JP5974719B2 - Zoom lens, optical device, and zoom lens manufacturing method - Google Patents

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 2010-250233 A

  With a conventional two-group zoom lens having a negative and positive configuration, it is difficult to correct various aberrations and achieve high imaging performance and miniaturization.

  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, the first lens group having a negative refractive power and the second lens group having a positive refractive power substantially consist of two lens groups ,
When 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 directed toward the image plane side, and a positive cemented lens composed of a negative lens and a positive lens.
The cemented surface of the positive cemented lens is concave on the image plane side,
A zoom lens characterized by satisfying the following conditions is provided.
0.70 <ft × Z / TLmax <1.90
Where ft is the focal length of the zoom lens in the telephoto end state, Z is the zoom ratio, TLmax is the distance on the optical axis from the lens surface closest to the object side to the image plane in the wide-angle end state when focusing at infinity. And the longer distance among the distances on the optical axis from the lens surface closest to the object side to the image plane in the telephoto end state.

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

The present invention also provides:
In order from the object side, there is provided a zoom lens manufacturing method comprising substantially two lens groups by a first lens group having a negative refractive power and a second lens group having a positive refractive power,
The first lens group includes, in order from the object side, a negative meniscus lens having a concave surface facing the image plane side, and a positive cemented lens of a negative lens and a positive lens.
The cemented surface of the positive cemented lens has a convex shape on the image surface side,
Ensure that the following conditions are met:
A zoom lens manufacturing method is provided in which the distance between the first lens group and the second lens group is changed during zooming from the wide-angle end state to the telephoto end state.
0.70 <ft × Z / TLmax <1.90
Where ft is the focal length of the zoom lens in the telephoto end state, Z is the zoom ratio, TLmax is the distance on the optical axis from the lens surface closest to the object side to the image plane in the wide-angle end state when focusing at infinity. And the longer distance among the distances on the optical axis from the lens surface closest to the object side to the image plane in the telephoto 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. 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, an optical device, and a method for manufacturing the zoom lens according to an embodiment of the present application 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 group having a negative refractive power and a second lens group having a positive refractive power, and the first lens group during zooming from the wide-angle end state to the telephoto end state. And the interval between the second lens groups is changed. With this configuration, the zoom lens of the present application can move the exit pupil position sufficiently far from the image plane.

  In the zoom lens of the present application, the first lens group includes, in order from the object side, a negative meniscus lens having a concave surface directed toward the image side, and a positive cemented lens of the negative lens and the positive lens. The joining surface is concave on the image surface side. With this configuration, the zoom lens of the present application is zoomed with a negative meniscus lens that is disposed closest to the object side while maintaining sufficient negative refractive power in the first lens group in order to displace the exit pupil toward the object side. In order to suppress lateral chromatic aberration caused by the above, it is preferable to dispose a negative lens on the image plane side of the negative meniscus lens. In particular, in order to achieve simplification and downsizing of the first lens group, the first lens group is arranged in order from the object side, a negative meniscus lens having a concave surface on the image plane side, a negative lens and a positive lens. It is desirable that the lens is composed of a positive cemented lens formed by bonding with a lens.

  In the zoom lens of the present application, the first lens group is configured as described above, so that it is possible to achieve a reduction in size while favorably correcting various aberrations. In addition, the first lens group can be constituted by two lenses, a negative meniscus lens and a positive cemented lens, and deterioration of optical performance based on a lens position error during manufacturing can be suppressed.

The zoom lens according to the present application satisfies the following conditional expression (1).
(1) 0.70 <ft × Z / TLmax <1.90
Where ft is the focal length of the zoom lens in the telephoto end state, Z is the zoom ratio, TLmax is the distance on the optical axis from the lens surface closest to the object side to the image plane in the wide-angle end state when focusing at infinity. This is the longer distance of the distances on the optical axis from the lens surface closest to the object side to the image plane in the telephoto end state.

  Conditional expression (1) is the product of the zoom ratio and the product of the distance on the optical axis from the lens surface closest to the object side to the image plane in the wide-angle end state at the time of focusing at infinity and the focal length in the telephoto end state. The size of the entire optical system is defined by the ratio of the longer distance (maximum total length) of the distances on the optical axis from the lens surface closest to the object side to the image plane in the end state. By satisfying the conditional expression (1), it is possible to achieve a compact zoom lens having high image forming performance that is small but has corrected various aberrations such as coma and distortion.

  When the upper limit value of conditional expression (1) is exceeded, the amount of movement of the second lens group increases to obtain the zoom ratio, and the distance between the first lens group and the second lens group cannot be maintained in the telephoto end state. In order to secure the distance between the two groups, it is necessary to increase the distance between the first lens group and the second lens group, and as a result, miniaturization becomes difficult. In addition, the focal length of the second lens group becomes larger than necessary, making it difficult to reduce the size of the zoom lens. If it is attempted to reduce the size, the refractive power of the first lens unit increases, and it becomes difficult to correct off-axis coma and distortion well.

  If the lower limit of conditional expression (1) is exceeded, the focal length of the second lens group becomes small, which makes it difficult to satisfactorily correct spherical aberration and coma aberration, which is not preferable. Further, it is not preferable because the radius of curvature of each lens in the second lens group is reduced, the fluctuation of coma due to zooming increases, and it is difficult to correct off-axis aberrations.

  In order to secure the effect of the present application, it is preferable to set the upper limit of conditional expression (1) to 1.60. In order to further secure the effect, the upper limit value is preferably 1.45. In order to secure the effect of the present application, it is preferable to set the lower limit of conditional expression (1) to 0.75. In order to further secure the effect, it is preferable to set the lower limit value to 0.80.

In addition, it is desirable that the zoom lens of the present application satisfies the following conditional expression (2).
(2) 1.00 <(− f1) / S1 <3.00
Here, f1 is the focal length of the first lens group, and S1 is the distance on the optical axis from the lens surface closest to the object side to the lens surface closest to the image plane.

  Conditional expression (2) defines an appropriate range of the total thickness of the first lens group (the distance on the optical axis from the most object-side lens surface to the most image-side lens surface of the first lens group). Is. By satisfying the conditional expression (2), it is possible to achieve a small zoom lens having high imaging performance in which various aberrations such as spherical aberration are favorably corrected.

  Exceeding the upper limit of conditional expression (2) is not preferable because the amount of movement of the first lens unit at the time of zooming becomes large and miniaturization cannot be achieved. An attempt to reduce the size is not preferable because it is difficult to satisfactorily correct various aberrations such as spherical aberration.

  Exceeding the lower limit value of conditional expression (2) is not preferable because the total thickness of the first lens unit is too large and cannot be reduced in size when the lens is housed. Further, it is not preferable to reduce the size because it is difficult to correct various aberrations such as spherical aberration.

  In order to secure the effect of the present application, it is preferable to set the upper limit of conditional expression (2) to 2.70. In order to further secure the effect, the upper limit value is preferably 2.45. In order to secure the effect of the present application, it is preferable to set the lower limit of conditional expression (2) to 1.30. In order to further secure the effect, the upper limit value is preferably 1.45.

Moreover, it is desirable that the zoom lens of the present application satisfies the following conditional expression (3).
(3) 0.50 <f2 / ft <0.85
Here, f2 is the focal length of the second lens group, and ft is the focal length of the zoom lens in the telephoto end state.

  Conditional expression (3) defines the focal length of the second lens group as the focal length in the telephoto end state. By satisfying conditional expression (3), it is possible to achieve a small zoom lens having high imaging performance in which various aberrations such as spherical aberration and coma are corrected well.

  If the upper limit of conditional expression (3) is exceeded, the focal length of the second lens group becomes longer and the refractive power becomes smaller, so that the amount of movement of the second lens group becomes larger in order to obtain the zoom ratio, and the back focus also increases. Since it becomes long, as a result, the whole system will be enlarged, which is not preferable. An attempt to reduce the size is not preferable because it is difficult to satisfactorily correct various aberrations such as spherical aberration.

  If the lower limit of conditional expression (3) is exceeded, the focal length of the second lens group will be shortened and the refractive power will be increased, which makes it difficult to satisfactorily correct spherical aberration, coma and astigmatism. It is not preferable.

  In order to secure the effect of the present application, it is preferable to set the upper limit of conditional expression (3) to 0.80. In order to further secure the effect, it is preferable to set the upper limit value to 0.75. In order to secure the effect of the present application, it is preferable to set the lower limit of conditional expression (3) to 0.53. In order to further secure the effect, the lower limit is preferably set to 0.56.

Moreover, it is desirable that the zoom lens of the present application satisfies the following conditional expression (4).
(4) 1.00 <(− f1) / fw <2.00
Here, f1 is the focal length of the first lens group, and fw is the focal length of the zoom lens in the wide-angle end state.

  Conditional expression (4) defines the focal length of the first lens group as the focal length in the wide-angle end state. By satisfying the conditional expression (4), it is possible to achieve a small zoom lens having high imaging performance in which various aberrations such as curvature of field and spherical aberration are well corrected.

  Exceeding the upper limit of conditional expression (4) is not preferable because the total length and diameter of the zoom lens are increased. An attempt to reduce the size is not preferable because fluctuations in field curvature increase.

  Exceeding the lower limit of conditional expression (4) is not preferable because the back focus is shortened, the imaging performance is deteriorated in the telephoto end state, and it becomes difficult to correct spherical aberration in particular.

  In order to secure the effect of the present application, it is preferable to set the upper limit of conditional expression (4) to 1.95. In order to further secure the effect, it is preferable to set the upper limit value to 1.90. In order to secure the effect of the present application, it is preferable to set the lower limit of conditional expression (4) to 1.20. In order to further secure the effect, the lower limit value is preferably 1.40.

Moreover, it is desirable that the zoom lens of the present application satisfies the following conditional expression (5).
(5) −0.50 <(TLw−TLt) / (fw × ft) ^1/2 <0.50
However, TLw is the distance on the optical axis from the lens surface closest to the object side to the image plane when focusing at infinity in the wide-angle end state, and TLt is from the lens surface closest to the object side when focusing at infinity in the telephoto end state. The distance on the optical axis to the image plane, fw is the focal length of the zoom lens in the wide-angle end state, and ft is the focal length of the zoom lens in the telephoto end state.

  Conditional expression (5) is a condition relating to the miniaturization of the zoom lens, and defines the state of the trajectory of the first lens group from the wide-angle end state to the telephoto end state by the intermediate focal length. By satisfying conditional expression (5), it is possible to achieve a small zoom lens having high imaging performance in which various aberrations such as curvature of field, distortion, and spherical aberration are well corrected.

  Exceeding the upper limit of conditional expression (5) is not preferable because the amount of movement of the first lens unit increases with respect to the change in focal length, and the entire system increases in size. In addition, since fluctuation of aberration due to zooming becomes large, it is difficult to correct field curvature and distortion well, which is not preferable.

  Exceeding the lower limit of conditional expression (5) is not preferable because the refractive power of each lens unit increases and it becomes difficult to correct various aberrations including spherical aberration. Alternatively, it is not preferable because a sufficient angle of view cannot be obtained and a zoom ratio cannot be secured. Further, the total length is too short, and the exit pupil is displaced toward the image plane, which causes vignetting of light on the image plane, so-called shading, which is not preferable.

  In order to secure the effect of the present application, it is preferable to set the upper limit of conditional expression (5) to 0.46. In order to further secure the effect, the upper limit value is preferably set to 0.42. In order to secure the effect of the present application, it is preferable to set the lower limit of conditional expression (5) to −0.25. In order to further secure the effect, it is preferable to set the lower limit to −0.10.

In the zoom lens of the present application, it is desirable that the second lens group has at least one negative lens that satisfies the following conditional expression (6).
(6) 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 (6) defines the refractive index for the d-line (λ = 587.6 nm) of at least one negative lens included in the second lens group. By satisfying conditional expression (6), the radius of curvature of the second lens group can be increased, so that higher-order aberrations can be suppressed, and the lens is small and highly corrected for various aberrations such as field curvature. A zoom lens with imaging performance can be achieved.

  Exceeding the lower limit of conditional expression (6) is not preferable because the radius of curvature of the lens surface of the negative lens becomes too small and higher-order aberrations increase. Further, correction of Petzval sum becomes difficult, and field curvature in the wide-angle end state is deteriorated, which is not preferable.

  If the lower limit of conditional expression (6) is set to 1.820, the Petzval sum is increased, and the effects of the present application can be exhibited. Further, when the lower limit value of conditional expression (6) is set to 1.900, the Petzval sum is increased, and the effects of the present invention can be maximized.

In addition, it is desirable that the zoom lens of the present application satisfies the following conditional expression (7).
(7) 53.00 <νdn
Where νdn is an Abbe number with respect to the d-line (λ = 587.6 nm) of the negative lens in the positive cemented lens.

  Conditional expression (7) defines an appropriate range for the Abbe number with respect to the d-line (λ = 587.6 nm) of the negative lens included in the positive cemented lens in the first lens group. By satisfying the range of the conditional expression (7), it is possible to satisfactorily correct axial chromatic aberration and the like, and it is possible to achieve a compact zoom lens having high image forming performance in which various aberrations are favorably corrected.

  If the lower limit value of conditional expression (7) is set to 60.00, the Petzval sum increases, and the effects of the present application can be exhibited. Further, when the lower limit value of conditional expression (7) is set to 72.00, the Petzval sum is increased, and the effects of the present invention can be exhibited to the maximum.

  In the zoom lens according to the present application, it is desirable that the second lens group includes three lens components. By configuring the second lens group from three lens components, it is possible to satisfactorily correct spherical aberration and coma aberration while achieving a small size even with a small number of components. In addition, a lens component means a single lens or a cemented lens.

  Further, in the zoom lens of the present application, it is desirable that two of the three lens components are cemented lenses, so that it is possible to satisfactorily correct axial chromatic aberration and lateral chromatic aberration with a small number of components. it can.

  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 a first example, which will be described later, mounted on the camera 1 as the photographing lens 2 is a zoom lens having a high imaging performance in which various aberrations are favorably corrected while being small. Accordingly, 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 and third 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 example described later is provided in 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 when mounted, the same effects 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. 8 is a zoom lens manufacturing method having a second lens group having a positive refractive power in order from the object side, and includes the following steps S1 to S4.

(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, and a positive cemented lens of a negative lens and a positive lens.

(Step S2)
The cemented surface of the positive cemented lens is convex on the image plane side.

(Step S3)
The first lens group and the second lens group satisfy the following conditional expression (1).
0.70 <ft × Z / TLmax <1.90
However,
ft: focal length of the zoom lens in the telephoto end state Z: zoom ratio TLmax: distance on the optical axis from the lens surface closest to the object side to the image plane in the wide-angle end state at the time of focusing on infinity and the telephoto end state The longer of the distances on the optical axis from the lens surface closest to the object to the image plane

(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.

(Example)
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 directed toward the object side, a positive cemented lens L23 of a biconcave negative lens L2 and a positive meniscus lens L3 having a convex surface directed toward the object side. It consists of. That is, the first lens group G1 includes two lens components.

  The second lens group G2 includes, in order from the object side, a positive meniscus lens L4 having a convex surface directed toward the object side, a cemented lens L56 of a biconvex positive lens L5 and a biconcave negative lens L6, and an image side. It comprises a negative meniscus lens L7 having a concave surface and a cemented lens L78 of a biconvex positive lens L8. That is, the second lens group G2 includes three lens components.

  In the zoom lens according to the present embodiment, an aperture stop S is disposed between the positive meniscus lens L4 and the positive lens L5 in 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 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 30.0962 1.248 1.75520 27.51
* 2 9.1545 5.000 1.00000
3 -36.7473 1.000 1.45600 91.21
4 12.2261 3.000 1.80610 33.27
5 161.9256 Variable 1.00000
* 6 15.4078 2.922 1.61272 58.75
7 181.7372 1.000 1.00000
8 (Aperture S) ∞ 1.000 1.00000
9 16.8222 2.500 1.83400 37.16
10 -17.6687 1.000 1.68893 31.07
11 12.3216 0.578 1.00000
12 42.2653 1.500 1.74950 35.28
13 8.1000 3.000 1.48749 70.40
14 -17.3520 Variable 1.00000
15 ∞ 2.790 1.51680 64.20
16 ∞ 2.110 1.00000
Image plane ∞

[Aspherical data]
Surface number κ A4 A6 A8 A10
2 0.9321 -9.72069E-06 -6.44591E-07 1.34440E-08 -2.12354E-10
6 -0.6215 -1.66386E-05 -2.04213E-07 9.88711E-09 -3.31447E-10

[Various data]
Scaling ratio 2.04

W M T
f 13.20 18.00 27.00
FNO 3.62 4.42 5.42
2ω 65.4 ° 48.9 ° 33.2 °
Y 8.0 8.0 8.0
TL 63.8451 58.2455 56.6395
Air equivalent TL 62.8945 57.2949 55.6889
BF 21.2691 24.9494 31.8499
Air equivalent BF 20.3185 23.9988 30.8993

W M T
d5 18.8280 9.5481 1.0416
d14 16.3691 20.0494 26.9499

[Lens group data]
Group start surface f
1 1 -24.48
2 6 18.77

[Conditional expression values]
(1) ft × Z / TLmax = 0.87
(2) (−f1) /S1=2.39
(3) f2 / ft = 0.70
(4) (−f1) /fw=1.85
(5) (TLw−TLt) / (fw × ft) ^1/2 = 0.38
(7) νdn = 91.21

  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 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. It consists of a positive cemented lens L23. That is, the first lens group G1 includes two lens components.

  The second lens group G2 includes, in order from the object side, a positive meniscus lens L4 having a convex surface directed toward the object side, a biconvex positive lens L5, a biconcave negative lens L6, and a biconvex positive lens L7. It includes a cemented lens L567, and a cemented lens L89 of a negative meniscus lens L8 having a concave surface facing the image side and a biconvex positive lens L9. That is, the second lens group G2 includes three lens components.

  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 49.6532 1.100 1.85135 40.10
* 2 7.5514 4.350 1.00000
3 99.1117 0.800 1.49782 82.57
4 10.9350 3.000 1.90265 35.73
5 58.1511 Variable 1.00000
6 (Aperture S) ∞ 1.000 1.00000
7 15.0000 1.314 1.90366 31.27
8 37.2654 0.375 1.00000
9 13.3283 1.753 1.64000 60.20
10 -27.9642 1.000 1.95000 29.37
11 18.6774 1.466 1.49782 82.57
12 -52.0470 3.177 1.00000
13 46.2917 1.000 1.81600 46.59
14 7.6982 1.960 1.58313 59.53
* 15 -69.3368 Variable 1.00000
16 ∞ 2.790 1.51680 64.12
17 ∞ 2.110 1.00000
Image plane ∞

[Aspherical data]
Surface number κ A4 A6 A8 A10
2 0.5051 1.19515E-05 -1.56149E-07 7.53879E-09 -1.30476E-10
15 -5.3508 2.18774E-04 -2.69124E-06 5.48276E-07 -1.60877E-08

[Various data]
Scaling ratio 2.48

W M T
f 11.30 18.00 28.00
FNO 3.63 4.60 5.93
2ω 74.1 ° 48.5 ° 31.9 °
Y 8.0 8.0 8.0
TL 59.6748 56.3445 60.1895
Air equivalent TL 58.7242 55.3939 59.2389
BF 20.0976 26.6704 36.4806
Air conversion BF 19.1470 25.7198 35.5300

W M T
d5 17.2822 7.3791 1.4140
d15 15.1976 21.7704 31.5806

[Lens group data]
Group start surface f
1 1 -17.51
2 7 17.17

[Conditional expression values]
(1) ft × Z / TLmax = 1.15
(2) (−f1) /S1=1.89
(3) f2 / ft = 0.61
(4) (−f1) /fw=1.55
(5) (TLw−TLt) / (fw × ft) ^1/2 = −0.03
(6) ndLi = 1.950 (L6)
ndLi = 1.816 (L8)
(7) νdn = 82.57

  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 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. It consists of a positive cemented lens L23. That is, the first lens group G1 includes two lens components.

  The second lens group G2, in order from the object side, has a biconvex positive lens L4, a cemented lens L56 of a biconvex positive lens L5 and a biconcave negative lens L6, and a concave surface directed to the image side. It consists of a cemented lens L78 of a negative meniscus lens L7 and a biconvex positive lens L8. That is, the second lens group G2 includes three lens components.

  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 48.7180 1.1000 1.85135 40.10
* 2 7.4194 5.3196 1.00000
3 66.7623 0.8000 1.57957 53.71
4 10.2257 3.2346 1.80610 33.27
5 119.5589 Variable 1.00000
6 (Aperture S) ∞ 1.0000 1.00000
7 13.1802 2.2476 1.60300 65.46
8 -97.5145 0.1000 1.00000
9 14.2043 4.6303 1.61272 58.73
10 -12.1342 3.5026 1.88300 40.76
11 9.7129 0.6481 1.00000
12 13.8990 0.8000 2.00330 28.27
13 8.5356 2.6279 1.57957 53.71
14 -15.8589 Variable 1.00000
15 ∞ 2.7900 1.51680 64.20
16 ∞ 2.1100 1.00000
Image plane ∞

[Aspherical data]
Surface number κ A4 A6 A8 A10
2 0.0486 1.31430E-04 1.48940E-08 1.41810E-08 -7.96720E-11

[Various data]
Scaling ratio 2.87

W M T
f 9.86 17.00 28.30
FNO 3.63 4.41 5.41
2ω 69.3 ° 49.7 ° 33.2 °
Y 8.2 8.2 8.2
TL 65.0000 59.9981 65.0000
TL 64.0494 59.0475 64.0494
BF 18.5562 26.0811 37.9894
Air conversion BF 17.6056 25.1305 37.0388

W M T
d5 20.4332 7.9064 1.0000
d14 13.6562 21.1811 33.0894

[Lens group data]
Group start surface f
1 1 -16.70
2 7 17.60

[Conditional expression values]
(1) ft × Z / TLmax = 1.25
(2) (−f1) /S1=1.60
(3) f2 / ft = 0.62
(4) (−f1) /fw=1.69
(5) (TLw−TLt) / (fw × ft) ^1/2 = 0.00
(6) ndLi = 1.883 (L6)
ndLi = 2.003 (L7)
(7) νdn = 53.71

  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.

  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 be configured. Specifically, a configuration in which a lens or a lens group is added to the most object side or the most image side of the zoom lens of the present application may be used. Further, the zoom lens of the present application may have a configuration in which a lens or a lens group having substantially no refractive power is added to the most object side or the most image side. 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 in the direction of the optical axis using a part of the lens group, the entire lens group, or a plurality of lens groups as the focusing lens group. 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.

  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 to 9.5 mm.

G1 1st lens group G2 2nd lens group LPF filter S Aperture stop I Image plane 1 Camera 2 Shooting lens 3 Imaging unit 4 EVF

Claims (11)

In order from the object side, the first lens group having a negative refractive power and the second lens group having a positive refractive power substantially consist of two lens groups ,
When 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 directed toward the image plane side, and a positive cemented lens composed of a negative lens and a positive lens.
The cemented surface of the positive cemented lens is concave on the image plane side,
A zoom lens satisfying the following conditions:
0.70 <ft × Z / TLmax <1.90
However,
ft: focal length of the zoom lens in the telephoto end state Z: zoom ratio TLmax: distance on the optical axis from the lens surface closest to the object side to the image plane in the wide-angle end state at the time of focusing on infinity and the telephoto end state The longer of the distances on the optical axis from the lens surface closest to the object to the image plane The zoom lens according to claim 1, wherein the following condition is satisfied.
1.00 <(− f1) / S1 <3.00
However,
f1: Focal length of the first lens group S1: Distance on the optical axis from the most object side lens surface to the most image side lens surface of the first lens group The zoom lens according to claim 1, wherein the zoom lens satisfies the following condition.
0.50 <f2 / ft <0.85
However,
f2: focal length of the second lens group ft: focal length of the zoom lens in the telephoto end state The zoom lens according to claim 1, wherein the zoom lens satisfies the following condition.
1.00 <(-f1) / fw <2.00
However,
f1: focal length of the first lens group fw: focal length of the zoom lens in the wide-angle end state The zoom lens according to claim 1, wherein the zoom lens satisfies the following condition.
−0.50 <(TLw−TLt) / (fw × ft) ^1/2 <0.50
However,
TLw: Distance on the optical axis from the lens surface closest to the object side to the image plane when focused at infinity in the wide-angle end state TLt: From the lens surface closest to the object side when focused at infinity in the telephoto end state On the optical axis fw: focal length of the zoom lens in the wide-angle end state ft: focal length of the zoom lens in the telephoto end state The zoom lens according to claim 1, wherein the second lens group includes at least one negative lens that satisfies the following condition.
1.810 <ndLi
However,
ndLi: Refractive index with respect to d-line (λ = 587.6 nm) of the negative lens The zoom lens according to claim 1, wherein the following condition is satisfied.
53.00 <νdn
However,
νdn: Abbe number with respect to d-line (λ = 587.6 nm) of the negative lens in the positive cemented lens   The zoom lens system according to claim 1, wherein the second lens group includes three lens components.   The zoom lens according to claim 8, wherein two of the three lens components are cemented lenses.   An optical apparatus comprising the zoom lens according to claim 1. In order from the object side, there is provided a zoom lens manufacturing method comprising substantially two lens groups by a first lens group having a negative refractive power and a second lens group having a positive refractive power,
The first lens group includes, in order from the object side, a negative meniscus lens having a concave surface facing the image plane side, and a positive cemented lens of a negative lens and a positive lens.
The cemented surface of the positive cemented lens is concave on the image plane side,
Ensure that the following conditions are met:
A zoom lens manufacturing method, characterized in that the distance between the first lens group and the second lens group changes during zooming from the wide-angle end state to the telephoto end state.
0.70 <ft × Z / TLmax <1.90
However,
ft: focal length of the zoom lens in the telephoto end state Z: zoom ratio TLmax: distance on the optical axis from the lens surface closest to the object side to the image plane in the wide-angle end state at the time of focusing on infinity and the telephoto end state The longer of the distances on the optical axis from the lens surface closest to the object to the image plane

Images