JP6031778B2 - Zoom lens, optical device, and method of manufacturing zoom lens - Google Patents

Description

  The present invention relates to a zoom lens, an optical apparatus, and a method for manufacturing a zoom lens.

  In recent years, in digital cameras, portability and cost reduction have been emphasized, and the lens system mounted on the camera has been reduced in size and price. For example, a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power, which are arranged in order from the object side along the optical axis, A zoom lens is disclosed in which the number of lenses and the cost are reduced by forming one lens group with only two spherical lenses. (For example, see Patent Document 1).

JP 2010-85875 A

  In recent years, zoom lenses are desired to have a wide angle and a high zoom ratio while maintaining a reduction in size and price as in the prior art.

  The present invention has been made in view of such problems, and is suitable for a video camera, an electronic still camera, or the like using a solid-state imaging device, and is small and low in size while achieving high zooming and widening. An object of the present invention is to provide a high-quality zoom lens, an optical apparatus, and a manufacturing method of the zoom lens at a low price.

In order to achieve such an object, a zoom lens according to the present invention includes a first lens group having a negative refractive power and a second lens having a positive refractive power, which are arranged in order from the object side along the optical axis. The lens group and the third lens group having a positive refractive power substantially consist of three lens groups, and the distance between adjacent lens groups changes at the time of zooming, and the first lens group is spaced apart from the air. Further, it is composed of only one spherical negative lens and one spherical positive lens, and the negative lens is disposed closest to the image side in the second lens group, and the following conditional expression is satisfied. In the present embodiment, the spherical lens includes a lens whose one surface is a flat surface.

0.40 <(DG1 + DG2 + DG3) / ft <0.65
0.20 <(− f1) /ft≦0.58
9.00 <(R3 + R2) / (R3-R2) <15.00
1.90 <(DG1 + DG2 + DG3) / fw <2.50
However,
DG1: thickness on the optical axis of the first lens group;
DG2: thickness of the second lens group on the optical axis,
DG3: thickness on the optical axis of the third lens group,
ft: focal length of the entire lens system in the telephoto end state,
f1: the focal length of the first lens group,
R2: image-side radius of curvature of the object-side lens constituting the first lens group,
R3: Object-side radius of curvature of the image-side lens constituting the first lens group,
fw: focal length of the entire lens system in the wide-angle end state.

  An optical apparatus according to the present invention (for example, the digital still camera CAM in the embodiment) includes any one of the zoom lenses.

The zoom lens manufacturing method according to the present invention includes a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a positive refraction arranged in order from the object side along the optical axis. a method of manufacturing a substantially three lenses ing the zoom lens from the group by a third lens group having a force distance of the lens group is changed adjacent during zooming, the first lens group, air The lens barrel is composed of only one spherical negative lens and one spherical positive lens spaced apart from each other, and the negative lens is disposed closest to the image side in the second lens group, and satisfies the following conditional expression: Each lens is built in.

0.40 <(DG1 + DG2 + DG3) / ft <0.65
0.20 <(− f1) /ft≦0.58
9.00 <(R3 + R2) / (R3-R2) <15.00
1.90 <(DG1 + DG2 + DG3) / fw <2.50
However,
DG1: thickness on the optical axis of the first lens group;
DG2: thickness of the second lens group on the optical axis,
DG3: thickness on the optical axis of the third lens group,
ft: focal length of the entire lens system in the telephoto end state,
f1: the focal length of the first lens group,
R2: image-side radius of curvature of the object-side lens constituting the first lens group,
R3: Object-side radius of curvature of the image-side lens constituting the first lens group,
fw: focal length of the entire lens system in the wide-angle end state.

INDUSTRIAL APPLICABILITY According to the present invention, it is suitable for a video camera or an electronic still camera using a solid-state image pickup device or the like, and is a compact, low-priced, high-quality zoom lens and optical device while achieving high zoom ratio and wide angle. In addition, a method for manufacturing a zoom lens can be provided.

It is a figure which shows the structure of the zoom lens which concerns on 1st Example, and the zoom track | orbit from a wide-angle end state to a telephoto end state. FIG. 6A is a diagram illustrating various aberrations of the zoom lens according to Example 1, wherein FIG. 10A is a diagram illustrating various aberrations at an infinite shooting distance in the wide-angle end state, and FIG. FIG. 7C is a diagram illustrating various aberrations at an imaging distance of infinity in the telephoto end state. FIG. 6 is a diagram illustrating a configuration of a zoom lens according to Example 2 and a zoom trajectory from a wide-angle end state to a telephoto end state. FIG. 6A is a diagram illustrating various aberrations of the zoom lens according to Example 2, wherein FIG. 9A is a diagram illustrating various aberrations at an imaging distance infinite at the wide-angle end state, and FIG. FIG. 7C is a diagram illustrating various aberrations at an imaging distance of infinity in the telephoto end state. It is a figure which shows the zoom locus | trajectory from the wide-angle end state to a telephoto end state, and the structure of the zoom lens which concerns on 3rd Example. FIG. 6A is a diagram illustrating various aberrations of the zoom lens according to Example 3, wherein FIG. 9A is a diagram illustrating various aberrations at an imaging distance infinite at the wide-angle end state, and FIG. FIG. 7C is a diagram illustrating various aberrations at an imaging distance of infinity in the telephoto end state. It is a figure which shows the structure of the zoom lens concerning 4th Example, and the zoom track | orbit from a wide-angle end state to a telephoto end state. FIG. 6A is a diagram illustrating various aberrations of the zoom lens according to Example 4, wherein FIG. 9A is a diagram illustrating aberrations at an imaging distance infinite in a wide-angle end state, and FIG. FIG. 7C is a diagram illustrating various aberrations at an imaging distance of infinity in the telephoto end state. It is a figure which shows the structure of the zoom lens concerning 5th Example, and the zoom track | orbit from a wide-angle end state to a telephoto end state. FIG. 10A is a diagram illustrating various aberrations of the zoom lens according to Example 5, wherein FIG. 10A is a diagram illustrating aberrations at an imaging distance infinite in the wide-angle end state, and FIG. FIG. 7C is a diagram illustrating various aberrations at an imaging distance of infinity in the telephoto end state. It is a figure which shows the zoom locus | trajectory from the wide-angle end state to a telephoto end state, and the structure of the zoom lens which concerns on 6th Example. FIG. 10A is a diagram illustrating various aberrations of the zoom lens according to Example 6, wherein FIG. 10A is a diagram illustrating aberrations at an imaging distance infinite in the wide-angle end state, and FIG. FIG. 7C is a diagram illustrating various aberrations at an imaging distance of infinity in the telephoto end state. It is a figure which shows the structure of the zoom lens which concerns on 7th Example, and the zoom track | orbit from a wide-angle end state to a telephoto end state. FIG. 10A is a diagram illustrating various aberrations of the zoom lens according to Example 7, wherein FIG. 10A is a diagram illustrating aberrations at an imaging distance infinite in the wide-angle end state, and FIG. FIG. 7C is a diagram illustrating various aberrations at an imaging distance of infinity in the telephoto end state. It is a figure explaining the digital camera (optical apparatus) carrying the zoom lens which concerns on this embodiment, (a) is a front view, (b) is a rear view. It is sectional drawing along the AA 'line of Fig.15 (a). 5 is a flowchart for explaining a method of manufacturing a zoom lens according to the present embodiment.

  Hereinafter, the present embodiment will be described with reference to the drawings. As shown in FIG. 1, the zoom lens ZL according to the present embodiment includes a first lens group G1 having a negative refractive power and a second lens having a positive refractive power, which are arranged in order from the object side along the optical axis. It has a lens group G2 and a third lens group G3 having a positive refractive power, and the first lens group G1 is composed of only one spherical negative lens and one spherical positive lens with an air gap therebetween. (In FIG. 1, the negative lens L11 and the positive lens L12 are applicable). By configuring the first lens group G1 with only two lenses, a spherical negative lens and a spherical positive lens in this way, optical performance degradation due to processing errors can be suppressed to a small extent, and astigmatism variation during assembly can be greatly reduced. Can be suppressed. In addition, since it is not necessary to use an expensive negative meniscus aspheric lens, the manufacturing cost can be greatly reduced.

  And the group of the said structure and the following conditional expressions (1) and (2) are satisfied.

0.40 <(DG1 + DG2 + DG3) / ft <0.65 (1)
0.20 <(− f1) / ft <0.60 (2)
However,
DG1: Thickness on the optical axis of the first lens group G1,
DG2: thickness on the optical axis of the second lens group G2,
DG3: thickness of the third lens group G3 on the optical axis,
ft: focal length of the entire lens system in the telephoto end state,
f1: Focal length of the first lens group G1.

  Conditional expression (1) defines an appropriate ratio of the sum of the thicknesses DG1 to DG3 of each lens group to the focal length ft of the entire lens system in the telephoto end state. If the upper limit value of conditional expression (1) is exceeded, the entire optical system becomes large and deviates from the purpose of the present zoom lens to be downsized. Moreover, since coma aberration is deteriorated, it is not preferable. If the lower limit of conditional expression (1) is not reached, it will be difficult to correct astigmatism.

  In order to secure the above effect, it is preferable to set the lower limit of conditional expression (1) to 0.40. In order to secure the above effect, it is preferable to set the upper limit of conditional expression (1) to 0.55.

  Conditional expression (2) defines an appropriate ratio of the focal length f1 of the first lens group G1 to the focal length ft of the entire lens system in the telephoto end state. Exceeding the upper limit value of conditional expression (2) is not preferable because coma becomes worse. If the lower limit value of conditional expression (2) is not reached, coma will deteriorate, which is not preferable.

  In order to secure the above effect, it is preferable to set the lower limit of conditional expression (2) to 0.40. In order to secure the above effect, it is preferable to set the upper limit of conditional expression (2) to 0.59. In order to secure the above effect, it is preferable to set the upper limit of conditional expression (2) to 0.56.

  The zoom lens according to the present embodiment preferably satisfies the following conditional expression (3).

9.00 <(R3 + R2) / (R3-R2) <15.00 (3)
However,
R2: image-side radius of curvature of the object-side lens constituting the first lens group G1,
R3: Object-side radius of curvature of the image-side lens constituting the first lens group G1.

  Conditional expression (3) defines the form factor of the air lens when the air space between the spherical negative lens L11 and the spherical positive lens L12 of the first lens group G1 is regarded as an “air lens”. Exceeding the upper limit value of conditional expression (3) is not preferable because coma becomes worse. If the lower limit value of conditional expression (3) is not reached, coma will deteriorate, which is not preferable.

  In order to secure the above effect, it is preferable to set the lower limit of conditional expression (3) to 9.50. In order to secure the above effect, it is preferable to set the upper limit of conditional expression (3) to 14.0.

  The zoom lens according to the present embodiment preferably satisfies the following conditional expression (4).

1.90 <(DG1 + DG2 + DG3) / fw <2.50 (4)
However,
fw: focal length of the entire lens system in the wide-angle end state.

  Conditional expression (4) defines an appropriate ratio of the sum of the thicknesses DG1 to DG3 of the lens groups to the focal length fw of the entire lens system in the wide-angle end state. If the upper limit value of conditional expression (4) is exceeded, the entire optical system becomes large and deviates from the purpose of the present zoom lens to be downsized. Moreover, since coma aberration is deteriorated, it is not preferable. If the lower limit of conditional expression (4) is not reached, it will be difficult to correct astigmatism.

  In order to secure the above effect, it is preferable to set the lower limit of conditional expression (4) to 2.00. In order to secure the above effect, it is preferable to set the upper limit of conditional expression (4) to 2.20.

  The zoom lens according to the present embodiment preferably satisfies the following conditional expression (5).

4.5 <TLw / fw <8.0 (5)
However,
TLw: total lens length in the wide-angle end state,
fw: focal length of the entire lens system in the wide-angle end state.

  Conditional expression (5) defines an appropriate ratio of the total lens length TLw in the wide-angle end state to the focal length fw of the entire lens system in the wide-angle end state. Exceeding the upper limit of conditional expression (5) is not preferable because coma becomes worse. If the lower limit value of conditional expression (5) is not reached, coma aberration and chromatic aberration (particularly axial chromatic aberration) deteriorate, which is not preferable.

  In order to secure the above effect, it is preferable to set the lower limit of conditional expression (5) to 5.5. In order to secure the above effect, it is preferable to set the upper limit of conditional expression (5) to 7.5.

  The zoom lens according to the present embodiment preferably satisfies the following conditional expression (6).

60.0 <νd2p <150.0 (6)
However,
νd2p: d-line (wavelength 587.6 nm) of the positive lens arranged closest to the object side in the second lens group G2.
Abbe number based on).

Conditional expression (6) defines an appropriate value of the Abbe number of the most object-side positive lens included in the second lens group G2. Exceeding the upper limit of conditional expression (6) is not preferable because axial chromatic aberration deteriorates. If the lower limit of conditional expression (6) is not reached, the longitudinal chromatic aberration is deteriorated.

  In order to secure the above effect, it is preferable to set the lower limit of conditional expression (6) to 65.0. In order to secure the above effect, it is preferable to set the upper limit of conditional expression (6) to 100.0.

  In the zoom lens according to the present embodiment, it is preferable that the second lens group G2 has at least one negative lens and satisfies the following conditional expression (7).

25.0 <νd2n <55.0 (7)
However,
νd2n: d-line (wavelength 587.6 nm) of the negative lens arranged closest to the image side of the second lens group G2.
Abbe number based on.

  Conditional expression (7) defines an appropriate value of the Abbe number of the most image-side negative lens included in the second lens group G2. Exceeding the upper limit of conditional expression (7) is not preferable because chromatic aberration (particularly axial chromatic aberration) deteriorates. If the lower limit of conditional expression (7) is not reached, chromatic aberration (especially axial chromatic aberration) deteriorates, which is not preferable.

  In order to secure the above effect, it is preferable to set the lower limit of conditional expression (7) to 30.0. In order to secure the above effect, it is preferable to set the upper limit of conditional expression (7) to 45.0.

  In the zoom lens according to the present embodiment, it is preferable that the lens constituting the third lens group G3 is a plastic aspheric lens. In general, in a plastic lens, a change in refractive index due to a temperature change tends to be a problem. However, since the zoom lens according to the present embodiment is used for the third lens group G3 close to the image plane I, the performance change due to the temperature change can be almost ignored. Therefore, it is more preferable to use a plastic lens for the third lens group G3 from the viewpoint of manufacturing cost. Furthermore, by using this lens as an aspheric lens, it is possible to satisfactorily correct astigmatism and distortion that cannot be corrected by the first lens group G1.

  15 and 16 show a configuration of a digital still camera CAM (optical device) as an optical device including the zoom lens ZL described above as a photographing lens. In this digital still camera CAM, when a power button (not shown) is pressed, a shutter (not shown) of the photographing lens ZL is opened, and light from a subject (object) is condensed by the photographing lens ZL, and an image plane I (FIG. 1). The image is formed on an image sensor C (for example, a CCD, a CMOS, or the like) arranged in the reference). The subject image formed on the image sensor C is displayed on the liquid crystal monitor M disposed behind the digital still camera CAM. The photographer determines the composition of the subject image while looking at the liquid crystal monitor M, and then depresses the release button B1. Then, the subject image is captured by the image sensor C and recorded and stored in a memory (not shown).

  The digital still camera CAM includes an auxiliary light emitting unit EF that emits auxiliary light when the subject is dark, and a wide (W) -tele (T) button B2 for zooming the photographing lens ZL from the wide-angle end state to the telephoto end state. In addition, function buttons B3 and the like used for setting various conditions of the digital still camera CAM are arranged. Here, a compact type camera in which the camera CAM and the photographing lens ZL are integrally formed is illustrated. However, as an optical device, a single lens reflex camera in which a lens barrel having the photographing lens ZL and a camera body main body can be attached and detached is used. good.

  Next, a method for manufacturing the zoom lens ZL will be described with reference to FIG. First, the first lens group G1, the second lens group G2, and the third lens group G3 are assembled in the lens barrel (step ST10). In this incorporation step, each lens is incorporated such that the first lens group G1 has a negative refractive power, the second lens group G2 has a positive refractive power, and the third lens group G3 has a positive refractive power. . Next, each lens is incorporated so that the first lens group G1 includes only the spherical negative lens L11 and the spherical positive lens L12 with an air gap therebetween (step ST20). At this time, each lens is incorporated in the lens barrel so as to satisfy the following conditional expressions (1) and (2) (step ST30).

0.40 <(DG1 + DG2 + DG3) / ft <0.65 (1)
0.20 <(− f1) / ft <0.60 (2)
However,
DG1: Thickness on the optical axis of the first lens group G1,
DG2: thickness on the optical axis of the second lens group G2,
DG3: thickness of the third lens group G3 on the optical axis,
ft: focal length of the entire lens system in the telephoto end state,
f1: Focal length of the first lens group G1.

  Here, as an example of the lens arrangement in the present embodiment, as shown in FIG. 1, as the first lens group G1, a negative meniscus arrayed in order from the object side along the optical axis and having a convex surface directed toward the object side. A spherical negative lens L11 having a shape and a positive meniscus spherical positive lens L12 having a convex surface facing the object side with an air space from the lens L11 are arranged. As the second lens group G2, a cemented lens composed of a biconvex positive lens L21, a biconvex positive lens L22, and a biking negative lens L23 arranged in order from the object side along the optical axis is arranged. did. As the third lens group G3, a biconvex plastic aspheric lens L31 is disposed. With this configuration, the corresponding value of conditional expression (1) is 0.43, the corresponding value of conditional expression (2) is 0.52, and both satisfy the ranges of conditional expressions (1) and (2). .

  As described above, the zoom lens manufacturing method according to the present embodiment is suitable for a video camera or an electronic still camera using a solid-state imaging device or the like, and is small in size while achieving high zooming and widening. A high-quality zoom lens can be obtained at a low price.

  Hereinafter, each example according to the present embodiment will be described with reference to the drawings. Tables 1 to 7 are shown below, but these are tables of specifications in the first to seventh examples.

  In [Lens Specifications] in the table, the surface number indicates the order of the optical surfaces from the object side along the light traveling direction, R indicates the radius of curvature of each optical surface, and D indicates the next optical element from each optical surface. The distance between surfaces on the optical axis to the surface (or image surface), nd is the refractive index for the d-line (wavelength 587.56 nm) of the lens material, and νd is the d-line (wavelength 587.56 nm) of the lens material. Indicates the Abbe number with reference to. Also, the object surface is the object surface, (variable) is the variable surface interval, the curvature radius “∞” is the plane or aperture, (aperture AS) is the aperture aperture AS, (aperture FS) is the flare cut aperture FS. The image plane represents the image plane I. The refractive index of air “1.0000” is omitted. When the lens surface is an aspherical surface, the surface number is marked with *, and the column of curvature radius R indicates the paraxial curvature radius.

  In [Overall specifications] in the table, f is the focal length of the entire lens system, Fno is the F-number, ω is the half angle of view, and Bf is the image plane side of the optical member arranged closest to the image plane side. Bf (air conversion) indicates the distance from the last optical surface to the paraxial image surface, and the distance from the final optical surface to the paraxial image surface.

In [Aspherical data] in the table, the shape of the aspherical surface shown in [Lens specifications] is shown by the following equation (a). X (y) is the distance along the optical axis direction from the tangential plane at the apex of the aspheric surface to the position on the aspheric surface at height y, R is the radius of curvature of the reference sphere (paraxial radius of curvature), and κ is Ai represents the i-th aspherical coefficient. “E-n” indicates “× 10 ⁻ⁿ ”. For example, 1.234E-05 = 1.234 × 10 ⁻⁵ .

X (y) = y ² / [R × {1+ (1−κ × y ² / R ² ) ^1/2 }] + A4 × y ⁴ + A6 × y ⁶ (a)

  In [Variable interval data] in the table, f indicates the focal length of the entire lens system, and Di (where i is an integer) indicates the variable interval between the i-th surface and the (i + 1) -th surface.

  In [Lens Group Data] in the table, the group number indicates the order of the lens groups from the object side along the direction in which the light beam travels, the group initial surface indicates the surface number on the most object side of each group, and the group focal length indicates The focal length of each group is shown.

  In [Conditional Expression] in the table, values corresponding to the conditional expressions (1) to (7) are shown.

  Hereinafter, in all the specification values, “mm” is generally used for the focal length f, curvature radius R, surface distance D, and other lengths, etc. unless otherwise specified, but the optical system is proportionally enlarged. Alternatively, the same optical performance can be obtained even by proportional reduction, and the present invention is not limited to this. The unit is not limited to “mm”, and other suitable units can be used.

  The description regarding the table so far is common to all the embodiments, and the description below will be omitted.

(First embodiment)
A first embodiment will be described with reference to FIGS. 1 and 2 and Table 1. FIG. FIG. 1 shows the configuration of the zoom lens ZL (ZL1) according to the first embodiment and the zoom trajectory from the wide-angle end state to the telephoto end state. As shown in FIG. 1, the zoom lens ZL1 according to the first example includes a first lens group G1 having negative refractive power arranged in order from the object side along the optical axis, and a first lens group G1 having positive refractive power. A second lens group G2 and a third lens group G3 having a positive refractive power.

  The first lens group G1 includes a biconcave spherical negative lens L11 arranged in order from the object side along the optical axis, and a positive meniscus spherical positive lens L12 having a convex surface facing the object side.

  The second lens group G2 includes a biconvex positive lens L21 and a cemented lens of a biconvex positive lens L22 and a biconcave negative lens L23 arranged in order from the object side along the optical axis. .

  The third lens group G3 includes a biconvex plastic positive lens L3.

  An aperture stop AS for adjusting the amount of light is disposed between the first lens group G1 and the second lens group G2.

  A low-pass filter between the third lens group G3 and the image plane I for cutting a spatial frequency higher than the limit resolution of a solid-state imaging device C (for example, a CCD or a CMOS) disposed on the image plane I. LPF is arranged.

In the zoom lens ZL1 having such a configuration, the first lens group G1, the second lens group G2, and the aperture stop AS move during zooming from the wide-angle end state to the telephoto end state, and the third lens group G3 is always fixed. To do.

  Table 1 below shows the values of each item in the first example. The surface numbers 1 to 16 in Table 1 correspond to the optical surfaces having the curvature radii R1 to R16 shown in FIG. In the first embodiment, the sixth surface, the seventh surface, the eleventh surface, and the twelfth surface are formed in an aspherical shape.

(Table 1)
[Lens specifications]
Surface number R D nd νd
Object ∞
1 -145.0146 1.5488 1.7550 52.34
2 13.3937 3.8721
3 15.6641 2.8395 1.8467 23.80
4 22.7064 D4 (variable)
5 (Aperture AS) ∞ 0.0000
* 6 (Aspherical surface) 12.2789 3.3558 1.4959 82.24
* 7 (Aspherical surface) -23.2898 0.2581
8 8.9512 3.3558 1.8061 40.97
9 -32.6314 1.1616 1.9037 31.27
10 6.0112 D10 (variable)
* 11 (Aspherical) 234.0115 3.8721 1.5327 56.19
* 12 (Aspherical) -21.2536 D12 (Variable)
13 ∞ 0.7744 1.5444 70.51
14 ∞ 0.7744
15 ∞ 1.2907 1.5163 64.14
16 ∞ Bf
Image plane ∞

[Overall specifications]
Zoom ratio 4.713
Wide angle end Intermediate position Telephoto end
f 10.00 21.71 47.13
Fno 2.7 4.0 6.9
ω 38.8 19.6 9.4
Bf 1.00 1.00 1.00
Bf (air equivalent) 7.16 7.16 7.16

[Aspherical data]
6th surface κ = -0.017, A4 = 4.843E-06, A6 = 4.033E-07
7th surface κ = -1.438, A4 = 1.533E-05, A6 = 4.275E-07
11th surface κ = 1.000, A4 = 1.784E-04, A6 = 1.215E-07
12th surface κ = 1.000, A4 = 2.740E-04, A6 = -3.547E-07

[Variable interval data]
Variable interval Wide angle end Intermediate position Telephoto end D4 29.62 10.63 1.89
D10 7.39 18.06 41.22
D12 4.00 4.00 4.00

[Lens group data]
Group number Group first surface Group focal length G1 1 -24.59
G2 6 17.91
G3 11 36.77

[Conditional expression]
(1) (DG1 + DG2 + DG3) /ft=0.43
(2) (-f1) /ft=0.52
(3) (R3 + R2) / (R3-R2) = 12.80
(4) (DG1 + DG2 + DG3) /fw=2.03
(5) TLw / fw = 6.44
(6) νd2p = 82.2
(7) νd2n = 31.3

  From the table of specifications shown in Table 1, it can be seen that the zoom lens ZL1 according to the present example satisfies the conditional expressions (1) to (7).

  FIG. 2 is a diagram showing various aberrations (spherical aberration diagram, astigmatism diagram, distortion aberration diagram, chromatic aberration diagram of magnification, and coma aberration diagram) of the zoom lens ZL1 according to the first example, and FIG. FIG. 2B is a diagram showing various aberrations at an infinite shooting distance in the intermediate focal length state, and FIG. 2C is an infinite shooting distance in the telephoto end state. It is an aberration diagram at a distance.

  In each aberration diagram, FNO represents an F number, and A represents an angle of view. In the spherical aberration diagram, the solid line indicates the spherical aberration, and the broken line indicates the sine condition. In the astigmatism diagram, the solid line indicates the sagittal image plane, and the broken line indicates the meridional image plane. In the coma aberration diagram, meridional coma is shown. d and g indicate aberrations at the d-line (wavelength 587.6 nm) and g-line (wavelength 435.8 nm), respectively, and those not described indicate aberrations at the d-line.

  The description regarding the aberration diagrams so far is common to all the examples, and the description below is omitted.

  As is apparent from each aberration diagram, in the first example, various aberrations other than distortion aberration are favorably corrected in each focal length state from the wide-angle end state to the telephoto end state, and the optical performance is excellent. I understand. With respect to distortion aberration, optical correction is not necessary because this amount of aberration can be sufficiently corrected by image processing after imaging.

(Second embodiment)
A second embodiment will be described with reference to FIGS. 3 and 4 and Table 2. FIG. FIG. 3 shows the configuration of the zoom lens ZL (ZL2) according to the second embodiment and the zoom trajectory from the wide-angle end state to the telephoto end state. As shown in FIG. 3, the zoom lens ZL2 according to the second example includes a first lens group G1 having negative refractive power arranged in order from the object side along the optical axis, and a first lens group G1 having positive refractive power. A second lens group G2 and a third lens group G3 having a positive refractive power.

  The first lens group G1 includes a biconcave spherical negative lens L11 arranged in order from the object side along the optical axis, and a positive meniscus spherical positive lens L12 having a convex surface facing the object side.

  The second lens group G2 includes a biconvex positive lens L21 and a cemented lens of a biconvex positive lens L22 and a biconcave negative lens L23 arranged in order from the object side along the optical axis. .

  The third lens group G3 includes a biconvex plastic positive lens L3.

  An aperture stop AS for adjusting the amount of light is disposed between the first lens group G1 and the second lens group G2.

  A low-pass filter between the third lens group G3 and the image plane I for cutting a spatial frequency higher than the limit resolution of a solid-state imaging device C (for example, a CCD or a CMOS) disposed on the image plane I. LPF is arranged.

  In the zoom lens ZL2 having such a configuration, the first lens group G1, the second lens group G2, and the aperture stop AS move during zooming from the wide-angle end state to the telephoto end state, and the third lens group G3 is always fixed. To do.

  Table 2 below shows the values of each item in the second embodiment. The surface numbers 1 to 16 in Table 2 correspond to the optical surfaces having the curvature radii R1 to R16 shown in FIG. In the second embodiment, the sixth surface, the seventh surface, the eleventh surface, and the twelfth surface are formed in an aspherical shape.

(Table 2)
[Lens specifications]
Surface number R D nd νd
Object ∞
1 -90.7547 1.5489 1.7550 52.34
2 14.9886 4.3886
3 17.4249 2.5815 1.9229 20.88
4 23.8032 D4 (variable)
5 (Aperture AS) ∞ 0.0000
* 6 (Aspherical) 11.8689 3.3559 1.4959 82.24
* 7 (Aspherical surface) -22.3206 0.2581
8 8.5444 3.3559 1.7292 54.61
9 -106.1697 1.1617 1.9027 35.73
10 6.0051 D10 (variable)
* 11 (Aspherical surface) -210.8959 3.8723 1.5327 56.19
* 12 (Aspherical) -18.0377 D12 (Variable)
13 ∞ 0.7744 1.5444 70.51
14 ∞ 0.7744
15 ∞ 1.2908 1.5163 64.14
16 ∞ Bf
Image plane ∞

[Overall specifications]
Zoom ratio 4.713
Wide angle end Intermediate position Telephoto end
f 10.00 21.71 47.13
Fno 2.7 4.1 7.0
ω 38.8 19.5 9.3
Bf 1.00 1.00 1.00
Bf (air equivalent) 7.61 7.61 7.61

[Aspherical data]
6th surface κ = 0.136, A4 = 7.393E-06, A6 = 1.126E-06
7th surface κ = -1.768, A4 = 3.297E-05, A6 = 1.105E-06
11th surface κ = 1.000, A4 = 1.784E-04, A6 = 1.215E-07
12th surface κ = 1.000, A4 = 2.76E-04, A6 = -2.082E-07

[Variable interval data]
Variable interval Wide angle end Intermediate position Telephoto end D4 29.43 10.44 1.70
D10 6.80 17.47 40.63
D12 4.45 4.45 4.45

[Lens group data]
Group number Group first surface Group focal length G1 1 -24.59
G2 6 17.91
G3 11 36.77

[Conditional expression]
(1) (DG1 + DG2 + DG3) /ft=0.44
(2) (-f1) /ft=0.52
(3) (R3 + R2) / (R3-R2) = 13.30
(4) (DG1 + DG2 + DG3) /fw=2.05
(5) TLw / fw = 6.44
(6) νd2p = 82.2
(7) νd2n = 35.7

  From the table of specifications shown in Table 2, it can be seen that the zoom lens ZL2 according to the present example satisfies the conditional expressions (1) to (7).

  FIG. 4 is a diagram showing various aberrations (spherical aberration diagram, astigmatism diagram, distortion aberration diagram, chromatic aberration diagram of magnification, and coma aberration diagram) of the zoom lens ZL2 according to the second example, and FIG. FIG. 4B is a diagram of various aberrations at an imaging distance of infinity in the intermediate focal length state, and FIG. 4C is an imaging distance of infinity in the telephoto end state. It is an aberration diagram at a distance.

  As is apparent from each aberration diagram, in the second example, various aberrations other than distortion aberration are favorably corrected in each focal length state from the wide-angle end state to the telephoto end state, and the optical performance is excellent. I understand. With respect to distortion aberration, optical correction is not necessary because this amount of aberration can be sufficiently corrected by image processing after imaging.

(Third embodiment)
A third embodiment will be described with reference to FIGS. FIG. 5 shows the configuration of the zoom lens ZL (ZL3) according to the third embodiment and the zoom trajectory from the wide-angle end state to the telephoto end state. As shown in FIG. 5, the zoom lens ZL3 according to the third example includes a first lens group G1 having negative refractive power arranged in order from the object side along the optical axis, and a first lens group G1 having positive refractive power. A second lens group G2 and a third lens group G3 having a positive refractive power.

  The first lens group G1 includes a biconcave spherical negative lens L11 arranged in order from the object side along the optical axis, and a positive meniscus spherical positive lens L12 having a convex surface facing the object side.

  The second lens group G2 includes a biconvex positive lens L21 and a cemented lens of a biconvex positive lens L22 and a biconcave negative lens L23 arranged in order from the object side along the optical axis. .

  The third lens group G3 includes a positive meniscus plastic positive lens L3 having a convex surface facing the image side.

  An aperture stop AS for adjusting the amount of light is disposed between the first lens group G1 and the second lens group G2.

  A low-pass filter between the third lens group G3 and the image plane I for cutting a spatial frequency higher than the limit resolution of a solid-state imaging device C (for example, a CCD or a CMOS) disposed on the image plane I. LPF is arranged.

  In the zoom lens ZL3 having such a configuration, the first lens group G1, the second lens group G2, and the aperture stop AS move during zooming from the wide-angle end state to the telephoto end state, and the third lens group G3 is always fixed. To do.

  Table 3 below shows values of various specifications in the third example. Surface numbers 1 to 16 in Table 3 correspond to the optical surfaces having the curvature radii R1 to R16 shown in FIG. In the third embodiment, the sixth surface, the seventh surface, the eleventh surface and the twelfth surface are formed in an aspherical shape.

(Table 3)
[Lens specifications]
Surface number R D nd νd
Object ∞
1 -84.6956 1.5560 1.7550 52.34
2 14.8770 4.6681
3 18.1481 2.3341 1.9229 20.88
4 25.3283 D4 (variable)
5 (Aperture AS) ∞ 0.0000
* 6 (Aspherical surface) 10.2839 3.3714 1.4959 82.24
* 7 (Aspherical surface) -21.2948 0.2593
8 8.9594 2.8527 1.7292 54.61
9 -2204.8306 1.2967 1.9027 35.73
10 5.9648 D10 (variable)
* 11 (Aspherical surface) -31.7158 3.3714 1.5327 56.19
* 12 (Aspherical) -12.5923 D12 (Variable)
13 ∞ 0.7780 1.5444 70.51
14 ∞ 0.7780
15 ∞ 1.2967 1.5163 64.14
16 ∞ Bf
Image plane ∞

[Overall specifications]
Zoom ratio 4.713
Wide angle end Intermediate position Telephoto end
f 10.00 21.71 47.13
Fno 2.8 4.1 7.0
ω 38.9 19.4 9.2
Bf 0.46 0.46 0.46
Bf (air equivalent) 6.46 6.46 6.46

[Aspherical data]
6th surface κ = 0.106, A4 = -5.850E-06, A6 = 1.323E-06
7th surface κ = -0.338, A4 = 5.128E-05, A6 = 1.260E-06
11th surface κ = 1.000, A4 = 1.757E-04, A6 = 1.187E-07
12th surface κ = 1.000, A4 = 3.450E-04, A6 = -3.039E-07

[Variable interval data]
Variable interval Wide angle end Intermediate position Telephoto end D4 29.63 9.94 0.87
D10 8.56 18.36 39.61
D12 3.87 3.87 3.87

[Lens group data]
Group number Group first surface Group focal length G1 1 -24.24
G2 6 17.47
G3 11 36.94

[Conditional expression]
(1) (DG1 + DG2 + DG3) /ft=0.42
(2) (-f1) /ft=0.51
(3) (R3 + R2) / (R3-R2) = 10.10
(4) (DG1 + DG2 + DG3) /fw=1.97
(5) TLw / fw = 6.44
(6) νd2p = 82.2
(7) νd2n = 35.7

  From the table of specifications shown in Table 3, it can be seen that the zoom lens ZL3 according to the present example satisfies the conditional expressions (1) to (7).

  FIG. 6 is a diagram showing various aberrations (spherical aberration diagram, astigmatism diagram, distortion aberration diagram, chromatic aberration diagram of magnification, and coma aberration diagram) of the zoom lens ZL3 according to the third example, and FIG. FIG. 6B is a diagram showing various aberrations at an infinite shooting distance in the intermediate focal length state, and FIG. 6C is an infinite shooting distance in the telephoto end state. It is an aberration diagram at a distance.

  As is apparent from each aberration diagram, in the third example, various aberrations other than distortion aberration are favorably corrected in each focal length state from the wide-angle end state to the telephoto end state, and excellent optical performance is obtained. I understand. With respect to distortion aberration, optical correction is not necessary because this amount of aberration can be sufficiently corrected by image processing after imaging.

(Fourth embodiment)
A fourth embodiment will be described with reference to FIGS. FIG. 7 shows the configuration of the zoom lens ZL (ZL4) according to the fourth example and the zoom trajectory from the wide-angle end state to the telephoto end state. As shown in FIG. 7, the zoom lens ZL4 according to the fourth example includes a first lens group G1 having negative refractive power arranged in order from the object side along the optical axis, and a first lens group G1 having positive refractive power. A second lens group G2 and a third lens group G3 having a positive refractive power.

  The first lens group G1 includes a biconcave spherical negative lens L11 arranged in order from the object side along the optical axis, and a positive meniscus spherical positive lens L12 having a convex surface facing the object side.

  The second lens group G2 includes a biconvex positive lens L21 arranged in order from the object side along the optical axis, a positive meniscus lens L22 having a convex surface on the object side, and a negative meniscus having a concave surface on the image surface side. A cemented lens with the lens L23.

  The third lens group G3 includes a positive meniscus plastic positive lens L3 having a convex surface facing the image side.

  Between the first lens group G1 and the second lens group G2, a flare-cut stop FS arranged in order from the object side along the optical axis to cut off the flare component in the wide-angle end state, and the amount of light An aperture stop AS for adjusting the aperture is disposed.

  A low-pass filter between the third lens group G3 and the image plane I for cutting a spatial frequency higher than the limit resolution of a solid-state imaging device C (for example, a CCD or a CMOS) disposed on the image plane I. LPF is arranged.

  In the zoom lens ZL4 having such a configuration, during zooming from the wide-angle end state to the telephoto end state, the first lens group G1, the flare cut stop FS, the second lens group G2, and the aperture stop AS move, and the third lens group G3 is always fixed.

  Table 4 below shows values of various specifications in the fourth embodiment. Surface numbers 1 to 17 in Table 4 correspond to the optical surfaces having the curvature radii R1 to R17 shown in FIG. In the fourth embodiment, the seventh surface, the eighth surface, the twelfth surface and the thirteenth surface are formed in an aspherical shape.

(Table 4)
[Lens specifications]
Surface number R D nd νd
Object ∞
1 -103.2694 1.5560 1.7550 52.34
2 14.2214 4.6680
3 17.2441 2.3340 1.9229 20.88
4 23.5042 D4 (variable)
5 (Aperture FS) ∞ D5 (Variable)
6 (Aperture AS) ∞ 0.0000
* 7 (Aspherical) 10.3617 3.3714 1.4959 82.24
* 8 (Aspherical surface) -21.3498 0.2593
9 8.9146 2.8527 1.7292 54.61
10 3251.3379 1.2967 1.9027 35.73
11 5.9647 D11 (variable)
* 12 (Aspherical surface) -31.0760 2.9824 1.5327 56.19
* 13 (Aspherical) -13.1114 D13 (Variable)
14 ∞ 0.7780 1.5444 70.51
15 ∞ 0.7780
16 ∞ 1.2967 1.5163 64.14
17 ∞ Bf
Image plane ∞

[Overall specifications]
Zoom ratio 4.713
Wide angle end Intermediate position Telephoto end
f 10.00 21.71 47.13
Fno 2.83 4.17 7.11
ω 38.88 19.50 9.29
Bf 0.456 0.456 0.456
Bf (air equivalent) 6.897 6.897 6.897

[Aspherical data]
7th surface κ = 0.103, A4 = -6.309E-06, A6 = 1.403E-06
8th surface κ = -0.277, A4 = 5.005E-05, A6 = 1.379E-06
12th surface κ = 1.000, A4 = 1.758E-04, A6 = 1.187E-07
Surface 13 κ = 1.000, A4 = 3.141E-04, A6 = -2.479E-07

[Variable interval data]
Variable interval Wide angle end Intermediate position Telephoto end D4 16.59 1.28 1.28
D5 12.97 8.92 0.00
D11 8.45 18.41 40.02
D13 4.30 4.30 4.30

[Lens group data]
Group number Group first surface Group focal length G1 1 -23.83
G2 7 17.47
G3 12 40.25

[Conditional expression]
(1) (DG1 + DG2 + DG3) /ft=0.41
(2) (-f1) /ft=0.51
(3) (R3 + R2) / (R3-R2) = 10.41
(4) (DG1 + DG2 + DG3) /fw=1.93
(5) TLw / fw = 6.42
(6) νd2p = 82.2
(7) νd2n = 35.7

  From the table of specifications shown in Table 4, it can be seen that the zoom lens ZL4 according to the present example satisfies the conditional expressions (1) to (7).

  FIG. 8 is a diagram showing various aberrations (spherical aberration diagram, astigmatism diagram, distortion aberration diagram, chromatic aberration diagram of magnification, and coma aberration diagram) of the zoom lens ZL4 according to Example 4, and FIG. FIG. 8B is a diagram illustrating various aberrations at an infinite shooting distance in the intermediate focal length state, and FIG. 8C is an infinite shooting distance in the telephoto end state. It is an aberration diagram at a distance.

  As is apparent from each aberration diagram, in the fourth example, various aberrations other than distortion aberration are favorably corrected in each focal length state from the wide-angle end state to the telephoto end state, and the optical performance is excellent. I understand. With respect to distortion aberration, optical correction is not necessary because this amount of aberration can be sufficiently corrected by image processing after imaging.

(5th Example)
The fifth embodiment will be described with reference to FIGS. 9 and 10 and Table 5. FIG. FIG. 9 shows the configuration of the zoom lens ZL (ZL5) according to Example 5 and the zoom trajectory from the wide-angle end state to the telephoto end state. As shown in FIG. 9, the zoom lens ZL5 according to the fifth example includes a first lens group G1 having negative refractive power arranged in order from the object side along the optical axis, and a first lens group G1 having positive refractive power. A second lens group G2 and a third lens group G3 having a positive refractive power.

  The first lens group G1 includes a biconcave spherical negative lens L11 arranged in order from the object side along the optical axis, and a positive meniscus spherical positive lens L12 having a convex surface facing the object side.

  The second lens group G2 includes a biconvex positive lens L21 and a cemented lens of a biconvex positive lens L22 and a biconcave negative lens L23 arranged in order from the object side along the optical axis. .

  The third lens group G3 includes a positive meniscus plastic positive lens L3 having a convex surface facing the image side.

  Between the first lens group G1 and the second lens group G2, a flare-cut stop FS arranged in order from the object side along the optical axis to cut off the flare component in the wide-angle end state, and the amount of light An aperture stop AS for the purpose of adjusting is provided.

  A low-pass filter between the third lens group G3 and the image plane I for cutting a spatial frequency higher than the limit resolution of a solid-state imaging device C (for example, a CCD or a CMOS) disposed on the image plane I. LPF is arranged.

  In the zoom lens ZL5 having such a configuration, the first lens group G1, the flare cut stop FS, the second lens group G2, the aperture stop AS, and the third lens group G3 move during zooming from the wide-angle end state to the telephoto end state. To do.

  Table 5 below shows values of various specifications in the fifth example. Surface numbers 1 to 17 in Table 5 correspond to the optical surfaces having the curvature radii R1 to R17 shown in FIG. In the fifth embodiment, the seventh surface, the eighth surface, the twelfth surface and the thirteenth surface are formed in an aspherical shape.

(Table 5)
[Lens specifications]
Surface number R D nd νd
Object ∞
1 323.1419 1.6502 1.8160 46.59
2 13.2084 4.9505
3 15.6264 2.4752 1.9229 20.88
4 20.6584 D4 (variable)
5 (Aperture FS) ∞ D5 (Variable)
6 (Aperture AS) ∞ 0.0000
* 7 9.8197 3.5754 1.4959 82.24
* 8 -20.8043 0.275
9 11.2721 3.0253 1.7725 49.62
10 -52.9059 1.3751 1.9027 35.73
11 6.5627 D11 (variable)
* 12 (Aspherical surface) -25.3724 3.1628 1.5327 56.19
* 13 (Aspherical) -12.5119 D13 (Variable)
14 ∞ 0.8251 1.5444 70.51
15 ∞ 0.8251
16 ∞ 1.3751 1.5163 64.14
17 ∞ Bf
Image plane ∞

[Overall specifications]
Zoom ratio 4.336
Wide angle end Intermediate position Telephoto end
f 10.00 20.82 43.36
Fno 3.00 4.25 6.94
ω 40.54 21.31 10.59
Bf 0.013 0.013 0.013
Bf (air equivalent) 7.269 7.814 7.269

[Aspherical data]
7th surface κ = -0.047, A4 = -1.178E-05, A6 = 1.601E-06
8th surface κ = -1.300, A4 = 2.484E-05, A6 = 1.691E-06
12th surface κ = 1.000, A4 = 2.169E-04, A6 = -1.058E-06
Surface 13 κ = 1.000, A4 = 3.509E-04, A6 = -1.202E-06

[Variable interval data]
Variable interval Wide angle end Intermediate position Telephoto end D4 20.70 3.15 0.73
D5 13.89 9.91 2.41
D11 8.52 17.14 36.53
D13 4.99 5.53 4.99

[Lens group data]
Group number Group first surface Group focal length G1 1 -25.27
G2 7 18.53
G3 12 42.69

[Conditional expression]
(1) (DG1 + DG2 + DG3) /ft=0.47
(2) (-f1) /ft=0.58
(3) (R3 + R2) / (R3-R2) = 11.93
(4) (DG1 + DG2 + DG3) /fw=2.05
(5) TLw / fw = 7.08
(6) νd2p = 82.2
(7) νd2n = 35.7

  It can be seen from the table of specifications shown in Table 5 that the zoom lens ZL5 according to the present example satisfies the conditional expressions (1) to (7).

  FIG. 10 is a diagram showing various aberrations (spherical aberration diagram, astigmatism diagram, distortion aberration diagram, chromatic aberration diagram of magnification, and coma aberration diagram) of the zoom lens ZL5 according to Example 5, and FIG. FIG. 10B is a diagram of various aberrations at an imaging distance of infinity in the intermediate focal length state, and FIG. 10C is an imaging distance of infinity in the telephoto end state. It is an aberration diagram at a distance.

  As is apparent from each aberration diagram, in the fifth example, various aberrations other than distortion aberration are favorably corrected in each focal length state from the wide-angle end state to the telephoto end state, and the optical performance is excellent. I understand. With respect to distortion aberration, optical correction is not necessary because this amount of aberration can be sufficiently corrected by image processing after imaging.

(Sixth embodiment)
A sixth embodiment will be described with reference to FIGS. 11 and 12 and Table 6. FIG. FIG. 11 shows the configuration of the zoom lens ZL (ZL6) according to the sixth example and the zoom trajectory from the wide-angle end state to the telephoto end state. As shown in FIG. 11, the zoom lens ZL6 according to the sixth example includes a first lens group G1 having negative refractive power arranged in order from the object side along the optical axis, and a first lens group G1 having positive refractive power. It has a second lens group G2, a third lens group G 3 having a positive refractive power.

  The first lens group G1 includes a biconcave spherical negative lens L11 arranged in order from the object side along the optical axis, and a positive meniscus spherical positive lens L12 having a convex surface facing the object side.

  The second lens group G2 includes a biconvex positive lens L21 arranged in order from the object side along the optical axis, a positive meniscus lens L22 having a convex surface on the object side, and a negative meniscus lens having a concave surface on the image side. And a cemented lens with L23.

The third lens group G3 includes a positive meniscus plastic positive lens L3 having a convex surface facing the image side, and a plastic aspheric lens L4 having no refractive power .

  Between the first lens group G1 and the second lens group G2, a flare-cut stop FS arranged in order from the object side along the optical axis to cut off the flare component in the wide-angle end state, and the amount of light An aperture stop AS for the purpose of adjusting is provided.

  A low-pass filter between the third lens group G3 and the image plane I for cutting a spatial frequency higher than the limit resolution of a solid-state imaging device C (for example, a CCD or a CMOS) disposed on the image plane I. LPF is arranged.

In the zoom lens ZL6 having such a configuration, during zooming from the wide-angle end state to the telephoto end state, the first lens group G1, the flare cut stop FS, the second lens group G2, and the aperture stop AS move, and the third lens group G3 is always fixed.

  Table 6 below shows values of various specifications in the sixth example. The surface numbers 1 to 19 in Table 6 correspond to the optical surfaces having the curvature radii R1 to R19 shown in FIG. In the sixth embodiment, the seventh surface, the eighth surface, the thirteenth surface, and the fourteenth surface are formed in an aspherical shape.

(Table 6)
[Lens specifications]
Surface number R D nd νd
Object ∞
1 -69.5077 1.5560 1.7550 52.34
2 15.1814 4.6680
3 18.4845 2.3340 1.9229 20.88
4 26.1561 D4 (variable)
5 (Aperture FS) ∞ D5 (Variable)
6 (Aperture AS) ∞ 0.0000
* 7 9.5254 3.3714 1.4959 82.24
* 8 -18.9882 0.2593
9 10.5813 2.8527 1.7292 54.61
10 317.1899 1.2967 1.9027 35.73
11 6.3797 D11 (variable)
12 -24.9356 2.9824 1.5327 56.19
* 13 -12.0083 2.97
* 14 ∞ 1.2967 1.5327 56.19
15 ∞ 1.0000
16 ∞ 1.0747 1.5163 64.14
17 ∞ 0.2967
18 ∞ 1.0000 1.5163 64.14
19 ∞ Bf
Image plane ∞

[Overall specifications]
Zoom ratio 4.713
Wide angle end Intermediate position Telephoto end
f 10.00 21.71 47.13
Fno 2.82 4.15 7.07
ω 38.90 19.25 9.11
Bf 0.75 0.75 0.75
Bf (air equivalent) 3.412 3.412 3.412

[Aspherical data]
7th surface κ = -0.077, A4 = -6.789E-06, A6 = 2.657E-07
8th surface κ = -1.810, A4 = 2.832E-05, A6 = 2.034E-07
Surface 13 κ = 1.000, A4 = 3.592E-05, A6 = 7.425E-07
14th surface κ = 1.000, A4 = -2.818E-04, A6 = 2.225E-06

[Variable interval data]
Variable interval Wide angle end Intermediate position Telephoto end D4 17.53 0.86 0.86
D5 11.61 8.92 0.00
D11 8.18 18.14 39.76

[Lens group data]
Group number Group first surface Group focal length G1 1 -23.83
G2 7 17.47
G3 12 40.25

[Conditional expression]
(1) (DG1 + DG2 + DG3) /ft=0.41
(2) (-f1) /ft=0.51
(3) (R3 + R2) / (R3-R2) = 10.19
(4) (DG1 + DG2 + DG3) /fw=1.93
(5) TLw / fw = 6.38
(6) νd2p = 82.2
(7) νd2n = 35.7

  From the table of specifications shown in Table 6, it can be seen that the zoom lens ZL6 according to the present example satisfies the conditional expressions (1) to (7).

  FIG. 12 is a diagram showing various aberrations (spherical aberration diagram, astigmatism diagram, distortion diagram, magnification chromatic aberration diagram, and coma aberration diagram) of the zoom lens ZL6 according to Example 6, and FIG. FIG. 12B is a diagram of various aberrations at an infinite shooting distance in the intermediate focal length state, and FIG. 12C is an infinite shooting distance in the telephoto end state. It is an aberration diagram at a distance.

  As is apparent from the respective aberration diagrams, in the sixth example, various aberrations other than distortion aberration are favorably corrected in each focal length state from the wide-angle end state to the telephoto end state, and the optical performance is excellent. I understand. With respect to distortion aberration, optical correction is not necessary because this amount of aberration can be sufficiently corrected by image processing after imaging.

(Seventh embodiment)
A seventh embodiment will be described with reference to FIGS. 13 and 14 and Table 7. FIG. FIG. 13 shows the configuration of the zoom lens ZL (ZL7) according to the seventh example and the zoom trajectory from the wide-angle end state to the telephoto end state. As shown in FIG. 13, the zoom lens ZL7 according to the seventh example includes a first lens group G1 having a negative refractive power arranged in order from the object side along the optical axis, and a first lens group G1 having a positive refractive power. It has a second lens group G2, a third lens group G3 having positive refractive power.

  The first lens group G1 includes a biconcave spherical negative lens L11 arranged in order from the object side along the optical axis, and a positive meniscus spherical positive lens L12 having a convex surface facing the object side.

  The second lens group G2 includes a biconvex positive lens L21 arranged in order from the object side along the optical axis, a positive meniscus lens L22 having a convex surface on the object side, and a negative meniscus lens having a concave surface on the image side. And a cemented lens with L23.

The third lens group G3 includes a positive meniscus plastic positive lens L3 having a convex surface facing the image side and a positive meniscus plastic positive lens L4 having a convex surface facing the image side .

  Between the first lens group G1 and the second lens group G2, a flare-cut stop FS arranged in order from the object side along the optical axis to cut off the flare component in the wide-angle end state, and the amount of light An aperture stop AS for the purpose of adjusting is provided.

  A low-pass filter between the third lens group G3 and the image plane I for cutting a spatial frequency higher than the limit resolution of a solid-state imaging device C (for example, a CCD or a CMOS) disposed on the image plane I. LPF is arranged.

In the zoom lens ZL7 having such a configuration, during zooming from the wide-angle end state to the telephoto end state, the first lens group G1, the flare cut stop FS, the second lens group G2, and the aperture stop AS move, and the third lens group G3 is always fixed.

  Table 7 below shows values of each item in the seventh example. Surface numbers 1 to 19 in Table 7 correspond to the optical surfaces having the curvature radii R1 to R19 shown in FIG. In the seventh embodiment, the seventh surface, the eighth surface, the thirteenth surface, and the fourteenth surface are formed in an aspherical shape.

(Table 7)
[Lens specifications]
Surface number R D nd νd
Object ∞
1 -86.4141 1.5841 1.7550 52.34
2 14.9313 4.7523
3 18.0242 2.3761 1.9229 20.88
4 24.8622 D4 (variable)
5 (Aperture FS) ∞ D5 (Variable)
6 (Aperture AS) ∞ 0.0000
* 7 9.751 3.4322 1.4959 82.24
* 8 -19.4499 0.2640
9 10.6936 2.9042 1.7292 54.61
10 322.1013 1.3201 1.9027 35.73
11 6.4948 D11 (variable)
12 -27.9229 3.0362 1.5327 56.19
* 13 -12.7148 2.44
* 14 -394.7049 1.8481 1.5327 56.19
15 -77.6499 0.8561
16 ∞ 1.1121 1.5163 64.14
17 ∞ 0.2000
18 ∞ 1.0000 1.5163 64.14
19 ∞ Bf
Image plane ∞

[Overall specifications]
Zoom ratio 4.713
Wide angle end Intermediate position Telephoto end
f 10.00 21.71 47.13
Fno 2.77 4.08 6.94
ω 39.40 19.55 9.26
Bf 1.06 1.06 1.06
Bf (air equivalent) 3.505 3.505 3.505

[Aspherical data]
7th surface κ = -0.075, A4 = -8.133E-06, A6 = 3.087E-07
8th surface κ = -2.108, A4 = 1.861E-05, A6 = 3.064E-07
13th surface κ = 1.000, A4 = 2.551E-05, A6 = 6.361E-07
14th surface κ = 1.000, A4 = -2.403E-04, A6 = 1.754E-06

[Variable interval data]
Variable interval Wide angle end Intermediate position Telephoto end D4 18.01 1.04 1.04
D5 11.80 9.05 0.00
D11 8.47 18.61 40.62

[Lens group data]
Group number Group first surface Group focal length G1 1 -24.26
G2 7 17.78
G3 12 33.78

[Conditional expression]
(1) (DG1 + DG2 + DG3) /ft=0.42
(2) (-f1) /ft=0.51
(3) (R3 + R2) / (R3-R2) = 10.66
(4) (DG1 + DG2 + DG3) /fw=1.97
(5) TLw / fw = 6.58
(6) νd2p = 82.2
(7) νd2n = 35.7

  From the table of specifications shown in Table 7, it can be seen that the zoom lens ZL7 according to the present example satisfies the conditional expressions (1) to (7).

  FIG. 14 is a diagram showing various aberrations (spherical aberration diagram, astigmatism diagram, distortion aberration diagram, chromatic aberration diagram of magnification, and coma aberration diagram) of the zoom lens ZL7 in accordance with the seventh example, and FIG. FIG. 14B is a diagram showing various aberrations at an infinite shooting distance in the intermediate focal length state, and FIG. 14C is an infinite shooting distance in the telephoto end state. It is an aberration diagram at a distance.

  As is apparent from each aberration diagram, in the seventh example, various aberrations other than distortion aberration are favorably corrected in each focal length state from the wide-angle end state to the telephoto end state, and the optical performance is excellent. I understand. With respect to distortion aberration, optical correction is not necessary because this amount of aberration can be sufficiently corrected by image processing after imaging.

  In the above-described embodiment, the following description can be appropriately adopted as long as the optical performance is not impaired.

In each embodiment, a three-group configuration is shown as a zoom lens, but it can also be applied to other group configurations such as a four-group . Further, a configuration in which a lens or a lens group is added to the most object side, or a configuration in which a lens or a lens group is added to the most image side may be used. The lens group refers to a portion having at least one lens separated by an air interval that changes during zooming.

  In the present embodiment, a single lens group, a plurality of lens groups, or a partial lens group may be moved in the optical axis direction to be a focusing lens group that performs focusing from an object at infinity to a near object. This focusing lens group can be applied to autofocus, and is also suitable for driving a motor for autofocus (using an ultrasonic motor or the like). In particular, it is preferable that at least a part of the third lens group is a focusing lens group.

In this embodiment, the lens group or the partial lens group is vibrated in a direction perpendicular to the optical axis, or rotated (swayed) in the in-plane direction including the optical axis to correct image blur caused by camera shake. A vibration-proof lens group may be used. In particular, the second lens group is preferably an anti-vibration lens group.

  In the present embodiment, the lens surface may be formed as a spherical surface or a flat surface, or may be formed as an aspheric surface. When the lens surface is a spherical surface or a flat surface, lens processing and assembly adjustment are facilitated, and optical performance deterioration due to errors in processing and assembly adjustment can be prevented. If the lens surface is aspherical, the aspherical surface is an aspherical surface by grinding, a glass mold aspherical surface that is formed of glass with an aspherical shape, or a composite type nonspherical surface that is formed of a resin on the surface of glass. Any aspherical surface may be used. 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 present embodiment, it is preferable that the aperture stop is disposed in the vicinity of the second lens group or in the second lens group, but the role may be substituted by a lens frame without providing a member as the aperture stop.

  In the present embodiment, each lens surface may be provided with an antireflection film having high transmittance in a wide wavelength region in order to reduce flare and ghost and achieve high optical performance with high contrast.

  The zoom lens of this embodiment has a zoom ratio of about 3 to 10 times.

  So far, in order to make the present invention easy to understand, the configuration requirements of the embodiment have been described, but it goes without saying that the present invention is not limited to this.

  As described above, according to the present embodiment, it is suitable for a video camera or an electronic still camera using a solid-state imaging device or the like, and is small in size, low in price, and high in image quality while achieving high zoom ratio and wide angle. Zoom lens could be achieved.

ZL (ZL1 to ZL7) Zoom lens G1 First lens group G2 Second lens group G3 Third lens group G4 Fourth lens group L11 Spherical negative lens L12 Spherical positive lens FS Flare cut aperture AS Aperture aperture LPF Low pass filter I Image surface CAM Digital still camera (optical equipment)

Claims (7)

A first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power, which are arranged in order from the object side along the optical axis. Consists of three lens groups,
The distance between adjacent lens groups changes during zooming,
The first lens group is composed of only one spherical negative lens and one spherical positive lens with an air gap therebetween,
A negative lens is disposed closest to the image side in the second lens group;
A zoom lens satisfying the following conditional expression:
0.40 <(DG1 + DG2 + DG3) / ft <0.65
0.20 <(− f1) /ft≦0.58
9.00 <(R3 + R2) / (R3-R2) <15.00
1.90 <(DG1 + DG2 + DG3) / fw <2.50
However,
DG1: thickness on the optical axis of the first lens group;
DG2: thickness of the second lens group on the optical axis,
DG3: thickness on the optical axis of the third lens group,
ft: focal length of the entire lens system in the telephoto end state,
f1: the focal length of the first lens group,
R2: image-side radius of curvature of the object-side lens constituting the first lens group,
R3: Object-side radius of curvature of the image-side lens constituting the first lens group,
fw: focal length of the entire lens system in the wide-angle end state. The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
4.5 <TLw / fw <8.0
However,
TLw: Air-converted lens total length in the wide-angle end state,
fw: focal length of the entire lens system in the wide-angle end state. The second lens group has a positive lens closest to the object side,
The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
60.0 <νd2p <150.0
However,
νd2p: Abbe number based on the d-line of the positive lens arranged closest to the object side in the second lens group. The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
25.0 <νd2n <55.0
However,
νd2n: Abbe number based on the d-line of the negative lens arranged closest to the image side in the second lens group.   The zoom lens according to claim 1, wherein the lens constituting the third lens group is a plastic aspheric lens.   An optical apparatus comprising the zoom lens according to any one of claims 1 to 5. A first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power, which are arranged in order from the object side along the optical axis. And a zoom lens manufacturing method comprising three lens groups,
The distance between adjacent lens groups changes during zooming,
The first lens group is composed of only one spherical negative lens and one spherical positive lens with an air gap therebetween,
A negative lens is disposed closest to the image side in the second lens group;
A zoom lens manufacturing method, wherein each lens is incorporated in a lens barrel so as to satisfy the following conditional expression:
0.40 <(DG1 + DG2 + DG3) / ft <0.65
0.20 <(− f1) /ft≦0.58
9.00 <(R3 + R2) / (R3-R2) <15.00
1.90 <(DG1 + DG2 + DG3) / fw <2.50
DG1: thickness on the optical axis of the first lens group;
DG2: thickness of the second lens group on the optical axis,
DG3: thickness on the optical axis of the third lens group,
ft: focal length of the entire lens system in the telephoto end state,
f1: the focal length of the first lens group,
R2: image-side radius of curvature of the object-side lens constituting the first lens group,
R3: Object-side radius of curvature of the image-side lens constituting the first lens group,
fw: focal length of the entire lens system in the wide-angle end state.

Images