JP2015191055A - 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 excellent 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, a third lens group G3 having negative refractive power, and a fourth lens group G4 having positive refractive power. The variable power optical system performs focusing by moving at least a portion of the third lens group G3 in an optical axis direction and satisfies the following conditional expression (1): (1) 0.249<fw/f1<2.00, where fw is the focal length of the entire system in a wide angle end state and f1 is the focal length of the first lens group G1.

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-A-63-298210

  In recent years, a variable magnification optical system having better optical performance has been demanded.

  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 good 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 negative refractive power and a fourth lens group having a positive refractive power, and focusing is achieved by moving at least a part of the third lens group along the optical axis direction. And satisfy the following conditional expression.

0.249 <fw / f1 <2.00
However,
fw: focal length of the entire system in the wide-angle end state,
f1: Focal length of the first lens group.

  The zoom optical system according to the present invention has 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, It is preferable to change the air gap between the three lens groups and the fourth lens group.

  The zoom optical system according to the present invention enlarges the air gap between the first lens group and the second lens group and reduces the air gap between the third lens group and the fourth lens group during zooming. It is preferable to make it.

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

0.80 <fw / f4 <3.00
However,
f4: focal length of the fourth lens group.

  The zoom optical system according to the present invention preferably moves the first lens group along the optical axis during zooming.

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

0.10 <f1 / (− f3) <2.00
However,
f3: focal length of the third lens group.

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

0.80 <(− f2) / f4 <5.00
However,
f2: focal length of the second lens group,
f4: focal length of the fourth lens group.

  In the zoom optical system according to the present invention, it is preferable that the third lens group includes a single lens.

  In the zoom optical system according to the present invention, it is preferable that the third lens group includes a negative meniscus lens component having a concave surface directed toward the object side (where the lens component indicates a single lens or a cemented lens). .

  In the variable magnification optical system according to the present invention, it is preferable that the second lens group includes two negative lenses and one positive lens.

  In the zoom optical system according to the present invention, it is preferable that the second lens group includes a negative lens, a negative lens, and a positive lens arranged in order from the object side.

  In the zoom optical system according to the present invention, it is preferable that the first lens group includes one cemented lens.

  In the zoom optical system according to the present invention, it is preferable that the fourth lens group includes at least four lens components (provided that the lens component indicates a single lens or a cemented lens).

  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: focal length of the entire system in the telephoto end state.

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

  A 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, a third lens group having a negative refractive power, and a positive lens power. A variable power optical system having a fourth lens group having a refractive power of at least one of the third lens group, moving at least a part of the third lens group along the optical axis direction, Each lens is arranged in the lens barrel so as to satisfy the conditional expression.

0.249 <fw / f1 <2.00
However,
fw: focal length of the entire system in the wide-angle end state,
f1: Focal length of the first 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 good optical performance.

It is sectional drawing which shows the lens structure of the variable magnification optical system which concerns on 1st Example. FIG. 4A is an aberration diagram in the wide-angle end state (f = 18.50) 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. (A correction angle θ = 0.30 °) is a coma aberration diagram, and (c) is an aberration diagram when focusing on a short distance (shooting distance R = 1 m for the entire system). FIG. 3A is an aberration diagram in an intermediate focal length state (f = 29.99) of the variable magnification optical system according to the first example, FIG. A coma aberration diagram when correction is performed (correction angle θ = 0.30 °), and (c) shows various aberration diagrams when focusing on a short distance (shooting distance R = 1 m for the entire system). FIG. 6A is an aberration diagram in the telephoto end state (f = 53.29) 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. (A correction angle θ = 0.30 °) is a coma aberration diagram, and (c) is an aberration diagram when focusing on a short distance (shooting distance R = 1 m for the entire system). It is sectional drawing which shows the lens structure of the variable magnification optical system which concerns on 2nd Example. FIG. 6A is an aberration diagram in the wide-angle end state (f = 18.57) of the zoom optical system according to Example 2; FIG. 5A is a diagram illustrating aberrations at the time of focusing on infinity, and FIG. (A correction angle θ = 0.30 °) is a coma aberration diagram, and (c) is an aberration diagram when focusing on a short distance (shooting distance R = 1 m for the entire system). FIG. 6A is an aberration diagram in an intermediate focal length state (f = 30.16) of the variable magnification optical system according to the second example. FIG. 5A is an aberration diagram at the time of focusing on infinity, and FIG. A coma aberration diagram when correction is performed (correction angle θ = 0.30 °), and (c) shows various aberration diagrams when focusing on a short distance (shooting distance R = 1 m for the entire system). FIG. 6A is an aberration diagram in the telephoto end state (f = 53.65) of the variable magnification optical system according to the second example. FIG. 5A is a diagram illustrating various aberrations at the time of focusing on infinity, and FIG. (A correction angle θ = 0.30 °) is a coma aberration diagram, and (c) is an aberration diagram when focusing on a short distance (shooting distance R = 1 m for the entire system). 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 = 18.50) of the variable magnification optical system according to Example 3, (a) Various aberration diagrams when focusing on infinity, and (b) Image blur correction when focusing on infinity. (A correction angle θ = 0.30 °) is a coma aberration diagram, and (c) is an aberration diagram when focusing on a short distance (shooting distance R = 1 m for the entire system). FIG. 6A is an aberration diagram in the intermediate focal length state (f = 30.00) 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. A coma aberration diagram when correction is performed (correction angle θ = 0.30 °), and (c) shows various aberration diagrams when focusing on a short distance (shooting distance R = 1 m for the entire system). FIG. 6A is an aberration diagram in the telephoto end state (f = 53.30) 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. (A correction angle θ = 0.30 °) is a coma aberration diagram, and (c) is an aberration diagram when focusing on a short distance (shooting distance R = 1 m for the entire system). 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. A third lens group G3 having a negative refractive power and a fourth lens group G4 having a positive refractive power, and at least a part of the third lens group G3 (for example, a concave surface on the object side in FIG. 1). Focusing is performed by moving the negative meniscus lens L31) facing the direction of the optical axis.

  With this configuration, it is possible to achieve downsizing of the lens barrel and good correction of aberration fluctuations during focusing (for example, spherical aberration and curvature of field).

  Under the above configuration, the variable magnification optical system ZL satisfies the following conditional expression (1).

0.249 <fw / f1 <2.00 (1)
However,
fw: focal length of the entire system in the wide-angle end state,
f1: Focal length of the first lens group G1.

  Conditional expression (1) defines the ratio between the focal length of the entire system in the wide-angle end state and the focal length of the first lens group G1. 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. If the refractive powers of the second lens group G2 and the fourth lens group G4 are increased in order to reduce the size, it becomes difficult to correct spherical aberration and coma aberration. If the upper limit of conditional expression (1) is exceeded, the refractive power of the first lens group G1 will become strong, and it will be difficult to correct coma and field curvature.

  By setting the lower limit of conditional expression (1) to 0.260, better aberration correction becomes possible. By setting the lower limit of conditional expression (1) to 0.270, better aberration correction becomes possible. Further, by setting the lower limit value of conditional expression (1) to 0.280, the effect of the present embodiment can be maximized.

  By setting the upper limit of conditional expression (1) to 1.00, better aberration correction becomes possible. By setting the upper limit value of conditional expression (1) to 0.50, the effect of the present embodiment can be maximized.

  The zoom optical system ZL according to the present embodiment has an air gap between the first lens group G1 and the second lens group G2 and an air gap between the second lens group G2 and the third lens group G3 during zooming. It is preferable to change the air gap between the third lens group G3 and the fourth lens group G4.

  With this configuration, the coma aberration in the telephoto end state and the field curvature in the wide-angle end state can be favorably corrected during zooming.

  The zoom optical system ZL according to the present embodiment enlarges the air gap between the first lens group G1 and the second lens group G2 during zooming, and the air gap between the third lens group G3 and the fourth lens group G4. Is preferably reduced.

  With this configuration, the coma aberration in the telephoto end state and the field curvature in the wide-angle end state can be favorably corrected during zooming.

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

0.80 <fw / f4 <3.00 (2)
However,
f4: focal length of the fourth lens group G4.

  Conditional expression (2) defines the ratio between the focal length of the entire system in the wide-angle end state and the focal length of the fourth lens group G4. If the lower limit of conditional expression (2) is not reached, the refractive power of the fourth lens group G4 becomes weak, and it becomes difficult to reduce the size. If the refractive powers of the first lens group G1 and the second lens group G2 are increased in order to reduce the size, it becomes difficult to correct coma, astigmatism, and field curvature. If the upper limit value of conditional expression (2) is exceeded, the refractive power of the fourth lens group G4 becomes strong, and it becomes difficult to correct spherical aberration and coma aberration.

  By setting the lower limit value of conditional expression (2) to 0.83, even better aberration correction can be achieved.

  By setting the upper limit value of conditional expression (2) to 2.00, even better aberration correction becomes possible.

  The zoom optical system ZL according to the present embodiment preferably moves the first lens group G1 along the optical axis during zooming.

  With this configuration, it is possible to satisfactorily correct the downsizing of the lens barrel and the spherical aberration and coma aberration in the telephoto end state.

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

0.10 <f1 / (− f3) <2.00 (3)
However,
f3: focal length of the third lens group G3.

  Conditional expression (3) defines the ratio between the focal length of the first lens group G1 and the focal length of the third lens group G3. If the lower limit value of conditional expression (3) is not reached, the refractive power of the first lens group G1 becomes strong, and it becomes difficult to correct coma, astigmatism, and field curvature. If the upper limit value 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 the variation in curvature of field at the closest point.

  By setting the lower limit of conditional expression (3) to 0.50, good aberration correction can be performed. By setting the lower limit of conditional expression (3) to 1.00, better aberration correction can be performed. By setting the lower limit of conditional expression (3) to 1.25, the effect of this embodiment can be maximized.

  By setting the upper limit value of the conditional expression (3) to 1.80, it is possible to perform better aberration correction. By setting the upper limit value of conditional expression (3) to 1.70, the effect of this embodiment can be maximized.

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

0.80 <(− f2) / f4 <5.00 (4)
However,
f2: focal length of the second lens group G2,
f4: focal length of the fourth lens group G4.

  Conditional expression (4) defines the ratio between the focal length of the second lens group G2 and the focal length of the fourth lens group G4. If the lower limit value of conditional expression (4) is not reached, the refractive power of the second lens group G2 becomes strong, and it becomes difficult to correct coma and astigmatism. If the upper limit value of conditional expression (4) is exceeded, the refractive power of the fourth lens group G4 becomes strong, and it becomes difficult to correct spherical aberration and coma aberration in the telephoto end state.

  By setting the lower limit value of conditional expression (4) to 0.90, it becomes possible to perform better aberration correction. By setting the lower limit of conditional expression (4) to 1.00, the effect of this embodiment can be maximized.

  By setting the upper limit value of conditional expression (4) to 3.00, good aberration correction can be achieved. By setting the upper limit of conditional expression (4) to 2.00, better aberration correction can be achieved. By setting the upper limit value of conditional expression (4) to 1.50, the effect of this embodiment can be maximized.

  In the zoom optical system ZL according to the present embodiment, it is preferable that the third lens group G3 is composed of one lens.

  With this configuration, the third lens group G3, which is the focusing group, is lightweight, so that quick focusing is possible. In addition, the simple configuration facilitates assembly adjustment, and can prevent deterioration of optical performance due to errors in assembly adjustment.

  In the variable magnification optical system ZL according to the present embodiment, the third lens group G3 is preferably composed of a negative meniscus lens component having a concave surface facing the object side (however, the lens component is a single lens or a cemented lens). Show).

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

  In the variable magnification optical system ZL according to the present embodiment, it is preferable that the second lens group G2 includes two negative lenses and one positive lens.

  With this configuration, coma aberration and field curvature in the wide-angle end state can be corrected well.

  In the zoom optical system ZL according to the present embodiment, it is preferable that the second lens group G2 includes a negative lens, a negative lens, and a positive lens arranged in order from the object side.

  With this configuration, coma aberration and field curvature in the wide-angle end state can be corrected well.

  In the zoom optical system ZL according to this embodiment, it is preferable that the first lens group G1 includes one cemented lens.

  With this configuration, it is possible to achieve downsizing of the lens barrel and good correction of lateral chromatic aberration in the telephoto end state.

  In the variable magnification optical system ZL according to the present embodiment, the fourth lens group G4 preferably includes at least four lens components (however, the lens component indicates a single lens or a cemented lens).

  With this configuration, spherical aberration and coma can be favorably corrected.

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

30.00 ° <ωw <80.00 ° (5)
However,
ωw: Half angle of view in the wide-angle end state.

  Conditional expression (5) is a condition that defines the value of the half angle of view in the wide-angle end state. By satisfying this conditional expression (5), coma aberration, distortion aberration, and field curvature can be favorably corrected while having a wide angle of view.

  By setting the lower limit value of conditional expression (5) to 33.00 °, it is possible to perform better aberration correction. By setting the lower limit value of conditional expression (5) to 36.00 °, the effect of the present embodiment can be maximized.

  By setting the upper limit value of conditional expression (5) to 77.00 °, it becomes possible to perform better aberration correction.

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

2.00 <ft / fw <15.00 (6)
However,
ft: focal length of the entire system in the telephoto end state.

  Conditional expression (6) 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. By satisfying the conditional expression (6), a high zoom ratio can be obtained, and spherical aberration and coma aberration can be corrected well.

  By setting the lower limit value of conditional expression (6) to 2.30, it is possible to correct aberrations satisfactorily. By setting the lower limit value of conditional expression (6) to 2.50, better aberration correction can be achieved. By setting the lower limit of conditional expression (6) to 2.70, the effect of the present embodiment can be maximized.

  By setting the upper limit value of conditional expression (6) to 10.00, even better aberration correction can be achieved. By setting the upper limit value of conditional expression (6) to 7.00, the effect of the present embodiment can be maximized.

  According to the present embodiment as described above, a variable magnification optical system ZL having good 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. 13, the camera 1 is an interchangeable lens 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 good optical performance due to its characteristic lens configuration, as can be seen from each example described later. Therefore, according to the present camera 1, it is possible to realize an imaging device having good optical performance.

  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, in the lens barrel, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, a third lens group G3 having a negative refractive power, and a positive refraction. Each lens is arranged so as to have the fourth lens group G4 having power (step ST10). At this time, each lens is arranged in the lens barrel so as to perform focusing by moving at least a part of the third lens group G3 along the optical axis direction (step ST20). Then, each lens is arranged in the lens barrel so as to satisfy the following conditional expression (1) (step ST30).

0.249 <fw / f1 <2.00 (1)
However,
fw: focal length of the entire system in the wide-angle end state,
f1: Focal length of the first lens group G1.

  As an example of the lens arrangement in this 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 concave surface on the image side and a convex surface on the object side are directed. A cemented lens including 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 concave surface directed toward the image side, a biconcave lens L22, and a biconvex lens L23 are disposed. As the third lens group G3 (focusing group), a negative meniscus lens L31 having a concave surface facing the object side is disposed. As the fourth lens group G4, in order from the object side, a biconvex lens L41, a cemented lens composed of a biconvex lens L42 and a biconcave lens L43, a positive meniscus lens L44 having a convex surface on the image side, and a concave surface on the object side A cemented lens including a negative meniscus lens L45 and a biconvex lens L46 are disposed. Each lens is disposed so as to satisfy the conditional expression (1) (the corresponding value of the conditional expression (1) is 0.250).

  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 good optical performance can be obtained.

  Hereinafter, each example according to the present embodiment will be described with reference to the drawings. Tables 1 to 3 are shown below, but these are tables of specifications in the first to third examples.

  1, FIG. 5 and FIG. 9 are cross-sectional views showing a configuration of a variable magnification optical system ZL (ZL1 to ZL3) according to each example. In the cross-sectional views of the zoom optical systems ZL1 to ZL3, the movement trajectory along the optical axis of each lens group G1 to G4 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. Further, (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 indicated 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” represents “× 10 ⁻ⁿ ”, for example “1.234E-05” represents “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 [Variable interval data] in the table, f is the focal length of the entire lens system, R is the shooting distance, D0 is the distance from the object surface to the first surface, and Di (where i is an integer) is the i-th surface and the first surface. The variable interval of (i + 1) plane is shown.

  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 (6) 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. The second lens group G2 having a refractive power, the third lens group G3 having a negative refractive power, and the fourth lens group G4 having a positive refractive power.

  The first lens group G1 includes a cemented lens that is arranged in order from the object side and includes a negative meniscus lens L11 having a concave surface facing the image side and a positive meniscus lens L12 having a convex surface facing the object side.

  The second lens group G2 includes a negative meniscus lens L21 having a concave surface directed toward the image side, a biconcave lens L22, and a biconvex lens L23, which are arranged in order from the object side.

  The third lens group G3 includes a negative meniscus lens L31 having a concave surface directed toward the object side.

  The fourth lens group G4 has a biconvex lens L41, a cemented lens composed of a biconvex lens L42 and a biconcave lens L43, an aperture stop S that determines the F number, and a convex surface directed to the image side, which are arranged in order from the object side. It consists of a cemented lens composed of a positive meniscus lens L44 and a negative meniscus lens L45 having a concave surface facing the object side, and a biconvex lens L46. The object side surface of the positive meniscus lens L44 is aspheric.

  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 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 to the fourth lens group G4 move toward the object side with respect to the image plane I. The aperture stop S moves to the object side together with the fourth lens group G4 during zooming.

  The variable magnification optical system ZL1 according to the first example is configured to focus by moving the third lens group G3 along the optical axis direction, and as shown by the arrows in FIG. When the in-focus state is changed to the in-focus state to the near object, the third lens group G3 moves from the image side to the object side.

  When image blurring occurs, image blur correction (anti-shake) on the image plane I is performed by moving the biconvex lens L41 of the fourth lens group G4 so as to have a component perpendicular to the optical axis. Do.

  Table 1 below shows the values of each item in the first example. Surface numbers 1 to 22 in Table 1 correspond to the optical surfaces m1 to m22 shown in FIG.

(Table 1)
[Lens data]
Surface number r D νd nd
1 43.6089 0.8000 56.06 1.846663
2 26.7076 8.7676 27.04 1.804199
3 168.7089 D3 (variable)
4 60.1788 0.8000 41.64 1.903658
5 13.1274 6.8449
6 -40.4915 0.8000 23.57 1.739905
7 22.2763 0.2000
8 20.5255 3.7229 64.97 1.922860
9 -63.7521 D9 (variable)
10 -21.8570 0.8000 38.96 1.806099
11 -58.8880 D11 (variable)
12 2824.2386 1.3308 27.04 1.804199
13 -46.2898 0.2000
14 19.5419 2.8008 28.71 1.785897
15 -21.4622 0.8000 56.06 1.846663
16 88.8419 1.0643
17 ∞ 13.9355 (Aperture S)
* 18 -164.5357 5.8435 17.31 1.487496
19 -10.4013 0.8000 33.08 1.758900
20 -44.2438 0.2000
21 42.0115 2.6551 33.02 1.890489
22 -765.8628 Bf (variable)

[Aspherical data]
18th surface κ = 1.0000
A4 = -3.13683E-05
A6 = -3.13787E-08
A8 = -1.62732E-09
A10 = 3.69350E-12

[Various data]
f 18.50 29.99 53.29
Fno 3.27 4.24 4.65
ω 41.98 26.95 15.03
TL 87.66 92.68 113.67
Bf 19.36 32.55 38.06
Y 14.25 14.25 14.25

[Variable interval data]
(Infinity) (shooting distance 1m)
Wide-angle end Medium telephoto end Wide-angle end Medium telephoto end
f & β 18.50490 29.99155 53.29045 -0.01970 -0.03208 -0.05496
D0 0.0000 0.0000 0.0000 912.3355 907.3154 886.3268
D3 0.20000 0.53995 18.55691 0.20000 0.53995 18.55691
D9 2.68588 2.97437 4.48690 2.20641 2.48985 3.43365
D11 13.05009 4.25341 0.20000 13.52956 4.73793 1.25325
Bf 19.36323 32.55157 38.06404 19.36323 32.55157 38.06404

[Lens group data]
Group number Group first surface Group focal length G1 1 73.938
G2 4 -26.003
G3 10 -43.538
G4 12 22.176

[Conditional expression values]
Conditional expression (1): fw / f1 = 0.250
Conditional expression (2): fw / f4 = 0.834
Conditional expression (3): f1 / (− f3) = 1.698
Conditional expression (4): (−f2) /f4=1.173
Conditional expression (5): ωw = 41.98
Conditional expression (6): ft / fw = 2.880

  From Table 1, it is understood that the variable magnification optical system ZL1 according to the first example satisfies the conditional expressions (1) to (6).

  2A and 2B are aberration diagrams of the variable magnification optical system ZL1 according to the first example in the wide-angle end state (f = 18.50). FIG. A coma aberration diagram when image blur correction is performed at the time of focus (correction angle θ = 0.30 °), and (c) shows various aberration diagrams when focusing at a short distance (shooting distance R = 1 m for the entire system). FIG. 3 is an aberration diagram in the intermediate focal length state (f = 29.99) 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) at infinity. A coma aberration diagram when image blur correction is performed at the time of focusing (correction angle θ = 0.30 °), and (c) shows various aberration diagrams when focusing at a short distance (shooting distance R = 1 m of the entire system). 4A and 4B are aberration diagrams in the telephoto end state (f = 53.29) of the variable magnification optical system ZL1 according to the first example. FIG. 4A is a diagram illustrating various aberrations at the time of focusing on infinity, and FIG. A coma aberration diagram when image blur correction is performed at the time of focus (correction angle θ = 0.30 °), and (c) shows various aberration diagrams when focusing at a short distance (shooting distance R = 1 m for the entire system). In this embodiment, the optical performance at the time of image stabilization is shown in FIG. 2 (b), FIG. 3 (b) and FIG. 4 (b). A coma aberration diagram corresponding to is shown.

  In each aberration diagram, FNO is the F number, 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 F-number value corresponding to the maximum aperture is shown, and in the astigmatism diagram and the distortion diagram, the maximum image height is shown. 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, a solid line indicates a meridional coma, and a broken line indicates a sagittal 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. The second lens group G2 having a refractive power, the third lens group G3 having a negative refractive power, and the fourth lens group G4 having a positive refractive power.

  The first lens group G1 includes a cemented lens that is arranged in order from the object side and includes a negative meniscus lens L11 having a concave surface facing the image side and a positive meniscus lens L12 having a convex surface facing the object side.

  The second lens group G2 includes a negative meniscus lens L21 having a concave surface directed toward the image side, a biconcave lens L22, and a biconvex lens L23, which are arranged in order from the object side.

  The third lens group G3 includes a negative meniscus lens L31 having a concave surface directed toward the object side.

  The fourth lens group G4 includes, in order from the object side, a positive meniscus lens L41 having a convex surface directed toward the image side, a cemented lens including a biconvex lens L42 and a biconcave lens L43, and an aperture stop S that determines an F number. And a cemented lens including a biconvex lens L44 and a negative meniscus lens L45 having a concave surface facing the object side, and a positive meniscus lens L46 having a convex surface facing the object side. The object side surface of the biconvex lens L44 is aspheric.

  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 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 to the fourth lens group G4 move toward the object side with respect to the image plane I. The aperture stop S moves to the object side together with the fourth lens group G4 during zooming.

  The variable magnification optical system ZL2 according to the second example is configured to perform focusing by moving the third lens group G3 along the optical axis direction. As shown by the arrows in FIG. When the in-focus state is changed to the in-focus state to the near object, the third lens group G3 moves from the image side to the object side.

  When image blurring occurs, image blur correction (antivibration) on the image plane I is performed by moving the positive meniscus lens L41 of the fourth lens group G4 so as to have a component perpendicular to the optical axis. I do.

  Table 2 below shows the values of each item in the second embodiment. Surface numbers 1 to 22 in Table 2 correspond to the optical surfaces m1 to m22 shown in FIG.

(Table 2)
[Lens data]
Surface number r D νd nd
1 36.2988 0.8000 56.06 1.846663
2 22.9300 6.9961 26.97 1.816000
3 114.2134 D3 (variable)
4 35.9155 0.8000 36.55 1.910822
5 10.5558 7.1298
6 -82.0417 0.8000 25.39 1.743197
7 20.5024 0.2000
8 17.2134 3.1607 64.97 1.922860
9 -4490.3075 D9 (variable)
10 -29.7462 0.8000 38.96 1.806099
11 -109.4759 D11 (variable)
12 -377.5996 1.0745 27.04 1.804199
13 -63.0373 0.2000
14 13.6966 2.6756 25.19 1.772500
15 -24.3635 0.8000 56.06 1.846663
16 116.0533 1.0643
17 ∞ 7.5048 (Aperture S)
* 18 65996.0514 2.4131 24.74 1.658440
19 -9.9097 0.8000 31.23 1.883000
20 -696.0403 5.3367
21 28.8802 2.0264 22.66 1.680436
22 93.8568 Bf (variable)

[Aspherical data]
18th surface κ = -0.6712E + 09
A4 = -1.46479E-04
A6 = -5.44840E-07
A8 = -2.43857E-08
A10 = -1.48292E-10

[Various data]
f 18.57 30.16 53.65
Fno 3.86 5.01 5.71
ω 38.88 25.76 14.66
TL 77.82 82.22 98.84
Bf 17.65 28.15 34.48
Y 14.25 14.25 14.25

[Variable interval data]
(Infinity) (shooting distance 1m)
Wide-angle end Medium telephoto end Wide-angle end Medium telephoto end
f & β 18.56510 30.16136 53.64561 -0.01959 -0.03187 -0.05511
D0 0.0000 0.0000 0.0000 922.1816 917.7766 901.1552
D3 0.20000 1.76658 15.19035 0.20000 1.76658 15.19035
D9 4.00268 3.19861 4.39731 3.50042 2.64674 3.29926
D11 11.38347 4.52189 0.19742 11.88573 5.07376 1.29547
Bf 17.65025 28.15431 34.47771 17.65025 28.15431 34.47771

[Lens group data]
Group number Group first surface Group focal length G1 1 64.373
G2 4 -21.741
G3 10 -50.897
G4 12 19.226

[Conditional expression values]
Conditional expression (1): fw / f1 = 0.288
Conditional expression (2): fw / f4 = 0.966
Conditional expression (3): f1 / (− f3) = 1.265
Conditional expression (4): (−f2) /f4=1.131
Conditional expression (5): ωw = 38.88
Conditional expression (6): ft / fw = 2.890

  From Table 2, it can be seen that the variable magnification optical system ZL2 according to the second example satisfies the conditional expressions (1) to (6).

  6A and 6B are aberration diagrams in the wide-angle end state (f = 18.57) 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. A coma aberration diagram when image blur correction is performed at the time of focus (correction angle θ = 0.30 °), and (c) shows various aberration diagrams when focusing at a short distance (shooting distance R = 1 m for the entire system). FIG. 7 is an aberration diagram in the intermediate focal length state (f = 30.16) 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) at infinity. A coma aberration diagram when image blur correction is performed at the time of focusing (correction angle θ = 0.30 °), and (c) shows various aberration diagrams when focusing at a short distance (shooting distance R = 1 m of the entire system). 8A and 8B are aberration diagrams in the telephoto end state (f = 53.65) of the variable magnification optical system ZL2 according to the second example. FIG. 8A is a diagram illustrating various aberrations at the time of focusing on infinity, and FIG. A coma aberration diagram when image blur correction is performed at the time of focus (correction angle θ = 0.30 °), and (c) shows various aberration diagrams when focusing at a short distance (shooting distance R = 1 m for the entire system). In this embodiment, the optical performance at the time of image stabilization is shown in FIG. 6 (b), FIG. 7 (b) and FIG. 8 (b). 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. The second lens group G2 having a refractive power, the third lens group G3 having a negative refractive power, and the fourth lens group G4 having a positive refractive power.

  The first lens group G1 includes a cemented lens that is arranged in order from the object side and includes a negative meniscus lens L11 having a concave surface facing the image side and a positive meniscus lens L12 having a convex surface facing the object side. The image side surface of the positive meniscus lens L12 is aspheric.

  The second lens group G2 includes a negative meniscus lens L21 having a concave surface directed toward the image side, a biconcave lens L22, and a biconvex lens L23, which are arranged in order from the object side.

  The third lens group G3 includes a negative meniscus lens L31 having a concave surface directed toward the object side.

  The fourth lens group G4 includes, in order from the object side, a cemented lens including a biconvex lens L41 and a biconcave lens L42, an aperture stop S that determines an F number, and a positive meniscus lens L43 with a convex surface facing the object side. And a cemented lens composed of a biconvex lens L44 and a biconcave lens L45, and a positive meniscus lens L46 having a convex surface facing the image side. The object side surface of the biconvex lens L44 is aspheric.

  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 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, the third lens group G3, and the fourth lens group G4 move toward the object side with respect to the image plane I. The second lens group moves along the optical axis so as to draw a convex locus on the image side. The aperture stop S moves to the object side together with the fourth lens group G4 during zooming.

  The variable magnification optical system ZL3 according to the third example is configured to perform focusing by moving the third lens group G3 along the optical axis direction. As shown by the arrows in FIG. When the in-focus state is changed to the in-focus state to the near object, the third lens group G3 moves from the image side to the object side.

  When image blurring occurs, image blur correction (anti-vibration) on the image plane I is performed by moving the positive meniscus lens L43 of the fourth lens group G4 so as to have a component perpendicular to the optical axis as a vibration-proof lens group. I do.

  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 35.1980 0.8000 56.15 1.846660
2 24.4358 7.3655 22.71 1.729160
* 3 211.9356 D3 (variable)
4 82.8733 0.8000 31.23 1.883000
5 10.8309 6.4839
6 -75.6483 0.8000 26.51 1.788000
7 27.8532 0.2000
8 19.3959 3.8899 56.15 1.846660
9 -68.0805 D9 (variable)
10 -27.8595 0.8000 38.96 1.806099
11 -122.2398 D11 (variable)
12 12.8893 3.0252 23.57 1.741000
13 -32.2900 0.8000 56.06 1.846663
14 422.4616 0.8347
15 ∞ 2.6582 (Aperture S)
16 24.2267 1.3307 27.81 1.795000
17 72.2003 1.3014
* 18 56.1806 2.7586 23.57 1.741000
19 -8.2233 0.8000 31.23 1.883000
20 23.9411 1.71720
21 -25.3892 1.3324 38.58 1.647690
22 -17.5029 Bf (variable)

[Aspherical data]
Third surface κ = -39.7100
A4 = -9.89369E-09
A6 = -2.05283E-09
A8 = 1.18853E-11
A10 = -1.78987E-14

18th surface κ = 4.8409
A4 = -1.61115E-04
A6 = 1.91543E-07
A8 = -6.86409E-08
A10 = 1.23380E-09

[Various data]
f 18.50 30.00 53.30
Fno 3.63 4.27 5.55
ω 38.65 24.10 14.09
TL 76.66 83.75 96.53
Bf 22.79 28.26 39.05
Y 14.25 14.25 14.25

[Variable interval data]
(Infinity) (shooting distance 1m)
Wide-angle end Medium telephoto end Wide-angle end Medium telephoto end
f & β 18.50000 30.00231 53.29585 -0.01949 -0.03121 -0.05478
D0 0.0000 0.0000 0.0000 923.3407 916.2461 903.4746
D3 0.80000 8.47829 14.74203 0.80000 8.47829 14.74203
D9 4.20131 2.95126 4.23229 3.76248 2.28904 3.28726
D11 11.16869 6.36877 0.80000 11.60752 7.03100 1.74503
Bf 22.79163 28.25792 39.05340 22.79163 28.25792 39.05340

[Lens group data]
Group number Group first surface Group focal length G1 1 61.828
G2 4 -24.305
G3 10 -44.933
G4 12 22.921

[Conditional expression values]
Conditional expression (1): fw / f1 = 0.299
Conditional expression (2): fw / f4 = 1.032
Conditional expression (3): f1 / (− f3) = 1.376
Conditional expression (4): (−f2) /f4=1.356
Conditional expression (5): ωw = 38.65
Conditional expression (6): ft / fw = 2.881

  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 (6).

  FIG. 10 is an aberration diagram in the wide-angle end state (f = 18.50) of the variable magnification optical system ZL3 according to Example 3, (a) Various aberration diagrams at the time of focusing on infinity, and (b) of FIG. A coma aberration diagram when image blur correction is performed at the time of focus (correction angle θ = 0.30 °), and (c) shows various aberration diagrams when focusing at a short distance (shooting distance R = 1 m for the entire system). FIG. 11 is an aberration diagram in the intermediate focal length state (f = 30.00) 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 infinity. A coma aberration diagram when image blur correction is performed at the time of focusing (correction angle θ = 0.30 °), and (c) shows various aberration diagrams when focusing at a short distance (shooting distance R = 1 m of the entire system). 12A and 12B are aberration diagrams in the telephoto end state (f = 53.30) of the variable magnification optical system ZL3 according to the third example. FIG. 12A is a diagram illustrating various aberrations at the time of focusing on infinity, and FIG. A coma aberration diagram when image blur correction is performed at the time of focus (correction angle θ = 0.30 °), and (c) shows various aberration diagrams when focusing at a short distance (shooting distance R = 1 m for the entire system). In this embodiment, the optical performance at the time of image stabilization is shown in FIG. 10B, FIG. 11B, and FIG. 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.

  According to each of the embodiments described above, a variable magnification optical system having good 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, a four-group configuration is shown, but the present invention can also be applied to other group configurations such as a five-group configuration. 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. The 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 fourth lens group G4 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 arranged in or near the fourth lens group G4. However, the role may be substituted by a lens frame without providing a member as the 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 ZL3) 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, a third lens group having a negative refractive power, and a first lens group having a positive refractive power, arranged in order from the object side. 4 lens groups,
Focusing by moving at least a part of the third lens group along the optical axis direction;
A zoom optical system characterized by satisfying the following conditional expression:
0.249 <fw / f1 <2.00
However,
fw: focal length of the entire system in the wide-angle end state,
f1: Focal length of the first lens group.   Upon zooming, the air gap between the first lens group and the second lens group, the air gap between the second lens group and the third lens group, the third lens group and the fourth lens group, The variable magnification optical system according to claim 1, wherein the air spacing is changed.   2. The zoom lens according to claim 1, wherein, upon zooming, an air gap between the first lens group and the second lens group is enlarged, and an air gap between the third lens group and the fourth lens group is reduced. The zoom optical system according to 2. The zoom lens system according to any one of claims 1 to 3, wherein the following conditional expression is satisfied.
0.80 <fw / f4 <3.00
However,
f4: focal length of the fourth lens group.   5. The zoom optical system according to claim 1, wherein the first lens unit is moved along an optical axis during zooming. 6. The zoom lens system according to any one of claims 1 to 5, wherein the following conditional expression is satisfied.
0.10 <f1 / (− f3) <2.00
However,
f3: focal length of the third lens group. The zoom lens system according to claim 1, wherein the following conditional expression is satisfied.
0.80 <(− f2) / f4 <5.00
However,
f2: focal length of the second lens group,
f4: focal length of the fourth lens group.   The variable power optical system according to any one of claims 1 to 7, wherein the third lens group includes one lens.   9. The variable magnification optical system according to claim 1, wherein the third lens group includes a negative meniscus lens component having a concave surface facing the object side. , Indicating single lens or cemented lens).   The variable power optical system according to any one of claims 1 to 9, wherein the second lens group includes two negative lenses and one positive lens.   The variable power optical system according to any one of claims 1 to 10, wherein the second lens group includes a negative lens, a negative lens, and a positive lens arranged in order from the object side.   The variable power optical system according to any one of claims 1 to 11, wherein the first lens group includes one cemented lens.   The variable-power optical system according to claim 1, wherein the fourth lens group includes at least four lens components (provided that the lens component is a single lens or a cemented lens). Showing). 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: focal length of the entire system in the telephoto end state.   An imaging apparatus comprising the variable magnification optical system according to any one of claims 1 to 15. A variable lens having a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a negative refractive power, and a fourth lens group having a positive refractive power. A method of manufacturing a double optical system,
Focusing by moving at least a part of the third lens group 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:
0.249 <fw / f1 <2.00
However,
fw: focal length of the entire system in the wide-angle end state,
f1: Focal length of the first lens group.

Images