JP2015191057A - Variable power optical system, imaging apparatus, and method for manufacturing the variable power optical system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a variable power optical system having high optical performance, an imaging apparatus, and a method for manufacturing the variable power optical system.SOLUTION: A variable power optical system includes, in order from an object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, and a third lens group G3 having positive refractive power. When varying power from a wide angle end state to a telephoto end state, the variable power optical system moves the first lens group G1 in a direction toward an object in an optical axis direction and satisfies the following conditional expressions (1) and (2): (1) 0.14<fw/f1<0.26 and (2) 0.77<fw/f3<1.05, where fw is the focal length of the entire system in the wide angle end state, f1 is the focal length of the first lens group G1, and f3 is the focal length of the third lens group G3.

Description

  The present invention relates to a variable magnification optical system, an imaging apparatus, and a method for manufacturing the variable magnification optical system.

  Conventionally, a variable magnification optical system suitable for a photographic camera, an electronic still camera, a video camera, and the like has been proposed (see, for example, Patent Document 1).

JP 2012-42557 A

  However, the conventional variable magnification optical system has a problem that aberration variation at the time of zooming is large.

  The present invention has been made in view of such problems, and an object thereof is to provide a variable magnification optical system, an imaging apparatus, and a method for manufacturing the variable magnification optical system having high optical performance.

  In order to achieve such an object, a variable magnification optical system according to the present invention includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, arranged in order from the object side, A third lens group having a positive refractive power, and when zooming from the wide-angle end state to the telephoto end state, the first lens group is moved in the object direction along the optical axis direction. Satisfied.

0.14 <fw / f1 <0.26
0.77 <fw / f3 <1.05
However,
fw: focal length of the entire system in the wide-angle end state,
f1: the focal length of the first lens group,
f3: focal length of the third lens group.

  The zoom optical system according to the present invention includes an air gap between the first lens group and the second lens group, an air gap between the second lens group and the third lens group, and the third lens group. It is preferable to perform zooming by changing the air gap from the fourth lens group.

  In the variable magnification optical system according to the present invention, at least a part of the second lens group or at least a part of the third lens group is used as an anti-vibration lens group for correcting image blur in the direction perpendicular to the optical axis. It is preferable to be configured to be movable so as to have components.

  In the zoom optical system according to the present invention, it is preferable that focusing is performed by moving at least a part of the third lens group along the optical axis direction.

  In the zoom optical system according to the present invention, the third lens group includes a thirty-first lens group, a thirty-second lens group, and a thirty-third lens group, which are arranged in order from the object side. The anti-vibration lens group is preferably configured to be movable so as to have a component perpendicular to the optical axis.

  In the zoom optical system according to the present invention, it is preferable that the thirty-second lens group has a negative refractive power.

  The variable magnification optical system according to the present invention preferably satisfies the following conditional expression.

2.00 <(− f32) / f3 <6.00
However,
f32: focal length of the thirty-second lens group,
f3: focal length of the third lens group.

  The variable magnification optical system according to the present invention preferably satisfies the following conditional expression.

0.50 <| f31 | / f3 <2.00
However,
f31: focal length of the thirty-first lens group,
f3: focal length of the third lens group.

  The variable magnification optical system according to the present invention preferably satisfies the following conditional expression.

1.00 <| f33 | / f3
However,
f33: focal length of the thirty-third lens group,
f3: focal length of the third lens group.

  In the zoom optical system according to the present invention, it is preferable that the thirty-second lens group is composed of a single lens.

  In the variable magnification optical system according to the present invention, the thirty-first lens group includes a front group having a positive refractive power and a rear group arranged in order from the object side, and the front group is arranged along the optical axis direction. It is preferable to perform focusing by moving it.

  The zoom optical system according to the present invention preferably includes a diaphragm, and the diaphragm moves along the optical axis direction together with the third lens group during zooming.

  The zoom optical system according to the present invention preferably includes a stop, and the stop is disposed between the second lens group and the image plane.

  The variable magnification optical system according to the present invention preferably satisfies the following conditional expression.

30.00 ° <ωw <80.00 °
However,
ωw: Half angle of view in the wide-angle end state.

  The variable magnification optical system according to the present invention preferably satisfies the following conditional expression.

2.00 <ft / fw <15.00
However,
ft: The focal length of the entire system in the telephoto end state when focusing on infinity.

  An imaging apparatus according to the present invention includes any one of the above-described variable magnification optical systems.

  The variable magnification optical system manufacturing method according to the present invention includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a positive refractive power, which are arranged in order from the object side. A variable magnification optical system having a third lens group, wherein the first lens group is moved in the object direction along the optical axis direction upon zooming from the wide-angle end state to the telephoto end state. Each lens is arranged in the lens barrel so as to satisfy the conditional expression (1).

0.14 <fw / f1 <0.26
0.77 <fw / f3 <1.05
However,
fw: focal length of the entire system in the wide-angle end state,
f1: the focal length of the first lens group,
f3: focal length of the third lens group.

  According to the present invention, it is possible to provide a variable magnification optical system, an imaging apparatus, and a method for manufacturing the variable magnification optical system having high optical performance.

It is sectional drawing which shows the lens structure of the variable magnification optical system which concerns on 1st Example. FIG. 6 is an aberration diagram in the wide-angle end state (f = 18.500) of the variable magnification optical system according to Example 1, (a) Various aberration diagrams at the time of focusing on infinity, and (b) at the time of focusing at a short distance (imaging magnification) Aberration diagrams (β = −0.0196), (c) shows a coma aberration diagram when image blur correction is performed at the time of focusing on infinity (correction angle θ = 0.30 °). FIG. 4A is an aberration diagram in an intermediate focal length state (f = 35.000) of the variable magnification optical system according to the first example. FIG. 5A is a diagram illustrating various aberrations at the time of focusing on infinity, and FIG. Aberration diagrams with a magnification β = −0.0365), and FIG. 9C shows a coma aberration diagram when image blur correction is performed at the time of focusing on infinity (correction angle θ = 0.30 °). FIG. 4A is an aberration diagram in the telephoto end state (f = 53.500) of the variable magnification optical system according to the first example. FIG. 5A is a diagram illustrating various aberrations at the time of focusing on infinity, and FIG. Aberration diagrams (β = −0.0554), (c) shows a coma aberration diagram when image blur correction is performed at the time of focusing on infinity (correction angle θ = 0.30 °). It is sectional drawing which shows the lens structure of the variable magnification optical system which concerns on 2nd Example. FIG. 6 is an aberration diagram in the wide-angle end state (f = 18.500) of the variable magnification optical system according to Example 2, (a) Various aberration diagrams at the time of focusing on infinity, and (b) at the time of focusing at a short distance (imaging magnification) Aberration diagrams (β = −0.0196), (c) shows a coma aberration diagram when image blur correction is performed at the time of focusing on infinity (correction angle θ = 0.30 °). FIG. 6A is an aberration diagram in the intermediate focal length state (f = 34.176) of the variable magnification optical system according to the second example. FIG. 4A is a diagram illustrating various aberrations at the time of focusing on infinity, and FIG. Aberration diagrams with a magnification β = −0.0358), and FIG. 10C shows a coma aberration diagram when image blur correction is performed at the time of focusing on infinity (correction angle θ = 0.30 °). FIG. 6A is an aberration diagram in the telephoto end state (f = 53.500) of the zoom optical system according to Example 2; FIG. 5A is a diagram illustrating various aberrations at the time of focusing on infinity, and FIG. (c = -0.0556) shows various aberration diagrams, and (c) shows a coma aberration diagram when image blur correction is performed at the time of focusing on infinity (correction angle θ = 0.30 °). It is sectional drawing which shows the lens structure of the variable magnification optical system which concerns on 3rd Example. FIG. 10 is an aberration diagram in the wide-angle end state (f = 18.477) of the variable magnification optical system according to Example 3, (a) Various aberration diagrams at the time of focusing on infinity, and (b) when focusing at a short distance (imaging magnification) Aberration diagrams (β = −0.0194), (c) shows a coma aberration diagram when image blur correction is performed at the time of focusing on infinity (correction angle θ = 0.30 °). FIG. 6A is an aberration diagram in an intermediate focal length state (f = 34.000) of the variable magnification optical system according to the third example. FIG. 5A is a diagram illustrating various aberrations at the time of focusing on infinity, and FIG. Aberration diagrams with a magnification β = −0.0355), and FIG. 8C shows a coma aberration diagram when image blur correction is performed at the time of focusing on infinity (correction angle θ = 0.30 °). FIG. 6A is an aberration diagram in the telephoto end state (f = 53.500) of the zoom optical system according to Example 3; FIG. 5A is a diagram illustrating aberrations at the time of focusing on infinity, and FIG. Aberration diagrams (β = −0.0552), (c) shows a coma aberration diagram when image blur correction is performed at infinity focusing (correction angle θ = 0.30 °). It is sectional drawing which shows the lens structure of the variable magnification optical system which concerns on 4th Example. FIG. 9A is an aberration diagram in the wide-angle end state (f = 18.500) of the zoom optical system according to Example 4; FIG. 9A is a diagram illustrating various aberrations at the time of focusing on infinity, and FIG. Aberration diagrams (β = −0.0194), (c) shows a coma aberration diagram when image blur correction is performed at the time of focusing on infinity (correction angle θ = 0.30 °). FIG. 10A is an aberration diagram in the intermediate focal length state (f = 34.061) of the zoom optical system according to Example 4; FIG. 10A is a diagram illustrating various aberrations at the time of focusing on infinity, and FIG. Aberration diagrams with a magnification β = −0.0355), and FIG. 8C shows a coma aberration diagram when image blur correction is performed at the time of focusing on infinity (correction angle θ = 0.30 °). FIG. 10A is an aberration diagram in the telephoto end state (f = 53.500) of the variable magnification optical system according to Example 4; (a) Various aberration diagrams at the time of focusing on infinity, and (b) (c = -0.0556) shows various aberration diagrams, and (c) shows a coma aberration diagram when image blur correction is performed at the time of focusing on infinity (correction angle θ = 0.30 °). It is a schematic sectional drawing which shows the structure of the camera which concerns on this embodiment. It is a flowchart for demonstrating the manufacturing method of the variable magnification optical system which concerns on this embodiment.

  Hereinafter, the present embodiment will be described with reference to the drawings. As shown in FIG. 1, the variable magnification optical system ZL according to this embodiment 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. And a third lens group G3 having a positive refractive power.

  With this configuration, it is possible to reduce the size of the lens barrel in the wide-angle end state.

  The zoom optical system ZL according to the present embodiment moves the first lens group G1 in the object direction along the optical axis direction when zooming from the wide-angle end state to the telephoto end state.

  With this configuration, a sufficient zoom ratio can be ensured.

    The following conditional expressions (1) and (2) are satisfied under the above configuration.

0.14 <fw / f1 <0.26 (1)
0.77 <fw / f3 <1.05 (2)
However,
fw: focal length of the entire system in the wide-angle end state,
f1: Focal length of the first lens group G1
f3: focal length of the third lens group G3.

  Conditional expression (1) defines the focal length of the entire system in the proper wide-angle end state with respect to the focal length of the first lens group G1. By satisfying conditional expression (1), it is possible to achieve good optical performance and downsizing of the optical system.

  If the lower limit value of conditional expression (1) is not reached, the refractive power of the first lens group G1 becomes weak, and it becomes difficult to reduce the size of the lens barrel. If the refractive power of the second lens group G2 is increased in order to reduce the size, it is not preferable because correction of coma, astigmatism, and field curvature becomes difficult.

  By setting the lower limit value of conditional expression (1) to 0.15, the effect of this embodiment can be ensured.

  Exceeding the upper limit of conditional expression (1) is not preferable because the refractive power of the first lens group G1 becomes strong and it becomes difficult to correct coma, astigmatism, and field curvature in the telephoto end state.

  By setting the upper limit value of conditional expression (1) to 0.25, the effect of this embodiment can be ensured.

  Conditional expression (2) defines the focal length of the entire system in the proper wide-angle end state with respect to the focal length of the third lens group G3. Satisfying conditional expression (2) makes it possible to achieve good optical performance and downsizing of the optical system.

  If the lower limit of conditional expression (2) is not reached, the refractive power of the third lens group G3 becomes weak, and it becomes difficult to reduce the size of the lens barrel. If the refractive power of the first lens group G1 and the second lens group G2 is increased in order to reduce the size, it is not preferable because correction of coma, astigmatism, and field curvature becomes difficult.

  By setting the lower limit value of conditional expression (2) to 0.80, the effect of this embodiment can be ensured.

  Exceeding the upper limit of conditional expression (2) is not preferable because the refractive power of the third lens group G3 increases and it becomes difficult to correct spherical aberration, coma aberration, and astigmatism.

  By setting the upper limit of conditional expression (2) to 1.02, the effect of this embodiment can be ensured.

  The zoom optical system ZL according to the present embodiment includes an air gap between the first lens group G1 and the second lens group G2, an air gap between the second lens group G2 and the third lens group G3, and a third lens group. It is preferable to perform zooming by changing the air gap between G3 and the fourth lens group G4.

  With this configuration, it is possible to ensure a sufficient zoom ratio while suppressing variations in spherical aberration and field curvature during zooming.

  The variable magnification optical system ZL according to the present embodiment includes an anti-vibration lens group for correcting image blur (caused by camera shake) on at least part of the second lens group G2 or at least part of the third lens group G3. As such, it is preferable to be configured to be movable so as to have a component perpendicular to the optical axis.

  With this configuration, it is possible to reduce the size of the image blur correction mechanism including the image stabilizing lens group.

  The zoom optical system ZL according to the present embodiment preferably performs focusing by moving at least a part of the third lens group G3 along the optical axis direction.

  With this configuration, aberration variation (for example, spherical aberration) during focusing can be suppressed.

  In the zoom optical system ZL according to the present embodiment, the third lens group G3 includes a thirty-first lens group G31, a thirty-second lens group G32, and a thirty-third lens group G33, which are arranged in order from the object side. It is preferable that the 32 lens group G32 is configured to be movable so as to have a component in a direction perpendicular to the optical axis as the vibration-proof lens group.

  With this configuration, it is possible to achieve good optical performance during image blur correction (anti-vibration). Further, the image blur correction mechanism can be reduced in size.

  In the zoom optical system ZL according to this embodiment, it is preferable that the thirty-second lens group G32 has a negative refractive power.

  With this configuration, it is possible to achieve good optical performance during image blur correction (anti-vibration).

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

2.00 <(− f32) / f3 <6.00 (3)
However,
f32: focal length of the thirty-second lens group G32.
f3: focal length of the third lens group G3.

  Conditional expression (3) defines an appropriate focal length of the thirty-second lens group G32 with respect to the focal length of the third lens group G3. By satisfying conditional expression (3), it is possible to achieve good optical performance during image blur correction (anti-vibration) and downsizing of the optical system.

  If the lower limit of conditional expression (3) is not reached, the refractive power of the third lens group G3 becomes weak, and it becomes difficult to reduce the size of the lens barrel. If the refractive power of the first lens group G1 and the second lens group G2 is increased in order to reduce the size, it is not preferable because correction of coma, astigmatism, and field curvature becomes difficult.

  By setting the lower limit value of conditional expression (3) to 2.50, the effect of this embodiment can be ensured.

  If the upper limit of conditional expression (3) is exceeded, the refractive power of the third lens group G3 will become strong, and it will be difficult to correct spherical aberration and coma in the telephoto end state. Further, the refractive power of the thirty-second lens group G32 becomes weak, the shift amount during image blur correction (anti-vibration) increases, and it becomes difficult to reduce the size of the lens barrel.

  By setting the upper limit value of conditional expression (3) to 4.00, the effect of the present embodiment can be ensured.

  The variable magnification optical system ZL according to the present embodiment preferably satisfies the following conditional expression (4).

0.50 <| f31 | / f3 <2.00 (4)
However,
f31: focal length of the 31st lens group G31,
f3: focal length of the third lens group G3.

  Conditional expression (4) defines an appropriate focal length of the 31st lens group G31 with respect to the focal length of the third lens group G3. Satisfying conditional expression (4) makes it possible to achieve good optical performance and downsizing of the optical system.

  If the lower limit value of conditional expression (4) is not reached, the refractive power of the third lens group G3 becomes weak, and it becomes difficult to reduce the size of the lens barrel. If the refractive power of the first lens group G1 and the second lens group G2 is increased in order to reduce the size, it is difficult to correct coma, astigmatism, and field curvature.

  By setting the lower limit of conditional expression (4) to 0.70, the effect of the present embodiment can be ensured.

  Exceeding the upper limit of conditional expression (4) is not preferable because the refractive power of the third lens group G3 increases and it becomes difficult to correct spherical aberration and coma in the telephoto end state.

  By setting the upper limit of conditional expression (4) to 1.50, the effect of this embodiment can be ensured.

  The variable magnification optical system ZL according to the present embodiment preferably satisfies the following conditional expression (5).

1.00 <| f33 | / f3 (5)
However,
f33: focal length of the 33rd lens group G33,
f3: focal length of the third lens group G3.

  Conditional expression (5) defines an appropriate focal length of the 33rd lens group G33 with respect to the focal length of the third lens group G3. Satisfying conditional expression (5) makes it possible to achieve good optical performance and downsizing of the optical system.

  If the lower limit of conditional expression (5) is not reached, the refractive power of the third lens group G3 becomes weak, and it becomes difficult to reduce the size of the lens barrel. If the refractive power of the first lens group G1 and the second lens group G2 is increased in order to reduce the size, it is difficult to correct coma, astigmatism, and field curvature.

  By setting the lower limit value of conditional expression (5) to 2.00, the effect of this embodiment can be ensured.

  In the variable magnification optical system ZL according to the present embodiment, the thirty-second lens group G32 is preferably composed of a single lens.

  With this configuration, it is possible to satisfactorily correct decentration coma and image plane fluctuation during image blur correction. In addition, the image blur correction mechanism can be reduced in size.

  In the zoom optical system ZL according to the present embodiment, the thirty-first lens group G31 includes a front group G3F having a positive refractive power and a rear group G3R, which are arranged in order from the object side. It is preferable to perform focusing by moving along the direction.

  With this configuration, aberration variation (for example, spherical aberration) during focusing can be suppressed.

  The zoom optical system ZL according to the present embodiment preferably includes a stop S, and the stop S moves along the optical axis direction integrally with the third lens group G3 during zooming.

  With this configuration, the lens barrel structure can be simplified, and the size of the lens barrel can be reduced.

  The zoom optical system ZL according to the present embodiment preferably includes a stop S, and the stop S is preferably disposed between the second lens group G2 and the image plane I.

  With this configuration, field curvature and astigmatism can be corrected well.

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

30.00 ° <ωw <80.00 ° (6)
However,
ωw: Half angle of view in the wide-angle end state.

  Conditional expression (6) is a condition that defines the value of the angle of view in the wide-angle end state. By satisfying this conditional expression (6), coma aberration, distortion aberration, and field curvature can be favorably corrected while having a wide angle of view.

  By setting the lower limit of conditional expression (6) to 33.00 °, better aberration correction can be achieved. By setting the lower limit value of conditional expression (6) to 36.00 °, it becomes possible to perform better aberration correction.

  By setting the upper limit value of conditional expression (6) to 77.00 °, better aberration correction can be performed.

  The zoom optical system ZL according to the present embodiment preferably satisfies the following conditional expression (7).

2.00 <ft / fw <15.00 (7)
However,
ft: focal length of the entire system in the telephoto end state,
fw: focal length of the entire system in the wide-angle end state.

  Conditional expression (7) is a condition that defines the ratio between the focal length of the entire system in the telephoto end state and the focal length of the entire system in the wide-angle end state. The present variable magnification optical system ZL can obtain a high zoom ratio by satisfying conditional expression (7), and can satisfactorily correct spherical aberration and coma.

  By setting the lower limit of conditional expression (7) to 2.30, better aberration correction becomes possible. By setting the lower limit value of conditional expression (7) to 2.50, better aberration correction can be achieved. By setting the lower limit of conditional expression (7) to 2.70, the effect of the present embodiment can be maximized.

  By setting the upper limit of conditional expression (7) to 10.00, better aberration correction becomes possible. By setting the upper limit value of conditional expression (7) to 7.00, even better aberration correction can be achieved.

  According to the present embodiment as described above, a variable magnification optical system ZL having high optical performance can be realized.

  Next, a camera (imaging device) 1 including the above-described variable magnification optical system ZL will be described with reference to FIG. As shown in FIG. 17, the camera 1 is a lens interchangeable camera (so-called mirrorless camera) provided with the above-described variable magnification optical system ZL as the photographing lens 2.

  In the camera 1, light from an object (subject) (not shown) is collected by the photographing lens 2, and the subject is placed on the imaging surface of the imaging unit 3 via an OLPF (Optical low pass filter) not shown. Form an image. 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.

  The variable magnification optical system ZL according to this embodiment mounted on the camera 1 as the photographing lens 2 has high optical performance due to its characteristic lens configuration, as can be seen from each example described later. Therefore, according to the camera 1, an imaging device having high optical performance can be realized.

  Even when the above-described variable magnification optical system ZL is mounted on a single-lens reflex camera that has a quick return mirror and observes a subject with a finder optical system, the same effect as the camera 1 can be obtained. Further, even when the above-described variable magnification optical system ZL is mounted on a video camera, the same effects as the camera 1 can be obtained.

  Next, an outline of a method for manufacturing the variable magnification optical system ZL having the above configuration will be described with reference to FIG. First, the lens barrel includes a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a third lens group G3 having a positive refractive power. Each lens is arranged (step ST10). At this time, in zooming from the wide-angle end state to the telephoto end state, each lens is arranged in the lens barrel so that the first lens group G1 moves in the object direction along the optical axis direction (step ST20). . Further, each lens is arranged in the lens barrel so as to satisfy the following conditional expressions (1) and (2) (step ST30).

0.14 <fw / f1 <0.26 (1)
0.77 <fw / f3 <1.05 (2)
However,
fw: focal length of the entire system in the wide-angle end state,
f1: Focal length of the first lens group G1
f3: focal length of the third lens group G3.

  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 on the object side and a convex surface on the object side are directed. A cemented lens with the positive meniscus lens L12 is disposed. As the second lens group G2, in order from the object side, a negative meniscus lens L21 having a convex surface facing the object side, a biconcave lens L22, a biconvex lens L23, and a negative meniscus lens L24 having a concave surface facing the object side are arranged. . As the third lens group G3, in order from the object side, a positive meniscus lens L31 having a concave surface directed toward the object side, a cemented lens of a biconvex lens L32 and a biconcave lens L33, a biconcave lens L34, a biconvex lens L35, and a biconvex lens L36 and a negative meniscus lens L37 having a concave surface facing the object side are arranged. Further, the lenses are arranged so as to satisfy the conditional expressions (1) and (2) (the corresponding value of the conditional expression (1) is 0.22 and the corresponding value of the conditional expression (2) is 0.90).

  According to the method for manufacturing a variable magnification optical system according to the present embodiment as described above, a variable magnification optical system ZL having high optical performance can be obtained.

  Hereinafter, 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.

  1, FIG. 5, FIG. 9 and FIG. 13 are cross-sectional views showing a configuration of a variable magnification optical system ZL (ZL1 to ZL4) according to each example. In the cross-sectional views of the zoom optical systems ZL1 to ZL4, the movement trajectory along the optical axis of each lens unit when zooming from the wide-angle end state (W) to the telephoto end state (T) is indicated by an arrow.

  Each reference code for 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 data] in the table, the surface number is the order of the optical surfaces from the object side along the traveling direction of the light beam, r is the radius of curvature of each optical surface, D is the next optical surface from each optical surface (or The distance between the surfaces on the optical axis to the image plane), νd is the Abbe number based on the d-line of the material of the optical member, and nd is the refractive index of the material of the optical member with respect to the d-line. (Variable) indicates a variable surface interval, “∞” of the radius of curvature indicates a plane or an aperture, and (aperture S) indicates an aperture aperture S. The refractive index of air (d-line) “1.000000” is omitted. When the optical surface is an aspherical surface, “*” is attached to the left side of the surface number, and the paraxial radius of curvature is shown in the column of the radius of curvature r.

In [Aspherical data] in the table, the shape of the aspherical surface shown in [Lens data] is shown by the following equation (a). Here, y is the height in the direction perpendicular to the optical axis, X (y) is the amount of displacement (sag amount) in the optical axis direction at height y, r is the radius of curvature of the reference sphere (paraxial radius of curvature), κ Denotes a conic constant, and An denotes an nth-order aspheric coefficient. “E-n” indicates “× 10 ⁻ⁿ ”, for example “1.234E-05” indicates “1.234 × 10 ⁻⁵ ”.

X (y) = (y ² / r) / [1+ {1−κ (y ² / r ² )} ^1/2 ] + A 4 × y ⁴ + A 6 × y ⁶ + A 8 × y ⁸ + A 10 × y ¹⁰ (a)

  In [Various data] in the table, f is the focal length of the entire lens system, Fno is the F number, ω is the half angle of view (unit: °), Y is the image height, TL is the total length of the lens system (on the optical axis) Bf represents the back focus (distance from the last lens surface to the image plane I on the optical axis).

  In the [variable interval data] in the table, the focal length f of the entire system in the wide-angle end state, the intermediate focal length state, and the telephoto end state at the time of focusing on an object at infinity and a short distance object (shooting distance R = 1.0 m) Or the imaging magnification β and the value of each variable interval are shown. D0 is the distance from the object surface to the first surface, and Di (where i is an integer) indicates the variable interval between the i-th surface and the (i + 1) -th surface.

  In [Lens Group Data] in the table, the starting surface number (most surface number on the object side) of each group is shown on the first group surface, and the focal length of each group is shown on the group focal length.

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

  Hereinafter, in all the specification values, “mm” is generally used for the focal length f, the radius of curvature r, the surface interval D, and other lengths, etc. unless otherwise specified, but the optical system is proportionally enlarged. Alternatively, the same optical performance can be obtained even by proportional reduction, and the present invention is not limited to this. 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. As shown in FIG. 1, the variable magnification optical system ZL (ZL1) according to the first example includes a first lens group G1 having a positive refractive power arranged in order from the object side along the optical axis, and a negative lens group G1. It is composed of a second lens group G2 having a refractive power and a third lens group G3 having a positive refractive power.

  The first lens group G1 includes a cemented lens of a negative meniscus lens L11 having a convex surface facing the object side and a positive meniscus lens L12 having a convex surface facing the object side, which are arranged in order from the object side.

  The second lens group G2 is composed of a negative meniscus lens L21 having a convex surface directed toward the object side, a biconcave lens L22, a biconvex lens L23, and a negative meniscus lens L24 having a concave surface directed toward the object side. Composed.

  The third lens group G3 includes a thirty-first lens group G31, a thirty-second lens group G32, and a thirty-third lens group G33 arranged in order from the object side.

  The thirty-first lens group G31 includes a front group G3F having a positive refractive power and a rear group G3R arranged in order from the object side. The front group G3F (focusing group) includes a positive meniscus lens L31 having a concave surface directed toward the object side. The rear group G3R is composed of cemented lenses of a biconvex lens L32 and a biconcave lens L33 arranged in order from the object side.

  The thirty-second lens group G32 (anti-vibration lens group) includes a biconcave lens L34. The thirty-third lens group G33 includes a biconvex lens L35, a biconvex lens L36, and a negative meniscus lens L37 having a concave surface directed toward the object side, which are arranged in order from the object side.

  An aperture stop S that determines the F number is provided in the third lens group G3.

  The image plane I is formed on an image sensor (not shown), and the image sensor is composed of a CCD, a CMOS, or the like.

  The variable magnification optical system ZL1 according to the first example changes the air gap between the first lens group G1 and the second lens group G2 and the air gap between the second lens group G2 and the third lens group G3. Thus, zooming from the wide-angle end state to the telephoto end state is performed. At this time, the first lens group G1 moves monotonously with respect to the image plane I toward the object side. The second lens group G2 moves along the optical axis so as to draw a convex locus on the image side. The third lens group G3 moves monotonously to the object side. The aperture stop S moves monotonously to the object side together with the third lens group G3 during zooming.

  Specifically, in the variable magnification optical system ZL1 according to the first example, the air gap between the first lens group G1 and the second lens group G2 is enlarged, and the air between the second lens group G2 and the third lens group G3 is expanded. Zooming from the wide-angle end state to the telephoto end state is performed by moving the lens groups G1 to G3 along the optical axis so that the interval is reduced.

  The variable magnification optical system ZL1 according to the first example performs focusing by moving the front lens group G3F of the third lens group G3, that is, the positive meniscus lens L31 having a concave surface toward the object side, along the optical axis direction. The positive meniscus lens L31 moves from the object side to the image side when it is changed from a state focused on an object at infinity to a state focused on a short distance object, as indicated by an arrow in FIG. .

  When an image blur occurs, the image blur correction (anti-vibration) on the image plane I is performed by moving the thirty-second lens group G32, that is, the biconcave lens L34, to have a component perpendicular to the optical axis. I do.

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

(Table 1)
[Lens data]
Surface number r D νd nd
1 41.994 1.800 23.80 1.846660
2 31.917 6.967 67.90 1.593190
3 1604.312 D3 (variable)
4 79.168 1.500 32.35 1.850 260
5 11.927 5.219
6 -52.994 1.000 42.73 1.834810
7 32.701 0.418
8 22.013 4.124 23.80 1.846660
9 -31.216 0.747
10 -21.084 1.000 42.73 1.834810
11 -79.290 D11 (variable)
12 -459.370 1.607 49.62 1.772500
13 -32.039 D13 (variable)
14 ∞ 2.000 (Aperture S)
15 11.886 6.181 82.57 1.497820
16 -23.884 0.800 23.80 1.846660
17 297.976 2.028
18 -1480.750 0.800 49.62 1.772500
19 47.464 1.000
20 76.691 6.975 38.03 1.603420
21 -38.339 0.200
22 83.747 2.496 50.27 1.719990
23 -62.763 2.711
24 -9.776 1.000 42.73 1.834810
25 -16.921 Bf

[Various data]
f 18.500 35.000 53.500
Fno 3.747 4.644 5.669
ω 39.556 21.350 14.391
Y 14.250 14.250 14.250
TL 88.166 99.495 109.353
Bf 17.445 26.392 35.677

[Variable interval data]
(Infinity) (shooting distance 1m)
Wide-angle end Medium telephoto end Wide-angle end Medium telephoto end
f, β 18.500 35.000 53.500 -0.0196 -0.0365 -0.0554
D0 0.000 0.000 0.000 911.8 900.5 890.6
D1 1.086 12.752 18.159 1.086 12.752 18.159
D11 15.129 5.845 1.011 15.637 6.644 2.065
D13 3.924 3.924 3.924 3.416 3.125 2.871

[Lens group data]
Group number Group first surface Group focal length G1 1 83.101
G2 4 -15.594
G3 12 20.444

[Conditional expression values]
Conditional expression (1): fw / f1 = 0.22
Conditional expression (2): fw / f3 = 0.90
Conditional expression (3): (−f32) /f3=2.91
Conditional expression (4): | f31 | /f3=1.02
Conditional expression (5): | f33 | /f3=3.59
Conditional expression (6): ωw = 39.556
Conditional expression (7): ft / fw = 2.89

  From Table 1, it can be seen that the variable magnification optical system ZL1 according to the first example satisfies the conditional expressions (1) to (7).

  2A and 2B are aberration diagrams in the wide-angle end state (f = 18.500) of the variable magnification optical system ZL1 according to the first example. FIG. 2A is a diagram illustrating various aberrations at the time of focusing on infinity, and FIG. Aberration diagrams at the time of focusing (shooting magnification β = −0.0196), (c) shows a coma aberration diagram when image blur correction is performed at the time of focusing on infinity (correction angle θ = 0.30 °). FIG. 3 is an aberration diagram in the intermediate focal length state (f = 35.000) of the variable magnification optical system ZL1 according to the first example, (a) various aberration diagrams at the time of focusing on infinity, and (b) is a short distance diagram. Various aberration diagrams at the time of focusing (shooting magnification β = −0.0365), (c) shows a coma aberration diagram when image blur correction is performed at the time of focusing on infinity (correction angle θ = 0.30 °). 4A and 4B are aberration diagrams in the telephoto end state (f = 53.500) of the variable magnification optical system ZL1 according to the first example. FIG. 4A is an aberration diagram at the time of focusing on infinity, and FIG. Various aberration diagrams at the time of focusing (photographing magnification β = −0.0554), and FIG. 9C shows a coma aberration diagram when image blur correction is performed at the time of focusing on infinity (correction angle θ = 0.30 °). In this embodiment, the optical performance at the time of image stabilization is as follows. As shown in FIG. 2C, FIG. A coma aberration diagram corresponding to is shown.

  In each aberration diagram, FNO is the F number, NA is the numerical aperture of the light beam incident on the first lens group G1, A is the light beam incident angle, that is, the half field angle (unit: °), H0 is the object height (unit: mm), Y is the image height, d is the aberration at the d-line, and g is the aberration at the g-line. Those without d and g indicate aberration 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 explanation of the above aberration diagrams is the same in the other examples, and the explanation is omitted.

  2 to 4, it can be seen that the variable magnification optical system ZL1 according to the first example has excellent imaging performance with various aberrations corrected well from the wide-angle end state to the telephoto end state. . It can also be seen that the image forming performance is high even when image blur correction is performed.

(Second embodiment)
A second embodiment will be described with reference to FIGS. As shown in FIG. 5, the variable magnification optical system ZL (ZL2) according to the second example includes a first lens group G1 having a positive refractive power and arranged in order from the object side along the optical axis. It is composed of a second lens group G2 having a refractive power and a third lens group G3 having a positive refractive power.

  The first lens group G1 includes a cemented lens of a negative meniscus lens L11 having a convex surface facing the object side and a positive meniscus lens L12 having a convex surface facing the object side, which are arranged in order from the object side.

  The second lens group G2 is composed of a negative meniscus lens L21 having a convex surface directed toward the object side, a biconcave lens L22, a biconvex lens L23, and a negative meniscus lens L24 having a concave surface directed toward the object side. Composed.

  The third lens group G3 includes a thirty-first lens group G31, a thirty-second lens group G32, and a thirty-third lens group G33 arranged in order from the object side.

  The thirty-first lens group G31 includes a front group G3F having a positive refractive power and a rear group G3R arranged in order from the object side. The front group G3F (focusing group) includes a positive meniscus lens L31 having a concave surface directed toward the object side. The rear group G3R is composed of a cemented lens of a biconvex lens L32 and a negative meniscus lens L33 having a concave surface facing the object side, which are arranged in order from the object side.

  The thirty-second lens group G32 (anti-vibration lens group) includes a negative meniscus lens L34 having a convex surface directed toward the object side. The thirty-third lens group G33 includes a biconvex lens L35 arranged in order from the object side, and a negative meniscus lens L36 having a concave surface directed toward the object side.

  An aperture stop S that determines the F number is provided in the third lens group G3.

  The image plane I is formed on an image sensor (not shown), and the image sensor is composed of a CCD, a CMOS, or the like.

  The variable magnification optical system ZL2 according to the second example changes the air gap between the first lens group G1 and the second lens group G2 and the air gap between the second lens group G2 and the third lens group G3. Thus, zooming from the wide-angle end state to the telephoto end state is performed. At this time, the first lens group G1 moves monotonously with respect to the image plane I toward the object side. The second lens group G2 moves monotonously to the object side. The third lens group G3 moves monotonously to the object side. The aperture stop S moves monotonously to the object side together with the third lens group G3 during zooming.

  Specifically, in the variable magnification optical system ZL2 according to the second example, the air gap between the first lens group G1 and the second lens group G2 is enlarged, and the air between the second lens group G2 and the third lens group G3 is expanded. Zooming from the wide-angle end state to the telephoto end state is performed by moving the lens groups G1 to G3 along the optical axis so that the interval is reduced.

  The zoom optical system ZL2 according to the second example performs focusing by moving the front lens group G3F of the third lens group G3, that is, the positive meniscus lens L31 having a concave surface toward the object side, along the optical axis direction. The positive meniscus lens L31 moves from the object side to the image side when it is changed from a state focused on an object at infinity to a state focused on a short distance object, as indicated by an arrow in FIG. .

  When image blurring occurs, the thirty-second lens group G32, that is, the negative meniscus lens L34 having a convex surface directed toward the object side is moved so as to have a component in the direction perpendicular to the optical axis. Image blur correction (anti-vibration).

  Table 2 below shows the values of each item in the second embodiment. Surface numbers 1 to 23 in Table 2 correspond to the optical surfaces m1 to m23 shown in FIG.

(Table 2)
[Lens data]
Surface number r D νd nd
1 45.608 1.800 23.80 1.846660
2 33.721 6.519 67.90 1.593190
3 45648.551 D3 (variable)
4 45.310 1.500 32.35 1.850 260
5 11.154 5.514
6 -66.392 1.000 42.73 1.834810
7 28.177 0.200
8 19.025 4.190 23.80 1.846660
9 -36.189 0.897
10 -20.633 1.000 42.73 1.834810
11 -125.484 D11 (variable)
12 -244.725 1.512 42.73 1.834810
13 -35.967 D13 (variable)
14 ∞ 2.000 (Aperture S)
15 11.692 7.246 82.57 1.497820
16 -15.635 0.800 23.80 1.846660
17 -55.007 2.028
18 119.072 0.800 55.52 1.696800
19 30.792 1.886
20 46.232 7.366 34.92 1.801000
21 -29.295 2.129
22 -9.299 1.000 35.72 1.902650
23 -17.109 Bf

[Various data]
f 18.500 34.176 53.500
Fno 3.606 4.649 5.743
ω 38.474 21.695 14.318
Y 14.250 14.250 14.250
TL 84.418 96.972 109.393
Bf 17.330 26.452 35.995

[Variable interval data]
(Infinity) (shooting distance 1m)
Wide-angle end Medium telephoto end Wide-angle end Medium telephoto end
f, β 18.500 34.176 53.500 -0.0196 -0.0358 -0.0556
D0 0.000 0.000 0.000 915.6 903.0 890.6
D3 1.003 12.242 19.287 1.003 12.242 19.287
D11 12.973 5.166 1.000 13.423 5.869 1.977
D13 3.717 3.717 3.717 3.266 3.013 2.739

[Lens group data]
Group number Group first surface Group focal length G1 1 89.519
G2 4 -14.853
G3 12 18.756

[Conditional expression values]
Conditional expression (1): fw / f1 = 0.21
Conditional expression (2): fw / f3 = 0.99
Conditional expression (3): (−f32) /f3=3.19
Conditional expression (4): | f31 | /f3=1.00
Conditional expression (5): | f33 | /f3=0.80
Conditional expression (6): ωw = 38.474
Conditional expression (7): ft / fw = 2.89

  From Table 2, it can be seen that the zoom optical system ZL2 according to the second example satisfies the conditional expressions (1) to (7).

  6A and 6B are aberration diagrams in the wide-angle end state (f = 18.500) of the variable magnification optical system ZL2 according to the second example. FIG. 6A is a diagram illustrating various aberrations at the time of focusing on infinity, and FIG. Aberration diagrams at the time of focusing (shooting magnification β = −0.0196), (c) shows a coma aberration diagram when image blur correction is performed at the time of focusing on infinity (correction angle θ = 0.30 °). FIG. 7 is an aberration diagram in the intermediate focal length state (f = 34.176) of the variable magnification optical system ZL2 according to the second example, (a) various aberration diagrams at the time of focusing on infinity, and (b) is a short distance diagram. Various aberration diagrams at the time of focusing (photographing magnification β = −0.0358), and FIG. 9C are coma aberration diagrams when image blur correction is performed at the time of focusing on infinity (correction angle θ = 0.30 °). FIG. 8 is an aberration diagram in the telephoto end state (f = 53.500) of the variable magnification optical system ZL2 according to the second example. (A) Various aberration diagrams at the time of focusing on infinity, (b) Aberration diagrams at the time of focusing (shooting magnification β = −0.0556), (c) shows a coma aberration diagram when image blur correction is performed at the time of focusing on infinity (correction angle θ = 0.30 °). In this embodiment, the optical performance at the time of image stabilization is shown in FIG. 6C, FIG. 7C, and FIG. A coma aberration diagram corresponding to is shown.

  6 to 8 show that the variable magnification optical system ZL2 according to the second example has excellent imaging performance with various aberrations corrected well from the wide-angle end state to the telephoto end state. . It can also be seen that the image forming performance is high even when image blur correction is performed.

(Third embodiment)
A third embodiment will be described with reference to FIGS. 9 to 12 and Table 3. FIG. As shown in FIG. 9, the variable magnification optical system ZL (ZL3) according to the third example includes a first lens group G1 having positive refractive power arranged in order from the object side along the optical axis, and a negative lens group G1. It is composed of a second lens group G2 having a refractive power and a third lens group G3 having a positive refractive power.

  The first lens group G1 is composed of a cemented lens composed of a negative meniscus lens L11 and a biconvex lens L12 arranged in order from the object side and having a convex surface directed toward the object side.

  The second lens group G2 is composed of a negative meniscus lens L21 having a convex surface facing the object side, a biconcave lens L22, and a positive meniscus lens L23 having a convex surface facing the object side, which are arranged in order from the object side. The object side surface of the negative meniscus lens L21 is aspheric.

  The third lens group G3 includes a thirty-first lens group G31, a thirty-second lens group G32, and a thirty-third lens group G33 arranged in order from the object side.

  The thirty-first lens group G31 includes a front group G3F having a positive refractive power and a rear group G3R arranged in order from the object side. The front group G3F (focusing group) includes a biconvex lens L31. The rear group G3R is composed of a cemented lens of a biconvex lens L32 and a negative meniscus lens L33 having a concave surface facing the object side, which are arranged in order from the object side.

  The thirty-second lens group G32 (anti-vibration lens group) includes a negative meniscus lens L34 having a convex surface directed toward the object side. The thirty-third lens group G33 includes a biconvex lens L35 arranged in order from the object side, and a negative meniscus lens L36 having a concave surface directed toward the object side. The object side surface of the negative meniscus lens L34 is aspheric. The object side surface of the negative meniscus lens L36 is aspheric.

  An aperture stop S that determines the F number is provided in the third lens group G3.

  The image plane I is formed on an image sensor (not shown), and the image sensor is composed of a CCD, a CMOS, or the like.

  The variable magnification optical system ZL3 according to the third example changes the air gap between the first lens group G1 and the second lens group G2 and the air gap between the second lens group G2 and the third lens group G3. Thus, zooming from the wide-angle end state to the telephoto end state is performed. At this time, the first lens group G1 moves monotonously with respect to the image plane I toward the object side. The second lens group G2 moves monotonously to the object side. The third lens group G3 moves monotonously to the object side. The aperture stop S moves monotonously to the object side together with the third lens group G3 during zooming.

  Specifically, in the variable magnification optical system ZL3 according to the third example, the air distance between the first lens group G1 and the second lens group G2 is increased, and the air between the second lens group G2 and the third lens group G3 is expanded. Zooming from the wide-angle end state to the telephoto end state is performed by moving the lens groups G1 to G3 along the optical axis so that the interval is reduced.

  The variable magnification optical system ZL3 according to the third example is configured to perform focusing by moving the front group G3F of the third lens group G3, that is, the biconvex lens L31, along the optical axis direction. As shown in FIG. 5, when the state of focusing on an object at infinity is changed to the state of focusing on an object at a short distance, the biconvex lens L31 moves from the object side to the image side.

  When image blurring occurs, the thirty-second lens group G32, that is, the negative meniscus lens L34 having a convex surface directed toward the object side is moved so as to have a component in the direction perpendicular to the optical axis. Image blur correction (anti-vibration).

  Table 3 below shows values of various specifications in the third example. Surface numbers 1 to 22 in Table 3 correspond to the optical surfaces m1 to m22 shown in FIG.

(Table 3)
[Lens data]
Surface number r D νd nd
1 54.753 1.500 23.80 1.846660
2 38.695 5.554 67.90 1.593190
3 -34295.201 D3 (variable)
* 4 78.694 0.160 38.09 1.553890
5 98.152 1.200 42.73 1.834810
6 10.847 3.606
7 -970.417 1.000 42.73 1.834810
8 23.052 1.059
9 17.651 2.718 25.45 1.805180
10 124.240 D10 (variable)
11 756.198 1.530 44.80 1.744000
12 -42.339 D12 (variable)
13 ∞ 2.000 (Aperture S)
14 10.744 4.744 82.57 1.497820
15 -14.187 0.800 32.35 1.850 260
16 -36.052 2.298
* 17 61.167 0.800 49.26 1.743200
18 25.724 3.680
19 40.116 2.998 36.40 1.620040
20 -27.927 2.317
* 21 -8.706 1.000 31.27 1.903660
22 -17.386 Bf

[Aspherical data]
4th surface κ = 1.0000
A4 = -8.92993E-06
A6 = -3.84277E-08
A8 = 5.03368E-10
A10 = -1.64069E-12

17th surface κ = 1.0000
A4 = 4.87068E-06
A6 = -6.89267E-08
A8 = 0.00000E + 00
A10 = 0.00000E + 00

21st surface κ = 1.0000
A4 = -3.24561E-05
A6 = -9.10280E-07
A8 = 2.25192E-08
A10 = -6.24358E-10

[Various data]
f 18.477 34.000 53.500
Fno 3.630 4.663 5.630
ω 39.444 21.946 14.295
Y 14.250 14.250 14.250
TL 74.395 88.467 104.339
Bf 17.318 26.476 34.918

[Variable interval data]
(Infinity) (shooting distance 1m)
Wide-angle end Medium telephoto end Wide-angle end Medium telephoto end
f, β 18.477 34.000 53.500 -0.0194 -0.0355 -0.0552
D0 0.000 0.000 0.000 925.6 911.5 895.7
D3 1.000 14.075 25.532 1.000 14.075 25.532
D10 13.187 5.026 1.000 13.679 5.760 2.066
D12 3.919 3.919 3.919 3.428 3.185 2.852

[Lens group data]
Group number Group first surface Group focal length G1 1 110.968
G2 4 -16.768
G3 11 18.415

[Conditional expression values]
Conditional expression (1): fw / f1 = 0.17
Conditional expression (2): fw / f3 = 1.00
Conditional expression (3): (−f32) /f3=3.28
Conditional expression (4): | f31 | /f3=0.93
Conditional expression (5): | f33 | /f3=7.37
Conditional expression (6): ωw = 39.444
Conditional expression (7): ft / fw = 2.90

  From Table 3, it can be seen that the variable magnification optical system ZL3 according to the third example satisfies the conditional expressions (1) to (7).

  FIG. 10 is an aberration diagram in the wide-angle end state (f = 18.477) of the variable magnification optical system ZL3 according to Example 3, (a) Various aberration diagrams at the time of focusing on infinity, and (b) Aberration diagrams at the time of focusing (shooting magnification β = −0.0194), (c) shows a coma aberration diagram when image blur correction is performed at the time of focusing on infinity (correction angle θ = 0.30 °). FIG. 11 is an aberration diagram in the intermediate focal length state (f = 34.000) of the variable magnification optical system ZL3 according to the third example, (a) various aberration diagrams at the time of focusing on infinity, and (b) is a short distance diagram. Various aberration diagrams at the time of focusing (photographing magnification β = −0.0355), and FIG. 10C shows a coma aberration diagram when image blur correction is performed at the time of focusing on infinity (correction angle θ = 0.30 °). FIG. 12 is an aberration diagram in the telephoto end state (f = 53.500) of the variable magnification optical system ZL3 according to Example 3, (a) Various aberration diagrams at the time of focusing on infinity, and (b) FIG. 6C shows various aberrations during focusing (shooting magnification β = −0.0552), and FIG. 8C shows a coma aberration diagram when image blur correction is performed at infinity focusing (correction angle θ = 0.30 °). In this embodiment, the optical performance at the time of image stabilization is shown in FIG. 10 (c), FIG. 11 (c), and FIG. 12 (c). A coma aberration diagram corresponding to is shown.

  10 to 12, it is understood that the variable magnification optical system ZL3 according to the third example has excellent imaging performance with various aberrations corrected well from the wide-angle end state to the telephoto end state. . It can also be seen that the image forming performance is high even when image blur correction is performed.

(Fourth embodiment)
A fourth embodiment will be described with reference to FIGS. 13 to 16 and Table 4. FIG. As shown in FIG. 13, the variable magnification optical system ZL (ZL4) according to the fourth example includes a first lens group G1 having positive refractive power arranged in order from the object side along the optical axis, and a negative lens group G1. The lens unit includes a second lens group G2 having a refractive power, a third lens group G3 having a positive refractive power, and a fourth lens group G4 having a positive refractive power.

  The first lens group G1 is composed of a cemented lens composed of a negative meniscus lens L11 and a biconvex lens L12 arranged in order from the object side and having a convex surface directed toward the object side.

  The second lens group G2 is composed of a negative meniscus lens L21 having a convex surface facing the object side, a biconcave lens L22, and a positive meniscus lens L23 having a convex surface facing the object side, which are arranged in order from the object side. The object side surface of the negative meniscus lens L21 is aspheric.

  The third lens group G3 includes a thirty-first lens group G31, a thirty-second lens group G32, and a thirty-third lens group G33 arranged in order from the object side.

  The thirty-first lens group G31 includes a front group G3F having a positive refractive power and a rear group G3R arranged in order from the object side. The front group G3F (focusing group) includes a biconvex lens L31. The rear group G3R is composed of cemented lenses of a biconvex lens L32 and a biconcave lens L33 arranged in order from the object side.

  The thirty-second lens group G32 (anti-vibration lens group) includes a negative meniscus lens L34 having a convex surface directed toward the object side. The thirty-third lens group G33 is composed of a biconvex lens L35 and a biconcave lens L36 arranged in order from the object side. The object side surface of the negative meniscus lens L36 is aspheric.

  The fourth lens group G4 includes a biconvex lens L41.

  An aperture stop S that determines the F number is provided in the third lens group G3.

  The image plane I is formed on an image sensor (not shown), and the image sensor is composed of a CCD, a CMOS, or the like.

  The variable magnification optical system ZL4 according to the fourth example includes an air gap between the first lens group G1 and the second lens group G2, an air gap between the second lens group G2 and the third lens group G3, and a third lens. By changing the air gap between the group G3 and the fourth lens group G4, zooming from the wide-angle end state to the telephoto end state is performed. At this time, the first lens group G1 moves monotonously with respect to the image plane I toward the object side. The second lens group G2 moves monotonously to the object side. The third lens group G3 moves monotonously to the object side. The fourth lens group G4 monotonously moves toward the object side. The aperture stop S moves monotonously to the object side together with the third lens group G3 during zooming.

  More specifically, in the variable magnification optical system ZL4 according to the fourth example, the air gap between the first lens group G1 and the second lens group G2 is enlarged, and the air between the second lens group G2 and the third lens group G3 is expanded. By moving the lens groups G1 to G4 along the optical axis so that the distance between the third lens group G3 and the fourth lens group G4 increases, the distance between the third lens group G3 and the fourth lens group G4 increases. Perform zooming up to.

  The variable magnification optical system ZL4 according to the fourth example is configured to perform focusing by moving the front group G3F of the third lens group G3, that is, the biconvex lens L31, along the optical axis direction. As shown in FIG. 5, when the state of focusing on an object at infinity is changed to the state of focusing on an object at a short distance, the biconvex lens L31 moves from the object side to the image side.

  When image blurring occurs, the thirty-second lens group G32, that is, the negative meniscus lens L34 having a convex surface directed toward the object side is moved so as to have a component in the direction perpendicular to the optical axis. Image blur correction (anti-vibration).

  Table 4 below shows values of various specifications in the fourth embodiment. Surface numbers 1 to 23 in Table 4 correspond to the optical surfaces m1 to m23 shown in FIG.

(Table 4)
[Lens data]
Surface number r D νd nd
1 67.912 1.500 42.73 1.834810
2 44.077 4.405 67.90 1.593190
3 -288.500 D3 (variable)
* 4 33.454 1.200 42.73 1.834810
5 10.199 4.749
6 -36.627 1.000 50.27 1.719990
7 36.778 0.404
8 19.164 2.419 23.80 1.846660
9 95.617 D9 (variable)
10 89.310 1.766 65.44 1.603000
11 -30.641 D11 (variable)
12 ∞ 2.000 (Aperture S)
13 9.587 3.001 58.54 1.612720
14 -1767.044 1.000 23.80 1.846660
15 20.932 2.301
16 151.332 1.699 82.57 1.497820
17 24.318 1.805
18 16.814 3.077 69.89 1.518600
19 -24.653 1.282
* 20 -12.479 1.000 35.72 1.902650
21 194.680 D21 (variable)
22 41.253 2.502 23.80 1.846660
23 -90.972 Bf

[Aspherical data]
4th surface κ = 1.0000
A4 = -1.31511E-05
A6 = -1.12654E-07
A8 = 7.35232E-10
A10 = -2.69203E-12

20th surface κ = 1.0000
A4 = -1.69994E-04
A6 = -2.07858E-06
A8 = 6.76235E-09
A10 = -8.84176E-10

[Various data]
f 18.500 34.061 53.500
Fno 3.568 4.700 5.851
ω 39.495 21.888 14.364
Y 14.250 14.250 14.250
TL 74.382 87.897 104.318
Bf 17.380 27.437 37.937

[Variable interval data]
(Infinity) (shooting distance 1m)
Wide-angle end Medium telephoto end Wide-angle end Medium telephoto end
f, β 18.500 34.061 53.500 -0.0194 -0.0355 -0.0556
D0 0.000 0.000 0.000 925.6 912.1 895.7
D3 1.000 12.968 22.438 1.000 12.968 22.438
D9 14.194 5.413 1.000 14.671 6.042 1.837
D11 3.342 3.342 3.342 2.865 2.712 2.504
D21 1.346 1.617 2.481 1.346 1.617 2.481

[Lens group data]
Group number Group first surface Group focal length G1 1 112.838
G2 4 -17.024
G3 10 20.227
G4 22 33.817

[Conditional expression values]
Conditional expression (1): fw / f1 = 0.16
Conditional expression (2): fw / f3 = 0.91
Conditional expression (3): (−f32) /f3=2.89
Conditional expression (4): | f31 | /f3=0.92
Conditional expression (5): | f33 | /f3=2.97
Conditional expression (6): ωw = 39.495
Conditional expression (7): ft / fw = 2.89

  From Table 4, it can be seen that the variable magnification optical system ZL4 according to the fourth example satisfies the conditional expressions (1) to (7).

  14A and 14B are aberration diagrams in the wide-angle end state (f = 18.500) of the variable magnification optical system ZL4 according to the fourth example. FIG. 14A is a diagram illustrating various aberrations at the time of focusing on infinity, and FIG. Aberration diagrams at the time of focusing (shooting magnification β = −0.0194), (c) shows a coma aberration diagram when image blur correction is performed at the time of focusing on infinity (correction angle θ = 0.30 °). FIG. 15 is an aberration diagram in the intermediate focal length state (f = 34.061) of the variable magnification optical system ZL4 according to the fourth example. (A) Various aberration diagrams at the time of focusing on infinity, (b) is a short distance diagram. Various aberration diagrams at the time of focusing (photographing magnification β = −0.0355), and FIG. 10C shows a coma aberration diagram when image blur correction is performed at the time of focusing on infinity (correction angle θ = 0.30 °). FIG. 16 is an aberration diagram in the telephoto end state (f = 53.500) of the variable magnification optical system ZL4 according to Example 4, (a) Various aberration diagrams at the time of focusing on infinity, and (b) Aberration diagrams at the time of focusing (shooting magnification β = −0.0556), (c) shows a coma aberration diagram when image blur correction is performed at the time of focusing on infinity (correction angle θ = 0.30 °). In this embodiment, the optical performance at the time of image stabilization is shown in FIG. 14C, FIG. 15C, and FIG. A coma aberration diagram corresponding to is shown.

  From FIG. 14 to FIG. 16, it can be seen that the variable magnification optical system ZL4 according to the fourth example has a high imaging performance with various aberrations corrected well from the wide-angle end state to the telephoto end state. . It can also be seen that the image forming performance is high even when image blur correction is performed.

  According to each of the above embodiments, a variable magnification optical system having high optical performance can be realized.

  Each of the above examples shows a specific example of the variable magnification optical system according to the present embodiment, and the variable magnification optical system according to the present embodiment is not limited to these. In the present embodiment, the following contents can be appropriately adopted as long as the optical performance is not impaired.

  In the numerical examples of the present embodiment, the three-group and four-group configurations are shown, but the present invention can also be applied to other group configurations such as five groups. For example, a configuration in which a lens or a lens group is added closest to the object side, or a configuration in which a lens or a lens group is added closest to the image side may be used. The lens group refers to a portion having at least one lens separated by an air interval that changes at the time of zooming or focusing.

  In the present embodiment, a single lens group, a plurality of lens groups, or a partial lens group may be moved in the optical axis direction to be a focusing lens group that performs focusing from an object at infinity to a short distance object. This focusing lens group can be applied to autofocus, and is also suitable for driving a motor for autofocus (using an ultrasonic motor or the like). In particular, it is preferable that at least a part of the third lens group G3 is a focusing lens group.

  In this embodiment, 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 rotated (swinged) in the in-plane direction including the optical axis, and is caused by camera shake. A vibration-proof lens group that corrects image blur may be used. In particular, it is preferable that at least a part of the third lens group G3 is an anti-vibration lens group.

  In the present embodiment, 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. If the lens surface is aspherical, the aspherical surface is an aspherical surface by grinding, a glass mold aspherical surface that is formed of glass with an aspherical shape, or a composite type nonspherical surface that is formed of a resin on the surface of glass. Any aspherical surface may be used. The lens surface may be a diffractive surface, and the lens may be a gradient index lens (GRIN lens) or a plastic lens.

  In the present embodiment, the aperture stop S is preferably disposed in or near the third lens group G3. However, the role may be substituted by a lens frame without providing a member as an aperture stop.

  In this embodiment, 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 variable magnification optical system ZL of this embodiment has a variable magnification ratio of about 2 to 7.

ZL (ZL1 to ZL4) Variable magnification optical system G1 First lens group G2 Second lens group G3 Third lens group G4 Fourth lens group S Aperture stop I Image plane 1 Camera (imaging device)
2 Shooting lens (variable magnification optical system)

Claims (17)

A first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power, arranged in order from the object side;
When zooming from the wide-angle end state to the telephoto end state, the first lens group is moved in the object direction along the optical axis direction,
A zoom optical system characterized by satisfying the following conditional expression:
0.14 <fw / f1 <0.26
0.77 <fw / f3 <1.05
However,
fw: focal length of the entire system in the wide-angle end state,
f1: the focal length of the first lens group,
f3: focal length of the third lens group.   An air gap between the first lens group and the second lens group, an air gap between the second lens group and the third lens group, and an air gap between the third lens group and the fourth lens group. The zoom optical system according to claim 1, wherein zooming is performed by changing.   At least a part of the second lens group or at least a part of the third lens group is configured to be movable so as to have a component perpendicular to the optical axis as an anti-vibration lens group for correcting image blur. The variable magnification optical system according to claim 1 or 2, wherein   4. The zoom optical system according to claim 1, wherein focusing is performed by moving at least a part of the third lens group along an optical axis direction. 5. The third lens group is composed of a thirty-first lens group, a thirty-second lens group, and a thirty-third lens group arranged in order from the object side.
5. The zoom lens according to claim 1, wherein the thirty-second lens group is configured to be movable as the vibration-proof lens group so as to have a component in a direction perpendicular to the optical axis. Optical system.   6. The variable magnification optical system according to claim 5, wherein the thirty-second lens group has a negative refractive power. The zoom lens system according to claim 5 or 6, wherein the following conditional expression is satisfied.
2.00 <(− f32) / f3 <6.00
However,
f32: focal length of the thirty-second lens group,
f3: focal length of the third lens group. The zoom lens system according to any one of claims 5 to 7, wherein the following conditional expression is satisfied.
0.50 <| f31 | / f3 <2.00
However,
f31: focal length of the thirty-first lens group,
f3: focal length of the third lens group. The zoom lens system according to claim 5, wherein the following conditional expression is satisfied.
1.00 <| f33 | / f3
However,
f33: focal length of the thirty-third lens group,
f3: focal length of the third lens group.   The variable power optical system according to any one of claims 5 to 9, wherein the thirty-second lens group includes a single lens. The thirty-first lens group is composed of a front group having a positive refractive power and a rear group arranged in order from the object side,
The variable magnification optical system according to claim 5, wherein focusing is performed by moving the front group along an optical axis direction. Having an aperture,
The variable magnification optical system according to any one of claims 1 to 11, wherein the diaphragm moves along the optical axis direction integrally with the third lens group at the time of zooming. Having an aperture,
The variable magnification optical system according to any one of claims 1 to 12, wherein the diaphragm is disposed between the second lens group and an image plane. The zoom lens system according to any one of claims 1 to 13, wherein the following conditional expression is satisfied.
30.00 ° <ωw <80.00 °
However,
ωw: Half angle of view in the wide-angle end state. The zoom lens system according to any one of claims 1 to 14, wherein the following conditional expression is satisfied.
2.00 <ft / fw <15.00
However,
ft: The focal length of the entire system in the telephoto end state when focusing on infinity.   An imaging apparatus comprising the variable magnification optical system according to any one of claims 1 to 15. Manufacture of a variable magnification optical system having a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power, arranged in order from the object side A method,
When zooming from the wide-angle end state to the telephoto end state, the first lens group is moved in the object direction along the optical axis direction,
A variable magnification optical system manufacturing method, wherein each lens is arranged in a lens barrel so as to satisfy the following conditional expression:
0.14 <fw / f1 <0.26
0.77 <fw / f3 <1.05
However,
fw: focal length of the entire system in the wide-angle end state,
f1: the focal length of the first lens group,
f3: focal length of the third lens group.

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