JP2012103675A - Zoom lens, optical instrument, and manufacturing method for zoom lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a zoom lens that has a satisfactory image performance with a small size and at a low cost while having a wide field angle and a high variable power ratio.SOLUTION: The zoom lens comprises a first lens group G1 of negative refractive power, a second lens group G2 of positive refractive power, and a third lens group G3 of positive refractive power. The first lens group G1 is composed of a first lens of negative refractive power and a second lens of positive refractive power, which is a plastic lens. The second lens group G2 is composed of a third lens of positive refractive power, a fourth lens of positive refractive power, and a fifth lens of negative refractive power. The third lens group G3 is composed of the sixth lens of positive refractive power. The zoom lens satisfies the following conditional expressions: 1.50<(-f1)/fw<2.52, 0.4<(-f1)/fL2<0.8, and n2×n2×ν2<77.0. In the expressions, f1 is the focal distance of the first lens group, fw is the focal distance of the zoom lens at the wide angle end, fL2 is the focal distance of the second lens, n2 is the refractive index of the second lens, and ν2 is the Abbe number of the second lens.

Description

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

  In recent years, in imaging devices such as digital cameras and video cameras, miniaturization and high performance have been demanded.As lenses that satisfy these demands, a group of lenses having negative refractive power arranged in order from the object side, A zoom lens including a lens group having a positive refractive power and a lens group having a positive refractive power is widely used. With regard to such a zoom lens, a lens system is disclosed that is configured with a small number of lenses and uses a plastic lens instead of a glass lens to reduce weight and cost (for example, Patent Document 1). See).

JP 2008-181118 A

  However, such a conventional zoom lens achieves a reduction in size, weight, and cost, but has a narrow angle of view and a low zoom ratio.

  The present invention has been made in view of such problems, and has a zoom lens, an optical apparatus, and a zoom lens having a wide angle of view, a high zoom ratio, a small size, low cost, and good imaging performance. It is an object to provide a method for manufacturing a lens.

In order to achieve such an object, a zoom lens according to the present invention includes a first lens group having negative refracting power, a second lens group having positive refracting power, arranged in order from the object side along the optical axis, A zoom lens having a third lens group having a positive refractive power, and at least the first lens group and the second lens group move along the optical axis at the time of zooming from the wide-angle end state to the telephoto end state The first lens group includes a first lens having negative refracting power and a second lens having positive refracting power, which are arranged in order from the object side along the optical axis. A plastic lens having an aspherical surface, and the second lens group is composed of a third lens having positive refractive power, a fourth lens, and a fifth lens arranged in order from the object side along the optical axis; Of the fourth lens and the fifth lens Deviation or the other is an in the other positive lenses in the negative lens, the third lens group consists of a sixth lens having a positive refractive power, and satisfies the following conditional expression, respectively.
1.50 <(− f1) / fw <2.52
0.4 <(− f1) / fL2 <0.8
n2 × n2 × ν2 <77.0
However,
f1: the focal length of the first lens group,
fw: focal length in the wide-angle end state of the zoom lens,
fL2: focal length of the second lens,
n2: refractive index of the second lens,
ν2: Abbe number of the second lens.

In the zoom lens described above, when the focal length of the second lens group is f2, and the focal length of the negative lens among the fourth lens and the fifth lens is fLn, 89 <f2 / (− fLn) <2.85
It is preferable to satisfy the following conditions.

In the zoom lens described above, when the radius of curvature of the lens surface closest to the image side in the sixth lens is Rb and the radius of curvature of the lens surface closest to the object in the sixth lens is Ra, .8 <(Rb + Ra) / (Rb−Ra) <0.1
It is preferable to satisfy the following conditions.

In the zoom lens described above, when the focal length of the second lens group is f2, the following expression 0.9 <(− f1) / f2 <1.4
It is preferable to satisfy the following conditions.

In the zoom lens described above, when the curvature radius of the image-side lens surface of the first lens is Rd and the curvature radius of the object-side lens surface of the first lens is Rc, the following equation −1.2 <(Rd + Rc) / (Rd-Rc) <-0.1
It is preferable to satisfy the following conditions.

In the zoom lens described above, when the distance on the optical axis from the object-side lens surface of the first lens to the image-side lens surface of the second lens is ΣD1, the following expression 0.30 <ΣD1 / (−f1) <0.50
It is preferable to satisfy the following conditions.

  In the zoom lens described above, it is preferable that the sixth lens has an aspherical surface.

  In the zoom lens described above, it is preferable that the sixth lens is a plastic lens.

In the zoom lens described above, when the Abbe number of the third lens is ν3, the following expression 48.0 <ν3
It is preferable to satisfy the following conditions.

  In the zoom lens described above, it is preferable that the third lens has an aspherical surface.

  In the zoom lens described above, it is preferable that the fourth lens and the fifth lens are bonded lenses.

  In the zoom lens described above, it is preferable that focusing from an object at infinity to an object at finite distance is performed by moving the third lens group along the optical axis.

  An optical apparatus according to the present invention is an optical apparatus including a zoom lens that forms an image of an object on a predetermined surface, and the zoom lens is the zoom lens according to the present invention. .

The zoom lens manufacturing method according to the present invention has a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a positive refractive power in order from the object side along the optical axis. A zoom lens manufacturing method in which a third lens group is arranged, wherein at least the first lens group and the second lens group move along an optical axis at the time of zooming from a wide-angle end state to a telephoto end state, respectively. The first lens group includes a first lens having negative refracting power and a second lens having positive refracting power arranged in order from the object side along the optical axis, and the second lens is an aspherical surface. The second lens group includes a third lens having a positive refractive power, a fourth lens, and a fifth lens, which are arranged in order from the object side along the optical axis. 4 lenses and 5th lens Or it is one of a negative lens while a positive lens, the third lens group consists of a sixth lens having a positive refractive power, so as to satisfy the following condition, respectively.
1.50 <(− f1) / fw <2.52
0.4 <(− f1) / fL2 <0.8
n2 × n2 × ν2 <77.0
However,
f1: the focal length of the first lens group,
fw: focal length in the wide-angle end state of the zoom lens,
fL2: focal length of the second lens,
n2: refractive index of the second lens,
ν2: Abbe number of the second lens.

  According to the present invention, it is possible to obtain good imaging performance with a small size and low cost while having a wide angle of view and a high zoom ratio.

(A) is sectional drawing in the wide-angle end state of the zoom lens which concerns on 1st Example, (b) is sectional drawing in the intermediate focal distance state of a zoom lens, (c) is in the telephoto end state of a zoom lens. It is sectional drawing. (A) is various aberration diagrams at the time of focusing on infinity in the wide angle end state in the first embodiment, (b) is a diagram of various aberrations at the time of focusing on infinity in the intermediate focal length state, (c) These are various aberration diagrams when focusing on infinity in the telephoto end state. (A) is sectional drawing in the wide-angle end state of the zoom lens which concerns on 2nd Example, (b) is sectional drawing in the intermediate focal distance state of a zoom lens, (c) is in the telephoto end state of a zoom lens. It is sectional drawing. (A) is an aberration diagram at the time of infinity focusing in the wide-angle end state in the second embodiment, (b) is an aberration diagram at the time of focusing at infinity in the intermediate focal length state, (c) These are various aberration diagrams when focusing on infinity in the telephoto end state. (A) is sectional drawing in the wide-angle end state of the zoom lens which concerns on 3rd Example, (b) is sectional drawing in the intermediate focal distance state of a zoom lens, (c) is in the telephoto end state of a zoom lens. It is sectional drawing. (A) is an aberration diagram at the time of infinity focusing in the wide angle end state in the third embodiment, (b) is an aberration diagram at the time of focusing at infinity in the intermediate focal length state, (c) These are various aberration diagrams when focusing on infinity in the telephoto end state. (A) is sectional drawing in the wide-angle end state of the zoom lens which concerns on 4th Example, (b) is sectional drawing in the intermediate focal distance state of a zoom lens, (c) is in the telephoto end state of a zoom lens. It is sectional drawing. (A) is various aberration diagrams at the time of focusing at infinity in the wide-angle end state in the fourth embodiment, (b) is a diagram of various aberrations at focusing at infinity in the intermediate focal length state, (c) These are various aberration diagrams when focusing on infinity in the telephoto end state. (A) is sectional drawing in the wide-angle end state of the zoom lens which concerns on 5th Example, (b) is sectional drawing in the intermediate focal distance state of a zoom lens, (c) is in the telephoto end state of a zoom lens. It is sectional drawing. (A) is an aberration diagram at the time of focusing at infinity in the wide angle end state in the fifth embodiment, (b) is an aberration diagram at the time of focusing at infinity in the intermediate focal length state, (c) These are various aberration diagrams when focusing on infinity in the telephoto end state. (A) is sectional drawing in the wide-angle end state of the zoom lens which concerns on 6th Example, (b) is sectional drawing in the intermediate focal distance state of a zoom lens, (c) is in the telephoto end state of a zoom lens. It is sectional drawing. (A) is an aberration diagram at the time of focusing at infinity in the wide angle end state in the sixth embodiment, (b) is an aberration diagram at the time of focusing at infinity in the intermediate focal length state, (c) These are various aberration diagrams when focusing on infinity in the telephoto end state. (A) is a front view of a digital still camera, (b) is a rear view of a digital still camera. It is a flowchart which shows the manufacturing method of a zoom lens.

  Hereinafter, preferred embodiments of the present application will be described with reference to the drawings. A digital still camera CAM provided with the zoom lens according to the present application is shown in FIG. 13A is a front view of the digital still camera CAM, and FIG. 13B is a rear view of the digital still camera CAM.

  In the digital still camera CAM shown in FIG. 13, when a power button (not shown) is pressed, a shutter (not shown) of the photographing lens (ZL) is opened, and light from the subject (object) is condensed by the photographing lens (ZL). Then, an image is formed on an imaging element (not shown) (for example, a CCD or a CMOS) arranged on the image plane I (for example, see FIG. 1). The subject image formed on the image sensor 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 to photograph the subject image with the image sensor, and records and saves it in a memory (not shown).

  The taking lens is composed of a zoom lens ZL according to an embodiment described later. Also, in the digital still camera CAM, the auxiliary light emitting unit D that emits auxiliary light when the subject is dark and the photographing lens (zoom lens ZL) are zoomed from the wide-angle end state (W) to the telephoto end state (T). Wide (W) -Tele (T) button B2 and function button B3 used for setting various conditions of the digital still camera CAM are arranged.

  For example, as shown in FIG. 1, the zoom lens ZL includes a first lens group G1 having negative refracting power, a second lens group G2 having positive refracting power, and a positive lens arranged in order from the object side along the optical axis. And a third lens group G3 having refractive power. Also, at the time of zooming from the wide-angle end state to the telephoto end state, at least the first lens group G1 and the second lens group G2 are moved along the optical axis. A filter group FL including a low-pass filter and an infrared cut filter is disposed between the zoom lens ZL and the image plane I.

  The first lens group G1 includes a first lens L1 having negative refracting power and a second lens L2 having positive refracting power, which are arranged in order from the object side along the optical axis, and the second lens L2. Is a plastic lens having an aspherical surface. The second lens group G2 includes a third lens L3 having a positive refractive power, a fourth lens L4, and a fifth lens L5, which are arranged in order from the object side along the optical axis. One of the fifth lenses L5 is a negative lens and the other is a positive lens. The third lens group G3 includes a sixth lens L6 having positive refractive power. In the zoom lens ZL having such a configuration, when the focal length of the first lens group G1 is f1, and the focal length in the wide-angle end state of the zoom lens ZL is fw, the condition expressed by the following conditional expression (1) Is satisfied.

  1.50 <(− f1) / fw <2.52 (1)

  In the zoom lens ZL of the present embodiment, the first lens group G1 is composed of only a negative lens and a positive lens in order from the object side, so that coma, astigmatism, field curvature, and distortion in the wide-angle end state are established. Aberration can be corrected, and spherical aberration in the telephoto end state can be corrected. In addition, since the first lens group G1 has a small number of lenses, it is effective for reducing the weight and cost of the zoom lens and reducing the thickness of the zoom lens ZL in the retracted state.

  In addition, using a plastic lens for the positive lens in the first lens group G1, that is, the second lens L2, is a more preferable form in terms of weight reduction and cost reduction. The second lens L2 preferably has an aspherical surface. By making the lens surface of the second lens L2 an aspherical surface, coma aberration, astigmatism, and field curvature in the wide-angle end state can be corrected, and spherical aberration in the telephoto end state can be corrected. .

  Moreover, spherical aberration and coma aberration can be corrected by configuring the second lens group G2 only with a positive lens, a positive lens, and a negative lens (concave lens). In addition, since the second lens group G2 has a small number of lenses, it is effective for reducing the weight and cost of the zoom lens and reducing the thickness of the zoom lens ZL in the retracted state.

  Further, by satisfying conditional expression (1), it is possible to widen the angle and reduce the aberrations satisfactorily while reducing the overall length of the optical system. As described above, according to the present embodiment, the zoom lens ZL having a wide angle of view and a high zoom ratio, a small size, low cost, and good imaging performance, and an optical apparatus (digital still) including the zoom lens ZL. Camera CAM).

  Here, the conditional expression (1) is a conditional expression for defining the refractive power of the first lens group G1 within an appropriate range. When the condition is less than the lower limit value of conditional expression (1), it is not preferable because correction of distortion is difficult. On the other hand, when the condition exceeds the upper limit value of the conditional expression (1), the refractive power of the first lens group G1 decreases, and the Petzval sum increases, so that it is difficult to correct astigmatism and field curvature. Further, the total length of the optical system at the time of zooming becomes large, which is not preferable. Moreover, it is difficult to achieve a wide angle, which is not preferable.

  In order to secure the effect of the present application, it is desirable to set the lower limit of conditional expression (1) to 1.85. In order to further secure the effect of the present application, it is desirable to set the lower limit of conditional expression (1) to 2.20. In order to secure the effect of the present application, it is desirable to set the upper limit of conditional expression (1) to 2.48. In order to further secure the effect of the present application, it is desirable to set the upper limit of conditional expression (1) to 2.44.

  In addition, it is preferable that the zoom lens ZL of the present embodiment satisfies the condition represented by the following conditional expression (2) when the focal length of the second lens L2 is fL2.

  0.4 <(− f1) / fL2 <0.8 (2)

  Conditional expression (2) is a conditional expression for defining the refractive power of the second lens L2, which is a plastic lens, within an appropriate range. When the condition is less than the lower limit value of conditional expression (2), it is difficult to correct spherical aberration, which is not preferable. On the other hand, when the condition exceeds the upper limit value of the conditional expression (2), it is difficult to correct astigmatism and field curvature. In addition, the focal point movement and the performance deterioration due to the temperature change of the plastic lens increase, which is not preferable. Satisfying the conditional expression (2) makes it possible to correct aberrations satisfactorily while reducing the influence of temperature change.

  In order to secure the effect of the present application, it is desirable to set the lower limit of conditional expression (2) to 0.45. In order to further secure the effect of the present application, it is desirable to set the lower limit of conditional expression (2) to 0.5. In order to secure the effect of the present application, it is desirable to set the upper limit of conditional expression (2) to 0.73. In order to further secure the effect of the present application, it is desirable to set the upper limit of conditional expression (2) to 0.65.

  For the second lens L2, the refractive index for the d-line (wavelength λ = 587.6 nm) of the second lens L2 is n2, and the Abbe number for the d-line (wavelength λ = 587.6 nm) of the second lens L2 is When ν2, it is preferable to satisfy the condition represented by the following conditional expression (3).

  n2 × n2 × ν2 <77.0 (3)

  Conditional expression (3) is a conditional expression for defining the refractive index and Abbe number of the second lens L2 within an appropriate range. If the condition exceeds the upper limit value of the conditional expression (3), it is difficult to correct the axial chromatic aberration that increases as the zoom ratio is increased. In addition, the field curvature in the wide-angle end state increases, which is not preferable. Satisfying conditional expression (3) makes it possible to correct aberrations satisfactorily.

  In order to secure the effect of the present application, it is desirable to set the lower limit of conditional expression (3) to 73.0. In order to further secure the effect of the present application, it is desirable to set the lower limit of conditional expression (3) to 70.0.

  In the zoom lens ZL of the present embodiment, when the focal length of the second lens group G2 is f2, and the focal length of the negative lens of the fourth lens L4 and the fifth lens L5 is fLn, It is preferable that the condition represented by conditional expression (4) is satisfied.

  1.89 <f2 / (− fLn) <2.85 (4)

  Conditional expression (4) is a conditional expression for defining the ratio of the focal length of the negative lens of the fourth lens L4 and the fifth lens L5 to the focal length of the second lens group G2. When the condition is less than the lower limit value of the conditional expression (4), the spherical aberration in the telephoto end state becomes insufficiently corrected, which is not preferable. On the other hand, when the condition exceeds the upper limit value of the conditional expression (4), the spherical aberration in the telephoto end state becomes excessively corrected, which is not preferable. Satisfying conditional expression (4) makes it possible to correct aberrations satisfactorily.

  In order to secure the effect of the present application, it is desirable to set the lower limit of conditional expression (4) to 1.94. In order to further secure the effect of the present application, it is desirable to set the lower limit of conditional expression (4) to 1.99. In order to secure the effect of the present application, it is desirable to set the upper limit of conditional expression (4) to 2.78. In order to further secure the effect of the present application, it is desirable to set the upper limit of conditional expression (4) to 2.70.

  In the zoom lens ZL of the present embodiment, when the radius of curvature of the lens surface closest to the image side in the sixth lens L6 is Rb and the radius of curvature of the lens surface closest to the object in the sixth lens L6 is Ra, It is preferable that the condition represented by the conditional expression (5) is satisfied.

  −1.8 <(Rb + Ra) / (Rb−Ra) <0.1 (5)

  Conditional expression (5) is a conditional expression for defining an appropriate range for the shape of the third lens group G3. When the condition is less than the lower limit value of conditional expression (5), it is difficult to correct coma, astigmatism, and field curvature, which is not preferable. On the other hand, when the condition exceeds the upper limit value of the conditional expression (5), it is difficult to correct astigmatism, curvature of field, and distortion in the wide-angle end state, which is not preferable. Satisfying conditional expression (5) makes it possible to perform favorable aberration correction.

  In order to secure the effect of the present application, it is desirable to set the lower limit of conditional expression (5) to −1.5. In order to further secure the effect of the present application, it is desirable to set the lower limit of conditional expression (5) to −1.2. In order to secure the effect of the present application, it is desirable to set the upper limit of conditional expression (5) to −0.4. In order to further secure the effect of the present application, it is desirable to set the upper limit of conditional expression (5) to −0.7.

  In addition, it is preferable that the zoom lens ZL of the present embodiment satisfies the condition represented by the following conditional expression (6) when the focal length of the second lens group G2 is f2.

  0.9 <(− f1) / f2 <1.4 (6)

  Conditional expression (6) is a conditional expression for defining the ratio of the focal length of the first lens group G1 to the focal length of the second lens group G2. When the condition is lower than the lower limit value of the conditional expression (6), it is difficult to correct distortion in the wide-angle end state, which is not preferable. On the other hand, when the condition exceeds the upper limit value of conditional expression (6), the refractive power of the second group lens G2 becomes strong, and it becomes difficult to correct spherical aberration and coma. Satisfying conditional expression (6) makes it possible to correct aberrations satisfactorily.

  In order to secure the effect of the present application, it is desirable to set the lower limit of conditional expression (6) to 1.0. In order to further secure the effect of the present application, it is desirable to set the lower limit of conditional expression (6) to 1.1. In order to secure the effect of the present application, it is desirable to set the upper limit of conditional expression (6) to 1.38. In order to further secure the effect of the present application, it is desirable to set the upper limit of conditional expression (6) to 1.35.

  In the zoom lens ZL of the present embodiment, when the radius of curvature of the image side lens surface of the first lens L1 is Rd and the radius of curvature of the object side lens surface of the first lens L1 is Rc, the following conditions are satisfied. It is preferable that the condition represented by Formula (7) is satisfied.

  −1.2 <(Rd + Rc) / (Rd−Rc) <− 0.1 (7)

  Conditional expression (7) is a conditional expression for defining an appropriate range with respect to the shape of the first lens L1. If the condition is lower than the lower limit value of conditional expression (7), it is difficult to correct coma, astigmatism, and field curvature, which is not preferable. On the other hand, when the condition exceeds the upper limit value of the conditional expression (7), it becomes difficult to correct distortion in the wide-angle end state, which is not preferable. Satisfying conditional expression (7) makes it possible to correct aberrations satisfactorily.

  In order to secure the effect of the present application, it is desirable to set the lower limit of conditional expression (7) to −1.1. In order to further secure the effect of the present application, it is desirable to set the lower limit of conditional expression (7) to −1.05. In order to secure the effect of the present application, it is desirable to set the upper limit of conditional expression (7) to −0.4. In order to further secure the effect of the present application, it is desirable to set the upper limit of conditional expression (7) to −0.6.

  In the zoom lens ZL of the present embodiment, when the distance on the optical axis from the object-side lens surface of the first lens L1 to the image-side lens surface of the second lens L2 is ΣD1, the following conditional expression ( It is preferable to satisfy the condition represented by 8).

  0.30 <ΣD1 / (− f1) <0.50 (8)

  Conditional expression (8) is a conditional expression for defining an appropriate range with respect to the thickness of the first lens group G1 on the optical axis. If the condition is lower than the lower limit value of conditional expression (8), it is not preferable because correction of astigmatism and curvature of field becomes difficult in the wide-angle end state. On the other hand, when the condition exceeds the upper limit value of the conditional expression (8), it is difficult to correct spherical aberration in the telephoto end state. Moreover, since the thickness in a retracted state will become large, it is not preferable. Satisfying conditional expression (8) makes it possible to perform favorable aberration correction while reducing the thickness in the retracted state.

  In order to secure the effect of the present application, it is desirable to set the lower limit of conditional expression (8) to 0.33. In order to further secure the effect of the present application, it is desirable to set the lower limit of conditional expression (8) to 0.35. In order to secure the effect of the present application, it is desirable to set the upper limit of conditional expression (8) to 0.46. In order to further secure the effect of the present application, it is desirable to set the upper limit of conditional expression (8) to 0.42.

  In the zoom lens ZL of the present embodiment, it is preferable that the sixth lens L6 has an aspherical surface. Astigmatism and curvature of field can be corrected by making the lens surface of the sixth lens L6 an aspherical surface.

  In the zoom lens ZL of the present embodiment, the sixth lens L6 is preferably a plastic lens. When the sixth lens L6 is a plastic lens, it is preferable because lens processing becomes easy and deterioration of optical performance due to processing errors can be prevented. Further, even when the image plane is deviated, it is preferable because there is little deterioration in drawing performance.

  The zoom lens ZL of the present embodiment satisfies the condition represented by the following conditional expression (9) when the Abbe number of the third lens L3 with respect to the d-line (wavelength λ = 587.6 nm) is ν3. It is preferable.

  48.0 <ν3 (9)

  Conditional expression (9) is a conditional expression for defining the Abbe number of the third lens L3 within an appropriate range. When the condition is less than the lower limit value of conditional expression (9), it is difficult to correct the axial chromatic aberration that increases as the zoom ratio is increased. Satisfying conditional expression (9) makes it possible to perform favorable aberration correction.

  In order to secure the effect of the present application, it is desirable to set the lower limit of conditional expression (9) to 54.0. In order to further secure the effect of the present application, it is desirable to set the lower limit of conditional expression (9) to 60.0.

  In the zoom lens ZL of the present embodiment, it is preferable that the third lens L3 has an aspherical surface. By making the lens surface of the third lens L3 an aspherical surface, spherical aberration and coma aberration can be corrected.

  In the zoom lens ZL of the present embodiment, it is preferable that the fourth lens L4 and the fifth lens L5 are bonded lenses. With this configuration, axial chromatic aberration and lateral chromatic aberration can be favorably corrected.

  In the zoom lens ZL of the present embodiment, focusing from an infinite object to a finite distance object is preferably performed by moving the third lens group G3 along the optical axis. By using the third lens group G3 for focusing, it is possible to reduce variations in various aberrations, particularly field curvature and astigmatism, while suppressing a decrease in peripheral light amount during focusing on a finite distance object.

  Here, a manufacturing method of the zoom lens ZL having the above-described configuration will be described with reference to FIG. First, the first lens group G1, the second lens group G2, and the third lens group G3 of the present embodiment are assembled in a cylindrical barrel (step S1). At this time, the lenses of the first to third lens groups G1 to G3 are respectively arranged so as to satisfy the conditional expression (1), the conditional expression (2), the conditional expression (3), and the like. When each lens is incorporated into the lens barrel, the lens groups may be incorporated into the lens barrel one by one in the order along the optical axis, and a part or all of the lens groups are integrally held by the holding member and then the lens barrel. You may assemble with a member. After assembling each lens group in the lens barrel, it is confirmed whether an object image is formed in a state where each lens group is incorporated in the lens barrel, that is, whether the centers of the lens groups are aligned (step S2). ). Then, after confirming whether an image is formed, various operations of the zoom lens ZL are confirmed (step S3).

  As an example of various operations, a zooming operation in which a lens group (for example, the first lens group G1 and the second lens group G2) for zooming moves along the optical axis direction, a long distance object to a short distance object A focusing operation in which a lens group (for example, the third lens group G3) that performs focusing on the lens moves along the optical axis direction, a hand that moves so that at least some of the lenses have a component orthogonal to the optical axis. An example is a shake correction operation. In the present embodiment, when zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group G1 and the second lens group G2 decreases, and the second lens group G2 and the third lens group G3. At least the first lens group G1 and the second lens group G2 are moved along the optical axis so that the distance between them increases. In addition, the confirmation order of various operations is arbitrary. According to such a manufacturing method, it is possible to obtain a zoom lens ZL that has a wide angle of view and a high zoom ratio, and that is compact, low-cost, and has good imaging performance.

(First embodiment)
Embodiments of the present application will be described below with reference to the accompanying drawings. First, a first embodiment of the present application will be described with reference to FIGS. 1A is a cross-sectional view of the zoom lens according to the first embodiment in a wide-angle end state, FIG. 1B is a cross-sectional view of the zoom lens in an intermediate focal length state, and FIG. 1C is a zoom view. It is sectional drawing in the telephoto end state of a lens. The zoom lens ZL according to the first example includes a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a positive lens arranged in order from the object side along the optical axis. And a third lens group G3 having a refractive power of 5. Then, during zooming from the wide-angle end state (W) to the telephoto end state (T), the distance between the first lens group G1 and the second lens group G2 decreases, and the second lens group G2 and the third lens group G3. The first lens group G1 and the second lens group G2 are configured to move along the optical axis so that the distance between the lens groups G3 increases. An aperture stop S is disposed between the first lens group G1 and the second lens group G2.

  The first lens group G1 includes a first lens L1 which is a biconcave negative lens arranged in order from the object side along the optical axis, and a second lens L2 which is a positive meniscus lens having a convex surface facing the object side. The lens surfaces on both sides of the second lens L2 are aspherical. The second lens group G2 includes a third lens L3 that is a biconvex positive lens arranged in order from the object side along the optical axis, and a fourth lens L4 that is a positive meniscus lens having a convex surface facing the object side. The fifth lens L5 is a negative meniscus lens having a convex surface facing the object side, and the lens surfaces on both sides of the third lens L3 are aspherical. The fourth lens L4 and the fifth lens L5 are bonded lenses that are cemented with each other. The third lens group G3 includes only a sixth lens L6, which is a biconvex positive lens. The lens surface on the image plane I side of the sixth lens L6 is aspheric. The second lens L2 and the sixth lens L6 are plastic lenses. In addition, focusing from an object at infinity to an object at a finite distance is performed by moving the third lens group G3 along the optical axis.

  The aperture stop S is disposed in the vicinity of the object side of the third lens L3 located closest to the object side in the second lens group G2, and is used for zooming from the wide-angle end state to the telephoto end state. It moves together with the two lens group G2. The filter group FL disposed between the third lens group G3 and the image plane I includes a low-pass filter, an infrared cut filter, and the like.

  In the following, Tables 1 to 6 are shown, and these are tables listing the values of the specifications of the zoom lenses according to the first to sixth examples. In [Overall specifications] in each table, f is the focal length, FNO is the F number, 2ω is the field angle (maximum incident angle: unit is “°”), Y is the maximum image height, and BF is the back focus. (Air conversion length), TL indicates the entire lens length (air conversion length). In [Lens Data], the surface number is the order of the lens surfaces counted from the object side, r is the radius of curvature of the lens surfaces, d is the distance between the lens surfaces, and nd is the d-line (wavelength λ = 587.6 nm). ), And νd represents the Abbe number for the d-line (wavelength λ = 587.6 nm). Note that * attached to the right of the surface number indicates that the lens surface is an aspherical surface. Also, the curvature radius “∞” indicates a plane, and the refractive index nd = 1.00000 of air is omitted from the description.

Further, the aspheric coefficient shown in [Aspherical data] is that the height in the direction perpendicular to the optical axis is y, the amount of displacement in the optical axis direction at the height y is X (y), and the radius of curvature of the reference spherical surface ( When the paraxial radius of curvature is R, the conic constant is κ, and the n-th order (n = 4, 6, 8, 10) aspheric coefficient is An, it is expressed by the following conditional expression (10). In each example, the secondary aspherical coefficient A2 is 0, and the description is omitted. In [Aspherical data], “En” indicates “× 10 ⁻ⁿ ”.

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 ... (10)

  [Variable interval data] indicates the focal length f from the wide-angle end to the telephoto end and the value of each variable interval. [Conditional Expression Corresponding Value] indicates the corresponding value of each conditional expression, where f1 is the focal length of the first lens group G1, f2 is the focal length of the second lens group G2, and fw is the zoom lens. ZL indicates the focal length of the wide-angle end state, fL2 indicates the focal length of the second lens L2, fLn indicates the focal length of the fourth lens L4 and the fifth lens L5, which is the negative lens, and ΣD1 indicates the first lens L1. The distance on the optical axis from the object-side lens surface to the image-side lens surface of the second lens L2 is shown. In addition, the focal length f, the radius of curvature r, the surface interval d, and other length units listed in all the following specification values are generally “mm”, but the optical system is proportionally enlarged or reduced. However, the same optical performance can be obtained, and the present invention is not limited to this. In addition, the same reference numerals as those in the present embodiment are used also in the specification values in the second to sixth embodiments described later.

  Table 1 below shows specifications in the first embodiment. The surface numbers 1 to 16 in Table 1 correspond to the surfaces 1 to 16 in FIG. 1, and the group numbers G1 to G3 in Table 1 correspond to the lens groups G1 to G3 in FIG. In the first embodiment, the lens surfaces of the third surface, the fourth surface, the sixth surface, the seventh surface, and the twelfth surface are formed in an aspherical shape.

(Table 1)
[Overall specifications]
Zoom ratio = 4.71
Wide angle end Intermediate focal length Telephoto end f = 4.11 8.92 19.37
FNO = 2.75 4.14 7.16
2ω = 80.14 40.36 19.06
Y = 2.90 3.25 3.25
BF = 2.82 3.00 3.46
TL = 27.33 24.49 32.01
[Lens specifications]
Surface number r d nd νd
1 -53.7096 0.6500 1.75500 52.34
2 4.5989 1.1000
3 * 9.5753 2.0000 1.60740 27.00
4 * 227.1210 (d4)
5 ∞ -0.4000 (aperture stop)
6 * 4.7065 1.6000 1.49589 82.24
7 * -9.3977 0.1000
8 4.4565 1.4500 1.83481 42.73
9 42.7350 0.4000 1.90366 31.27
10 2.7198 (d10)
11 200.0000 1.7000 1.53153 55.95
12 * -8.3030 (d12)
13 ∞ 0.2100 1.51680 63.88
14 ∞ 0.3000
15 ∞ 0.5000 1.51680 63.88
16 ∞ 0.6000
[Aspherical data]
3rd surface κ = 5.4923, A4 = -3.00120E-04, A6 = -8.05140E-05, A8 = 5.12070E-06, A10 = -8.89660E-08
4th surface κ = 1.0000, A4 = -6.76820E-04, A6 = -3.72700E-05, A8 = 2.11400E-06, A10 = 3.04940E-08
6th surface κ = 0.0395, A4 = -1.06920E-04, A6 = 0.00000E + 00, A8 = 0.00000E + 00, A10 = 0.00000E + 00
7th surface κ = -4.5000, A4 = 0.00000E + 00, A6 = 0.00000E + 00, A8 = 0.00000E + 00, A10 = 0.00000E + 00
12th surface κ = 1.0000, A4 = 7.62620E-04, A6 = -3.12830E-05, A8 = 9.28290E-07, A10 = 0.00000E + 00
[Variable interval data]
Wide angle end Intermediate focal length Telephoto end f = 4.11 8.92 19.37
d4 = 12.195 4.524 0.971
d10 = 3.709 8.363 18.975
d12 = 1.456 1.636 2.092
[Zoom lens group data]
Group number Group first surface Group focal length G1 1 -9.40026
G2 6 7.59000
G3 11 15.04092
[Conditional expression values]
f1 = −9.40026
f2 = 7.59000
fw = 4.11000
fL2 = 16.40125
fLn = -3.22968
ΣD1 = 3.75
Conditional expression (1) (−f1) /fw=2.28717
Conditional expression (2) (−f1) /fL2=0.57314
Conditional expression (3) n2 × n2 × ν2 = 69.76084
Conditional expression (4) f2 / (− fLn) = 2.35008
Conditional expression (5) (Rb + Ra) / (Rb−Ra) = − 0.92028
Conditional expression (6) (-f1) / f2 = 1.23851
Conditional expression (7) (Rd + Rc) / (Rd−Rc) = − 0.84226
Conditional expression (8) ΣD1 / (− f1) = 0.39893
Conditional expression (9) ν3 = 82.24

  Thus, in this embodiment, it can be seen that all the conditional expressions (1) to (9) are satisfied.

  FIGS. 2A to 2C are graphs showing various aberrations of the zoom lens ZL according to the first example. That is, FIG. 2A is a diagram showing various aberrations when focusing at infinity in the wide-angle end state (f = 4.11 mm), and FIG. 2B is infinite in the intermediate focal length state (f = 8.92 mm). FIG. 2C is a diagram of various aberrations at the time of focusing on infinity in the telephoto end state (f = 19.37 mm). In each aberration diagram, FNO represents an F number, and A represents a half angle of view for each image height. In each aberration diagram, d is d-line (λ = 587.6 nm), g is g-line (λ = 435.8 nm), C is C-line (λ = 656.3 nm), and F is F-line (λ = Aberration at 486.1 nm) is shown. In the aberration diagrams showing astigmatism, the solid line shows the sagittal image plane, and the broken line shows the meridional image plane. The description of the aberration diagrams is the same in the other examples.

  From the respective aberration diagrams, it can be seen that in the first example, various aberrations are well corrected in each focal length state from the wide-angle end state to the telephoto end state, and the optical performance is excellent. As a result, by mounting the zoom lens ZL of the first embodiment, excellent optical performance can be ensured even in the digital still camera CAM.

(Second embodiment)
Hereinafter, a second embodiment of the present application will be described with reference to FIGS. 3A is a cross-sectional view of the zoom lens according to the second embodiment in a wide-angle end state, FIG. 3B is a cross-sectional view of the zoom lens in an intermediate focal length state, and FIG. 3C is a zoom view. It is sectional drawing in the telephoto end state of a lens. The zoom lens of the second embodiment has the same configuration as that of the zoom lens of the first embodiment except for a part of the shape of the first lens group G1, and the same reference numerals as those of the first embodiment are used for the respective parts. The detailed description is omitted. The first lens group G1 of the second example includes a first lens L1 that is a negative meniscus lens that is arranged in order from the object side along the optical axis and has a convex surface facing the object side, and a convex surface facing the object side. The second lens L2 is a positive meniscus lens, and both lens surfaces of the second lens L2 are aspherical.

  Table 2 below shows specifications in the second embodiment. The surface numbers 1 to 16 in Table 2 correspond to the surfaces 1 to 16 in FIG. 3, and the group numbers G1 to G3 in Table 2 correspond to the lens groups G1 to G3 in FIG. In the second embodiment, the lens surfaces of the third surface, the fourth surface, the sixth surface, the seventh surface, and the twelfth surface are formed in an aspherical shape.

(Table 2)
[Overall specifications]
Zoom ratio = 4.71
Wide angle end Intermediate focal length Telephoto end f = 3.91 8.49 18.43
FNO = 2.85 4.24 7.25
2ω = 84.48 42.08 19.92
Y = 2.90 3.25 3.25
BF = 2.88 2.93 3.02
TL = 26.27 23.33 29.85
[Lens specifications]
Surface number r d nd νd
1 300.1141 0.6000 1.75500 52.34
2 4.6753 1.1000
3 * 6.6199 1.8500 1.63280 23.35
4 * 13.2374 (d4)
5 ∞ -0.2000 (aperture stop)
6 * 7.0117 1.2500 1.59201 67.05
7 * -12.9927 0.1000
8 3.5408 1.3000 1.81600 46.63
9 14.2745 0.4000 1.79504 28.69
10 2.3832 (d10)
11 1000.0000 1.9000 1.53110 55.91
12 * -6.9659 (d12)
13 ∞ 0.2100 1.51680 63.88
14 ∞ 0.3000
15 ∞ 0.5000 1.51680 63.88
16 ∞ 0.6000
[Aspherical data]
3rd surface κ = 1.9047, A4 = -7.31917E-04, A6 = -4.48631E-05, A8 = 4.75920E-06, A10 = -5.79203E-08
4th surface κ = 3.2860, A4 = -1.14753E-03, A6 = -8.71361E-06, A8 = 4.45605E-06, A10 = -8.73198E-08
6th surface κ = -3.6643, A4 = 9.48677E-04, A6 = -2.49585E-05, A8 = 0.00000E + 00, A10 = 0.00000E + 00
7th surface κ = -1.3464, A4 = 0.00000E + 00, A6 = 0.00000E + 00, A8 = 0.00000E + 00, A10 = 0.00000E + 00
12th surface κ = -1.5170, A4 = 3.82584E-04, A6 = -4.56444E-05, A8 = 1.33199E-06, A10 = 0.00000E + 00
[Variable interval data]
Wide angle end Intermediate focal length Telephoto end f = 3.91 8.49 18.43
d4 = 11.785 4.318 0.879
d10 = 3.307 7.786 17.646
d12 = 1.512 1.557 1.657
[Zoom lens group data]
Group number Group first surface Group focal length G1 1 -9.50000
G2 6 7.29182
G3 11 13.03376
[Conditional expression values]
f1 = -9.50000
f2 = 7.29182
fw = 3.91000
fL2 = 18.88077
fLn = -3.65272
ΣD1 = 3.55000
Conditional expression (1) (−f1) /fw=2.42967
Conditional expression (2) (−f1) /fL2=0.50316
Conditional expression (3) n2 × n2 × ν2 = 62.25194
Conditional expression (4) f2 / (− fLn) = 1.99627
Conditional expression (5) (Rb + Ra) / (Rb-Ra) =-0.98616
Conditional expression (6) (−f1) /f2=1.30283
Conditional expression (7) (Rd + Rc) / (Rd-Rc) =-1.03165
Conditional expression (8) ΣD1 / (− f1) = 0.37368
Conditional expression (9) ν3 = 67.05

  Thus, in this embodiment, it can be seen that all the conditional expressions (1) to (9) are satisfied.

  4A to 4C are graphs showing various aberrations of the zoom lens ZL according to the second example. That is, FIG. 4A is a diagram showing various aberrations when focusing at infinity in the wide-angle end state (f = 3.91 mm), and FIG. 4B is infinite in the intermediate focal length state (f = 8.49 mm). FIG. 4C is a diagram of various aberrations at the time of focusing on infinity in the telephoto end state (f = 18.43 mm). From the respective aberration diagrams, it can be seen that in the second example, various aberrations are well corrected in each focal length state from the wide-angle end state to the telephoto end state, and the optical performance is excellent. As a result, by mounting the zoom lens ZL of the second embodiment, excellent optical performance can be secured even in the digital still camera CAM.

(Third embodiment)
Hereinafter, the third embodiment of the present application will be described with reference to FIGS. 5A is a cross-sectional view of the zoom lens according to the third embodiment in the wide-angle end state, FIG. 5B is a cross-sectional view of the zoom lens in the intermediate focal length state, and FIG. 5C is a zoom view. It is sectional drawing in the telephoto end state of a lens. Note that the zoom lens of the third example has the same configuration as the zoom lens of the first example, and the same reference numerals as those in the case of the first example are given to the respective parts, and detailed description thereof is omitted.

  Table 3 below shows specifications in the third embodiment. The surface numbers 1 to 16 in Table 3 correspond to the surfaces 1 to 16 in FIG. 5, and the group numbers G1 to G3 in Table 3 correspond to the lens groups G1 to G3 in FIG. In the third embodiment, the third, fourth, sixth, seventh, and twelfth lens surfaces are aspherical.

(Table 3)
[Overall specifications]
Zoom ratio = 4.71
Wide angle end Intermediate focal length Telephoto end f = 4.11 8.92 19.37
FNO = 2.78 4.19 7.27
2ω = 78.24 40.52 19.06
Y = 2.80 3.25 3.25
BF = 2.82 3.00 3.48
TL = 27.39 24.83 32.66
[Lens specifications]
Surface number r d nd νd
1 -52.0251 0.7000 1.75500 52.34
2 4.5670 1.1000
3 * 9.5432 1.9000 1.60740 27.00
4 * 139.5530 (d4)
5 ∞ -0.4000 (aperture stop)
6 * 4.5356 1.4500 1.49589 82.24
7 * -9.4539 0.1000
8 4.5045 1.4000 1.83481 42.73
9 20.7499 0.4000 1.90366 31.27
10 2.7081 (d10)
11 1000.0000 1.7000 1.53153 55.95
12 * -8.3201 (d12)
13 ∞ 0.2100 1.51680 63.88
14 ∞ 0.3000
15 ∞ 0.5000 1.51680 63.88
16 ∞ 0.6000
[Aspherical data]
3rd surface κ = 5.7302, A4 = -4.55676E-04, A6 = -8.70426E-05, A8 = 5.22458E-06, A10 = -1.40954E-07
4th surface κ = 1.0000, A4 = -7.90538E-04, A6 = -4.08518E-05, A8 = 2.11308E-06, A10 = 8.73038E-09
6th surface κ = 0.0048, A4 = -8.48165E-05, A6 = 0.00000E + 00, A8 = 0.00000E + 00, A10 = 0.00000E + 00
7th surface κ = -4.6337, A4 = 0.00000E + 00, A6 = 0.00000E + 00, A8 = 0.00000E + 00, A10 = 0.00000E + 00
12th surface κ = 1.0000, A4 = 7.94093E-04, A6 = -3.86107E-05, A8 = 1.29274E-06, A10 = 0.00000E + 00
[Variable interval data]
Wide angle end Intermediate focal length Telephoto end f = 4.11 8.92 19.37
d4 = 12.279 4.775 1.295
d10 = 3.943 8.705 19.542
d12 = 1.447 1.628 2.109
[Zoom lens group data]
Group number Group first surface Group focal length G1 1 -9.10000
G2 6 7.59000
G3 11 15.53304
[Conditional expression values]
f1 = -9.10000
f2 = 7.59000
fw = 4.11000
fL2 = 16.777212
fLn = -3.48322
ΣD1 = 3.70000
Conditional expression (1) (-f1) /fw=2.21411
Conditional expression (2) (−f1) /fL2=0.54257
Conditional expression (3) n2 × n2 × ν2 = 69.76084
Conditional expression (4) f2 / (− fLn) = 2.11.7902
Conditional expression (5) (Rb + Ra) / (Rb-Ra) =-0.98350
Conditional expression (6) (-f1) /f2=1.19895
Conditional expression (7) (Rd + Rc) / (Rd−Rc) = − 0.83860
Conditional expression (8) ΣD1 / (− f1) = 0.40659
Conditional expression (9) ν3 = 82.24

  Thus, in this embodiment, it can be seen that all the conditional expressions (1) to (9) are satisfied.

  6A to 6C are graphs showing various aberrations of the zoom lens ZL according to the third example. That is, FIG. 6A is a diagram showing various aberrations when focusing on infinity in the wide-angle end state (f = 4.11 mm), and FIG. 6B is infinite in the intermediate focal length state (f = 8.92 mm). FIG. 6C is a diagram of various aberrations at the time of focusing on infinity in the telephoto end state (f = 19.37 mm). From the aberration diagrams, it can be seen that in the third example, various aberrations 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. As a result, by mounting the zoom lens ZL of the third embodiment, excellent optical performance can be secured even in the digital still camera CAM.

(Fourth embodiment)
Hereinafter, a fourth embodiment of the present application will be described with reference to FIGS. 7A is a cross-sectional view of the zoom lens according to the fourth example in the wide-angle end state, FIG. 7B is a cross-sectional view of the zoom lens in the intermediate focal length state, and FIG. 7C is a zoom view. It is sectional drawing in the telephoto end state of a lens. The zoom lens of the fourth example has the same configuration as that of the zoom lens of the first example except for a part of the shape of the third lens group G3. The detailed description is omitted. Note that the third lens group G3 of the fourth example includes only a sixth lens L6 that is a positive meniscus lens having a convex surface directed toward the image plane I. The lens surface on the image plane I side of the sixth lens L6 is It is aspherical.

  Table 4 below shows specifications in the fourth embodiment. The surface numbers 1 to 16 in Table 4 correspond to the surfaces 1 to 16 in FIG. 7, and the group numbers G1 to G3 in Table 4 correspond to the lens groups G1 to G3 in FIG. In the fourth embodiment, the lens surfaces of the third surface, the fourth surface, the sixth surface, the seventh surface, and the twelfth surface are formed in an aspherical shape.

(Table 4)
[Overall specifications]
Zoom ratio = 4.71
Wide angle end Intermediate focal length Telephoto end f = 4.11 8.92 19.37
FNO = 2.84 4.25 7.32
2ω = 80.02 40.32 19.04
Y = 2.90 3.25 3.25
BF = 2.88 3.06 3.47
TL = 26.67 23.73 30.79
[Lens specifications]
Surface number r d nd νd
1 -88.0628 0.6000 1.75500 52.34
2 4.5071 1.1000
3 * 8.3914 1.9000 1.60740 27.00
4 * 48.1025 (d4)
5 ∞ -0.2000 (aperture stop)
6 * 4.9940 1.4500 1.59252 67.87
7 * -12.2866 0.1000
8 4.1282 1.3000 1.80400 46.60
9 47.5532 0.4000 1.90366 31.27
10 2.5782 (d10)
11 -109.7494 1.7000 1.53153 55.95
12 * -7.7569 (d12)
13 ∞ 0.2100 1.51680 63.88
14 ∞ 0.3000
15 ∞ 0.5000 1.51680 63.88
16 ∞ 0.6000
[Aspherical data]
3rd surface κ = 3.7505, A4 = -5.23556E-04, A6 = -6.38822E-05, A8 = 4.09147E-06, A10 = 8.34490E-08
4th surface κ = 1.0000, A4 = -8.82339E-04, A6 = -2.97720E-05, A8 = 2.56702E-06, A10 = 1.00043E-07
6th surface κ = 0.2498, A4 = -1.27311E-04, A6 = 0.00000E + 00, A8 = 0.00000E + 00, A10 = 0.00000E + 00
7th surface κ = -9.5626, A4 = 0.00000E + 00, A6 = 0.00000E + 00, A8 = 0.00000E + 00, A10 = 0.00000E + 00
12th surface κ = 1.0000, A4 = 8.20445E-04, A6 = -3.35483E-05, A8 = 1.10407E-06, A10 = 0.00000E + 00
[Variable interval data]
Wide angle end Intermediate focal length Telephoto end f = 4.11 8.92 19.37
d4 = 11.899 4.311 0.809
d10 = 3.546 8.010 18.161
d12 = 1.508 1.689 2.099
[Zoom lens group data]
Group number Group first surface Group focal length G1 1 -9.40000
G2 6 7.40302
G3 11 15.61305
[Conditional expression values]
f1 = -9.40000
f2 = 7.40302
fw = 4.11000
fL2 = 16.43751
fLn = -3.02944
ΣD1 = 3.60000
Conditional expression (1) (−f1) /fw=2.28710
Conditional expression (2) (−f1) /fL2=0.57186
Conditional expression (3) n2 × n2 × ν2 = 69.76084
Conditional expression (4) f2 / (− fLn) = 2.44369
Conditional expression (5) (Rb + Ra) / (Rb-Ra) =-1.15211
Conditional expression (6) (−f1) /f2=1.26975
Conditional expression (7) (Rd + Rc) / (Rd−Rc) = − 0.90262
Conditional expression (8) ΣD1 / (− f1) = 0.38298
Conditional expression (9) ν3 = 67.87

  Thus, in this embodiment, it can be seen that all the conditional expressions (1) to (9) are satisfied.

  7A to 7C are graphs showing various aberrations of the zoom lens ZL according to the fourth example. That is, FIG. 7A is a diagram showing various aberrations when focusing on infinity in the wide-angle end state (f = 4.11 mm), and FIG. 7B is infinite in the intermediate focal length state (f = 8.92 mm). FIG. 7C is a diagram of various aberrations at the time of focusing on infinity in the telephoto end state (f = 19.37 mm). From the aberration diagrams, it can be seen that in the fourth example, various aberrations are well corrected in each focal length state from the wide-angle end state to the telephoto end state, and the optical performance is excellent. As a result, by mounting the zoom lens ZL of the fourth embodiment, excellent optical performance can be secured even in the digital still camera CAM.

(5th Example)
Hereinafter, a fifth embodiment of the present application will be described with reference to FIGS. 9 to 10 and Table 5. FIG. FIG. 9A is a cross-sectional view of the zoom lens according to Example 5 in the wide-angle end state, FIG. 9B is a cross-sectional view of the zoom lens in the intermediate focal length state, and FIG. 9C is a zoom view. It is sectional drawing in the telephoto end state of a lens. The zoom lens of the fifth example has the same configuration as that of the zoom lens of the first example except for a part of the shape of the second lens group G2, and the same reference numerals are used for the respective parts as in the case of the first example. The detailed description is omitted. The second lens group G2 of the fifth example includes a third lens L3 that is a biconvex positive lens and a biconvex positive lens that are arranged in order from the object side along the optical axis. The lens L4 and a fifth lens L5, which is a biconcave negative lens, have an aspheric surface on the object side in the third lens L3. The fourth lens L4 and the fifth lens L5 are bonded lenses that are cemented with each other.

  Table 5 below shows specifications in the fifth embodiment. The surface numbers 1 to 16 in Table 5 correspond to the surfaces 1 to 16 in FIG. 9, and the group numbers G1 to G3 in Table 5 correspond to the lens groups G1 to G3 in FIG. In the fifth embodiment, the third, fourth, sixth, and twelfth lens surfaces are aspherical.

(Table 5)
[Overall specifications]
Zoom ratio = 4.71
Wide angle end Intermediate focal length Telephoto end f = 4.12 8.94 19.40
FNO = 2.68 4.09 7.16
2ω = 80.08 39.9 19.08
Y = 2.90 3.25 3.25
BF = 2.91 2.91 2.91
TL = 25.06 22.98 30.05
[Lens specifications]
Surface number r d nd νd
1 -182.1496 0.6000 1.69680 55.52
2 4.3497 1.1500
3 * 6.5 115 1.6500 1.60740 27.00
4 * 14.2205 (d4)
5 ∞ -0.2000 (aperture stop)
6 * 5.4468 1.4000 1.59201 67.05
7 -11.5330 0.1000
8 3.7043 1.4500 1.69680 55.52
9 -17.8839 0.4000 1.80100 34.96
10 2.4415 (d10)
11 1000.0000 1.8500 1.53110 55.91
12 * -6.9478 (d12)
13 ∞ 0.2100 1.51680 63.88
14 ∞ 0.3000
15 ∞ 0.5000 1.51680 63.88
16 ∞ 0.6000
[Aspherical data]
3rd surface κ = 2.0284, A4 = -4.99236E-04, A6 = 1.29842E-05, A8 = -7.35509E-06, A10 = 3.77110E-07
4th surface κ = -4.4453, A4 = -4.69828E-04, A6 = 2.45045E-05, A8 = -1.00766E-05, A10 = 5.59250E-07
6th surface κ = 0.0983, A4 = -3.92054E-04, A6 = 4.86503E-06, A8 = -2.76862E-06, A10 = 0.00000E + 00
12th surface κ = -6.5208, A4 = -1.32246E-03, A6 = 1.48100E-05, A8 = 1.77832E-06, A10 = -6.60718E-08
[Variable interval data]
Wide angle end Intermediate focal length Telephoto end f = 4.12 8.94 19.40
d4 = 10.838 4.059 0.934
d10 = 2.910 7.609 17.806
d12 = 1.542 1.542 1.542
[Zoom lens group data]
Group number Group first surface Group focal length G1 1 -9.40000
G2 6 7.10682
G3 11 13.00000
[Conditional expression values]
f1 = -9.40000
f2 = 7.10682
fw = 4.12
fL2 = 18.29561
fLn = -2.65863
ΣD1 = 3.40000
Conditional expression (1) (−f1) /fw=2.28155
Conditional expression (2) (-f1) /fL2=0.51378
Conditional expression (3) n2 × n2 × ν2 = 69.76084
Conditional expression (4) f2 / (− fLn) = 2.67311
Conditional expression (5) (Rb + Ra) / (Rb-Ra) =-0.98620
Conditional expression (6) (−f1) /f2=1.32267
Conditional expression (7) (Rd + Rc) / (Rd−Rc) = − 0.995335
Conditional expression (8) ΣD1 / (− f1) = 0.36170
Conditional expression (9) ν3 = 67.05

  Thus, in this embodiment, it can be seen that all the conditional expressions (1) to (9) are satisfied.

  FIGS. 10A to 10C are graphs showing various aberrations of the zoom lens ZL according to the fifth example. That is, FIG. 10A is a diagram of various aberrations when focusing at infinity in the wide-angle end state (f = 4.12 mm), and FIG. 10B is infinite in the intermediate focal length state (f = 8.94 mm). FIG. 10C is a diagram of various aberrations at the time of focusing on infinity in the telephoto end state (f = 19.40 mm). From the aberration diagrams, it can be seen that in the fifth example, various aberrations are well corrected in each focal length state from the wide-angle end state to the telephoto end state, and the optical performance is excellent. As a result, by mounting the zoom lens ZL of the fifth embodiment, excellent optical performance can be secured even in the digital still camera CAM.

(Sixth embodiment)
Hereinafter, a sixth embodiment of the present application will be described with reference to FIGS. 11A is a cross-sectional view of the zoom lens according to the sixth example in the wide-angle end state, FIG. 11B is a cross-sectional view of the zoom lens in the intermediate focal length state, and FIG. 11C is a zoom view. It is sectional drawing in the telephoto end state of a lens. The zoom lens of the sixth example includes a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a positive refractive power, which are arranged in order from the object side along the optical axis. A third lens group G3 having power and a fourth lens group G4 having negative refractive power are configured. Then, during zooming from the wide-angle end state (W) to the telephoto end state (T), the distance between the first lens group G1 and the second lens group G2 decreases, and the second lens group G2 and the third lens group G3. The first lens group G1, the second lens group G2, and the third lens group G3 each have an optical axis so that the distance between the lens groups G3 increases and the distance between the third lens group G3 and the fourth lens group G4 decreases. It is comprised so that it may move along. An aperture stop S is disposed between the first lens group G1 and the second lens group G2.

  The first lens group G1 includes a first lens L1 which is a biconcave negative lens arranged in order from the object side along the optical axis, and a second lens L2 which is a positive meniscus lens having a convex surface facing the object side. The lens surfaces on both sides of the second lens L2 are aspherical. The second lens group G2 includes a third lens L3 that is a biconvex positive lens arranged in order from the object side along the optical axis, and a fourth lens L4 that is a negative meniscus lens having a convex surface facing the object side. The fifth lens L5 is a positive meniscus lens having a convex surface facing the object side, and the lens surface on the object side of the third lens L3 is an aspherical surface. The third lens group G3 includes only a sixth lens L6, which is a biconvex positive lens. The lens surface on the image plane I side of the sixth lens L6 is aspheric. The fourth lens group G4 includes solely a seventh lens L7, which is a negative meniscus lens having a convex surface directed toward the image plane I side. The second lens L2 and the sixth lens L6 are plastic lenses. In addition, focusing from an object at infinity to an object at a finite distance is performed by moving the third lens group G3 along the optical axis.

  The aperture stop S is disposed in the vicinity of the object side of the third lens L3 located closest to the object side in the second lens group G2, and is used for zooming from the wide-angle end state to the telephoto end state. It moves together with the two lens group G2. The filter group FL disposed between the fourth lens group G4 and the image plane I includes a low-pass filter, an infrared cut filter, and the like.

  Table 6 below shows specifications of the sixth embodiment. The surface numbers 1 to 19 in Table 6 correspond to the surfaces 1 to 19 in FIG. 11, and the group numbers G1 to G4 in Table 6 correspond to the lens groups G1 to G4 in FIG. In the sixth embodiment, the third, fourth, sixth, and thirteenth lens surfaces are aspherical.

(Table 6)
[Overall specifications]
Zoom ratio = 4.24
Wide angle end Intermediate focal length Telephoto end f = 4.20 8.65 17.80
FNO = 2.93 4.29 7.39
2ω = 79.00 42.28 20.74
Y = 2.90 3.25 3.25
BF = 1.57 1.57 1.57
TL = 26.64 24.59 30.53
[Lens specifications]
Surface number r d nd νd
1 -53.6797 0.6000 1.72916 54.61
2 4.4070 1.3000
3 * 10.1496 1.6000 1.60740 27.00
4 * 401.3754 (d4)
5 ∞ -0.2000 (aperture stop)
6 * 3.3492 1.4000 1.69350 53.18
7 -25.3374 0.3500
8 15.8658 0.4000 1.72825 28.38
9 2.6358 0.5000
10 6.2878 1.0000 1.77250 49.62
11 15.4609 (d11)
12 19.2128 1.8000 1.53110 55.91
13 * -11.7544 (d13)
14 -16.9195 0.6000 1.68893 31.16
15 -29.7442 (d15)
16 ∞ 0.2100 1.51680 63.88
17 ∞ 0.2000
18 ∞ 0.5000 1.51680 63.88
19 ∞ 0.6000
[Aspherical data]
3rd surface κ = 2.9663, A4 = 7.57948E-04, A6 = -5.54924E-06, A8 = -5.41331E-06, A10 = 3.88224E-07
4th surface κ = 5.0000, A4 = 4.03158E-05, A6 = -7.41052E-05, A8 = -7.73247E-07, A10 = 1.43586E-07
6th surface κ = 0.8784, A4 = -1.77737E-03, A6 = -1.44113E-04, A8 = -5.74580E-06, A10 = 0.00000E + 00
13th surface κ = 5.5518, A4 = 8.74312E-04, A6 = -5.81090E-05, A8 = 4.65809E-06, A10 = -9.31475E-08
[Variable interval data]
Wide angle end Intermediate focal length Telephoto end f = 4.20 8.65 17.80
d4 = 10.853 3.959 0.604
d11 = 3.649 8.732 18.498
d13 = 1.216 0.974 0.509
d15 = 0.303 0.303 0.303
[Zoom lens group data]
Group number Group first surface Group focal length G1 1 -9.28182
G2 6 7.93978
G3 12 14.01388
G4 14 -58.06828
[Conditional expression values]
f1 = -9.28182
f2 = 7.93978
fw = 4.20000
fL2 = 17.111699
fLn = -4.39645
ΣD1 = 3.50000
Conditional expression (1) (−f1) /fw=2.209957
Conditional expression (2) (−f1) /fL2=0.52422577
Conditional expression (3) n2 × n2 × ν2 = 69.76083852
Conditional expression (4) f2 / (− fLn) = 1.80595
Conditional expression (5) (Rb + Ra) / (Rb−Ra) = − 0.24085
Conditional expression (6) (-f1) /f2=1.16903
Conditional expression (7) (Rd + Rc) / (Rd-Rc) =-0.84826
Conditional expression (8) ΣD1 / (− f1) = 0.37708
Conditional expression (9) ν3 = 53.18000

  Thus, in this embodiment, it can be seen that all the conditional expressions (1) to (9) are satisfied.

  12A to 12C are graphs showing various aberrations of the zoom lens ZL according to the sixth example. That is, FIG. 12A is a diagram of various aberrations when focusing at infinity in the wide-angle end state (f = 4.20 mm), and FIG. 12B is infinite in the intermediate focal length state (f = 8.65 mm). FIG. 12C is a diagram of various aberrations at the time of focusing on infinity in the telephoto end state (f = 17.80 mm). Each aberration diagram shows that in the sixth example, various aberrations 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. As a result, by mounting the zoom lens ZL of the sixth embodiment, excellent optical performance can be ensured even in the digital still camera CAM.

  As described above, according to each embodiment, it is possible to realize a zoom lens and an optical apparatus (digital still camera) that have a wide angle of view and a high zoom ratio, and that have a small, low cost, and good imaging performance. .

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

  In each of the above-described embodiments, the three-group and four-group configurations are shown as the zoom lens. 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 addition, 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, the third lens group is preferably a focusing lens group.

  In addition, the lens group or the partial lens group is moved so as to have a component in a direction perpendicular to the optical axis, or is rotated (swayed) in the in-plane direction including the optical axis to reduce image blur caused by camera shake. A vibration-proof lens group to be corrected may be used. In particular, it is preferable that at least a part of the second lens group is an anti-vibration lens group.

  Further, the lens surface may be formed as a spherical surface, a flat surface, or 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. Further, even when the image plane is deviated, it is preferable because there is little deterioration in drawing performance. When the lens surface is an aspheric surface, the aspheric surface is an aspheric surface by grinding, a glass mold aspheric surface made of glass with an aspheric shape, or a composite aspheric surface made of resin with an aspheric shape on the glass surface. 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.

  The aperture stop is preferably disposed in the vicinity of the second lens group, but the role of the aperture stop may be substituted by a lens frame without providing a member as an aperture stop.

  Each lens surface may be provided with an antireflection film having a 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 (variable magnification optical system) of the present embodiment has a magnification ratio of about 3 to 10.

  In the zoom lens (variable magnification optical system) of the present embodiment, it is preferable that the first lens group has one positive lens component and one negative lens component. The second lens group preferably has two positive lens components and one negative lens component. The third lens group preferably has one positive lens component.

  Further, the zoom lens (variable magnification optical system) of the present embodiment is used in a digital still camera, but the present invention is not limited to this, and can also be used in an optical device such as a digital video camera.

CAM digital still camera (optical equipment)
ZL zoom lens G1 first lens group G2 second lens group G3 third lens group L1 first lens L2 second lens L3 third lens L4 fourth lens L5 fifth lens L6 sixth lens S aperture stop I image surface

Claims (14)

A first lens group having negative refracting power, a second lens group having positive refracting power, and a third lens group having positive refracting power, arranged in order from the object side along the optical axis, and having a wide-angle end A zoom lens in which at least the first lens group and the second lens group move along the optical axis at the time of zooming from a state to a telephoto end state,
The first lens group includes a first lens having negative refracting power and a second lens having positive refracting power, which are arranged in order from the object side along the optical axis, and the second lens has an aspherical surface. A plastic lens,
The second lens group includes a third lens having positive refracting power, a fourth lens, and a fifth lens, which are arranged in order from the object side along the optical axis, and the fourth lens and the fifth lens. One of them is a negative lens and the other is a positive lens,
The third lens group includes a sixth lens having positive refractive power,
A zoom lens that satisfies the following conditional expressions:
1.50 <(− f1) / fw <2.52
0.4 <(− f1) / fL2 <0.8
n2 × n2 × ν2 <77.0
However,
f1: the focal length of the first lens group,
fw: focal length in the wide-angle end state of the zoom lens,
fL2: focal length of the second lens,
n2: refractive index of the second lens,
ν2: Abbe number of the second lens. When the focal length of the second lens group is f2, and the focal length of the fourth lens and the fifth lens which is the negative lens is fLn, the following formula 1.89 <f2 / (− fLn) <2.85
The zoom lens according to claim 1, wherein the following condition is satisfied. When the radius of curvature of the lens surface closest to the image side in the sixth lens is Rb and the radius of curvature of the lens surface closest to the object side of the sixth lens is Ra, the following formula −1.8 <(Rb + Ra) / ( Rb-Ra) <0.1
The zoom lens according to claim 1, wherein the zoom lens satisfies the following condition. When the focal length of the second lens group is f2, the following formula 0.9 <(− f1) / f2 <1.4
The zoom lens according to claim 1, wherein the zoom lens satisfies the following condition. When the radius of curvature of the image-side lens surface of the first lens is Rd and the radius of curvature of the object-side lens surface of the first lens is Rc, the following equation −1.2 <(Rd + Rc) / (Rd− Rc) <− 0.1
The zoom lens according to claim 1, wherein the zoom lens satisfies the following condition. When the distance on the optical axis from the object-side lens surface of the first lens to the image-side lens surface of the second lens is ΣD1, the following expression 0.30 <ΣD1 / (− f1) <0.50
The zoom lens according to any one of claims 1 to 5, wherein the following condition is satisfied.   The zoom lens according to claim 1, wherein the sixth lens has an aspherical surface.   The zoom lens according to claim 1, wherein the sixth lens is a plastic lens. When the Abbe number of the third lens is ν3, the following formula 48.0 <ν3
The zoom lens according to claim 1, wherein the following condition is satisfied.   The zoom lens according to claim 1, wherein the third lens has an aspherical surface.   The zoom lens according to any one of claims 1 to 10, wherein the fourth lens and the fifth lens are bonded lenses.   The zoom lens according to claim 1, wherein focusing from an object at infinity to an object at a finite distance is performed by moving the third lens group along the optical axis. An optical apparatus including a zoom lens that forms an image of an object on a predetermined surface,
An optical apparatus, wherein the zoom lens is the zoom lens according to any one of claims 1 to 12. A zoom lens manufacturing method in which a first lens group having negative refracting power, a second lens group having positive refracting power, and a third lens group having positive refracting power are arranged in order from the object side along the optical axis. Because
At the time of zooming from the wide-angle end state to the telephoto end state, at least the first lens group and the second lens group respectively move along the optical axis,
The first lens group includes a first lens having negative refracting power and a second lens having positive refracting power, which are arranged in order from the object side along the optical axis, and the second lens has an aspherical surface. A plastic lens,
The second lens group includes a third lens having positive refracting power, a fourth lens, and a fifth lens, which are arranged in order from the object side along the optical axis, and the fourth lens and the fifth lens. One of them is a negative lens and the other is a positive lens,
The third lens group includes a sixth lens having positive refractive power,
A zoom lens manufacturing method characterized in that the following conditional expressions are satisfied:
1.50 <(− f1) / fw <2.52
0.4 <(− f1) / fL2 <0.8
n2 × n2 × ν2 <77.0
However,
f1: the focal length of the first lens group,
fw: focal length in the wide-angle end state of the zoom lens,
fL2: focal length of the second lens,
n2: refractive index of the second lens,
ν2: Abbe number of the second lens.

Images