JP2015102646A - Zoom lens, optical equipment, and method for manufacturing zoom lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a zoom lens that has a large aperture ratio and high optical performance, optical equipment, and a method for manufacturing a zoom lens.SOLUTION: The zoom lens includes, successively arranged from an object side, a front group GF having a negative refractive power and a rear group GR having a positive refractive power. The front group GF includes, successively arranged from the object side, a first lens group G1 having a positive refractive power and a second lens group G2 having a negative refractive power. Upon varying powers from a wide angle end state to a telephoto end state, the first lens group G1 is fixed in a direction of the optical axis with respect to an image plane. The zoom lens satisfies a conditional expression (1):0.30<fR/(-fFw)<0.80, where fR represents a focal distance of the rear group GR; and fFw represents a focal distance of the front group GF in a wide angle end state.

Description

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

  A zoom lens having a large aperture ratio has been proposed as an imaging lens used for a photographic camera, an electronic still camera, a video camera, and the like (see, for example, Patent Document 1).

JP 60-208723 A

  In recent years, zoom lenses are required to have higher optical performance while maintaining a large aperture ratio.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a zoom lens, an optical apparatus, and a zoom lens manufacturing method having a large aperture ratio and high optical performance.

  In order to achieve such an object, the zoom lens according to the present invention has a front group having negative refractive power, an aperture stop, and a rear group having positive refractive power, which are arranged in order from the object side. The front group includes a first lens group having a positive refractive power and a second lens group having a negative refractive power arranged in order from the object side, and changes from the wide-angle end state to the telephoto end state. At the time of magnification, the first lens group is fixed in the optical axis direction with respect to the image plane, and satisfies the following conditional expression.

0.30 <fR / (-fFw) <0.80
However,
fR: focal length of the rear group,
fFw: focal length in the wide-angle end state of the front group.

  The zoom lens according to the present invention preferably satisfies the following conditional expression.

0.20 <(− fB) / ΔZB <0.40
However,
fB: focal length of the second lens group,
ΔZB: a moving distance on the optical axis from the wide-angle end state to the telephoto end state of the second lens group.

  In the zoom lens according to the present invention, the second lens group includes a first negative lens component, a second negative lens component, and a positive lens component arranged in order from the object side. Is preferably satisfied.

0.10 <(-fB2) / fB3 <1.00
However,
fB2: a focal length of the second negative lens component in the second lens group,
fB3: focal length of the positive lens component in the second lens group.

  The zoom lens according to the present invention preferably satisfies the following conditional expression.

−0.90 <(rB12−rB11) / (rB12 + rB11) <− 0.40
However,
rB11: radius of curvature of the object-side lens surface of the first negative lens component in the second lens group;
rB12: radius of curvature of the image-side lens surface of the first negative lens component in the second lens group.

  In the zoom lens according to the present invention, the rear group includes two lens groups, and among the lens groups constituting the rear group, the lens group arranged closest to the object side is arranged in order from the object side, It is preferable that the lens unit includes one positive lens component and a negative lens component arranged closest to the object side in the rear group, and satisfies the following conditional expression.

0.40 <(-fD2) / fD1 <0.80
However,
fD1: a focal length of the positive lens component in the lens group disposed closest to the object among the lens groups constituting the rear group,
fD2: a focal length of the negative lens component in the lens group disposed closest to the object among the lens groups constituting the rear group.

  The zoom lens according to the present invention preferably satisfies the following conditional expression.

0.10 <| fE / fD | <0.50
However,
fD: the focal length of the lens group arranged closest to the object side among the lens groups constituting the rear group,
fE: the focal length of the second lens group arranged from the object side among the lens groups constituting the rear group.

  In the zoom lens according to the present invention, it is preferable that the rear group has a positive lens component and satisfies the following conditional expression.

1.70 <np <1.80
45.00 <νdp <60.00
However,
np: refractive index at d-line of the positive lens component in the rear group,
νdp: Abbe number at the d-line of the positive lens component in the rear group.

  An optical apparatus according to the present invention is equipped with any of the zoom lenses described above.

  A method for manufacturing a zoom lens according to the present invention is a method for manufacturing a zoom lens having a front group having negative refractive power, an aperture stop, and a rear group having positive refractive power, which are arranged in order from the object side. The front group includes a first lens group having a positive refractive power and a second lens group having a negative refractive power arranged in order from the object side, and changes from the wide-angle end state to the telephoto end state. At the time of zooming, the first lens group is fixed in the optical axis direction with respect to the image plane, and each lens is disposed in the lens barrel so as to satisfy the following conditional expression.

0.30 <fR / (-fFw) <0.80
However,
fR: focal length of the rear group,
fFw: focal length in the wide-angle end state of the front group.

  According to the present invention, it is possible to provide a zoom lens, an optical apparatus, and a method for manufacturing a zoom lens having a large aperture ratio and high optical performance.

FIG. 2 is a cross-sectional view illustrating a configuration of a zoom lens according to Example 1, where (W) indicates a wide-angle end state, (M) indicates an intermediate focal length state, and (T) indicates a position of each lens group in a telephoto end state. FIG. 4A is a diagram illustrating various aberrations of the zoom lens according to Example 1, where FIG. 9A illustrates various aberrations at an imaging distance infinite at a wide angle end state, and FIG. 9B illustrates various aberrations at an imaging distance infinite at an intermediate focal length state. FIG. 4C is a diagram of various aberrations at an imaging distance of infinity in the telephoto end state. FIG. 6 is a cross-sectional view illustrating a configuration of a zoom lens according to Example 2, where (W) indicates a wide-angle end state, (M) indicates an intermediate focal length state, and (T) indicates a position of each lens group in a telephoto end state. FIG. 6A is a diagram illustrating various aberrations of the zoom lens according to Example 2, wherein FIG. 9A illustrates various aberrations at an imaging distance infinite at a wide-angle end state, and FIG. 9B illustrates various aberrations at an imaging distance infinite at an intermediate focal length state. FIG. 4C is a diagram of various aberrations at an imaging distance of infinity in the telephoto end state. FIG. 6 is a cross-sectional view illustrating a configuration of a zoom lens according to Example 3, where (W) indicates a wide-angle end state, (M) indicates an intermediate focal length state, and (T) indicates a position of each lens group in a telephoto end state. FIG. 6A is a diagram illustrating various aberrations of the zoom lens according to Example 3, wherein FIG. 9A illustrates various aberrations at an imaging distance of infinity in the wide-angle end state, and FIG. 9B illustrates various aberrations at an imaging distance of infinity in the intermediate focal length state. FIG. 4C is a diagram of various aberrations at an imaging distance of infinity in the telephoto end state. FIG. 10 is a cross-sectional view illustrating a configuration of a zoom lens according to Example 4, where (W) indicates a wide-angle end state, (M) indicates an intermediate focal length state, and (T) indicates a position of each lens group in a telephoto end state. FIG. 6A is a diagram illustrating various aberrations of the zoom lens according to Example 4, wherein FIG. 9A illustrates various aberrations at an imaging distance infinite at a wide-angle end state, and FIG. 9B illustrates various aberrations at an imaging distance infinite at an intermediate focal length state. FIG. 4C is a diagram of various aberrations at an imaging distance of infinity in the telephoto end state. It is a figure which shows the structure of the camera carrying the zoom lens which concerns on this embodiment. 5 is a flowchart illustrating a method for manufacturing a zoom lens according to the present embodiment.

  Hereinafter, embodiments will be described with reference to the drawings. As shown in FIG. 1, the zoom lens ZL according to the present embodiment includes a front group GF that is a variable power group and has negative refractive power, arranged in order from the object side along the optical axis, an aperture stop S, A rear lens group GR having a positive refractive power and a front lens group GF arranged in order from the object side along the optical axis, and a first lens group G1 having a positive refractive power, and a negative lens group G1. The first lens group G1 is fixed in the optical axis direction with respect to the image plane I when zooming from the wide-angle end state to the telephoto end state. Formula (1) is satisfied.

0.30 <fR / (− fFw) <0.80 (1)
However,
fR: focal length of rear group GR,
fFw: focal length of the front group GF in the wide-angle end state.

  With this configuration, it is possible to realize a zoom lens having high optical performance while maintaining a large aperture ratio.

  Conditional expression (1) defines the focal length of the rear group GR with respect to the focal length of the front group GF in the wide-angle end state. The zoom lens ZL according to the present embodiment can satisfactorily correct the spherical aberration by satisfying the conditional expression (1), and can easily increase the diameter. If the upper limit of conditional expression (1) is exceeded, the refractive power of the front group GF at the wide-angle end state increases, and the spherical aberration that occurs in the front group GF increases significantly. Correction becomes difficult, which is not preferable. If the lower limit value of conditional expression (1) is not reached, the refractive power of the front group GF at the wide-angle end state becomes small, and spherical aberration occurs greatly negatively in the front group GF, making it difficult to correct spherical aberration in the rear group GR. Therefore, it is not preferable.

  In order to ensure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (1) to 0.60. In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (1) to 0.55.

  In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (1) to 0.40. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (1) to 0.44.

  The zoom lens ZL according to the present embodiment preferably satisfies the following conditional expression (2).

0.20 <(− fB) / ΔZB <0.40 (2)
However,
fB: focal length of the second lens group G2,
ΔZB: a moving distance on the optical axis from the wide-angle end state to the telephoto end state of the second lens group G2.

  Conditional expression (2) defines the focal length with respect to the moving distance from the wide-angle end state to the telephoto end state of the second lens group G2. The zoom lens ZL according to the present embodiment can increase the zoom magnification while maintaining the appropriate size of the optical system by satisfying conditional expression (2). If the corresponding value of the conditional expression (2) exceeds the upper limit value, the movement amount of the zooming group G2 due to zooming becomes small, and it becomes difficult to ensure the zoom magnification. If the zoom magnification is secured in the upper limit state of conditional expression (2), coma aberration in the telephoto end state is greatly increased. If the lower limit value of conditional expression (2) is not reached, the amount of movement of the zooming group G2 due to zooming becomes large, leading to an increase in the size of the entire optical system, which is inappropriate. If the size of the conditional expression (2) is not increased in the lower limit state, spherical aberration is greatly negatively generated.

  In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (2) to 0.30. In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (2) to 0.27.

  In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (2) to 0.22.

  In the zoom lens ZL according to the present embodiment, the second lens group G2 includes a first negative lens component, a second negative lens component, and a positive lens component arranged in order from the object side. It is preferable to satisfy conditional expression (3).

  Here, the “lens component” refers to a single lens or a cemented lens in which two or more single lenses are cemented, and a description thereof will be omitted below.

0.10 <(-fB2) / fB3 <1.00 (3)
However,
fB2: focal length of the second negative lens component in the second lens group G2,
fB3: focal length of the positive lens component in the second lens group G2.

  Conditional expression (3) defines the focal length of the second negative lens component with respect to the focal length of the positive lens component in the second lens group G2. The zoom lens ZL according to the present embodiment can reduce spherical aberration and coma aberration by satisfying conditional expression (3). When the upper limit of conditional expression (3) is exceeded, spherical aberration on the telephoto side is negative and coma aberration is positive. When the lower limit value of conditional expression (3) is not reached, spherical aberration on the telephoto side occurs positively and coma aberration occurs negatively.

  In order to ensure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (3) to 0.90.

  In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (3) to 0.15.

  In the zoom lens ZL according to this embodiment, it is preferable that the following conditional expression (4) is satisfied.

−0.90 <(rB12−rB11) / (rB12 + rB11) <− 0.40 (4)
However,
rB11: radius of curvature of the object side lens surface of the first negative lens component in the second lens group G2,
rB12: radius of curvature of the image side lens surface of the first negative lens component in the second lens group G2.

  Conditional expression (4) defines the shape of the first negative lens component in the second lens group G2. The zoom lens ZL according to the present embodiment can simultaneously reduce distortion and curvature of field by satisfying conditional expression (4). If the upper limit value of conditional expression (4) is exceeded, the field curvature in the wide-angle end state is greatly negative. If the lower limit value of conditional expression (4) is not reached, distortion in the wide-angle end state is greatly negatively generated.

  In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (4) to −0.50. In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (4) to −0.55.

  In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (4) to −0.80. In order to secure the effect of the present embodiment, it is preferable to set the lower limit value of conditional expression (4) to −0.75.

  In the zoom lens ZL according to the present embodiment, the rear group GR has two lens groups, and among the lens groups constituting the rear group GR, the lens groups arranged closest to the object side are arranged in order from the object side. It is preferable that the zoom lens includes at least one positive lens component and a negative lens component arranged closest to the object side in the rear group GR, and satisfies the following conditional expression (5).

  Specifically, the rear group GR is composed of two lens groups, a fourth lens group G4 and a fifth lens group GR, which are arranged in order from the object side (the lens group constituting the rear group GR described above). The fourth lens group G4 (corresponding to the lens group arranged closest to the object side) includes one positive lens component arranged in order from the object side, and a negative lens component arranged closest to the object side in the rear group GR. The fifth lens group G5 (corresponding to the lens group arranged second from the object side among the lens groups constituting the rear group GR described later) is arranged on the most object side in the rear group GR. It is composed of a plurality of lens components arranged closer to the image side than the negative lens component.

0.40 <(− fD2) / fD1 <0.80 (5)
However,
fD1: the focal length of the positive lens component in the lens group (fourth lens group G4) arranged closest to the object side among the lens groups constituting the rear group GR;
fD2: the focal length of the negative lens component in the lens group (fourth lens group G4) arranged closest to the object among the lens groups constituting the rear group GR.

  Conditional expression (5) indicates the focal length of the negative lens component with respect to the focal length of the positive lens component in the lens group (fourth lens group G4) arranged on the most object side among the lens groups constituting the rear group GR. It prescribes. The zoom lens ZL according to the present embodiment can reduce spherical aberration by satisfying conditional expression (5). If the upper limit of conditional expression (5) is exceeded, spherical aberration will be greatly negative. When the corresponding value of conditional expression (5) is below the lower limit value, spherical aberration is greatly increased.

  In order to ensure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (5) to 0.70. In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (5) to 0.65.

  In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (5) to 0.50. In order to secure the effect of the present embodiment, it is preferable to set the lower limit value of conditional expression (5) to 0.60.

  In the zoom lens ZL according to this embodiment, it is preferable that the following conditional expression (6) is satisfied.

0.10 <| fE / fD | <0.50 (6)
However,
fD: the focal length of the lens group (fourth lens group G4) arranged closest to the object among the lens groups constituting the rear group GR;
fE: the focal length of the lens group (fifth lens group G5) arranged second from the object side among the lens groups constituting the rear group GR.

  Conditional expression (6) is that the object side of the lens group constituting the rear group GR with respect to the focal length of the lens group (fourth lens group G4) arranged closest to the object side among the lens groups constituting the rear group GR. This defines the focal length of the second lens group (fifth lens group G5). The zoom lens ZL according to the present embodiment can shorten the overall length of the optical system by satisfying conditional expression (6). If the upper limit of conditional expression (6) is exceeded, it will be difficult to ensure the lens group spacing between the fourth lens group G4 and the fifth lens group G5. If the lens group spacing between the fourth lens group G4 and the fifth lens group G5 is ensured in the upper limit state of the conditional expression (6), spherical aberration is greatly increased. If the lower limit of conditional expression (6) is not reached, the total length of the optical system becomes longer. When the total length of the optical system is shortened in the lower limit state of conditional expression (6), spherical aberration is greatly negatively generated.

  In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (6) to 0.40. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (6) to 0.30.

  In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (6) to 0.15.

  In the zoom lens ZL according to the present embodiment, it is preferable that the rear group GR has a positive lens component and satisfies the following conditional expressions (7) and (8).

1.70 <np <1.80 (7)
45.00 <νdp <60.00 (8)
However,
np: refractive index of the positive lens component in the rear group GR at the d-line,
νdp: Abbe number on the d-line of the positive lens component in the rear group GR.

  Conditional expression (7) defines the refractive index at the d-line of the positive lens component in the rear group GR. Conditional expression (8) defines the Abbe number at the d-line of the positive lens component in the rear group GR. The zoom lens ZL according to the present embodiment can satisfactorily correct the spherical aberration and chromatic aberration of the d line simultaneously by satisfying conditional expressions (7) and (8).

  If the upper limit value of conditional expression (7) is exceeded, only a glass material having a small Abbe number can be used for the positive lens component in the rear group GR, and the g-line of axial chromatic aberration is negatively generated, which is not preferable. If the lower limit of conditional expression (7) is not reached, the spherical aberration becomes negative and correction becomes difficult.

  In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (7) to 1.79.

  In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (7) to 1.71.

  Exceeding the upper limit of conditional expression (8) is not preferable because only a glass material having a low refractive index can be used for the positive lens component in the rear group GR, and the spherical aberration becomes negative and correction becomes difficult. If the lower limit of conditional expression (8) is not reached, the g-line of axial chromatic aberration is greatly negatively generated, which is not preferable.

In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (8) to 55.00.
In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (8) to 46.00.

  In the zoom lens ZL of the present embodiment, the rear group GR has a fourth lens group G4 and a fifth lens group G5 arranged in order from the object side, and the fourth lens group G4 is closest to the image side. It is preferable that a lens component having a concave surface facing the image side is disposed, and in the fifth lens group G5, a lens component having a concave surface facing the object side is disposed closest to the object side. Thus, the fourth lens group G4 and the fifth lens group G5 can correct spherical aberration satisfactorily by making their concave surfaces face each other. The fourth lens group G4 is preferably composed of a positive lens and a negative lens in order from the object side. The fifth lens group G5 is preferably composed of a negative lens, a positive lens, and at least one lens in order from the object side.

  The zoom lens ZL according to this embodiment preferably satisfies the following conditional expression (9).

0.40 <φA / fA <0.80 (9)
However,
φA: the maximum effective diameter of the first lens group G1,
fA: focal length of the first lens group G1.

  Conditional expression (9) defines the maximum effective diameter of the first lens group G1 with respect to the focal length of the first lens group G1. The zoom lens ZL according to the present embodiment can increase the zoom magnification by satisfying conditional expression (9). If the upper limit value of conditional expression (9) is exceeded, coma aberration in the telephoto end state is greatly increased. If the lower limit of conditional expression (9) is not reached, the total length of the optical system becomes longer, which is not preferable. When the total length of the optical system is shortened in the lower limit state of the conditional expression (9), coma aberration in the telephoto end state is greatly negatively generated.

  In order to ensure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (9) to 0.70. In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (9) to 0.60.

  In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (9) to 0.45.

  According to the zoom lens ZL according to the present embodiment having the above configuration, it is possible to realize a zoom lens having a large aperture ratio and high optical performance.

  Next, a camera (optical apparatus) including the zoom lens ZL described above will be described with reference to FIG. As shown in FIG. 9, the camera 1 is an interchangeable lens camera that includes the zoom lens ZL described above as the photographing lens 2. In this camera 1, light from an object (subject) (not shown) is collected by the taking lens 2, and on the imaging surface of the imaging unit 3 via an OLPF (Optical Low Pass Filter) not shown. A subject image is formed on the screen. Then, the subject image is photoelectrically converted by the photoelectric conversion element provided in the imaging unit 3 to generate an image of the subject. This image is displayed on an EVF (Electronic view finder) 4 provided in the camera 1. Thus, the photographer can observe the subject via the EVF 4. When the release button (not shown) is pressed by the photographer, the subject image generated by the imaging unit 3 is stored in a memory (not shown). In this way, the photographer can shoot the subject with the camera 1.

  Here, the zoom lens ZL mounted as the photographing lens 2 in the camera 1 has a large aperture ratio and high optical performance. Therefore, according to the camera 1, the aperture is large and high optical performance can be realized. Even when the zoom lens ZL described above is mounted on a single-lens reflex camera that has a quick return mirror and observes a subject with a viewfinder optical system, the same effect as the camera 1 can be obtained. Even when the zoom lens ZL described above is mounted on a video camera, the same effects as the camera 1 can be obtained.

  Next, the method for manufacturing the zoom lens ZL described above will be outlined with reference to FIG. First, in the lens barrel, a front group GF having a negative refractive power, an aperture stop S, and a rear group GR having a positive refractive power are arranged in order from the object side along the optical axis. Each lens is arranged (step ST10). At this time, the front lens group GF includes each lens barrel so that the front lens group GF includes a first lens group G1 having a positive refractive power and a second lens group G2 having a negative refractive power, which are arranged in order from the object side. (Step ST20). In zooming from the wide-angle end state to the telephoto end state, the first lens group G1 is arranged in the lens barrel so that the first lens group G1 is fixed in the optical axis direction with respect to the image plane (step ST30). Then, each lens is arranged in the lens barrel so as to satisfy the following conditional expression (1) (step ST40).

0.30 <fR / (− fFw) <0.80 (1)
However,
fR: focal length of rear group GR,
fFw: focal length of the front group GF in the wide-angle end state.

  Here, as an example of the lens arrangement in the present embodiment, as shown in FIG. 1, as the first lens group G1, in order from the object side, a negative meniscus lens L11 having a convex surface facing the object side and a biconvex shape are formed. A cemented lens with the positive lens L12 and a positive meniscus lens having a convex surface facing the object side are arranged so as to have a positive refractive power as a whole. As the second lens group G2, in order from the object side, a negative meniscus lens L21 having a convex surface directed toward the object side, a biconcave negative lens L22, a biconvex positive lens L23, and a biconcave negative lens L24 Are arranged so as to have negative refractive power as a whole. As the third lens group G3, in order from the object side, a cemented lens of a biconvex positive lens L31 and a negative meniscus lens L32 having a convex surface facing the image side is disposed. Thereby, the front group GF has negative refractive power as a whole. Further, as the fourth lens group G4, a positive meniscus lens L41 having a convex surface facing the object side and a negative meniscus lens L42 having a convex surface facing the object side are arranged in this order from the object side. As the fifth lens group G5, in order from the object side, a negative meniscus lens L51 having a convex surface directed toward the image side, a positive meniscus lens L52 having a convex surface directed toward the image side, and a positive meniscus lens L53 having a convex surface directed toward the object side Is arranged. As a result, the rear group GR has a positive refractive power as a whole. The aperture stop S is disposed between the front group GF (third lens group G3) and the rear group GR (fourth lens group G4). At the time of zooming, each lens is arranged so that the first lens group G1 is fixed in the optical axis direction with respect to the image plane I. Further, the lenses are arranged so as to satisfy the conditional expression (1) (the corresponding value of the conditional expression (1) is 0.526).

  According to the manufacturing method according to the present embodiment, a zoom lens having a large aperture ratio and high optical performance can be manufactured.

  Each example according to the present embodiment will be described with reference to the drawings. Tables 1 to 4 are shown below, but these are tables of specifications in the first to fourth examples.

  In addition, each reference code with respect to FIG. 1 according to the first embodiment is used independently for each embodiment in order to avoid complication of explanation due to an increase in the number of digits of the reference code. Therefore, even if the same reference numerals as those in the drawings according to the other embodiments are given, they are not necessarily in the same configuration as the other embodiments.

  In each embodiment, d-line (wavelength 587.5620 nm) and g-line (wavelength 435.8350 nm) are selected as the calculation targets of the aberration characteristics.

  In [Lens Specifications] in the table, the surface number is the order of the optical surfaces from the object side along the light traveling direction, R is the radius of curvature of each optical surface, D is the next optical surface from each optical surface ( Or an optical surface distance to the image surface), nd is the refractive index of the d-line of the material of the optical member, νd is the Abbe number based on the d-line of the material of the optical member, and φA is the first lens The maximum effective diameter of group G1 is shown. Further, the object plane is an object plane, (variable) is a variable plane spacing, the curvature radius “∞” is a plane or an aperture, (aperture S) is an aperture stop S, and the image plane is an image plane I. The description of the refractive index of air “1.000000” is omitted.

  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 field angle (maximum incident angle, unit: °), Y is the image height, and Bf is on the optical axis. The distance from the lens final surface to the paraxial image plane, TL, indicates the total optical length (the distance from the lens frontmost surface to the lens final surface on the optical axis plus Bf).

  “Variable interval data” in the table indicates the variable interval value Di in each state of the wide-angle end, the intermediate focal length, and the telephoto end at an imaging distance of infinity. Di represents a variable interval between the i-th surface and the (i + 1) -th surface.

  In [Lens Group Data] in the table, G is the group number, the first group surface is the surface number of the most object side of each group, the group focal length is the focal length of each group, and the lens configuration length is the most object side of each group. The distance on the optical axis from the lens surface to the lens surface closest to the image plane is shown.

  [Conditional expression] in the table indicates values corresponding to the conditional expressions (1) to (9).

  Hereinafter, in all the specification values, “mm” is generally used for the focal length, the radius of curvature, the surface interval, and other lengths, etc. unless otherwise specified, but the zoom lens is proportionally enlarged or reduced. However, the same optical performance can be obtained, and the present invention is not limited to this. Further, the unit is not limited to “mm”, and other appropriate units can be used.

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

(First embodiment)
A first embodiment will be described with reference to FIGS. 1 and 2 and Table 1. FIG. As shown in FIG. 1, the zoom lens ZL (ZL1) according to the first example is arranged in order from the object side along the optical axis, and has a negative refractive power, the front group GF, and the amount of light. It is composed of an aperture stop S and a rear group GR having a positive refractive power.

  The front group GF is arranged in order from the object side along the optical axis. The first lens group G1 has a positive refractive power, the second lens group G2 has a negative refractive power, and the first lens group G2 has a positive refractive power. 3 lens group G3.

  The first lens group G1 is arranged in order from the object side along the optical axis, and is a cemented lens of a negative meniscus lens L11 having a convex surface facing the object side and a biconvex positive lens L12, and a convex surface facing the object side. And a positive meniscus lens L13. The second lens group G2 includes a negative meniscus lens L21 having a convex surface directed toward the object side, a biconcave negative lens L22, a biconvex positive lens L23, and both arranged in order from the object side along the optical axis. It is composed of a cemented lens with a concave negative lens L24. The third lens group G3 includes a cemented lens of a biconvex positive lens L31 and a negative meniscus lens L32 having a convex surface directed toward the image side, which are arranged in order from the object side along the optical axis.

  The rear group GR includes a fourth lens group G4 having a positive refractive power and a fifth lens group G5 having a positive refractive power, which are arranged in order from the object side along the optical axis.

  The fourth lens group G4 includes a positive meniscus lens L41 having a convex surface directed toward the object side and a negative meniscus lens L42 having a convex surface directed toward the object side, which are arranged in order from the object side along the optical axis. The fifth lens group G5 includes a negative meniscus lens L51 having a convex surface facing the image side, a positive meniscus lens L52 having a convex surface facing the image side, and a convex surface facing the object side. And a plano-convex lens L53 directed.

  In the zoom lens ZL1 according to the present embodiment, when zooming from the wide-angle end state to the telephoto end state, the first lens group G1 is fixed in the optical axis direction with respect to the image plane I, and the second lens group G2 and the third lens group G3. The lens group G3 is moved to the image plane side, and the aperture stop S, the fourth lens group G4, and the fifth lens group G5 are fixed with respect to the image plane I in the optical axis direction. At this time, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 changes, and the third lens group G3 and the fourth lens group G4. The interval between and decreases.

  Table 1 below shows the values of each item in the first example. Surface numbers 1 to 26 in Table 1 correspond to the optical surfaces m1 to m26 shown in FIG.

(Table 1)
[Lens specifications]
Surface number R D νd nd Maximum effective diameter Object surface ∞
1 824.7128 5.0000 49.62 1.772500 φA = 128.60
2 99.2443 27.0000 67.90 1.593190
3 -581.7281 0.5000
4 100.9913 19.0000 70.31 1.487490
5 373.9725 D5 (variable)
6 270.5323 3.0000 40.66 1.883000
7 46.5270 10.0000
8 -228.7009 3.0000 40.66 1.883000
9 171.1354 1.0000
10 61.8861 11.0000 20.88 1.922860
11 -118.1101 3.0000 47.86 1.757000
12 46.6743 D12 (variable)
13 123.5440 6.0000 67.90 1.593190
14 -150.0000 3.0000 22.74 1.808090
15 -475.7816 D15 (variable)
16 ∞ 5.0000 (Aperture S)
17 21.4176 5.0000 52.34 1.755000
18 133.8099 3.0000
19 936.7581 2.0000 27.57 1.755200
20 15.7325 12.0000
21 -13.0585 3.0000 22.74 1.808090
22 -17.5617 2.0000
23 -421.7556 5.0000 52.34 1.755000
24 -27.6957 2.0000
25 32.5864 5.0000 82.57 1.497820
26 ∞ Bf
Image plane ∞

[Overall specifications]
Zoom ratio 6.50
Wide angle end Intermediate focus Telephoto end f 10.00 25.00 65.00
Fno 1.9 1.9 1.9
ω 23.18699 9.61495 3.72602
Y 4.05 4.05 4.05
Bf 40.15837 40.15837 40.15837
TL 367.46869 367.46869 367.46869

[Zooming data]
Variable interval Wide-angle end Medium focus Telephoto end f 10.00000 25.00001 65.00000
D5 7.03993 91.49088 153.34441
D12 6.23467 41.01198 37.13903
D15 178.53573 59.30747 1.32689

[Lens group data]
Group number Group first surface Group focal length Lens construction length G1 1 262.0300 51.5000
G2 6 -37.1610 31.0000
G3 13 197.9079 9.0000
G4 17 158.1800 22.0000
G5 21 27.9923 17.0000
Focal length of the front group GF (G1 to G3) at the wide angle end state -72.3244
Focal length of the rear group GR (G4, G5) in the wide-angle end state 38.0500

[Conditional expression]
Conditional expression (1) fR / (-fFw) = 0.526
Conditional expression (2) (−fB) /ΔZB=0.254
Conditional expression (3) (-fB2) /fB3=0.20
Conditional expression (4) (rB12−rB11) / (rB12 + rB11) = − 0.707
Conditional expression (5) (−fD2) /fD1=0.640
Conditional expression (6) | fE / fD | = 0.177
Conditional expression (7) np = 1.755000
Conditional expression (8) νdp = 52.34
Conditional expression (9) φA / fA = 0.491

  From Table 1, it can be seen that the zoom lens ZL1 according to the present example satisfies the conditional expressions (1) to (9).

  FIG. 2 is a diagram showing various aberrations (spherical aberration diagram, astigmatism diagram, distortion aberration diagram, coma aberration diagram, and lateral chromatic aberration diagram) of the zoom lens according to the first example, and FIG. FIG. 2B is a diagram illustrating various aberrations at an imaging distance of infinity in the intermediate focal length state according to the present exemplary embodiment, and FIG. FIG. 5 is a diagram illustrating various aberrations at an imaging distance of infinity in the telephoto end state.

  In each aberration diagram, FNO represents an F number, and Y represents an image height. d represents the aberration at the d-line, and g represents the aberration at the g-line. Those not described indicate aberrations at the d-line. 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, the solid line indicates the meridional coma. The description regarding these aberration diagrams is common to all the examples, and the description below is omitted.

  As apparent from the respective aberration diagrams shown in FIG. 2, the zoom lens ZL1 according to the first example has various optical aberrations well corrected and high optical performance in each focal length state from the wide-angle end state to the telephoto end state. It can be seen that

(Second embodiment)
A second embodiment will be described with reference to FIGS. 3 and 4 and Table 2. FIG. As shown in FIG. 3, the zoom lens ZL (ZL2) according to the second embodiment is arranged in order from the object side along the optical axis and has a negative refractive power and a front group GF for adjusting the amount of light. It is composed of an aperture stop S and a rear group GR having a positive refractive power.

  The front group GF is arranged in order from the object side along the optical axis. The first lens group G1 has a positive refractive power, the second lens group G2 has a negative refractive power, and the first lens group G2 has a positive refractive power. 3 lens group G3.

  The first lens group G1 is arranged in order from the object side along the optical axis, and is a cemented lens of a negative meniscus lens L11 having a convex surface facing the object side and a biconvex positive lens L12, and a convex surface facing the object side. And a positive meniscus lens L13. The second lens group G2 is composed of a negative meniscus lens L21 having a convex surface facing the object side, a biconcave negative lens L22, and a biconvex positive lens L23 arranged in order from the object side along the optical axis. Composed. The third lens group G3 includes a cemented lens of a biconvex positive lens L31 and a negative meniscus lens L32 having a convex surface directed toward the image side, which are arranged in order from the object side along the optical axis.

  The rear group GR includes a fourth lens group G4 having a positive refractive power and a fifth lens group G5 having a positive refractive power, which are arranged in order from the object side along the optical axis.

  The fourth lens group G4 includes a positive meniscus lens L41 arranged in order from the object side along the optical axis and having a convex surface directed toward the object side, and a biconcave negative lens L42. The fifth lens group G5 includes a negative meniscus lens L51 having a convex surface facing the image side, a positive meniscus lens L52 having a convex surface facing the image side, and a convex surface facing the object side. And a plano-convex lens L53 directed.

  In the zoom lens ZL2 according to the present embodiment, when zooming from the wide-angle end state to the telephoto end state, the first lens group G1 is fixed in the optical axis direction with respect to the image plane I, and the second lens group G2 and the third lens group G3. The lens group G3 is moved to the image plane side, and the aperture stop S, the fourth lens group G4, and the fifth lens group G5 are fixed with respect to the image plane I in the optical axis direction. At this time, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 changes, and the third lens group G3 and the fourth lens group G4. The interval between and decreases.

  Table 2 below shows the values of each item in the second embodiment. Surface numbers 1 to 25 in Table 2 correspond to the optical surfaces m1 to m25 shown in FIG.

(Table 2)
[Lens specifications]
Surface number R D νd nd Maximum effective diameter Object surface ∞
1 309.5274 5.0000 49.62 1.772500 φA = 143.18
2 120.0659 28.0000 67.90 1.593190
3 -689.8330 0.5000
4 105.3469 15.0000 70.31 1.487490
5 174.4478 D5 (variable)
6 130.2649 3.0000 40.66 1.883000
7 25.9097 13.0000
8 -41.8316 3.0000 40.66 1.883000
9 431.6841 1.0000
10 107.4189 8.0000 20.88 1.922860
11 -83.7288 D11 (variable)
12 800.0000 8.0000 67.90 1.593190
13 -66.1197 3.0000 22.74 1.808090
14 -107.0847 D14 (variable)
15 ∞ 5.0000 (Aperture S)
16 25.1973 5.0000 52.34 1.755000
17 379.4920 3.0000
18 -211.4899 2.0000 27.57 1.755200
19 18.7420 12.0000
20 -13.8370 3.0000 22.74 1.808090
21 -17.9771 2.0000
22 -2665.5385 5.0000 52.34 1.755000
23 -30.2820 2.0000
24 35.7769 5.0000 82.57 1.497820
25 ∞ Bf
Image plane ∞

[Overall specifications]
Zoom ratio 6.50
Wide angle end Intermediate focus Telephoto end f 10.00 25.00 65.00
Fno 1.9 1.9 1.9
ω 23.20274 9.33445 3.61855
Y 4.05 4.05 4.05
Bf 43.31102 43.31102 43.31102
TL 375.56027 375.56027 375.56027

[Zooming data]
Variable interval Wide-angle end Intermediate focus Telephoto end f 10.00000 25.00002 65.00000
D5 30.05662 120.82350 180.38764
D11 38.08344 60.91532 51.83080
D14 229.70652 116.10775 65.62813

[Lens group data]
Group number Group first surface Group focal length Lens construction length G1 1 262.0300 48.5000
G2 6 -37.1610 28.0000
G3 12 197.9079 11.0000
G4 16 140.5100 22.0000
G5 20 29.0539 17.0000
Focal length of the front group GF (G1 to G3) at the wide angle end state -85.5879
Focal length of the rear group GR (G4, G5) in the wide-angle end state 38.7800

[Conditional expression]
Conditional expression (1) fR / (− fFw) = 0.453
Conditional expression (2) (−fB) /ΔZB=0.245
Conditional expression (3) (−fB2) /fB3=0.83
Conditional expression (4) (rB12−rB11) / (rB12 + rB11) = − 0.668
Conditional expression (5) (-fD2) / fD1 = 0.639
Conditional expression (6) | fE / fD | = 0.207
Conditional expression (7) np = 1.755000
Conditional expression (8) νdp = 52.34
Conditional expression (9) φA / fA = 0.546

  From Table 2, it can be seen that the zoom lens ZL2 according to the present example satisfies the conditional expressions (1) to (9).

  FIG. 4 is a diagram showing various aberrations (spherical aberration diagram, astigmatism diagram, distortion diagram, coma aberration diagram, and chromatic aberration diagram of magnification) of the zoom lens according to the second example, and FIG. 4A shows this example. FIG. 4B is a diagram illustrating various aberrations at an imaging distance of infinity in the intermediate focal length state according to the present embodiment, and FIG. FIG. 5 is a diagram illustrating various aberrations at an imaging distance of infinity in the telephoto end state.

  As apparent from the respective aberration diagrams shown in FIG. 4, the zoom lens ZL2 according to the second example has various optical aberrations well corrected and high optical performance in each focal length state from the wide-angle end state to the telephoto end state. It can be seen that

(Third embodiment)
A third embodiment will be described with reference to FIGS. As shown in FIG. 5, the zoom lens ZL (ZL3) according to the third example is arranged in order from the object side along the optical axis, and the front group GF having negative refractive power, and for adjusting the amount of light. It is composed of an aperture stop S and a rear group GR having a positive refractive power.

  The front group GF is arranged in order from the object side along the optical axis. The first lens group G1 has a positive refractive power, the second lens group G2 has a negative refractive power, and the first lens group G2 has a positive refractive power. 3 lens group G3.

  The first lens group G1 is arranged in order from the object side along the optical axis, and is a cemented lens of a negative meniscus lens L11 having a convex surface facing the object side and a biconvex positive lens L12, and a convex surface facing the object side. And a positive meniscus lens L13. The second lens group G2 includes a negative meniscus lens L21 having a convex surface directed toward the object side, a biconcave negative lens L22, a biconvex positive lens L23, and both arranged in order from the object side along the optical axis. It is composed of a cemented lens with a concave negative lens L24. The third lens group G3 includes a cemented lens of a biconvex positive lens L31 and a negative meniscus lens L32 having a convex surface directed toward the image side, which are arranged in order from the object side along the optical axis.

  The rear group GR includes a fourth lens group G4 having negative refractive power and a fifth lens group G5 having positive refractive power, which are arranged in order from the object side along the optical axis.

  The fourth lens group G4 includes a positive meniscus lens L41 having a convex surface directed toward the object side and a negative meniscus lens L42 having a convex surface directed toward the object side, which are arranged in order from the object side along the optical axis. The fifth lens group G5 includes a negative meniscus lens L51 having a convex surface facing the image side, a positive meniscus lens L52 having a convex surface facing the image side, and a convex surface facing the object side. And a plano-convex lens L53 directed.

  In the zoom lens ZL3 according to the present embodiment, when zooming from the wide-angle end state to the telephoto end state, the first lens group G1 is fixed in the optical axis direction with respect to the image plane I, and the second lens group G2 and the third lens group G3. The lens group G3 is moved to the image plane side, and the aperture stop S, the fourth lens group G4, and the fifth lens group G5 are fixed with respect to the image plane I in the optical axis direction. At this time, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 changes, and the third lens group G3 and the fourth lens group G4. The interval between and decreases.

  Table 3 below shows values of various specifications in the third example. Surface numbers 1 to 26 in Table 3 correspond to the optical surfaces m1 to m26 shown in FIG.

(Table 3)
[Lens specifications]
Surface number R D νd nd Maximum effective diameter Object surface ∞
1 824.7128 5.0000 49.62 1.772500 φA = 128.620
2 99.2443 27.0000 67.90 1.593190
3 -581.7281 0.5000
4 100.9913 19.0000 70.31 1.487490
5 373.9725 D5 (variable)
6 270.5323 3.0000 40.66 1.883000
7 46.5270 10.0000
8 -228.7009 3.0000 40.66 1.883000
9 169.7549 1.0000
10 61.8334 11.0000 20.88 1.922860
11 -132.6601 3.0000 47.86 1.757000
12 47.2183 D12 (variable)
13 123.9415 6.0000 67.90 1.593190
14 -167.7321 3.0000 22.74 1.808090
15 -517.2677 D15 (variable)
16 ∞ 5.0000 (Aperture S)
17 21.8045 5.0000 52.34 1.755000
18 114.6008 3.0000
19 400.6941 2.0000 27.57 1.755200
20 16.0672 12.0000
21 -13.0756 3.0000 22.74 1.808090
22 -17.3957 2.0000
23 -583.3978 5.0000 54.61 1.729160
24 -27.7763 2.0000
25 32.6982 5.0000 82.57 1.497820
26 ∞ Bf
Image plane ∞

[Overall specifications]
Zoom ratio 6.50
Wide angle end Intermediate focus Telephoto end f 10.00 25.00 65.00
Fno 1.9 1.9 1.9
ω 23.18313 9.61627 3.72614
Y 4.05 4.05 4.05
Bf 40.46418 40.46418 40.46418
TL 368.01327 368.01327 368.01327

[Zooming data]
Variable interval Wide-angle end Medium focus Telephoto end f 10.00000 25.00001 65.00000
D5 7.05612 91.50707 153.36060
D12 6.24523 41.02254 37.14959
D15 178.74774 59.51947 1.53889

[Lens group data]
Group number Group first surface Group focal length Lens construction length G1 1 262.0300 51.5000
G2 6 -37.1610 31.0000
G3 13 197.9079 9.0000
G4 17 -154.3800 22.0000
G5 21 28.1733 17.0000
Focal length at wide-angle end of front group GF -72.3244
Focal length of rear group GR at wide-angle end 38.0500

[Conditional expression]
Conditional expression (1) fR / (-fFw) = 0.526
Conditional expression (2) (−fB) /ΔZB=0.254
Conditional expression (3) (-fB2) /fB3=0.20
Conditional expression (4) (rB12−rB11) / (rB12 + rB11) = − 0.707
Conditional expression (5) (-fD2) / fD1 = 0.637
Conditional expression (6) | fE / fD | = 0.182
Conditional expression (7) np = 1.729160
Conditional expression (8) νdp = 54.61
Conditional expression (9) φA / fA = 0.491

  From Table 3, it can be seen that the zoom lens ZL3 according to the present example satisfies the conditional expressions (1) to (9).

  FIG. 6 is a diagram illustrating various aberrations (spherical aberration diagram, astigmatism diagram, distortion aberration diagram, coma aberration diagram, and chromatic aberration diagram of magnification) of the zoom lens according to the third example, and FIG. 6A illustrates this example. FIG. 6B is a diagram of various aberrations at an imaging distance of infinity in the intermediate focal length state according to the present embodiment, and FIG. FIG. 5 is a diagram illustrating various aberrations at an imaging distance of infinity in the telephoto end state.

  As is apparent from the respective aberration diagrams shown in FIG. 6, the zoom lens ZL3 according to the third example has various aberrations well corrected and high optical performance in each focal length state from the wide-angle end state to the telephoto end state. It can be seen that

(Fourth embodiment)
A fourth embodiment will be described with reference to FIGS. As shown in FIG. 7, the zoom lens ZL (ZL4) according to the fourth example is arranged in order from the object side along the optical axis, and has a negative refractive power, and a front group GF. It is composed of an aperture stop S and a rear group GR having a positive refractive power.

  The front group GF is arranged in order from the object side along the optical axis. The first lens group G1 has a positive refractive power, the second lens group G2 has a negative refractive power, and the first lens group G2 has a positive refractive power. 3 lens group G3.

  The first lens group G1 is arranged in order from the object side along the optical axis, and is a cemented lens of a negative meniscus lens L11 having a convex surface facing the object side and a biconvex positive lens L12, and a convex surface facing the object side. And a positive meniscus lens L13. The second lens group G2 includes a negative meniscus lens L21 having a convex surface directed toward the object side, a biconcave negative lens L22, a biconvex positive lens L23, and both arranged in order from the object side along the optical axis. It is composed of a cemented lens with a concave negative lens L24. The third lens group G3 includes a cemented lens of a biconvex positive lens L31 and a negative meniscus lens L32 having a convex surface directed toward the image side, which are arranged in order from the object side along the optical axis.

  The rear group GR includes a fourth lens group G4 having negative refractive power and a fifth lens group G5 having positive refractive power, which are arranged in order from the object side along the optical axis.

  The fourth lens group G4 includes a positive meniscus lens L41 arranged in order from the object side along the optical axis and having a convex surface directed toward the object side, and a biconcave negative lens L42. The fifth lens group G5 includes a negative meniscus lens L51 having a convex surface facing the image side, a positive meniscus lens L52 having a convex surface facing the image side, and a convex surface facing the object side. And a plano-convex lens L53 directed.

  In the zoom lens ZL4 according to the present embodiment, when zooming from the wide-angle end state to the telephoto end state, the first lens group G1 is fixed in the optical axis direction with respect to the image plane I, and the second lens group G2 and the third lens group G3. The lens group G3 is moved to the image plane side, and the aperture stop S, the fourth lens group G4, and the fifth lens group G5 are fixed with respect to the image plane I in the optical axis direction. At this time, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 changes, and the third lens group G3 and the fourth lens group G4. The interval between and decreases.

  Table 4 below shows values of various specifications in the fourth embodiment. Surface numbers 1 to 26 in Table 4 correspond to the optical surfaces m1 to m26 shown in FIG.

(Table 4)
[Lens specifications]
Surface number R D νd nd Maximum effective diameter Object surface ∞
1 604.8674 5.0000 49.62 1.772500 φA = 128.030
2 96.0276 27.0000 67.90 1.593190
3 -910.6294 0.5000
4 101.1785 19.0000 70.31 1.487490
5 416.5879 D5 (variable)
6 150.0000 3.0000 40.66 1.883000
7 37.0125 10.0000
8 -248.1000 3.0000 40.66 1.883000
9 175.8904 1.0000
10 58.5655 11.0000 20.88 1.922860
11 -200.5104 3.0000 47.86 1.757000
12 50.3791 D12 (variable)
13 110.0000 6.0000 67.90 1.593190
14 -475.0172 3.0000 22.74 1.808090
15 -7589.6660 D15 (variable)
16 ∞ 3.0000 (Aperture S)
17 20.4158 5.0000 52.34 1.755000
18 668.6378 3.0000
19 -189.6622 2.0000 27.57 1.755200
20 14.5946 12.0000
21 -12.7148 3.0000 22.74 1.808090
22 -17.5005 2.0000
23 -155.8818 5.0000 47.35 1.788000
24 -25.9092 2.0000
25 30.2358 5.0000 82.57 1.497820
26 ∞ Bf
Image plane ∞

[Overall specifications]
Zoom ratio 6.50
Wide angle end Intermediate focus Telephoto end f 10.00 25.00 65.00
Fno 1.9 1.9 1.9
ω 23.18313 9.61627 3.72614
Y 4.05 4.05 4.05
Bf 39.42953 39.42953 39.42953
TL 364.39786 364.39786 364.39786

[Zooming data]
Variable interval Wide-angle end Medium focus Telephoto end f 10.00000 25.00001 65.00000
D5 6.90426 91.35520 153.20873
D12 6.24560 41.02291 37.14997
D15 178.31848 59.09021 1.10963

[Lens group data]
Group number Group first surface Group focal length Lens construction length G1 1 262.0300 51.5000
G2 6 -37.1610 31.0000
G3 13 197.9079 9.0000
G4 17 -168.5000 22.0000
G5 21 27.3405 17.0000
Focal length at wide-angle end of front group GF -72.3244
Focal length of rear group GR at wide-angle end 38.0500

[Conditional expression]
Conditional expression (1) fR / (-fFw) = 0.526
Conditional expression (2) (−fB) /ΔZB=0.254
Conditional expression (3) (−fB2) /fB3=0.38
Conditional expression (4) (rB12−rB11) / (rB12 + rB11) = − 0.604
Conditional expression (5) (-fD2) / fD1 = 0.643
Conditional expression (6) | fE / fD | = 0.162
Conditional expression (7) np = 1.788000
Conditional expression (8) νdp = 47.35
Conditional expression (9) φA / fA = 0.489

  From Table 4, it can be seen that the zoom lens ZL4 according to the present example satisfies the conditional expressions (1) to (9).

  FIG. 8 is a diagram showing various aberrations (spherical aberration diagram, astigmatism diagram, distortion aberration diagram, coma aberration diagram, and lateral chromatic aberration diagram) of the zoom lens according to the fourth example, and FIG. 8A shows this example. FIG. 8B is a diagram of various aberrations at an imaging distance of infinity in the intermediate focal length state of the present example, and FIG. FIG. 5 is a diagram illustrating various aberrations at an imaging distance of infinity in the telephoto end state.

  As is apparent from the respective aberration diagrams shown in FIG. 8, the zoom lens ZL4 according to the fourth example has various aberrations well corrected and high optical performance in each focal length state from the wide-angle end state to the telephoto end state. It can be seen that

  According to each embodiment as described above, a zoom lens having a large aperture ratio and high optical performance can be provided.

  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.

  For example, in the above embodiment, the five-group configuration is shown, but the present invention can be applied to other group configurations. 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. In the above embodiment, the camera 1 has been described as an interchangeable lens camera. However, the present invention is not limited to this, and the zoom lens ZL can also be used as a video cam lens.

  In the zoom lens ZL according to 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 so as to perform 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 to perform focusing by moving the fourth lens group G4 and the fifth lens group G5 simultaneously. Any one of the second lens group G2 to the fifth lens group G5 may be used as the focusing lens group. It is also possible to focus by moving the entire zoom lens ZL.

  In the zoom lens ZL according to the present embodiment, any one of the first lens group G1 to the fifth lens group G5, or a part of the lenses in the lens group, has a component in a direction perpendicular to the optical axis. Or an anti-vibration lens group that corrects image blur caused by camera shake by rotating (swinging) in the in-plane direction including the optical axis.

  Each lens surface constituting the zoom lens ZL according to the present embodiment 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 S is preferably disposed between the third lens group G3 of the front group GF and the fourth lens group G4 of the rear group GR. That role may be substituted.

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

  In the zoom lens ZL according to the present embodiment, the F number can be reduced to 1.8-2.8.

  In the zoom lens ZL according to the present embodiment, the aperture stop S is fixed, so that the F number can be kept constant during zooming.

  The zoom lens ZL according to the present embodiment is applicable to a zoom lens having a focal length of about 50 to 350 mm in terms of 35 mm.

ZL (ZL1 to ZL4) Zoom lens GF Front group G1 First lens group G2 Second lens group G3 Third lens group S Aperture stop GR Rear group G4 Fourth lens group G5 Fifth lens group I Image plane 1 Camera (optical equipment) )

Claims (9)

A front group having negative refractive power, arranged in order from the object side, an aperture stop, and a rear group having positive refractive power,
The front group includes a first lens group having a positive refractive power and a second lens group having a negative refractive power, arranged in order from the object side,
During zooming from the wide-angle end state to the telephoto end state, the first lens group is fixed in the optical axis direction with respect to the image plane,
A zoom lens satisfying the following conditional expression:
0.30 <fR / (-fFw) <0.80
However,
fR: focal length of the rear group,
fFw: focal length in the wide-angle end state of the front group. The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
0.20 <(− fB) / ΔZB <0.40
However,
fB: focal length of the second lens group,
ΔZB: a moving distance on the optical axis from the wide-angle end state to the telephoto end state of the second lens group. The second lens group has a first negative lens component, a second negative lens component, and a positive lens component arranged in order from the object side,
The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
0.10 <(-fB2) / fB3 <1.00
However,
fB2: a focal length of the second negative lens component in the second lens group,
fB3: focal length of the positive lens component in the second lens group. The zoom lens according to claim 3, wherein the following conditional expression is satisfied.
−0.90 <(rB12−rB11) / (rB12 + rB11) <− 0.40
However,
rB11: radius of curvature of the object-side lens surface of the first negative lens component in the second lens group;
rB12: radius of curvature of the image-side lens surface of the first negative lens component in the second lens group. The rear group has two lens groups;
Among the lens groups constituting the rear group, the lens group arranged closest to the object side includes at least one positive lens component arranged in order from the object side, and a negative lens arranged closest to the object side in the rear group Consisting of ingredients,
The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
0.40 <(-fD2) / fD1 <0.80
However,
fD1: a focal length of the positive lens component in the lens group disposed closest to the object among the lens groups constituting the rear group,
fD2: a focal length of the negative lens component in the lens group disposed closest to the object among the lens groups constituting the rear group. The zoom lens according to claim 5, wherein the following conditional expression is satisfied.
0.10 <| fE / fD | <0.50
However,
fD: the focal length of the lens group arranged closest to the object side among the lens groups constituting the rear group,
fE: The focal length of the lens unit arranged second from the object side among the lens units constituting the rear group. The rear group has a positive lens component;
The zoom lens according to any one of claims 1 to 6, wherein the following conditional expression is satisfied.
1.70 <np <1.80
45.00 <νdp <60.00
However,
np: refractive index at d-line of the positive lens component in the rear group,
νdp: Abbe number at the d-line of the positive lens component in the rear group.   An optical apparatus comprising the zoom lens according to any one of claims 1 to 7. A method of manufacturing a zoom lens having a front group having negative refractive power, an aperture stop, and a rear group having positive refractive power, arranged in order from the object side,
The front group includes a first lens group having a positive refractive power and a second lens group having a negative refractive power, arranged in order from the object side,
During zooming from the wide-angle end state to the telephoto end state, the first lens group is fixed in the optical axis direction with respect to the image plane,
A method of manufacturing a zoom lens, wherein each lens is arranged in a lens barrel so as to satisfy the following conditional expression:
0.30 <fR / (-fFw) <0.80
However,
fR: focal length of the rear group,
fFw: focal length in the wide-angle end state of the front group.

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