JP6160817B2 - Variable magnification optical system, optical apparatus, and variable magnification optical system manufacturing method - Google Patents

Description

  The present invention relates to a variable magnification optical system, an optical 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 2006-308957 A

  However, since the conventional variable magnification optical system has an F number of about f / 3.5, there has been a problem that it cannot fully meet the demand for a larger aperture for a brighter lens.

  The present invention has been made in view of such problems, and provides a variable magnification optical system having bright and good optical performance, an optical apparatus having the variable magnification optical system, and a method for manufacturing the variable magnification optical system. With the goal.

In order to solve the above problems, a variable magnification optical system according to the present invention includes, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a positive refraction. a third lens group having a power, and a substantially fourth lens group having positive refractive power consists of four lens groups, upon zooming from the wide-angle end state to the telephoto end state, the first lens group The distance between the second lens group changes, the distance between the second lens group and the third lens group changes, the distance between the third lens group and the fourth lens group changes, and the third lens group An intermediate group having a positive lens, a negative lens, a negative lens, and a positive lens, arranged in order from the side, and an image side group having a negative refractive power arranged closer to the image plane than the intermediate group, upon focusing, the middle group is fixed in position relative to the image plane moves the image side groups along the optical axis, the condition of the following formula Characterized by foot.
4.0 <f4 / fw <11.0
However,
f4: focal length of the fourth lens unit
fw: focal length of the entire system in the wide-angle end state

  The zoom optical system according to the present invention includes, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens having a positive refractive power. And a fourth lens group having a positive refracting power. The zoom lens includes a first lens group and a second lens group at the time of zooming from the wide-angle end state to the telephoto end state. The distance changes, the distance between the second lens group and the third lens group changes, the distance between the third lens group and the fourth lens group changes, and the third lens group is arranged in order from the object side. An intermediate group having a positive lens, a negative lens, a negative lens, and a positive lens, and an image side group having a negative refractive power disposed on the image plane side with respect to the intermediate group. The group has a fixed position relative to the image plane, the image side group moves along the optical axis, and the image side group has at least one negative It has a lens, and satisfies the conditions of the following equation.
ndF + 0.0052 × νdF−1.965 <0
νdF> 60
  However,
  ndF: refractive index with respect to d-line of the medium of the negative lens included in the image side group
  νdF: Abbe number of the medium of the negative lens included in the image side group

The variable magnification optical system manufacturing method according to the present invention has, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a positive refractive power. A method of manufacturing a variable power optical system comprising substantially four lens groups of a third lens group and a fourth lens group having a positive refractive power, the zooming from a wide-angle end state to a telephoto end state At this time, the distance between the first lens group and the second lens group changes, the distance between the second lens group and the third lens group changes, and the distance between the third lens group and the fourth lens group changes. The third lens group is arranged in order from the object side, and includes a positive lens, a negative lens, a negative lens, an intermediate group having a positive lens, and a negative refractive power arranged on the image plane side relative to the intermediate group. And the intermediate group is fixed in position with respect to the image plane during focusing, and the image side group And arranged to move along the axis, characterized in that arranged so as to satisfy the condition of following equation.
4.0 <f4 / fw <11.0
However,
f4: focal length of the fourth lens group
fw: focal length of the entire system in the wide-angle end state

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

It is sectional drawing which shows the lens structure of the variable magnification optical system which concerns on 1st Example. FIG. 4 is a diagram illustrating various aberrations of the zoom optical system according to Example 1 in an infinitely focused state, where (a) shows a wide-angle end state, (b) shows an intermediate focal length state, and (c) shows telephoto. Indicates the end state. FIG. 5A is a diagram illustrating various aberrations of the variable magnification optical system according to the first example in a short-distance in-focus state, in which (a) shows a wide-angle end state, (b) shows an intermediate focal length state, and (c) shows telephoto. Indicates the end state. It is sectional drawing which shows the lens structure of the variable magnification optical system which concerns on 2nd Example. FIG. 6 is a diagram illustrating various aberrations of the variable magnification optical system according to Example 2 in an infinitely focused state, where (a) shows a wide-angle end state, (b) shows an intermediate focal length state, and (c) shows telephoto. Indicates the end state. FIG. 6A is a diagram illustrating various aberrations of the variable magnification optical system according to Example 2 in a short-distance in-focus state, where (a) shows a wide-angle end state, (b) shows an intermediate focal length state, and (c) shows telephoto. Indicates the end state. It is sectional drawing which shows the lens structure of the variable magnification optical system which concerns on 3rd Example. FIG. 6 is a diagram illustrating various aberrations of the zoom optical system according to Example 3 in the infinitely focused state, where (a) shows a wide-angle end state, (b) shows an intermediate focal length state, and (c) shows telephoto. Indicates the end state. FIG. 6 is a diagram illustrating various aberrations of the zoom optical system according to Example 3 in a short-distance in-focus state, where (a) shows a wide-angle end state, (b) shows an intermediate focal length state, and (c) shows telephoto. Indicates the end state. It is sectional drawing which shows the lens structure of the variable magnification optical system which concerns on 4th Example. FIG. 6A is a diagram illustrating various aberrations of the zoom optical system according to Example 4 in an infinitely focused state, where (a) shows a wide-angle end state, (b) shows an intermediate focal length state, and (c) shows telephoto. Indicates the end state. FIG. 7A is a diagram illustrating various aberrations of the zoom optical system according to Example 4 in a short-distance in-focus state, where (a) shows a wide-angle end state, (b) shows an intermediate focal length state, and (c) shows telephoto. Indicates the end state. It is sectional drawing which shows the lens structure of the variable magnification optical system which concerns on 5th Example. FIG. 10 is a diagram illustrating various aberrations of the zoom optical system according to Example 5 in the infinite focus state, where (a) shows the wide-angle end state, (b) shows the intermediate focal length state, and (c) shows the telephoto state. Indicates the end state. FIG. 7A is a diagram illustrating various aberrations of the zoom optical system according to Example 5 in a short distance in-focus state, in which (a) shows a wide-angle end state, (b) shows an intermediate focal length state, and (c) shows telephoto. Indicates the end state. It is sectional drawing of the camera carrying the said variable magnification optical system. It is a flowchart for demonstrating the manufacturing method of the said variable magnification optical system.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, the variable magnification optical system ZL according to the present embodiment includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, It has a third lens group G3 having a positive refractive power and a fourth lens group G4 having a positive refractive power. In addition, in the zoom optical system ZL, when the zoom is changed from the wide-angle end state to the telephoto end state, the distance between the first lens group G1 and the second lens group G2 changes, and the second lens group G2 and the third lens are changed. The distance between the group G3 changes and the distance between the third lens group G3 and the fourth lens group G4 changes. In the variable magnification optical system ZL, the third lens group G3 includes an intermediate group G3b having a positive lens, a negative lens, a negative lens, and a positive lens disposed from the object side, and an image plane that is more than the intermediate group G3b. And moving the image side group G3c along the optical axis in a state where the position of the intermediate group relative to the image plane is fixed. It is configured to focus on an object from a short distance to a short distance. By configuring the variable magnification optical system ZL according to the present embodiment in such a configuration, a lens having a bright F number can have good optical performance. In other words, the intermediate lens group G3b of the third lens group G3 is composed of four lenses that are positive, negative, negative, and positive so as to have a symmetric structure, so that the F-number brightness has spherical aberration, field curvature, and coma. It is possible to correct aberrations satisfactorily. In the configuration in which the aperture stop S is disposed between the second lens group G2 and the third lens group G3 (or on the object side of the third lens group G3), the focusing is disposed on the image plane side with respect to the intermediate group G3b. By using the image side group G3c, it is possible to increase the distance between the aperture stop S and the focusing group to suppress image plane fluctuations during focusing. The lens component is a single lens or a cemented lens in which a plurality of lenses are cemented.

  In addition, it is desirable that the variable magnification optical system ZL according to the present embodiment satisfies the following conditional expression (1).

0.4 <(− f2) / (fw × ft) ^1/2 <1.1 (1)
However,
f2: focal length of the second lens group G2 fw: focal length of the entire zooming optical system ZL in the wide-angle end state ft: focal length of the entire zooming optical system ZL in the telephoto end state

  Conditional expression (1) defines the focal length of the second lens group G2. Exceeding the upper limit of conditional expression (1) is not preferable because the refractive power of the second lens group G2 becomes weak, the amount of movement during zooming increases, and the optical total length becomes long. In order to secure the effect of the present application, it is desirable to set the upper limit of conditional expression (1) to 1.0. In order to further secure the effect of the present application, it is desirable to set the upper limit of conditional expression (1) to 0.9. On the other hand, if the lower limit of conditional expression (1) is not reached, the refractive power of the second lens group G2 becomes strong, and it is not preferable because the field curvature and astigmatism cannot be corrected well. In order to secure the effect of the present application, it is desirable to set the lower limit of conditional expression (1) to 0.5. In order to further secure the effect of the present application, it is desirable to set the lower limit of conditional expression (1) to 0.6.

  In the zoom optical system ZL according to the present embodiment, it is desirable that the third lens group G3 has an object side group G3a having a positive refractive power on the object side of the intermediate group G3b. With such a configuration, even better optical performance can be maintained with a bright F-number lens. It is possible to satisfactorily correct higher-order spherical aberration that is likely to occur with a bright lens.

  In the zoom optical system ZL according to this embodiment, it is desirable that the image side group G3c included in the third lens group G3 and used for focusing is composed of one negative lens. With such a configuration, the focusing lens can be lightened, and the focusing speed can be easily increased. Further, it is desirable that the image side group G3c is composed of a negative meniscus lens having a concave surface facing one image surface side. By adopting such a configuration, it is possible to suppress spherical aberration fluctuations that occur during focusing and to achieve high-speed focusing.

  In the variable magnification optical system ZL according to the present embodiment, the image side group G3c included in the third lens group G3 includes at least one negative lens, and the negative lens has the following conditional expression (2 ) Is desirable.

ndF + 0.0052 × νdF−1.965 <0 (2)
However,
ndF: refractive index with respect to d-line of the medium of the negative lens included in the image side group G3c

  Conditional expression (2) defines the refractive index for the d-line of the medium of the negative lens included in the image side group G3c. If the upper limit value of the conditional expression (2) is exceeded, a glass material having a relatively high refractive power and a large color dispersibility is used for the negative lens. In this range, the longitudinal chromatic aberration cannot be corrected well, which is not preferable.

  Further, it is desirable that the negative lens included in the image side group G3c of the third lens group G3 satisfies the following conditional expression (3).

νdF> 60 (3)
However,
νdF: Abbe number of the medium of the negative lens included in the image side group G3c

  Conditional expression (3) defines the Abbe number of the medium of the negative lens included in the image side group G3c. If the lower limit value of conditional expression (3) is not reached, the dispersibility of the focusing lens increases, and the axial chromatic aberration that is conspicuous with a bright lens cannot be sufficiently corrected in the range from infinity to a close object in focusing. Therefore, it is not preferable. In order to secure the effect of the present application, it is desirable to set the lower limit value of conditional expression (3) to 62.

  In the zoom optical system ZL according to the present embodiment, when the third lens group G3 has an object side group G3a having positive refractive power on the object side of the intermediate group G3b, the object side group G3a is 1 It is desirable to have one positive lens and satisfy the following conditional expression (4).

νdO> 60 (4)
However,
νdO: Abbe number of the medium of the positive lens included in the object side group G3a

  Conditional expression (4) defines the Abbe number of the medium of the positive lens included in the object side group G3a of the third lens group G3. If the lower limit value of conditional expression (4) is not reached, the axial chromatic aberration that tends to occur with a bright lens becomes large and correction becomes difficult, which is not preferable. In order to secure the effect of the present application, it is desirable to set the lower limit of conditional expression (4) to 62. In order to further secure the effect of the present application, it is desirable to set the lower limit of conditional expression (4) to 65.

  In addition, it is desirable that the variable magnification optical system ZL according to the present embodiment satisfies the following conditional expression (5).

4.0 <f4 / fw <11.0 (5)
However,
f4: focal length of the fourth lens group G4 fw: focal length of the entire variable magnification optical system ZL in the wide-angle end state

  Conditional expression (5) defines the focal length of the fourth lens group G4. Exceeding the upper limit of conditional expression (4) is not preferable because the refractive power of the fourth lens group G4 becomes weak and it becomes difficult to correct field curvature during zooming. In order to secure the effect of the present application, it is desirable to set the upper limit of conditional expression (5) to 10.0. In order to further secure the effect of the present application, it is desirable to set the upper limit of conditional expression (5) to 9.0. On the other hand, if the lower limit of conditional expression (5) is not reached, the refractive power of the fourth lens group G4 becomes strong, it becomes difficult to correct distortion, and back focus cannot be secured, which is not preferable. In order to secure the effect of the present application, it is desirable to set the lower limit of conditional expression (5) to 5.0. In order to further secure the effect of the present application, it is desirable to set the lower limit of conditional expression (5) to 6.0.

  Further, in the zoom optical system ZL according to the present embodiment, when zooming from the wide-angle end state to the telephoto end state, the first lens group G1 moves once to the image plane side and then moves to the object side. desirable. By adopting such a configuration, the diameter of the first lens group G1 can be kept small while preventing off-axis beam breakage when the distance between the first lens group G1 and the second lens group G2 is widened. In addition, a sharp change in distortion can be suppressed.

  In the variable magnification optical system ZL according to the present embodiment, in the third lens group G3, at least one positive lens component may be disposed between the intermediate group G3b and the image side group G3c, or omitted. May be. Similarly, the object side group G3a disposed on the object side of the intermediate group G3b of the third lens group G3 may be omitted. Further, the positive, negative, and positive four-lens elements included in the intermediate group G3b may be a combination of a positive lens and a negative lens, or may be arranged as a single lens.

  With the configuration described above, it is possible to provide a variable magnification optical system ZL that is bright and has good optical performance.

  Next, a camera that is an optical apparatus including the variable magnification optical system ZL according to the present embodiment will be described with reference to FIG. This camera 1 is a so-called mirrorless camera of interchangeable lens provided with a variable magnification optical system ZL according to the present embodiment as a photographing lens 2. In the camera 1, light from an object (subject) (not shown) is collected by the photographing lens 2 and is on the imaging surface of the imaging unit 3 via an OLPF (Optical low pass filter) (not shown). A subject image is formed on the screen. Then, the subject image is photoelectrically converted by the photoelectric conversion element provided in the imaging unit 3 to generate an image of the subject. This image is displayed on an EVF (Electronic view finder) 4 provided in the camera 1. Thus, the photographer can observe the subject via the EVF 4.

  Further, when a release button (not shown) is pressed by the photographer, an image photoelectrically converted 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. In the present embodiment, an example of a mirrorless camera has been described. However, a variable power optical system ZL according to the present embodiment is applied to a single-lens reflex camera that has a quick return mirror in the camera body and observes a subject with a finder optical system. Even when the camera is mounted, the same effect as the camera 1 can be obtained.

  The contents described below can be appropriately adopted as long as the optical performance is not impaired.

  In the present embodiment, the variable magnification optical system ZL having the four-group configuration is shown, but the above-described configuration conditions and the like can be applied to other group configurations such as the fifth group and the sixth group. Further, a configuration in which a lens or a lens group is added to the most object side or a configuration in which a lens or a lens group is added to the most image side may be used. The lens group refers to a portion having at least one lens separated by an air interval that changes during zooming. Further, in the zoom optical system ZL of the present embodiment, the first lens group G1 to the fourth lens group G4 move along the optical axis so that the air spacing between the groups changes during zooming.

  Alternatively, a single lens group, a plurality of lens groups, or a partial lens group may be moved in the optical axis direction to be a focusing lens group that performs focusing from an object at infinity to a near object. In this case, the focusing lens group can be applied to autofocus, and is also suitable for driving a motor for autofocus (such as an ultrasonic motor). In particular, it is preferable that a part of the third lens group G3 (as described above, the image side group G3c) is a focusing lens group, and the positions of the other lenses are fixed with respect to the image plane at the time of focusing.

  In addition, the lens group or the partial lens group is moved so as to have a component in a direction perpendicular to the optical axis, or is rotated (swayed) in the in-plane direction including the optical axis to reduce image blur caused by camera shake. A vibration-proof lens group to be corrected may be used. In particular, it is preferable that at least a part of the third lens group G3 (for example, a lens disposed on the image side of the positive, negative, and positive four lenses of the intermediate group G3b) be the anti-vibration lens group.

  Further, the lens surface may be formed as a spherical surface, a flat surface, or an aspheric surface. When the lens surface is a spherical surface or a flat surface, lens processing and assembly adjustment are facilitated, and optical performance deterioration due to errors in processing and assembly adjustment can be prevented. Further, even when the image plane is deviated, it is preferable because there is little deterioration in drawing performance. When the lens surface is an aspheric surface, the aspheric surface is an aspheric surface by grinding, a glass mold aspheric surface made of glass with an aspheric shape, or a composite aspheric surface made of resin with an aspheric shape on the glass surface. Any aspherical surface may be used. The lens surface may be a diffractive surface, and the lens may be a gradient index lens (GRIN lens) or a plastic lens.

  The aperture stop S is preferably arranged in the vicinity of the third lens group G3. However, the role of the aperture stop may be substituted by a lens frame without providing a member as an aperture stop.

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

  The variable magnification optical system ZL of the present embodiment has a variable magnification ratio of about 2.5 to 4 times.

  Hereinafter, an outline of a method for manufacturing the variable magnification optical system ZL according to the present embodiment will be described with reference to FIG. First, the first to fourth lens groups G1 to G4 are prepared by arranging each lens (step S100). Further, upon zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group G1 and the second lens group G2 changes, and the distance between the second lens group G2 and the third lens group G3 changes. The third lens group G3 and the fourth lens group G4 are arranged so that the distance between them changes (step S200). Further, the third lens group G3 includes an intermediate group G3b having a positive lens, a negative lens, a negative lens, and a positive lens disposed from the object side, and a negative lens disposed on the image plane side from the intermediate group G3b. An image side group G3c having refracting power, and at the time of focusing, the intermediate group G3b is fixed in position with respect to the image plane, and is arranged so that the image side group G3c moves along the optical axis (step) S300).

  Specifically, in this embodiment, for example, as shown in FIG. 1, 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 are cemented in order from the object side. A cemented lens is arranged to form the first lens group G1, a negative lens L21 having a spherical surface formed by providing a resin layer on the object-side lens surface of a negative meniscus lens having a convex surface facing the object side, and a biconcave lens L22. A cemented lens obtained by cementing the biconvex lens L23, a positive meniscus lens L24 having a concave surface facing the object side, and a negative lens L25 having a concave surface facing the object side and an image surface side lens surface formed in an aspheric shape. The cemented lens is disposed to form the second lens group G2, and the positive lens L31, the biconvex lens L32, and the biconcave lens L33, in which the object-side and image-side lens surfaces are formed in an aspheric shape, are joined. The cemented lens, the cemented lens in which the biconcave lens L34 and the biconvex lens L35 are cemented, the positive lens L36 in which the object-side and image-side lens surfaces are formed in an aspherical shape, and the negative meniscus with the convex surface facing the object side. A lens L37 is disposed to form a third lens group G3, and a positive lens L41 having an object-side lens surface formed in an aspheric shape is disposed to form a fourth lens group G4. The lens groups thus prepared are arranged in the above-described procedure to manufacture the variable magnification optical system ZL.

  Hereinafter, each example of the present application will be described with reference to the drawings. 1, FIG. 4, FIG. 7, FIG. 10 and FIG. 13 are cross-sectional views showing the configuration and refractive power distribution of the variable magnification optical system ZL (ZL1 to ZL5) according to each example. Further, in the lower part of the sectional views of these zoom optical systems ZL1 to ZL5, along the optical axes of the lens groups G1 to G4 when zooming from the wide-angle end state (W) to the telephoto end state (T) The direction of movement is indicated by an arrow.

In each embodiment, the height of the aspheric surface in the direction perpendicular to the optical axis is y, and the distance (sag amount) along the optical axis from the tangential plane of the apex of each aspheric surface to each aspheric surface at height y. Is S (y), r is the radius of curvature of the reference sphere (paraxial radius of curvature), K is the conic constant, and An is the nth-order aspherical coefficient, it is expressed by the following equation (a). . In the following examples, “E−n” indicates “× 10 ⁻ⁿ ”.

S (y) = (y ² / r) / {1+ (1−K × y ² / r ² ) ^1/2 }
+ A4 × y ⁴ + A6 × y ⁶ + A8 × y ⁸ + A10 × y ¹⁰ + A12 × y ¹² (a)

  In each embodiment, the secondary aspheric coefficient A2 is zero. In the table of each example, an aspherical surface is marked with * on the right side of the surface number.

[First embodiment]
FIG. 1 is a diagram showing a configuration of a variable magnification optical system ZL1 according to the first example. The variable magnification optical system ZL1 shown in FIG. 1 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. And a fourth lens group G4 having a positive refractive power.

  In the zoom optical system ZL1, the first lens group G1 is a cemented lens in which, in order from the object side, 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 are cemented. It is configured. The second lens group G2 includes, in order from the object side, a negative lens L21 in which an aspherical shape is formed by providing a resin layer on a lens surface on the object side of a negative meniscus lens having a convex surface facing the object side, and a biconcave lens L22. And a negative lens L25 having a concave surface facing the object side and a concave surface facing the object side, and a lens surface on the image side formed in an aspherical shape. It is comprised with the cemented lens which joined. The third lens group G3 includes, in order from the object side, a positive lens L31 in which the object-side and image-side lens surfaces are formed in an aspheric shape, a cemented lens in which a biconvex lens L32 and a biconcave lens L33 are cemented, The lens is composed of a cemented lens obtained by cementing a concave lens L34 and a biconvex lens L35, a positive lens L36 in which object-side and image-side lens surfaces are formed in an aspherical shape, and a negative meniscus lens L37 having a convex surface facing the object side. ing. The fourth lens group G4 is composed of a positive lens L41 having an aspheric lens surface on the object side. An aperture stop S is disposed between the second lens group G2 and the third lens group G3. A filter group FL having a low-pass filter, an infrared filter, and the like is disposed between the fourth lens group G4 and the image plane I. The negative lens L25, the positive lens L31, the positive lens L36, and the positive lens L41 are glass molded aspheric lenses.

  In the variable magnification optical system ZL1, the distance between the first lens group G1 and the second lens group G2 increases during the magnification change from the wide-angle end state to the telephoto end state, and the second lens group G2 and the third lens group G3. After the first lens group G1 and the second lens group G2 are moved to the image plane side so that the distance between the first lens group G3 and the fourth lens group G4 increases, the object side The third lens group G3 is moved to the object side, the fourth lens group G4 is once moved to the object side, and is then moved to the image plane side. The aperture stop S moves integrally with the third lens group G3.

  In the variable magnification optical system ZL1, focusing from an infinite distance to a close object is performed by moving the image side group G3c included in the third lens group G3 to the image plane side.

  Table 1 below lists values of specifications of the variable magnification optical system ZL1. In Table 1, f shown in the overall specifications is the focal length of the entire system, FNO is the F number, 2ω is the field angle, Y is the maximum image height, TL is the total length, and BF is the back focus value. This is shown for each state, intermediate focal length state, and telephoto end state. Here, the total length TL indicates the distance (air conversion length) on the optical axis from the most object side lens surface (first surface in FIG. 1) to the image plane I at the time of infinite focusing. Further, the back focus BF indicates the distance (air conversion length) on the optical axis from the most image side lens surface (the 27th surface in FIG. 1) to the image surface I at the time of focusing on infinity. In the lens data, the first column m indicates the order (surface number) of the lens surfaces from the object side along the traveling direction of the light beam, the second column r indicates the curvature radius of each lens surface, and the third column. d is the distance on the optical axis from each optical surface to the next optical surface (surface interval), the fourth column νd and the fifth column nd are the Abbe number and the refractive index with respect to the d-line (λ = 587.6 nm). Is shown. Further, the radius of curvature of 0.000 indicates a plane, and the refractive index of air of 1.0000 is omitted. The surface numbers 1 to 33 shown in Table 1 correspond to the numbers 1 to 33 shown in FIG. The lens group focal length indicates the start surface and focal length of each of the first to fourth lens groups G1 to G4.

  Here, the focal length f, the radius of curvature r, the surface interval d, and other length units listed in all the following specification values are generally “mm”, but the optical system is proportionally enlarged or proportional. Since the same optical performance can be obtained even if the image is reduced, the present invention is not limited to this. The description of these symbols and the description of the specification table are the same in the following embodiments.

(Table 1) First Example [Overall Specifications]
Zoom ratio = 3.14
Wide-angle end state Intermediate focal length state Telephoto end state f = 9.3 to 19.1 to 29.1
FNO = 1.8 to 2.5 to 2.9
2ω = 85.1 to 44.7 to 29.8
Y == 8.0-8.0-8.0
TL (air equivalent length) = 95.9 to 101.1 to 114.1
BF (air equivalent length) = 13.8 to 18.9 to 18.4

[Lens data]
m r d νd nd
Object ∞
1 52.520 1.60 17.98 1.94595
2 38.097 6.31 46.60 1.80400
3 299.948 D3
4 * 4632.762 0.20 36.64 1.56093
5 105.387 1.51 40.66 1.88300
6 11.700 6.42
7 -78.778 4.04 54.61 1.72916
8 44.775 3.44 23.78 1.84666
9 -31.132 1.04
10 -18.713 2.38 30.13 1.69895
11 -13.113 0.90 40.10 1.85135
12 * -35.882 D12
13 0.000 0.80 Aperture stop S
14 21.574 3.26 71.67 1.55332
15 * -59.840 0.30
16 35.781 4.78 23.78 1.84666
17 -14.139 0.80 28.38 1.72825
18 24.505 2.16
19 -28.756 1.50 22.74 1.80809
20 24.289 4.30 82.57 1.49782
21 -14.921 0.50
22 * 24.289 2.68 81.49 1.49710
23 * -70.000 D23
24 34.328 0.80 82.57 1.49782
25 16.185 D25
26 * 28.150 2.21 81.49 1.49710
27 254.991 D27
28 0.000 0.50 63.88 1.51680
29 0.000 1.11
30 0.000 1.59 63.88 1.51680
31 0.000 0.30
32 0.000 0.70 63.88 1.51680
33 0.000 0.70

[Lens focal length]
Lens group Start surface Focal length first lens group 1 84.50
Second lens group 4 -13.26
Third lens group 14 22.97
Fourth lens group 26 63.45

  In the zoom optical system ZL1, the fourth surface, the twelfth surface, the fourteenth surface, the fifteenth surface, the twenty-second surface, the twenty-third surface, and the twenty-sixth surface are formed in an aspheric shape. The following Table 2 shows aspheric data, that is, the values of the conic constant K and the aspheric constants A4 to A10.

(Table 2)
[Aspherical data]
K A4 A6 A8 A10
4th surface 0 4.41073E-05 -1.57931E-07 4.69697E-10 -7.44801E-13
12th surface 0 -1.20350E-05 -8.15569E-08 3.91594E-10 -3.58987E-12
14th face 0 -3.13883E-06 -1.57686E-08 -1.08799E-09 0.00000E + 00
15th face 0 5.63460E-05 4.70520E-09 0.00000E + 00 0.00000E + 00
Side 22 0 -1.41390E-05 -4.37524E-07 0.00000E + 00 0.00000E + 00
23rd face 0 -5.50201E-07 -4.06545E-07 -1.23018E-09 1.33941E-11
26th face 0 4.04787E-06 -4.49391E-08 2.97650E-10 0.00000E + 00

  In this variable magnification optical system ZL1, the axial air distance D3 between the first lens group G1 and the second lens group G2, and the axial air distance D12 between the second lens group G2 and the third lens group G3 (aperture stop S). As described above, the axial air gap D25 between the third lens group G3 and the fourth lens group G4 and the axial air gap D27 between the fourth lens group G4 and the filter group FL change during zooming. . Further, the object-side axial air distance D23 and the image-side axial air distance D25 of the image side group G3c of the third lens group G3 change upon focusing. Table 3 below shows variable intervals in each of the focal length states of the wide-angle end state, the intermediate focal length state, and the telephoto end state when focusing on infinity and focusing on a short distance. Note that only the values of D23 and D25 are shown at the time of focusing at a short distance, but other values are the same as at the time of focusing at infinity.

(Table 3)
[Variable interval data]
When focusing at infinity When focusing at close range Wide-angle end Medium telephoto end Wide-angle end Medium telephoto end f 9.3 19.1 29.1 9.3 19.1 29.1
D3 1.2 13.4 23.6
D12 21.4 5.4 1.5
D23 1.50 1.50 1.50 2.42 3.64 5.44
D25 5.20 8.94 16.23 4.28 6.80 12.30
D27 9.8 15.0 14.5

  Table 4 below shows values corresponding to the conditional expressions in the variable magnification optical system ZL1. In Table 4, f2 is the focal length of the second lens group G2, f4 is the focal length of the fourth lens group G4, fw is the focal length of the entire system in the wide-angle end state, and ft is the entire system in the telephoto end state. NdF is the refractive index with respect to the d-line of the medium of the negative lens included in the image side group G3c in the third lens group G3, and νdF is the refractive index of the negative lens included in the image side group G3c in the third lens group G3. ΝdO represents the Abbe number of the medium, and Abd number of the positive lens included in the object side group G3a of the third lens group G3. The description of the reference numerals is the same in the following embodiments. In the first example, the negative lens included in the image side group G3c in the third lens group G3 is a negative meniscus lens L37, and the positive lens included in the object side group G3a of the third lens group G3 is This is the positive lens L31.

(Table 4)
[Conditional expression values]
(1) (−f2) / (fw × ft) ^1/2 = 0.807
(2) ndF−0.0052 × νdF−1.965 = −0.038
(3) νdF = 82.6
(4) νdO = 71.7
(5) f4 / fw = 6.85

  As described above, the variable magnification optical system ZL1 satisfies all the conditional expressions (1) to (5).

  FIG. 2 is a spherical aberration diagram, astigmatism diagram, distortion diagram, magnification chromatic aberration diagram, and coma aberration diagram of the variable magnification optical system ZL1 in the wide-angle end state, the intermediate focal length state, and the telephoto end state at the time of focusing on infinity. FIG. 3 shows a spherical aberration diagram, an astigmatism diagram, a distortion diagram, a chromatic aberration diagram, and a coma aberration diagram in the wide-angle end state, the intermediate focal length state, and the telephoto end state at the time of focusing at a short distance. In each aberration diagram, FNO represents an F number, NA represents a numerical aperture, and Y represents an image height. The spherical aberration diagram at the time of focusing on infinity shows the F-number value corresponding to the maximum aperture, the spherical aberration diagram at the time of focusing at close distance shows the value of the numerical aperture corresponding to the maximum aperture, and the astigmatism diagram. In the distortion diagram, the maximum value of the image height is shown, and in the coma diagram, the value of each image height is shown. d represents a d-line (λ = 587.6 nm), and g represents a g-line (λ = 435.8 nm). In the astigmatism diagram, the solid line indicates the sagittal image plane, and the broken line indicates the meridional image plane. Also, in the aberration diagrams of the respective examples shown below, the same reference numerals as those of the present example are used. From these aberration diagrams, it is understood that various aberrations are satisfactorily corrected from the wide-angle end state to the telephoto end state in the variable magnification optical system ZL1.

[Second Embodiment]
FIG. 4 is a diagram showing a configuration of the variable magnification optical system ZL2 according to the second example. The zoom optical system ZL2 shown in FIG. 4 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. And a fourth lens group G4 having a positive refractive power.

  In the variable magnification optical system ZL2, the first lens group G1 is a cemented lens in which, in order from the object side, 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 are cemented. It is configured. The second lens group G2 includes, in order from the object side, a negative lens L21 in which an aspherical shape is formed by providing a resin layer on a lens surface on the object side of a negative meniscus lens having a convex surface facing the object side, and a biconcave lens L22. A cemented lens in which a biconvex lens L23, a positive meniscus lens L24 having a concave surface facing the object side, and a negative lens L25 having a concave surface facing the object side and an image surface side lens surface formed in an aspherical shape are cemented. It is configured. The third lens group G3 includes, in order from the object side, a positive lens L31 in which the object-side and image-side lens surfaces are formed in an aspheric shape, a cemented lens in which a biconvex lens L32 and a biconcave lens L33 are cemented, The lens is composed of a cemented lens obtained by cementing a concave lens L34 and a biconvex lens L35, a positive lens L36 in which object-side and image-side lens surfaces are formed in an aspherical shape, and a negative meniscus lens L37 having a convex surface facing the object side. ing. The fourth lens group G4 is composed of a positive lens L41 having an aspheric lens surface on the object side. An aperture stop S is disposed between the second lens group G2 and the third lens group G3. A filter group FL having a low-pass filter, an infrared filter, and the like is disposed between the fourth lens group G4 and the image plane I. The negative lens L25, the positive lens L31, the positive lens L36, and the positive lens L41 are glass molded aspheric lenses.

  In the variable magnification optical system ZL2, the distance between the first lens group G1 and the second lens group G2 increases during the magnification change from the wide-angle end state to the telephoto end state, and the second lens group G2 and the third lens group G3. After the first lens group G1 and the second lens group G2 are moved to the image plane side so that the distance between the first lens group G3 and the fourth lens group G4 increases, the object side The third lens group G3 is moved to the object side, the fourth lens group G4 is once moved to the object side, and is then moved to the image plane side. The aperture stop S moves integrally with the third lens group G3.

  In the variable magnification optical system ZL2, focusing from an infinite distance to a close object is performed by moving the image side group G3c included in the third lens group G3 to the image plane side.

  Table 5 below lists values of specifications of the variable magnification optical system ZL2. The surface numbers 1 to 34 shown in Table 5 correspond to the numbers 1 to 34 shown in FIG.

(Table 5) Second Example [Overall Specifications]
Zoom ratio = 3.13
Wide-angle end state Intermediate focal length state Telephoto end state f = 9.3 to 19.1 to 29.1
FNO = 1.8 to 2.5 to 2.9
2ω = 85.2 to 44.9 to 30.1
Y = 8.0 to 8.0 to 8.0
TL (air equivalent length) = 95.4 to 100.7 to 112.1
BF (Air equivalent length) = 13.8 to 18.7 to 19.8

[Lens data]
m r d νd nd
Object ∞
1 49.101 1.60 17.98 1.94595
2 35.955 6.34 46.60 1.80400
3 238.109 D3
4 * 32230.587 0.20 36.64 1.56093
5 92.951 1.51 40.66 1.88300
6 11.709 6.33
7 -61.701 1.00 54.61 1.72916
8 40.995 0.94
9 38.612 4.05 23.78 1.84666
10 -35.701 1.00
11 -18.790 2.40 31.16 1.68893
12 -13.145 1.00 40.10 1.85135
13 * -31.982 D13
14 0.000 0.80 Aperture stop S
15 * 22.706 3.20 71.68 1.55332
16 * -58.429 0.30
17 46.573 5.34 23.78 1.84666
18 -12.743 0.90 28.38 1.72825
19 35.112 1.91
20 -28.666 1.21 22.74 1.80809
21 24.685 4.43 82.57 1.49782
22 -15.272 0.50
23 * 24.333 2.63 81.56 1.49710
24 * -70.000 D24
25 43.446 0.80 63.88 1.51680
26 15.925 D26
27 * 24.203 2.37 81.56 1.49710
28 220.780 D28
29 0.000 0.50 63.88 1.51680
30 0.000 1.11
31 0.000 1.59 63.88 1.51680
32 0.000 0.30
33 0.000 0.70 63.88 1.51680
34 0.000 0.70

[Lens focal length]
Lens group Start surface Focal length First lens group 1 81.70
Second lens group 4 -13.37
Third lens group 15 23.47
Fourth lens group 27 54.46

  In the variable magnification optical system ZL2, the fourth surface, the thirteenth surface, the fifteenth surface, the sixteenth surface, the twenty-third surface, the twenty-fourth surface, and the twenty-seventh surface are formed in an aspherical shape. Table 6 below shows the aspheric data, that is, the values of the conic constant K and the aspheric constants A4 to A10.

(Table 6)
[Aspherical data]
K A4 A6 A8 A10
4th surface 0 4.81180E-05 -1.64047E-07 4.26213E-10 -5.47014E-13
13th surface 0 -8.45829E-06 2.53106E-08 -1.62200E-09 1.06953E-11
15th face 0 -8.35604E-06 3.00666E-08 -1.56105E-09 0.00000E + 00
16th face 0 4.98849E-05 4.71546E-08 0.00000E + 00 0.00000E + 00
Side 23 0 -1.46890E-05 -3.34594E-07 0.00000E + 00 0.00000E + 00
24th face 0 3.77210E-07 -3.15609E-07 -1.42238E-09 1.85664E-11
27th face 0 -9.43792E-07 -4.37993E-08 2.66683E-10 0.00000E + 00

  In the variable magnification optical system ZL2, the axial air distance D3 between the first lens group G1 and the second lens group G2, and the axial air distance D13 between the second lens group G2 and the third lens group G3 (aperture stop S). As described above, the axial air gap D26 between the third lens group G3 and the fourth lens group G4 and the axial air gap D28 between the fourth lens group G4 and the filter group FL change during zooming. . Further, the on-axis air space D24 on the object side and the on-axis air space D26 on the image plane side of the image side group G3c of the third lens group G3 change upon focusing. Table 7 below shows variable intervals in each of the focal length states of the wide-angle end state, the intermediate focal length state, and the telephoto end state when focusing on infinity and focusing on a short distance. Note that only the values of D24 and D26 are shown at the time of focusing at a short distance, but other values are the same as at the time of focusing at infinity.

(Table 7)
[Variable interval data]
When focusing at infinity When focusing at close range Wide-angle end Medium telephoto end Wide-angle end Medium telephoto end f 9.3 19.1 29.1 9.3 19.1 29.1
D3 1.2 13.9 23.2
D13 22.0 6.1 1.5
D24 1.50 1.50 1.50 2.21 3.19 4.68
D26 5.20 8.78 14.40 4.48 7.10 11.22
D28 9.8 14.8 15.9

  Table 8 below shows values corresponding to the conditional expressions in the variable magnification optical system ZL2. In the second example, the negative lens included in the image side group G3c in the third lens group G3 is a negative meniscus lens L37, and the positive lens included in the object side group G3a of the third lens group G3 is This is the positive lens L31.

(Table 8)
[Conditional expression values]
(1) (−f2) / (fw × ft) ^1/2 = 0.814
(2) ndF−0.0052 × νdF−1.965 = −0.116
(3) νdF = 63.9
(4) νdO = 71.7
(5) f4 / fw = 5.88

  Thus, this variable magnification optical system ZL2 satisfies all the conditional expressions (1) to (5).

  FIG. 5 shows spherical aberration diagrams, astigmatism diagrams, distortion diagrams, magnification chromatic aberration diagrams, and coma aberration diagrams of the variable magnification optical system ZL2 in the wide-angle end state, the intermediate focal length state, and the telephoto end state when focusing on infinity. FIG. 6 shows a spherical aberration diagram, an astigmatism diagram, a distortion diagram, a chromatic aberration diagram, and a coma diagram in the wide-angle end state, the intermediate focal length state, and the telephoto end state at the time of focusing at a short distance. From these aberration diagrams, it is understood that various aberrations are satisfactorily corrected from the wide-angle end state to the telephoto end state in the variable magnification optical system ZL2.

[Third embodiment]
FIG. 7 is a diagram showing a configuration of the variable magnification optical system ZL3 according to the third example. The variable magnification optical system ZL3 shown in FIG. 7 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. And a fourth lens group G4 having a positive refractive power.

  In the variable magnification optical system ZL3, the first lens group G1 is a cemented lens in which, from the object side, 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 are cemented. It is configured. Further, the second lens group G2, in order from the object side, has a negative lens L21 in which a convex surface is directed toward the object side, the lens surfaces on the object side and the image surface side are formed in an aspheric shape, and a negative surface in which a concave surface is directed toward the object side. The lens includes a meniscus lens L22, a cemented lens in which a biconcave lens L23 and a biconvex lens L24 are cemented, and a negative lens L25 in which a concave surface is directed to the object side and an image surface side lens surface is formed in an aspherical shape. The third lens group G3 includes, in order from the object side, a positive lens L31 in which the object-side and image-side lens surfaces are formed in an aspheric shape, a cemented lens in which a biconvex lens L32 and a biconcave lens L33 are cemented, A cemented lens in which a concave lens L34 and a biconvex lens L35 are cemented, a cemented positive lens in which a negative meniscus lens L36 having a convex surface facing the object side, and a positive lens L37 in which the lens surface on the image surface side is formed in an aspherical shape; In addition, the lens includes a negative lens L38 having a convex surface facing the object side and an aspheric lens surface on the image plane side. The fourth lens group G4 includes a positive meniscus lens L41 having a convex surface directed toward the object side. An aperture stop S is disposed between the second lens group G2 and the third lens group G3. A filter group FL having a low-pass filter, an infrared filter, and the like is disposed between the fourth lens group G4 and the image plane I. The negative lens L21, the negative lens L25, the positive lens L31, the negative lens L36, and the positive lens L37 are glass molded aspheric lenses.

  In the variable magnification optical system ZL3, the distance between the first lens group G1 and the second lens group G2 increases during the magnification change from the wide-angle end state to the telephoto end state, and the second lens group G2 and the third lens group G3. After the first lens group G1 and the second lens group G2 are moved to the image plane side so that the distance between the first lens group G3 and the fourth lens group G4 increases, the object side The third lens group G3 is moved to the object side, the fourth lens group G4 is once moved to the object side, and is then moved to the image plane side. The aperture stop S moves integrally with the third lens group G3.

  In the variable magnification optical system ZL3, focusing from an infinite distance to a close object is performed by moving the image side group G3c included in the third lens group G3 to the image plane side.

  Table 9 below provides values of specifications of the variable magnification optical system ZL3. The surface numbers 1 to 35 shown in Table 9 correspond to the numbers 1 to 35 shown in FIG.

(Table 9) Third Example [Overall Specifications]
Zoom ratio = 3.12
Wide-angle end state Intermediate focal length state Telephoto end state f = 9.3 to 19.1 to 29.1
FNO = 1.8 to 2.3 to 2.6
2ω = 84.3 to 45.3 to 30.7
Y = 8.0 to 8.0 to 8.0
TL (air equivalent length) = 93.4 to 99.2 to 110.9
BF (air equivalent length) = 13.7 to 21.1 to 21.5

[Lens data]
m r d νd nd
Object ∞
1 43.371 1.60 17.98 1.94595
2 32.926 6.90 45.31 1.79500
3 140.257 D3
4 * 175.520 1.50 42.65 1.82080
5 * 10.809 7.48
6 -15.455 0.92 29.14 2.00100
7 -20.858 0.28
8 -101.287 0.80 46.60 1.80400
9 38.949 0.00
10 36.831 4.78 23.78 1.84666
11 -25.842 0.94
12 -14.557 0.92 45.46 1.80139
13 * -25.880 D13
14 0.000 1.20 Aperture stop S
15 * 18.690 3.57 81.56 1.497103
16 * -63.173 0.78
17 42.863 3.79 22.74 1.80809
18 -17.820 1.00 28.69 1.79504
19 28.455 2.21
20 -54.464 0.90 22.74 1.80809
21 34.705 4.33 82.57 1.49782
22 -16.135 0.50
23 21.394 0.80 29.14 2.00 100
24 17.003 3.74 71.67 1.55332
25 * -60.926 D25
26 29.947 0.80 81.49 1.49710
27 * 14.925 D27
28 29.674 1.90 82.57 1.49782
29 96.000 D29
30 0.000 0.50 63.88 1.51680
31 0.000 1.11
32 0.000 1.59 63.88 1.51680
33 0.000 0.30
34 0.000 0.70 63.88 1.51680
35 0.000 0.70

[Lens focal length]
Lens group Start surface Focal length 1st lens group 1 82.51
Second lens group 4 -11.97
Third lens group 15 21.69
Fourth lens group 28 85.46

  In the variable magnification optical system ZL3, the fourth surface, the fifth surface, the thirteenth surface, the fifteenth surface, the sixteenth surface, the twenty-fifth surface, and the twenty-seventh surface are formed in an aspheric shape. Table 10 below shows the aspheric data, that is, the values of the conic constant K and the aspheric constants A4 to A12.

(Table 10)
[Aspherical data]
K A4 A6 A8 A10 A12
4th surface 0 6.79E-05 -4.38E-07 3.57E-09 -1.72E-11 3.66E-14
5th surface 0 3.02E-05 -1.77E-07 2.51E-09 2.36E-11 0.00E + 00
13th surface 0 -1.03E-05 -1.42E-07 2.00E-09 -1.18E-11 0.00E + 00
15th surface 0 1.60E-05 1.53E-08 4.77E-09 0.00E + 00 0.00E + 00
16th surface 0 9.01E-05 4.44E-09 5.55E-09 0.00E + 00 0.00E + 00
25th surface 0 2.01E-05 -2.52E-07 4.90E-09 -3.50E-11 0.00E + 00
27th face 0 -1.52E-05 2.25E-07 -5.15E-09 4.70E-11 0.00E + 00

  In the zoom optical system ZL3, the axial air distance D3 between the first lens group G1 and the second lens group G2, and the axial air distance D13 between the second lens group G2 and the third lens group G3 (aperture stop S). As described above, the axial air gap D27 between the third lens group G3 and the fourth lens group G4 and the axial air gap D29 between the fourth lens group G4 and the filter group FL change during zooming. . In addition, the on-axis air space D25 on the object side and the on-axis air space D27 on the image plane side of the image side group G3c of the third lens group G3 change during focusing. Table 11 below shows variable intervals in the respective focal length states of the wide-angle end state, the intermediate focal length state, and the telephoto end state when focusing on infinity and focusing on a short distance. Note that only the values of D25 and D27 are shown at the time of focusing at a short distance, but other values are the same as at the time of focusing at infinity.

(Table 11)
[Variable interval data]
When focusing at infinity When focusing at close range Wide-angle end Intermediate telephoto end Wide-angle end Intermediate telephoto end f 9.3 19.0 29.1 9.3 19.0 29.1
D3 1.0 13.9 23.9
D13 19.2 4.9 1.2
D25 1.60 1.60 1.60 2.52 4.05 5.19
D27 5.20 5.20 10.08 4.38 2.75 6.49
D29 9.8 17.2 17.5

  Table 12 below shows values corresponding to the conditional expressions in the variable magnification optical system ZL3. In the third example, the negative lens included in the image side group G3c in the third lens group G3 is the negative lens L38, and the positive lens included in the object side group G3a of the third lens group G3 is positive. This is the lens L31.

(Table 12)
[Conditional expression values]
(1) (−f2) / (fw × ft) ^1/2 = 0.736
(2) ndF−0.0052 × νdF−1.965 = −0.044
(3) νdF = 81.5
(4) νdO = 81.6
(5) f4 / fw = 9.22

  Thus, the zoom optical system ZL3 satisfies all the conditional expressions (1) to (5).

  FIG. 8 shows a spherical aberration diagram, an astigmatism diagram, a distortion diagram, a chromatic aberration diagram, and a coma diagram in the wide-angle end state, the intermediate focal length state, and the telephoto end state of the variable magnification optical system ZL3 when focusing on infinity. 9 shows a spherical aberration diagram, an astigmatism diagram, a distortion diagram, a chromatic aberration diagram, and a coma diagram in the wide-angle end state, the intermediate focal length state, and the telephoto end state when focusing on a short distance. From these respective aberration diagrams, it can be seen that various aberrations are satisfactorily corrected from the wide-angle end state to the telephoto end state in the variable magnification optical system ZL3.

[Fourth embodiment]
FIG. 10 is a diagram illustrating a configuration of the variable magnification optical system ZL4 according to the fourth example. The variable magnification optical system ZL4 shown in FIG. 10 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. And a fourth lens group G4 having a positive refractive power.

  In the variable magnification optical system ZL4, the first lens group G1 is a cemented lens in which, in order from the object side, 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 are cemented. It is configured. The second lens group G2 includes, in order from the object side, a negative lens L21 having a convex surface directed toward the object side and an object-side lens surface formed in an aspherical shape, a cemented lens of a biconcave lens L22 and a biconvex lens L23, In addition, it is composed of a cemented lens of a positive meniscus lens L24 having a concave surface facing the object side and a negative lens L25 having a concave surface facing the object side and a lens surface on the image side formed in an aspherical shape. The third lens group G3 includes, in order from the object side, a positive lens L31 in which the object-side and image-side lens surfaces are formed in an aspheric shape, a cemented lens in which a biconvex lens L32 and a biconcave lens L33 are cemented, The lens includes a cemented lens in which a concave lens L34 and a biconvex lens L35 are cemented, a positive lens L36 having an aspheric lens surface on the image side, and a negative meniscus lens L37 having a convex surface facing the object side. The fourth lens group G4 includes a positive lens L41 having a convex surface directed toward the object side and an object-side lens surface formed in an aspherical shape. An aperture stop S is disposed between the second lens group G2 and the third lens group G3. A filter group FL having a low-pass filter, an infrared filter, and the like is disposed between the fourth lens group G4 and the image plane I. The negative lens L21, the negative lens L25, the positive lens L31, the positive lens L36, and the positive lens L41 are glass mold aspheric lenses.

  In the zoom optical system ZL4, when zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group G1 and the second lens group G2 increases, and the second lens group G2 and the third lens group G3. After the first lens group G1 and the second lens group G2 are moved to the image plane side so that the distance between the first lens group G3 and the fourth lens group G4 increases, the object side The third lens group G3 is moved to the object side, the fourth lens group G4 is once moved to the object side, and is then moved to the image plane side. The aperture stop S moves integrally with the third lens group G3.

  In the variable magnification optical system ZL4, focusing from an infinite distance to a close object is performed by moving the image side group G3c included in the third lens group G3 to the image plane side.

  Table 13 below provides values of specifications of the variable magnification optical system ZL4. In addition, the surface numbers 1-32 shown in Table 13 respond | correspond to the numbers 1-32 shown in FIG.

(Table 13) Fourth Example [Overall Specifications]
Zoom ratio = 3.13
Wide-angle end state Intermediate focal length state Telephoto end state f = 9.26 to 19.1 to 29.1
FNO = 1.8 to 2.3 to 2.6
2ω = 85.1 to 45.0 to 29.9
Y = 8.0 to 8.0 to 8.0
TL (air equivalent length) = 93.2 to 98.8 to 110.7
BF (Air equivalent length) = 13.71 to 19.12 to 20.67

[Lens data]
m r d νd nd
Object ∞
1 47.558 1.60 17.98 1.94595
2 35.327 6.23 46.60 1.80400
3 222.036 D3
4 * 5814.989 1.61 40.10 1.85135
5 11.700 6.30
6 -90.767 1.94 49.62 1.77250
7 47.951 3.78 23.78 1.84666
8 -36.068 1.81
9 -14.307 2.06 22.74 1.80809
10 -12.194 0.90 45.46 1.80139
11 * -25.687 D11
12 0.000 0.80 Aperture stop S
13 * 16.293 3.67 67.05 1.59201
14 * -77.139 0.30
15 70.431 3.48 25.45 1.80518
16 -16.780 0.80 33.73 1.64769
17 24.325 2.59
18 -33.946 1.09 25.45 1.80518
19 18.705 4.24 82.57 1.49782
20 -16.422 0.50
21 21.829 2.84 81.49 1.49710
22 * -60.000 D22
23 113.472 0.80 82.57 1.49782
24 22.646 D24
25 * 26.180 2.35 81.49 1.49710
26 607.278 D26
27 0.000 0.50 63.88 1.51680
28 0.000 1.11
29 0.000 1.59 63.88 1.51680
30 0.000 0.30
31 0.000 0.70 63.88 1.51680
32 0.000 0.70

[Lens focal length]
Lens group Start surface Focal length First lens group 1 79.52
Second lens group 4 -12.62
Third lens group 13 22.96
Fourth lens group 25 54.96

  In the variable magnification optical system ZL4, the fourth surface, the eleventh surface, the thirteenth surface, the fourteenth surface, the twenty-second surface, and the twenty-fifth surface are formed in an aspherical shape. Table 14 below shows the aspheric data, that is, the values of the conic constant K and the aspheric constants A4 to A10.

(Table 14)
[Aspherical data]
K A4 A6 A8 A10
4th surface 0 3.94307E-05 -1.29628E-07 3.43564E-10 -3.78498E-13
11th surface 0 -1.30254E-05 -1.98133E-08 -6.57557E-10 4.01106E-12
13th face 0 -3.22653E-06 1.73408E-07 -7.04126E-11 0.00000E + 00
14th surface 0 7.18116E-05 1.79256E-07 0.00000E + 00 0.00000E + 00
Side 22 0 1.05439E-05 2.55453E-08 8.37397E-10 -1.64088E-12
25th surface 0 -1.35591E-05 1.71835E-07 -3.32810E-09 2.04907E-11

  In the variable magnification optical system ZL4, the axial air distance D3 between the first lens group G1 and the second lens group G2, and the axial air distance D11 between the second lens group G2 and the third lens group G3 (aperture stop S). As described above, the axial air gap D24 between the third lens group G3 and the fourth lens group G4 and the axial air gap D26 between the fourth lens group G4 and the filter group FL change during zooming. . Further, the object-side axial air distance D22 and the image-side axial air distance D24 of the image side group G3c of the third lens group G3 change during focusing. Table 15 below shows variable intervals in each of the focal length states of the wide-angle end state, the intermediate focal length state, and the telephoto end state when focusing on infinity and focusing on a short distance. Note that only the values of D22 and D24 are shown at the time of focusing at a short distance, but other values are the same as at the time of focusing at infinity.

(Table 15)
[Variable interval data]
When focusing at infinity When focusing at close range Wide-angle end Medium telephoto end Wide-angle end Medium telephoto end f 9.3 19.1 29.1 9.3 19.1 29.1
D3 1.0 13.9 23.9
D11 19.2 4.9 1.2
D22 1.60 1.60 1.60 2.44 3.60 5.50
D24 5.20 9.06 13.43 4.36 7.06 9.53
D26 9.8 17.2 17.5

  Table 16 below shows values corresponding to the conditional expressions in the variable magnification optical system ZL4. In the fourth example, the negative lens included in the image side group G3c of the third lens group G3 is a negative meniscus lens L37, and the positive lens included in the object side group G3a of the third lens group G3 is This is the positive lens L31.

(Table 16)
[Conditional expression values]
(1) (−f2) / (fw × ft) ^1/2 = 0.769
(2) ndF−0.0052 × νdF−1.965 = −0.038
(3) νdF = 82.6
(4) νdO = 67.1
(5) f4 / fw = 5.94

  Thus, this variable magnification optical system ZL4 satisfies all the conditional expressions (1) to (5).

  FIG. 11 shows spherical aberration diagrams, astigmatism diagrams, distortion diagrams, magnification chromatic aberration diagrams, and coma aberration diagrams of the variable magnification optical system ZL4 in the wide-angle end state, the intermediate focal length state, and the telephoto end state at the time of focusing on infinity. 12 shows a spherical aberration diagram, an astigmatism diagram, a distortion diagram, a chromatic aberration diagram, and a coma diagram in the wide-angle end state, the intermediate focal length state, and the telephoto end state at the time of focusing at a short distance. From these aberration diagrams, it is understood that various aberrations are satisfactorily corrected from the wide-angle end state to the telephoto end state in the variable magnification optical system ZL4.

[Fifth embodiment]
FIG. 13 is a diagram showing a configuration of a variable magnification optical system ZL5 according to the fifth example. The variable magnification optical system ZL5 shown in FIG. 13 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. And a fourth lens group G4 having a positive refractive power.

  In the zoom optical system ZL5, the first lens group G1 is a cemented lens in which, in order from the object side, 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 are cemented. It is configured. The second lens group G2 includes, in order from the object side, a negative lens L21 in which an aspherical shape is formed by providing a resin layer on a lens surface on the object side of a negative meniscus lens having a convex surface facing the object side, and a biconcave lens L22. A cemented lens in which a biconvex lens L23, a positive meniscus lens L24 having a concave surface facing the object side, and a negative lens L25 having a concave surface facing the object side and an image surface side lens surface formed in an aspherical shape are cemented. It is configured. The third lens group G3 includes, in order from the object side, a positive lens L31 in which the object-side and image-side lens surfaces are formed in an aspheric shape, a cemented lens in which a biconvex lens L32 and a biconcave lens L33 are cemented, The lens is composed of a cemented lens obtained by cementing a concave lens L34 and a biconvex lens L35, a positive lens L36 in which object-side and image-side lens surfaces are formed in an aspherical shape, and a negative meniscus lens L37 having a convex surface facing the object side. ing. The fourth lens group G4 is composed of a positive lens L41 having an aspheric lens surface on the object side. An aperture stop S is disposed between the second lens group G2 and the third lens group G3. A filter group FL having a low-pass filter, an infrared filter, and the like is disposed between the fourth lens group G4 and the image plane I. The negative lens L25, the positive lens L31, the positive lens L36, and the positive lens L41 are glass molded aspheric lenses.

  In the variable magnification optical system ZL5, when the magnification is changed from the wide-angle end state to the telephoto end state, the distance between the first lens group G1 and the second lens group G2 increases, and the second lens group G2 and the third lens group G3. After the first lens group G1 and the second lens group G2 are moved to the image plane side so that the distance between the first lens group G3 and the fourth lens group G4 increases, the object side The third lens group G3 is moved to the object side, the fourth lens group G4 is once moved to the object side, and is then moved to the image plane side. The aperture stop S moves integrally with the third lens group G3.

  In the variable magnification optical system ZL5, focusing from an infinite distance to a close object is performed by moving the image side group G3c included in the third lens group G3 to the image plane side.

  Table 17 below provides values of specifications of the variable magnification optical system ZL5. The surface numbers 1 to 34 shown in Table 17 correspond to the numbers 1 to 33 shown in FIG.

(Table 17 ) 5th Example [whole specification]
Zoom ratio = 3.14
Wide-angle end state Intermediate focal length state Telephoto end state f = 9.3 to 19.1 to 29.1
FNO = 1.8 to 2.6 to 2.9
2ω = 85.0 to 45.2 to 30.1
Y = 8.0 to 8.0 to 8.0
TL (air equivalent length) = 95.9 to 98.8 to 112.6
BF (Air equivalent length) = 13.79 to 20.56 to 21.34

[Lens data]
m r d νd nd
Object ∞
1 48.703 1.60 17.98 1.94595
2 34.692 6.38 42.73 1.83481
3 197.349 D3
4 * 5896.385 0.20 36.64 1.56093
5 93.609 1.51 40.66 1.88300
6 11.700 6.47
7 -54.231 1.00 54.61 1.72916
8 54.855 1.56
9 49.676 3.34 23.78 1.84666
10 -32.621 1.12
11 -18.908 2.35 33.73 1.64769
12 -13.263 0.90 44.98 1.79050
13 * -37.964 D13
14 0.000 0.80 Aperture stop S
15 * 20.379 3.57 71.67 1.55332
16 * -42.773 0.30
17 46.219 4.49 23.78 1.84666
18 -14.503 0.90 27.57 1.75520
19 27.482 2.80
20 -29.885 1.34 25.45 1.80518
21 23.770 4.30 82.57 1.49782
22 -15.009 0.50
23 * 23.770 2.70 81.49 1.49710
24 * -70.000 D24
25 54.480 0.80 67.90 1.59319
26 19.345 D26
27 * 26.011 2.37 81.49 1.49710
28 500.000 D28
29 0.000 0.50 63.88 1.51680
30 0.000 1.11
31 0.000 1.59 63.88 1.51680
32 0.000 0.30
33 0.000 0.70 63.88 1.51680
34 0.000 0.70

[Lens focal length]
Lens group Start surface Focal length 1st lens group 1 80.99
Second lens group 4 -12.86
Third lens group 15 23.62
Fourth lens group 27 55.11

In the variable magnification optical system ZL5, the fourth surface, the thirteenth surface, the fifteenth surface, the sixteenth surface, the twenty-third surface, the twenty-fourth surface, and the twenty-seventh surface are formed in an aspheric shape. Table 18 below shows the aspheric data, that is, the values of the conical constant K and the aspheric constants A4 to A10.

(Table 18 )
[Aspherical data]
K A4 A6 A8 A10
4th surface 0 4.87287E-05 -1.73017E-07 4.92743E-10 -6.73284E-13
13th face 0 -8.09198E-06 -3.28390E-08 -3.69807E-10 1.91943E-12
15th face 0 -1.61042E-05 3.65268E-08 -5.12033E-10 0.00000E + 00
16th face 0 4.30711E-05 5.71263E-08 0.00000E + 00 0.00000E + 00
Surface 23 0 -1.46815E-05 -3.11565E-07 0.00000E + 00 0.00000E + 00
24th face 0 -7.08073E-07 -3.08275E-07 -7.09313E-10 1.17051E-11
27th face 0 -2.64761E-06 -4.55080E-08 2.47961E-10 0.00000E + 00

  In the variable magnification optical system ZL5, the axial air distance D3 between the first lens group G1 and the second lens group G2, and the axial air distance D13 between the second lens group G2 and the third lens group G3 (aperture stop S). As described above, the axial air gap D26 between the third lens group G3 and the fourth lens group G4 and the axial air gap D28 between the fourth lens group G4 and the filter group FL change during zooming. . Further, the on-axis air space D24 on the object side and the on-axis air space D26 on the image plane side of the image side group G3c of the third lens group G3 change upon focusing. Table 19 below shows variable intervals in each of the focal length states of the wide-angle end state, the intermediate focal length state, and the telephoto end state when focusing on infinity and focusing on a short distance. Note that only the values of D24 and D26 are shown at the time of focusing at a short distance, but other values are the same as at the time of focusing at infinity.

(Table 19)
[Variable interval data]
When focusing at infinity When focusing at close range Wide-angle end Medium telephoto end Wide-angle end Medium telephoto end f 9.3 19.1 29.1 9.3 19.1 29.1
D3 1.2 11.3 22.9
D13 22.0 5.0 1.5
D24 1.50 1.50 1.50 2.24 3.25 4.86
D26 5.20 8.12 13.07 4.46 6.37 9.70
D28 9.8 16.6 16.9

  Table 20 below shows values corresponding to the conditional expressions in the variable magnification optical system ZL5. In the fifth example, the negative lens included in the image side group G3c in the third lens group G3 is a negative meniscus lens L37, and the positive lens included in the object side group G3a of the third lens group G3 is This is the positive lens L31.

(Table 20)
[Conditional expression values]
(1) (−f2) / (fw × ft) ^1/2 = 0.783
(2) ndF−0.0052 × νdF−1.965 = −0.019
(3) νdF = 67.9
(4) νdO = 71.7
(5) f4 / fw = 5.94

  Thus, this variable magnification optical system ZL5 satisfies all the conditional expressions (1) to (5).

  FIG. 14 shows spherical aberration diagrams, astigmatism diagrams, distortion diagrams, magnification chromatic aberration diagrams, and coma aberration diagrams of the variable magnification optical system ZL5 in the wide-angle end state, the intermediate focal length state, and the telephoto end state at the time of focusing on infinity. FIG. 15 shows a spherical aberration diagram, an astigmatism diagram, a distortion diagram, a chromatic aberration diagram, and a coma diagram in the wide-angle end state, the intermediate focal length state, and the telephoto end state at the time of focusing at a short distance. From these respective aberration diagrams, it is understood that various aberrations are satisfactorily corrected from the wide-angle end state to the telephoto end state in the variable magnification optical system ZL5.

DESCRIPTION OF SYMBOLS 1 Camera (optical apparatus) ZL (ZL1-ZL5) variable power optical system G1 1st lens group G2 2nd lens group G3 3rd lens group G3a Object side group G3b Intermediate group G3c Image side group G4 4th lens group

Claims (11)

From the object side,
A first lens group having a positive refractive power;
A second lens group having negative refractive power;
A third lens group having positive refractive power;
Substantially consisting of four lens groups with a fourth lens group having positive refractive power,
During zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group changes, and the distance between the second lens group and the third lens group changes, The distance between the third lens group and the fourth lens group changes,
The third lens group has an intermediate group having a positive lens, a negative lens, a negative lens, and a positive lens arranged in order from the object side, and a negative refractive power arranged on the image plane side with respect to the intermediate group. An image side group,
During focusing, the intermediate group is fixed in position relative to the image plane, and the image side group moves along the optical axis ,
A variable magnification optical system characterized by satisfying the following condition:
4.0 <f4 / fw <11.0
However,
f4: focal length of the fourth lens group
fw: focal length of the entire system in the wide-angle end state From the object side,
A first lens group having a positive refractive power;
A second lens group having negative refractive power;
A third lens group having positive refractive power;
Substantially consisting of four lens groups with a fourth lens group having positive refractive power,
During zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group changes, and the distance between the second lens group and the third lens group changes, The distance between the third lens group and the fourth lens group changes,
The third lens group has an intermediate group having a positive lens, a negative lens, a negative lens, and a positive lens arranged in order from the object side, and a negative refractive power arranged on the image plane side with respect to the intermediate group. An image side group,
During focusing, the intermediate group is fixed in position relative to the image plane, and the image side group moves along the optical axis ,
The image side group has at least one negative lens;
A variable magnification optical system characterized by satisfying the following condition:
ndF + 0.0052 × νdF−1.965 <0
νdF> 60
However,
ndF: refractive index with respect to d-line of the medium of the negative lens included in the image side group
νdF: Abbe number of the medium of the negative lens included in the image side group The variable magnification optical system according to claim 2 , wherein a condition of the following formula is satisfied.
4.0 <f4 / fw <11.0
However,
f4: focal length of the fourth lens group fw: focal length of the entire system in the wide-angle end state The zoom lens system according to any one of claims 1 to 3, wherein a condition of the following formula is satisfied.
0.4 <(− f2) / (fw × ft) ^1/2 <1.1
However,
f2: focal length of the second lens unit fw: focal length of the entire system in the wide-angle end state ft: focal length of the entire system in the telephoto end state 5. The variable magnification optical system according to claim 1, wherein the third lens group includes an object side group having a positive refractive power on the object side of the intermediate group. The image-side group, the variable magnification optical system according to any one of claims 1 to 5, characterized in that it consists of one negative lens. The variable power optical system according to any one of claims 1 to 6, wherein the image side group includes a negative meniscus lens having a concave surface facing one image surface side. The third lens group has an object side group having positive refractive power on the object side of the intermediate group,
The object side group has one positive lens,
The zoom lens system according to any one of claims 1 to 7, wherein a condition of the following formula is satisfied.
νdO> 60
However,
νdO: Abbe number of positive lens medium included in the object-side group   9. The zoom lens according to claim 1, wherein, when zooming from the wide-angle end state to the telephoto end state, the first lens group temporarily moves to the image plane side and then moves to the object side. The variable power optical system described.   An optical apparatus comprising the variable magnification optical system according to claim 1. In order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens having a positive refractive power A variable magnification optical system comprising substantially four lens groups with a group ,
During zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group changes, and the distance between the second lens group and the third lens group changes, Arrange so that the distance between the third lens group and the fourth lens group changes,
The third lens group has an intermediate group having a positive lens, a negative lens, a negative lens, and a positive lens arranged in order from the object side, and a negative refractive power arranged on the image plane side with respect to the intermediate group. An image side group, and in focusing, the intermediate group is fixed in position with respect to the image plane , and arranged so that the image side group moves along the optical axis ,
A method of manufacturing a variable magnification optical system, wherein the zoom lens is disposed so as to satisfy the condition of the following formula .
4.0 <f4 / fw <11.0
However,
f4: focal length of the fourth lens group
fw: focal length of the entire system in the wide-angle end state

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