourth Example
[Surface data]
Surface number r d nd νd
Object ∞
1 ∞ 1.00 1.51680 63.88
2 ∞ 2.00 1.00000
3 22.1410 1.10 1.85135 40.14
* 4 7.6618 4.23 1.00000
5 -97.7669 0.80 1.49782 82.57
6 29.9606 0.84 1.00000
7 14.8029 1.77 1.84666 23.80
8 30.8037 Variable 1.00000
9 (Aperture S) ∞ 0.65 1.00000
10 35.5510 1.46 1.63854 55.34
11 -30.6717 0.10 1.00000
12 9.6339 2.77 1.59319 67.90
13 -15.0148 3.28 1.74400 44.80
14 9.8040 1.78 1.00000
15 28.6661 1.00 1.90366 31.27
16 8.5586 2.77 1.61772 49.78
17 -17.3121 Variable 1.00000
18 ∞ 2.79 1.51680 63.88
19 ∞ 2.11 1.00000
Image plane ∞

[Aspherical data]
Surface number κ A4 A6 A8 A10
4 0.7721 -7.96219E-06 8.08394E-08 -3.39865E-09 -1.43235E-10

[Various data]
Scaling ratio 2.35

W M T
f 11.35 17.40 26.71
FNO 3.63 4.56 5.77
2ω 75.0 ° 51.4 ° 34.2 °
Y 8.19 8.19 8.19
TL 59.9000 56.7320 59.9056
Air equivalent TL 58.9494 55.7821 58.9493
BF 19.9000 25.8271 34.9480
Air conversion BF 18.9494 24.8765 33.9974

W M T
d8 17.4708 8.37574 2.42841
d17 15.0000 20.92712 30.04804

[Lens group data]
Group start surface f
1 3 -17.41
2 10 17.05

[Conditional expression values]
(1) f2 / fw = 1.503
(2) S2 / TLt = 0.220
(3) SA / r6R = 0.977
(4) f2 / | fL56 | = 0.131
(5) ndLi = 1.904 (L7)

  FIGS. 8A and 8B show various aberration diagrams of the zoom lens according to Example 4 of the present application at the time of focusing on infinity. FIG. 8A shows a wide-angle end state, FIG. 8B shows an intermediate focal length state, and FIG. Each end state is shown.

  From the respective aberration diagrams, it can be seen that the zoom lens according to the present embodiment has excellent imaging performance with various aberrations corrected well from the wide-angle end state to the telephoto end state.

(5th Example)
FIG. 9 is a cross-sectional view showing the lens configuration of a zoom lens according to Example 5 of the present application, in which (a) shows the wide-angle end state, (b) shows the intermediate focal length state, and (c) shows the telephoto end state. Each is shown.

  The zoom lens according to the present exemplary embodiment includes, in order from the object side, a first lens group G1 having a negative refractive power and a second lens group G2 having a positive refractive power.

  The first lens group G1, in order from the object side, includes a negative meniscus lens L1 having a convex surface facing the object side, a negative meniscus lens L2 having a convex surface facing the object side, and a positive meniscus lens L3 having a convex surface facing the object side. Consists of.

  The second lens group G2, in order from the object side, has a biconvex positive lens L4, a negative cemented lens L56 of a biconvex positive lens L5 and a biconcave negative lens L6, and a concave surface on the image side. And a positive cemented lens L78 of a biconvex positive lens L8.

  In the zoom lens according to the present embodiment, an aperture stop S is disposed between the first lens group G1 and the second lens group G2. A low-pass filter LPF is disposed between the second lens group G2 and the image plane I.

  The zoom lens according to the present example moves the first lens group G1 and the second lens group G2 in the optical axis direction so that the air gap between the first lens group G1 and the second lens group G2 changes. Thus, zooming from the wide-angle end state to the telephoto end state is performed. At this time, the aperture stop S moves in the optical axis direction together with the second lens group G2, and the position of the low-pass filter LPF in the optical axis direction is fixed.

  The zoom lens according to the present embodiment performs focusing from an object at infinity to a near object by moving the first lens group G1 as a focusing lens group in the optical axis direction.

Table 5 below provides values of specifications of the zoom lens according to the present example.
(Table 5) Fifth Example
[Surface data]
Surface number r d nd νd
Object ∞
1 21.8349 1.10 1.85135 40.10
* 2 6.9683 3.58 1.00000
3 232.0289 1.00 1.75700 47.73
4 29.0118 0.60 1.00000
5 13.9434 1.92 1.84666 23.78
6 38.9245 Variable 1.00000
7 (Aperture S) ∞ 1.00 1.00000
8 33.9295 1.47 1.67790 55.35
9 -31.2393 0.10 1.00000
10 8.7609 3.86 1.59319 67.90
11 -15.0893 1.00 1.79952 42.09
12 9.7880 2.30 1.00000
13 34.5787 1.00 1.90366 31.27
14 8.1693 2.33 1.61266 44.46
15 -14.8870 Variable 1.00000
16 ∞ 2.79 1.51680 63.88
17 ∞ 2.11 1.00000
Image plane ∞

[Aspherical data]
Surface number κ A4 A6 A8 A10
2 -0.8415 5.64840E-04 -1.28470E-06 3.29740E-08 5.58720E-11

[Various data]
Scaling ratio 2.35

W M T
f 11.35 17.30 26.71
FNO 3.59 4.40 5.78
2ω 73.0 ° 51.0 ° 34.1 °
Y 8.20 8.20 8.20
TL 58.4836 55.3260 58.4795
Air conversion TL 57.5330 54.3754 57.5289
BF 20.1001 25.9034 35.0772
Air conversion BF 19.1495 24.3528 34.1266

W M T
d6 17.1169 8.1560 2.1357
d15 15.2001 21.0034 30.1772

[Lens group data]
Group start surface f
1 1 -17.41
2 8 16.98

[Conditional expression values]
(1) f2 / fw = 1.496
(2) S2 / TLt = 0.206
(3) SA / r6R = 1.122
(4) f2 / | fL56 | = 0.160
(5) ndLi = 1.904 (L7)

  FIGS. 10A and 10B show various aberration diagrams of the zoom lens according to Example 5 of the present application at the time of focusing on infinity. FIG. 10A shows a wide-angle end state, FIG. 10B shows an intermediate focal length state, and FIG. 10C shows telephoto. Each end state is shown.

  From the respective aberration diagrams, it can be seen that the zoom lens according to the present embodiment has excellent imaging performance with various aberrations corrected well from the wide-angle end state to the telephoto end state.

  In addition, each said Example has shown one specific example of this invention, and this invention is not limited to these. The following contents can be appropriately adopted within a range that does not impair the optical performance of the zoom lens of the present application.

  Although a numerical example of the zoom lens of the present application is shown as having a two-group configuration, the present application is not limited to this, and a zoom lens of another group configuration (for example, three, four groups, etc.) can also be configured. Specifically, a configuration in which a lens or a lens group is added to the most object side or the most image plane side of the zoom lens of the present application may be used. A lens group refers to a portion having at least one lens separated by an air interval that changes during zooming.

  In addition, the zoom lens of the present application is used in order to focus from an object at infinity to an object at a short distance. It is good also as a structure moved to. In particular, it is preferable that at least a part of the first lens group is a focusing lens group. Such a focusing lens group can also be applied to autofocus, and is also suitable for driving by an autofocus motor, such as an ultrasonic motor.

  In the zoom lens of the present application, either the entire lens group or a part of the lens group is moved so as to include a component in a direction perpendicular to the optical axis as an anti-vibration lens group, or an in-plane direction including the optical axis It is also possible to adopt a configuration in which image blur caused by camera shake or the like is corrected by rotating (swinging) to the right. In particular, in the zoom lens of the present application, it is preferable that at least a part of the second lens group is an anti-vibration lens group.

  The lens surface of the lens constituting the zoom lens of the present application may be a spherical surface, a flat surface, or an aspheric surface. When the lens surface is a spherical surface or a flat surface, it is preferable because lens processing and assembly adjustment are easy, and deterioration of optical performance due to errors in lens processing and assembly adjustment can be prevented. Further, even when the image plane is deviated, it is preferable because there is little deterioration in drawing performance. When the lens surface is aspherical, any of aspherical surface by grinding, glass mold aspherical surface in which glass is molded into an aspherical shape, or composite aspherical surface in which resin provided on the glass surface is formed in an aspherical shape Good. The lens surface may be a diffractive surface, and the lens may be a gradient index lens (GRIN lens) or a plastic lens.

  In the zoom lens of the present application, it is preferable that the aperture stop is disposed between the first lens group and the second lens group, and the role may be substituted by a lens frame without providing a member as the aperture stop. .

  Further, an antireflection film having a high transmittance in a wide wavelength range may be provided on the lens surface of the lens constituting the zoom lens of the present application. Thereby, flare and ghost can be reduced, and high optical performance with high contrast can be achieved.

  In addition, the zoom lens according to the fourth example has an example in which a plane-parallel plate is provided on the object side of the first lens group, but is not limited thereto. The zoom lens of the present application may be configured to include a plane parallel plate or a lens having substantially no refractive power on the object side of the first lens group or the most object side in the first lens group. With this configuration, the most object side lens surface of the first lens unit can be protected from dust and dirt.

  The zoom lens of the present application is 10.0 to 30 in a state where the distance (back focus) on the optical axis from the lens surface on the image plane side of the lens component arranged closest to the image plane side to the image plane is the smallest. About 0.0 mm is preferable.

  In the zoom lens of the present application, the image height is preferably 5.0 to 12.5 mm, and more preferably 5.0 to 9.5 mm.

  As described above, the present application can provide a zoom lens having a high imaging performance in which various aberrations are favorably corrected while being small, an optical device having the zoom lens, and a method for manufacturing the zoom lens.

G1 First lens group G2 Second lens group L1 to L8 Lens L56 First cemented lens L78 Second cemented lens LPF Low pass filter S Aperture stop I Image plane 1 Camera 2 Shooting lens 3 Imaging unit 4 EVF

Claims (12)

In order from the object side, it has a first lens group with negative refractive power and a second lens group with positive refractive power,
During zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group changes,
The first lens group includes, in order from the object side, a negative meniscus lens having a concave surface facing the image surface side, a negative lens, and a positive lens having a convex surface facing the object side,
The second lens group includes, in order from the object side, a positive lens, a first cemented lens, and a second cemented lens.
A zoom lens satisfying the following conditions:
1.40 <f2 / fw <1.85
However,
f2: focal length of the second lens group fw: focal length of the zoom lens in the wide-angle end state   The zoom lens according to claim 1, wherein the first cemented lens has a negative refractive power.   The zoom lens according to claim 1, wherein the second cemented lens has a positive refractive power. The zoom lens according to claim 1, wherein the zoom lens satisfies the following condition.
0.15 <S2 / TLt <0.35
However,
S2: Distance on the optical axis from the most object side lens surface to the most image side lens surface of the second lens group TLt: Image from the most object side lens surface at the time of focusing on infinity in the telephoto end state Distance on the optical axis to the surface Having an aperture stop,
5. The zoom lens according to claim 1, wherein the aperture stop is disposed closer to the image plane side than a lens surface closest to the image plane of the first lens group. 6. The zoom lens according to claim 5, wherein the following condition is satisfied.
0.65 <SA / r6R ≦ 1.40
However,
SA: distance on the optical axis from the aperture stop to the lens surface on the image plane side of the first cemented lens r6R: radius of curvature of the lens surface on the image plane side of the first cemented lens The zoom lens according to claim 1, wherein the following condition is satisfied.
0.00 ≦ f2 / | fL56 | <0.70
However,
f2: focal length of the second lens group fL56: focal length of the first cemented lens The zoom lens according to any one of claims 1 to 7, wherein the second lens group includes at least one negative lens that satisfies the following condition.
1.810 <ndLi
However,
ndLi: refractive index of the negative lens with respect to d-line (λ = 587.6 nm)   The zoom lens according to any one of claims 1 to 8, wherein the first cemented lens includes a positive lens and a negative lens in order from the object side.   The zoom lens according to claim 1, wherein the second cemented lens includes a negative lens and a positive lens in order from the object side.   An optical apparatus comprising the zoom lens according to claim 1. A method of manufacturing a zoom lens having a first lens unit having a negative refractive power and a second lens group having a positive refractive power in order from the object side,
The first lens group includes, in order from the object side, a negative meniscus lens having a concave surface facing the image surface side, a negative lens, and a positive lens having a convex surface facing the object side.
The second lens group includes, in order from the object side, a positive lens, a first cemented lens, and a second cemented lens;
So that the following conditional expression is satisfied,
A zoom lens manufacturing method, characterized in that an interval between the first lens group and the second lens group is changed upon zooming from a wide-angle end state to a telephoto end state.
1.40 <f2 / fw <1.85
However,
f2: focal length of the second lens group fw: focal length of the zoom lens in the wide-angle end state

Images