JP5760964B2 - 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, various variable magnification optical systems suitable for photographic cameras, electronic still cameras, video cameras, and the like have been proposed (see, for example, Patent Document 1).

JP 2003-344768 A

  However, the conventional variable magnification optical system has a large aberration fluctuation at the time of zooming.

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

In order to achieve such an object, the variable magnification optical system according to the first invention has a first lens group having a positive refractive power arranged in order from the object side along the optical axis, and a negative refractive power. The second lens group, the third lens group having a positive refractive power, the fourth lens group having a positive refractive power, and the fifth lens group having a negative refractive power substantially from five lens groups. In the variable power optical system, when changing the magnification 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 second lens group and the third lens group change. The distance between the lens group changes, the distance between the third lens group and the fourth lens group changes, the distance between the fourth lens group and the fifth lens group changes, and the following conditional expression: Is pleased.
0.510 <f4 / fw <0.580
3.25 ≦ f3 / (− f5) <4.30
However,
f3: focal length of the third lens group,
f4: focal length of the fourth lens group,
f5: focal length of the fifth lens group,
fw: focal length in the wide-angle end state of the zoom optical system.

Further, the variable magnification optical system according to the second 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 along the optical axis, A variable power optical system that is substantially composed of five lens groups by a third lens group having a positive refractive power, a fourth lens group having a positive refractive power, and a fifth lens group having a negative refractive power. Thus, when 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, and the distance between the fourth lens group and the fifth lens group changes, and the following conditional expression is satisfied.
0.510 <f4 / fw <0.580
1.30 <f3 / f1 <3.00
3.20 <f3 / (− f5) <4.30
However,
f1: the focal length of the first lens group,
f3: focal length of the third lens group,
f4: focal length of the fourth lens group,
f5: focal length of the fifth lens group,
fw: focal length in the wide-angle end state of the zoom optical system.

A variable magnification optical system according to a third aspect of the 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 along the optical axis, A variable power optical system that is substantially composed of five lens groups by a third lens group having a positive refractive power, a fourth lens group having a positive refractive power, and a fifth lens group having a negative refractive power. Thus, when 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, and the distance between the fourth lens group and the fifth lens group changes, and the following conditional expression is satisfied.
0.510 <f4 / fw <0.580
1.42 ≦ f3 / f1 <3.00
However,
f1: the focal length of the first lens group,
f3: focal length of the third lens group,
f4: focal length of the fourth lens group,
fw: focal length in the wide-angle end state of the zoom optical system.

A variable magnification optical system according to a fourth aspect of the 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 along the optical axis, A variable power optical system that is substantially composed of five lens groups by a third lens group having a positive refractive power, a fourth lens group having a positive refractive power, and a fifth lens group having a negative refractive power. Thus, when 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, and the distance between the fourth lens group and the fifth lens group changes, and the following conditional expression is satisfied.
0.510 <f4 / fw <0.580
2.80 <f3 / (− f2) ≦ 3.18
However,
f2: focal length of the second lens group,
f3: focal length of the third lens group,
f4: focal length of the fourth lens group,
fw: focal length in the wide-angle end state of the zoom optical system.

In the above-described variable magnification optical system, it is preferable that the most object side lens in the third lens group is a lens having a positive refractive power and satisfies the following conditional expression.
0.50 <f3 / ft <0.70
However,
f3: focal length of the third lens group,
ft: focal length of the zoom optical system in the telephoto end state.

  Further, in the above-described zooming optical system, when zooming from the wide-angle end state to the telephoto end state, the distance between the second lens group and the third lens group is reduced, and the fourth lens group and the fourth lens group are reduced. It is preferable that the distance between the five lens groups is reduced.

  In the zooming optical system described above, a diaphragm is provided between the fourth lens group and the fifth lens group, and the zooming is performed from the image side when zooming from the wide-angle end state to the telephoto end state. It is preferable to move to the object side.

  In the above-described variable magnification optical system, it is preferable that at least a part of the second lens group is movable so as to have a component in a direction orthogonal to the optical axis.

  In the zoom optical system described above, it is preferable that focusing from an infinite object to a finite distance object is performed by moving the fourth lens group along the optical axis.

  In the above-described variable magnification optical system, it is preferable that the fifth lens group moves from the image side to the object side when zooming from the wide-angle end state to the telephoto end state.

In the above-described variable magnification optical system, it is preferable that the following conditional expression is satisfied.
2.00 <f1 / (− f5) <2.90
However,
f1: the focal length of the first lens group,
f5: focal length of the fifth lens group.

  An optical apparatus according to the present invention includes the variable magnification optical system according to the present invention.

The variable magnification optical system manufacturing method according to the present invention includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a positive lens in order from the object side along the optical axis. A variable power optical system substantially consisting of five lens groups in which a third lens group having a refracting power, a fourth lens group having a positive refracting power, and a fifth lens group having a negative refracting power are arranged. In this manufacturing method, when 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 second lens group and the third lens group , The distance between the third lens group and the fourth lens group changes, and the distance between the fourth lens group and the fifth lens group changes, satisfying the following conditional expression: I am doing so.
0.510 <f4 / fw <0.580
3.25 ≦ f3 / (− f5) <4.30
However,
f3: focal length of the third lens group,
f4: focal length of the fourth lens group,
f5: focal length of the fifth lens group,
fw: focal length in the wide-angle end state of the zoom optical system.

  According to the present invention, good optical performance can be obtained.

It is sectional drawing which shows the structure of the zoom lens which concerns on 1st Example. (A) is an aberration diagram at the time of focusing on infinity in the wide angle end state in the first embodiment, and (b) is an aberration diagram when image blur correction is performed at the time of focusing on infinity in the wide angle end state. . It is an aberration diagram at the time of focusing on infinity in the intermediate focal length state in the first example. (A) is an aberration diagram at the time of focusing on infinity in the telephoto end state in the first embodiment, and (b) is an aberration diagram when image blur correction is performed at the time of focusing on infinity in the telephoto end state. . It is sectional drawing which shows the structure of the zoom lens which concerns on 2nd Example. (A) is an aberration diagram when focusing on infinity in the wide-angle end state in the second embodiment, and (b) is an aberration diagram when image blur correction is performed when focusing on infinity in the wide-angle end state. . It is an aberration diagram at the time of focusing on infinity in the intermediate focal length state in the second example. (A) is an aberration diagram at the time of focusing on infinity in the telephoto end state in the second embodiment, and (b) is an aberration diagram when image blur correction is performed at the time of focusing on infinity in the telephoto end state. . It is sectional drawing which shows the structure of the zoom lens which concerns on 3rd Example. (A) is an aberration diagram when focusing on infinity in the wide-angle end state in the third embodiment, and (b) is an aberration diagram when image blur correction is performed when focusing on infinity in the wide-angle end state. . It is an aberration diagram at the time of focusing on infinity in the intermediate focal length state in the third example. (A) is an aberration diagram at the time of focusing on infinity in the telephoto end state in the third embodiment, and (b) is an aberration diagram when image blur correction is performed at the time of focusing on infinity in the telephoto end state. . It is sectional drawing which shows the structure of the zoom lens which concerns on 4th Example. (A) is an aberration diagram when focusing on infinity in the wide-angle end state in the fourth embodiment, and (b) is an aberration diagram when image blur correction is performed when focusing on infinity in the wide-angle end state. . It is an aberration diagram at the time of focusing on infinity in the intermediate focal length state in the fourth example. (A) is an aberration diagram at the time of focusing on infinity in the telephoto end state in the fourth embodiment, and (b) is an aberration diagram when image blur correction is performed at the time of focusing on infinity in the telephoto end state. . It is sectional drawing of a digital single-lens reflex camera. It is a flowchart which shows the manufacturing method of a zoom lens.

  Hereinafter, preferred embodiments of the present application will be described with reference to the drawings. A digital single-lens reflex camera CAM provided with a zoom lens ZL, which is a variable magnification optical system according to the present application, is shown in FIG. In the digital single-lens reflex camera CAM shown in FIG. 17, light from an object (subject) (not shown) is collected by a zoom lens (photographing lens) ZL and imaged on a focusing screen F via a quick return mirror M. Is done. The light imaged on the focusing screen F is reflected a plurality of times in the pentaprism P and guided to the eyepiece lens E. Thus, the photographer can observe the image of the object (subject) as an erect image through the eyepiece lens E.

When a release button (not shown) is pressed by the photographer, the quick return mirror M is retracted out of the optical path, and the light from the object (subject) collected by the zoom lens ZL forms an image on the image sensor C. To form an image of the subject. As a result, light from the object (subject) is imaged on the image sensor C, picked up by the image sensor C, and recorded in a memory (not shown) as an image of the object (subject). In this way, the photographer can photograph an object (subject) with the digital single-lens reflex camera CAM. Even if the camera does not have the quick return mirror M, the same effect as the camera CAM can be obtained. The digital single-lens reflex camera CAM shown in FIG. 17 may be configured to hold the zoom lens (photographing lens) ZL in a detachable manner, and is configured integrally with the zoom lens (photographing lens) ZL. Also good.

  For example, as shown in FIG. 1, the zoom lens ZL 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 along the optical axis. The third lens group G3 having a positive refractive power, the fourth lens group G4 having a positive refractive power, and the fifth lens group G5 having a negative refractive power. Further, during 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 second lens group G2 and the third lens group G3 are changed. The interval changes, the interval between the third lens group G3 and the fourth lens group G4 changes, and the interval between the fourth lens group G4 and the fifth lens group G5 changes.

  In the zoom lens ZL having such a configuration, when the focal length of the fourth lens group G4 is f4 and the focal length in the wide-angle end state of the zoom lens ZL is fw, the condition expressed by the following conditional expression (1) Is preferably satisfied.

  0.510 <f4 / fw <0.580 (1)

  The zoom lens ZL according to the present embodiment satisfies the conditional expression (1), thereby realizing good optical performance and ensuring a predetermined zoom ratio. Therefore, according to the present embodiment, it is possible to obtain a zoom lens ZL having good optical performance and an optical apparatus (digital still camera CAM) including the zoom lens ZL.

  Here, the conditional expression (1) defines an appropriate focal length of the fourth lens group G4 with respect to the focal length in the wide-angle end state of the zoom lens ZL. When the condition exceeds the upper limit value of the conditional expression (1), the refractive power of the fourth lens group G4 becomes weak, and the refractive power of the third lens group G3 becomes strong in order to secure a predetermined zoom ratio. It becomes difficult to correct spherical aberration in the telephoto end state. On the other hand, when the condition is lower than the lower limit value of the conditional expression (1), the refractive power of the fourth lens group G4 becomes strong, and it becomes difficult to correct spherical aberration in the wide-angle end state.

  In addition, the effect of this application can be made more reliable by making the upper limit of conditional expression (1) 0.570.

  The zoom lens ZL of the present embodiment is expressed by the following conditional expression (2), where f2 is the focal length of the second lens group G2, and fw is the focal length of the zoom lens ZL at the wide-angle end state. It is preferable to satisfy the conditions.

  0.35 <(− f2) / fw <0.49 (2)

  Conditional expression (2) defines an appropriate focal length of the second lens group G2 with respect to the focal length in the wide-angle end state of the zoom lens ZL. When the condition exceeds the upper limit value of the conditional expression (2), the refractive power of the second lens group G2 becomes weak, and the refractive power of the fourth lens group G4 becomes strong in order to secure a predetermined zoom ratio. It becomes difficult to correct spherical aberration in the wide-angle end state. On the other hand, when the condition is lower than the lower limit value of the conditional expression (2), the refractive power of the second lens group G2 becomes strong, and it is difficult to correct coma in the wide-angle end state.

  In addition, the effect of this application can be made more reliable by making the lower limit of conditional expression (2) 0.40.

  In the zoom lens ZL of the present embodiment, when the focal length of the third lens group G3 is f3 and the focal length of the first lens group G1 is f1, the condition expressed by the following conditional expression (3) is satisfied. It is preferable to satisfy.

  1.10 <f3 / f1 <3.00 (3)

  Conditional expression (3) defines an appropriate focal length of the first lens group G1 with respect to the focal length of the third lens group G3. When the condition exceeds the upper limit value of the conditional expression (3), the refractive power of the first lens group G1 becomes strong, and it becomes difficult to correct spherical aberration in the telephoto end state. On the other hand, when the condition is lower than the lower limit value of the conditional expression (3), the refractive power of the third lens group G3 becomes strong, and it becomes difficult to correct the field curvature aberration in the wide-angle end state.

  In addition, the effect of this application can be made more reliable by making the upper limit of conditional expression (3) 2.00. Moreover, the effect of this application can be made more reliable by making the lower limit of conditional expression (3) 1.30.

  In the zoom lens ZL of the present embodiment, when the focal length of the third lens group G3 is f3 and the focal length of the second lens group G2 is f2, the condition expressed by the following conditional expression (4) is satisfied. It is preferable to satisfy.

  2.80 <f3 / (− f2) <3.80 (4)

  Conditional expression (4) defines an appropriate focal length of the second lens group G2 with respect to the focal length of the third lens group G3. When the condition exceeds the upper limit value of conditional expression (4), the refractive power of the second lens group G2 becomes strong, and it becomes difficult to correct spherical aberration in the telephoto end state. On the other hand, when the condition is less than the lower limit value of the conditional expression (4), the refractive power of the second lens group G2 becomes weak, and it becomes difficult to correct the field curvature aberration in the wide-angle end state.

  In addition, the effect of this application can be made more reliable by making the upper limit of conditional expression (4) into 3.50. Moreover, the effect of this application can be made more reliable by making the lower limit of conditional expression (4) to 3.00.

  In the zoom lens ZL of the present embodiment, the most object side lens in the third lens group G3 is a lens having positive refractive power, and the focal length of the third lens group G3 is f3. When the focal length in the telephoto end state is ft, it is preferable that the condition expressed by the following conditional expression (5) is satisfied.

  0.50 <f3 / ft <0.70 (5)

  By disposing the lens having the positive refractive power closest to the object side of the third lens group G3, it is possible to quickly converge the light beam emitted from the second lens group G2 having the negative refractive power. The enlargement of the diameter of the lens arranged on the side can be prevented, and spherical aberration on the wide angle side can be corrected well. In such a lens arrangement, conditional expression (5) defines an appropriate focal length of the third lens group G3 with respect to the focal length of the zoom lens ZL in the telephoto end state. When the condition exceeds the upper limit value of the conditional expression (5), the refractive power of the third lens group G3 becomes weak, and the refractive power of the first lens group G1 becomes strong in order to secure a predetermined zoom ratio. It becomes difficult to correct field curvature aberration in the telephoto end state. On the other hand, when the condition is lower than the lower limit value of the conditional expression (5), the refractive power of the third lens group G3 becomes strong, and it becomes difficult to correct spherical aberration in the wide-angle end state.

  In addition, the effect of this application can be made more reliable by making the upper limit of conditional expression (5) 0.63. Moreover, the effect of this application can be made more reliable by making the lower limit of conditional expression (5) 0.57.

  Further, in the zoom lens ZL of the present embodiment, when zooming from the wide-angle end state to the telephoto end state, the distance between the second lens group G2 and the third lens group G3 decreases, and the fourth lens group G4 and the fourth lens group G4 It is preferable that the distance from the five lens group G5 is reduced. In this way, a predetermined zoom ratio can be ensured while effectively correcting variations in spherical aberration and field curvature.

  In addition, the zoom lens ZL of the present embodiment has a diaphragm S between the fourth lens group G4 and the fifth lens group G5, and when the magnification is changed from the wide-angle end state to the telephoto end state, the diaphragm S is an image. It is preferable to move from the side to the object side. In this way, enlargement of the lens diameter of the entire optical system can be prevented, and variations in spherical aberration and field curvature can be effectively corrected.

  In the zoom lens ZL of the present embodiment, it is preferable that at least a part of the second lens group G2 is movable so as to have a component in a direction orthogonal to the optical axis. By performing such movement, it is possible to effectively correct the coma aberration in the telephoto end state and the field curvature aberration in the wide-angle end state, and to secure a predetermined image plane movement amount in a direction substantially perpendicular to the optical axis. it can. Thereby, it is possible to deal with the problem of camera shake correction.

  In the zoom lens ZL according to the present embodiment, it is preferable that focusing from an object at infinity to an object at finite distance is performed by moving the fourth lens group G4 along the optical axis. In this way, aberration variations such as spherical aberration and field curvature during focusing can be effectively corrected.

  In the zoom lens ZL according to the present embodiment, when the focal length of the third lens group G3 is f3 and the focal length of the fifth lens group G5 is f5, the condition expressed by the following conditional expression (6) is satisfied. It is preferable to satisfy.

  3.00 <f3 / (− f5) <4.30 (6)

  Conditional expression (6) defines an appropriate focal length of the third lens group G3 with respect to the focal length of the fifth lens group G5. When the condition exceeds the upper limit value of conditional expression (6), the refractive power of the fifth lens group G5 becomes strong, and it becomes difficult to correct field curvature aberration in the wide-angle end state. On the other hand, when the condition is less than the lower limit value of conditional expression (6), the refractive power of the third lens group G3 becomes strong, and it becomes difficult to correct coma in the telephoto end state.

  In addition, the effect of this application can be made more reliable by making the upper limit of conditional expression (6) 4.00. Moreover, the effect of this application can be made more reliable by setting the lower limit of conditional expression (6) to 3.20.

  In the zoom lens ZL of the present embodiment, it is preferable that the fifth lens group moves from the image side to the object side when zooming from the wide-angle end state to the telephoto end state. In this way, a predetermined zoom ratio can be ensured while effectively correcting variations in spherical aberration and field curvature.

  In the zoom lens ZL of the present embodiment, when the focal length of the first lens group G1 is f1, and the focal length of the fifth lens group G5 is f5, the condition expressed by the following conditional expression (7) is satisfied. It is preferable to satisfy.

  2.00 <f1 / (− f5) <2.90 (7)

  Conditional expression (7) defines an appropriate focal length of the first lens group G1 with respect to the focal length of the fifth lens group G5. When the condition exceeds the upper limit value of conditional expression (7), the refractive power of the fifth lens group G5 becomes strong, and it becomes difficult to correct field curvature aberration in the wide-angle end state. On the other hand, when the condition is lower than the lower limit value of the conditional expression (7), the refractive power of the first lens group G1 becomes strong, and it becomes difficult to correct spherical aberration in the telephoto end state.

  In addition, the effect of this application can be made more reliable by making the upper limit of conditional expression (7) 2.80. Moreover, the effect of this application can be made more reliable by making the lower limit of conditional expression (7) 2.30.

  Here, a manufacturing method of the zoom lens ZL having the above-described configuration will be described with reference to FIG. First, the first lens group G1, the second lens group G2, the third lens group G3, the fourth lens group G4, and the fifth lens group G5 of this embodiment are incorporated in a cylindrical lens barrel (step S1). . At this time, the lenses of the first to fifth lens groups G1 to G5 are respectively arranged so as to satisfy the conditional expression (1), the conditional expression (2), the conditional expression (3), and the like. When each lens is incorporated into the lens barrel, the lens groups may be incorporated into the lens barrel one by one in the order along the optical axis, and a part or all of the lens groups are integrally held by the holding member and then the lens barrel. You may assemble with a member. After assembling each lens group in the lens barrel, it is confirmed whether an object image is formed in a state where each lens group is incorporated in the lens barrel, that is, whether the centers of the lens groups are aligned (step S2). ). Then, after confirming whether an image is formed, various operations of the zoom lens ZL are confirmed (step S3).

  As an example of various operations, a zooming operation in which a lens group (for example, the first to fifth lens groups G1 to G5) for zooming moves along the optical axis direction, from a long-distance object to a short-distance object. A focusing operation in which a lens group (for example, the fourth lens group G4) that performs focusing is moved along the optical axis direction, and a camera shake that moves so that at least some of the lenses have a component in a direction orthogonal to the optical axis. Corrective action etc. are mentioned. In the present embodiment, when zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group G1 and the second lens group G2 changes, and the second lens group G2 and the third lens group. The distance between the third lens group G3 and the fourth lens group G4 changes, and the distance between the fourth lens group G4 and the fifth lens group G5 changes. In addition, the confirmation order of various operations is arbitrary. According to such a manufacturing method, a zoom lens ZL having good optical performance can be obtained.

(First embodiment)
Embodiments of the present application will be described below with reference to the accompanying drawings. First, a first embodiment of the present application will be described with reference to FIGS. FIG. 1 is a cross-sectional view showing a configuration of a zoom lens according to the first embodiment. The zoom lens ZL according to the first example includes a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, arranged in order from the object side along the optical axis, and a positive lens. A third lens group G3 having a refractive power of 4, a fourth lens group G4 having a positive refractive power, and a fifth lens group G5 having a negative refractive power. During 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 second lens group G2 and the third lens group G3 are changed. The distance changes (decreases), the distance between the third lens group G3 and the fourth lens group G4 changes, and the distance between the fourth lens group G4 and the fifth lens group G5 changes (decreases). ing.

The first lens group G1 is arranged in order from the object side along the optical axis, and includes a positive meniscus lens L11 having a convex surface facing the object side, a negative meniscus lens L12 having a convex surface facing the object side, and a convex surface facing the object side. And a positive cemented lens formed by cementing with the positive meniscus lens L13. The second lens group G2 is arranged in order from the object side along the optical axis, the front group GA that performs image blur correction by shifting in a direction substantially perpendicular to the optical axis, and the second lens group G2 has an image more than the front group GA. The rear group GB is located on the surface I side. The front group GA having negative refractive power is composed of a biconcave negative lens L21. The rear group GB is composed of a positive meniscus lens L22 having a convex surface facing the object side and a biconcave negative lens L23 arranged in order from the object side along the optical axis.

  The third lens group G3 includes a biconvex positive lens L31 arranged in order from the object side along the optical axis, and a negative meniscus lens L32 having a convex surface directed toward the object side. The fourth lens group G4 is formed by joining together a biconvex positive lens L41, a biconvex positive lens L42, and a negative lens L43 having a concave surface facing the object, which are arranged in order from the object side along the optical axis. And a cemented positive lens. The fifth lens group G5 is arranged in order from the object side along the optical axis, and includes a negative meniscus lens L51 having a convex surface facing the object side, a negative lens L52 having a biconcave shape, and a positive lens L53 having a convex surface facing the object side. The zoom lens is configured to move from the image plane I side to the object side along the optical axis during zooming from the wide-angle end state to the telephoto end state. .

  The aperture stop S is disposed between the fourth lens group G4 and the fifth lens group G5, and from the image plane I side along the optical axis during zooming from the wide-angle end state to the telephoto end state. It moves to the object side. Further, focusing from an infinitely distant object to a short distance object (finite distance object) is performed by moving the fourth lens group G4 from the image plane I side to the object side along the optical axis.

  In the following, Tables 1 to 4 are shown, and these are the tables listing the values of the specifications of the zoom lenses according to the first to fourth examples. In [Overall Specifications] in each table, f is the focal length, FNO is the F number, 2ω is the angle of view (maximum incident angle: unit is “°”), and TL is the total lens length (air equivalent length). Show. In [Lens Data], the surface number is the order of the lens surfaces counted from the object side, r is the radius of curvature of the lens surfaces, d is the distance between the lens surfaces, and nd is the d-line (wavelength λ = 587.6 nm). ), And νd represents the Abbe number for the d-line (wavelength λ = 587.6 nm). Also, the curvature radius “∞” indicates a plane, and the refractive index nd = 1.00000 of air is omitted from the description.

In [Variable surface interval data], the focal length f at each in-focus position and the value of each variable surface interval are shown. It should be noted that the axial air gap D5 between the first lens group G1 and the second lens group G2, the axial air gap D11 between the second lens group G2 and the third lens group G3, the third lens group G3 and the fourth lens group. On-axis air gap D15 with respect to G4, on-axis air gap D20 between fourth lens group G4 and aperture stop S, on-axis air gap D21 between aperture stop S and fifth lens group G5, and back focus (air conversion length) ) BF changes during zooming.

  [Zoom lens group data] indicates the focal length of each lens group. [Conditional Expression Corresponding Value] indicates the corresponding value of each conditional expression. In addition, the focal length f, the radius of curvature r, the surface interval d, and other length units listed in all the following specification values are generally “mm”, but the optical system is proportionally enlarged or reduced. However, the same optical performance can be obtained, and the present invention is not limited to this. In addition, the same reference numerals as in the present embodiment are used in the specification values of the second to fourth embodiments described later.

Table 1 below shows specifications in the first embodiment. The surface numbers 1 to 26 in Table 1 correspond to the surfaces 1 to 26 in FIG. 1, and the group numbers G1 to G5 in Table 1 correspond to the lens groups G1 to G5 in FIG.

(Table 1)
[Overall specifications]
Image height = 21.60
Scaling ratio = 2.40
Wide-angle end state Intermediate focal length state Telephoto end state f = 200.00 to 293.16 to 480.00
FNO = 3.6 to 5.2 to 5.6
2ω = 12.21-8.32-5.11
TL = 269.97 to 280.13 to 315.05
[Lens data]
Surface number r d nd νd
(First lens group G1)
1 115.166 8.84 70.4 1.48749
2 797.997 0.20
3 110.806 1.40 37.16 1.834
4 71.134 11.23 81.63 1.497
5 290.404 (D5)
(Second lens group G2)
(Front group GA)
6 -269.955 1.40 35.7 1.90265
7 166.561 7.34
(Back group GB)
8 60.696 5.53 23.78 1.84666
9 199.318 2.40
10 -890.691 1.40 46.62 1.816
11 76.396 (D11)
(Third lens group G3)
12 75.969 9.22 59.71 1.60732
13 -177.298 0.20
14 200.388 1.40 47.63 1.795268
15 63.834 (D15)
(Fourth lens group G4)
16 99.540 4.87 64.11 1.5168
17 -1589.065 0.20
18 74.866 10.92 67.9 1.59319
19 -63.278 1.40 37.16 1.834
20 5319.698 (D20)
(Variable aperture stop S)
21 ∞ (D21)
(Fifth lens group G5)
22 52.457 1.40 49.61 1.772499
23 36.931 17.08
24 -103.993 1.40 55.52 1.696797
25 58.022 3.00 27.51 1.755199
26 1008.690 (BF)
[Variable surface interval data]
Wide-angle end state Intermediate focal length state Telephoto end state
f 200.00 293.16 480.00
D5 24.44 56.97 86.54
D11 51.98 19.03 1.5
D15 7.18 20.94 14.17
D20 47.60 1.52 1.52
D21 1.50 32.97 1.5
BF 46.44 57.88 119.00
[Zoom lens group data]
Group number Group first surface Group focal length
G1 1 207.33
G2 6 -95.62
G3 12 300.54
G4 16 102.41
G5 22 -77.03
[Conditional expression values]
Conditional expression (1) f4 / fw = 0.512
Conditional expression (2) (−f2) /fw=0.48
Conditional expression (3) f3 / f1 = 1.45
Conditional expression (4) f3 / (− f2) = 3.14
Conditional expression (5) f3 / ft = 0.63
Conditional expression (6) f3 / (− f5) = 3.90
Conditional expression (7) f1 / (− f5) = 2.69

  Thus, in the present embodiment, it can be seen that all the conditional expressions (1) to (7) are satisfied.

  2 to 4 are graphs showing various aberrations of the zoom lens ZL according to the first example. That is, FIG. 2A is an aberration diagram at the time of focusing at infinity in the wide-angle end state (f = 200.00 mm), and FIG. 2B is an image blur correction (image when focusing at infinity in the wide-angle end state). It is an aberration diagram when the shift amount of the front group GA of the second lens group G2 which is a shake correction group = 0.2). FIG. 3 is an aberration diagram when focusing on infinity in the intermediate focal length state (f = 293.16 mm). 4A is an aberration diagram at the time of focusing at infinity in the telephoto end state (f = 480.00 mm), and FIG. 4B is an image blur correction (image when focusing at infinity in the telephoto end state). It is an aberration diagram when the shift amount of the front group GA of the second lens group G2 which is a shake correction group = 0.2). In each aberration diagram, FNO represents an F number, and Y represents an image height. In each aberration diagram, d indicates the aberration at the d-line (λ = 587.6 nm), and g indicates the aberration at the g-line (λ = 435.8 nm). In the aberration diagrams showing astigmatism, the solid line shows the sagittal image plane, and the broken line shows the meridional image plane. The description of the aberration diagrams is the same in the other examples.

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

(Second embodiment)
Hereinafter, a second embodiment of the present application will be described with reference to FIGS. FIG. 5 is a sectional view showing a configuration of a zoom lens according to the second embodiment. The zoom lens of the second example has the same configuration as that of the zoom lens of the first example except for the configuration of the rear group GB of the second lens group G2, and each part has the same configuration as that of the first example. Reference numerals are assigned and detailed description is omitted. Note that the rear group GB of the second lens group G2 in the second example is arranged in order from the object side along the optical axis, and a negative meniscus lens L22 having a convex surface toward the object side and a positive lens having a convex surface toward the object side. The lens includes a cemented positive lens formed by cementing with the meniscus lens L23 and a biconcave negative lens L24.

  Table 2 below shows specifications in the second embodiment. The surface numbers 1 to 27 in Table 2 correspond to the surfaces 1 to 27 in FIG. 5, and the group numbers G1 to G5 in Table 2 correspond to the lens groups G1 to G5 in FIG. Further, the axial air gap D5 between the first lens group G1 and the second lens group G2, the axial air gap D12 between the second lens group G2 and the third lens group G3, the third lens group G3 and the fourth lens group. On-axis air distance D16 from G4, on-axis air distance D21 between fourth lens group G4 and aperture stop S, on-axis air distance D22 between aperture stop S and fifth lens group G5, and back focus (air equivalent length) ) BF changes during zooming.

(Table 2)
[Overall specifications]
Image height = 21.60
Scaling ratio = 2.40
Wide-angle end state Intermediate focal length state Telephoto end state f = 199.99 to 293.28 to 480.00
FNO = 4.1-5.1-5.6
2ω = 12.26-8.31-5.10
TL = 290.92 to 290.90 to 315.06
[Lens data]
Surface number r d nd νd
(First lens group G1)
1 116.447 9.11 70.4 1.48749
2 825.970 0.20
3 111.895 1.40 37.16 1.834
4 71.382 11.85 81.63 1.497
5 315.918 (D5)
(Second lens group G2)
(Front group GA)
6 -293.270 1.40 35.7 1.90265
7 156.662 6.40
(Back group GB)
8 63.083 1.40 45.29 1.794997
9 50.919 5.58 23.78 1.84666
10 142.829 2.71
11 -1198.433 1.40 46.62 1.816
12 82.795 (D12)
(Third lens group G3)
13 78.876 8.44 59.71 1.60732
14 -188.201 0.20
15 177.812 1.40 47.63 1.795268
16 65.726 (D16)
(Fourth lens group G4)
17 91.818 5.06 64.11 1.5168
18 -953.564 0.20
19 81.417 9.29 67.9 1.59319
20 -69.070 1.40 37.16 1.834
21 766.494 (D21)
(Variable aperture stop S)
22 ∞ (D22)
(Fifth lens group G5)
23 50.976 1.63 49.61 1.772499
24 37.701 25.43
25 -211.820 1.40 55.52 1.696797
26 48.962 3.00 27.51 1.755199
27 192.466 (BF)
[Variable surface interval data]
Wide-angle end state Intermediate focal length state Telephoto end state
f 199.99 293.28 480.00
D5 27.69 61.90 85.17
D12 61.78 21.87 1.50
D16 6.63 23.70 15.16
D21 48.18 1.65 1.65
D22 1.53 36.02 2.34
BF 46.20 46.86 110.34
[Zoom lens group data]
Group number Group first surface Group focal length
G1 1 205.30
G2 6 -86.48
G3 13 275.03
G4 17 108.92
G5 23 -84.53
[Conditional expression values]
Conditional expression (1) f4 / fw = 0.545
Conditional expression (2) (−f2) /fw=0.43
Conditional expression (3) f3 / f1 = 1.34
Conditional expression (4) f3 / (− f2) = 3.18
Conditional expression (5) f3 / ft = 0.57
Conditional expression (6) f3 / (− f5) = 3.25
Conditional expression (7) f1 / (− f5) = 2.43

  Thus, in the present embodiment, it can be seen that all the conditional expressions (1) to (7) are satisfied.

  6 to 8 are graphs showing various aberrations of the zoom lens ZL according to the second example. That is, FIG. 6A is an aberration diagram at the time of focusing at infinity in the wide-angle end state (f = 1999.99 mm), and FIG. 6B is an image blur correction (image) at the time of focusing at infinity in the wide-angle end state. It is an aberration diagram when the shift amount of the front group GA of the second lens group G2 which is a shake correction group = 0.2). FIG. 7 is an aberration diagram when focusing on infinity in the intermediate focal length state (f = 293.28 mm). FIG. 8A is an aberration diagram at the time of focusing at infinity in the telephoto end state (f = 480.00 mm), and FIG. 8B is an image blur correction (image at the time of focusing at infinity in the telephoto end state). It is an aberration diagram when the shift amount of the front group GA of the second lens group G2 which is a shake correction group = 0.2). From the respective aberration diagrams, it can be seen that in the second example, various aberrations are well corrected in each focal length state from the wide-angle end state to the telephoto end state, and the optical performance is excellent. As a result, by mounting the zoom lens ZL of the second embodiment, excellent optical performance can be secured even in the digital single-lens reflex camera CAM.

(Third embodiment)
Hereinafter, a third embodiment of the present application will be described with reference to FIGS. 9 to 12 and Table 3. FIG. FIG. 9 is a sectional view showing the structure of a zoom lens according to the third example. The zoom lens of the third example has the same configuration as that of the zoom lens of the first example except for the configuration of the first lens group G1 and the fourth lens group G4. The same reference numerals are assigned and detailed description is omitted. The first lens group G1 of the third example includes a positive meniscus lens L11 having a convex surface facing the object side and a negative meniscus lens L12 having a convex surface facing the object side, which are arranged in order from the object side along the optical axis. And a positive meniscus lens L13 having a convex surface directed toward the object side. The fourth lens group G4 of the third example includes a positive lens L41 having a convex surface facing the object side, a biconvex positive lens L42, and a concave surface facing the object side. And a positive cemented lens formed by cementing with a negative lens L43 facing the lens.

  Table 3 below shows specifications in the third embodiment. The surface numbers 1 to 27 in Table 3 correspond to the surfaces 1 to 27 in FIG. 9, and the group numbers G1 to G5 in Table 3 correspond to the lens groups G1 to G5 in FIG. Further, the axial air gap D6 between the first lens group G1 and the second lens group G2, the axial air gap D12 between the second lens group G2 and the third lens group G3, the third lens group G3 and the fourth lens group. On-axis air distance D16 from G4, on-axis air distance D21 between fourth lens group G4 and aperture stop S, on-axis air distance D22 between aperture stop S and fifth lens group G5, and back focus (air equivalent length) ) BF changes during zooming.

(Table 3)
[Overall specifications]
Image height = 21.60
Scaling ratio = 2.40
Wide-angle end state Intermediate focal length state Telephoto end state f = 200.00 to 293.02 to 480.00
FNO = 3.5 to 5.4 to 5.7
2ω = 12.21-8.32-5.11
TL = 276.56-283.10-315.01
[Lens data]
Surface number r d nd νd
(First lens group G1)
1 93.523 10.71 70.4 1.48749
2 492.877 0.20
3 102.501 2.50 37.16 1.834
4 63.325 7.51
5 65.802 11.46 81.63 1.497
6 249.064 (D6)
(Second lens group G2)
(Front group GA)
7 -563.807 3.00 35.7 1.90265
8 127.299 3.80
(Back group GB)
9 61.304 5.59 23.78 1.84666
10 250.308 2.46
11 -380.433 1.40 46.62 1.816
12 77.903 (D12)
(Third lens group G3)
13 95.781 8.20 59.71 1.60732
14 -127.034 0.20
15 200.101 1.40 47.63 1.795268
16 67.260 (D16)
(Fourth lens group G4)
17 83.812 4.33 64.11 1.5168
18 480.801 0.20
19 77.250 9.76 67.9 1.59319
20 -68.065 1.40 37.16 1.834
21 1240.988 (D21)
(Variable aperture stop S)
22 ∞ (D22)
(Fifth lens group G5)
23 44.462 1.40 49.61 1.772499
24 34.224 10.79
25 -90.280 1.40 55.52 1.696797
26 68.803 3.00 27.51 1.755199
27 -3808.900 (BF)
[Variable surface interval data]
Wide-angle end state Intermediate focal length state Telephoto end state
f 200.00 293.02 480.00
D6 19.35 50.27 79.59
D12 55.71 23.63 1.97
D16 6.17 17.69 5.59
D21 45.10 1.59 1.59
D22 13.11 38.41 1.50
BF 46.40 60.79 134.04
[Zoom lens group data]
Group number Group first surface Group focal length
G1 1 199.65
G2 7 -93.97
G3 13 283.68
G4 17 113.05
G5 23 -84.72
[Conditional expression values]
Conditional expression (1) f4 / fw = 0.565
Conditional expression (2) (−f2) /fw=0.47
Conditional expression (3) f3 / f1 = 1.42
Conditional expression (4) f3 / (− f2) = 3.02
Conditional expression (5) f3 / ft = 0.59
Conditional expression (6) f3 / (− f5) = 3.35
Conditional expression (7) f1 / (− f5) = 2.36

  Thus, in the present embodiment, it can be seen that all the conditional expressions (1) to (7) are satisfied.

10 to 12 are graphs showing various aberrations of the zoom lens ZL according to the third example. 10A is an aberration diagram at the time of focusing at infinity in the wide-angle end state (f = 200.00 mm), and FIG. 10B is an image blur correction (image when focusing at infinity in the wide-angle end state). It is an aberration diagram when the shift amount of the front group GA of the second lens group G2 which is a shake correction group = 0.2). FIG. 11 is an aberration diagram when focusing on infinity in the intermediate focal length state (f = 293.02 mm). 12A is an aberration diagram at the time of focusing at infinity in the telephoto end state (f = 480.00 mm), and FIG. 12B is an image blur correction (image when focusing at infinity in the telephoto end state). It is an aberration diagram when the shift amount of the front group GA of the second lens group G2 which is a shake correction group = 0.2). From the aberration diagrams, it can be seen that in the third example, various aberrations are favorably corrected in each focal length state from the wide-angle end state to the telephoto end state, and the optical performance is excellent. As a result, by mounting the zoom lens ZL of the third embodiment, excellent optical performance can be secured even in the digital single-lens reflex camera CAM.

(Fourth embodiment)
Hereinafter, the fourth embodiment of the present application will be described with reference to FIGS. FIG. 13 is a sectional view showing the structure of a zoom lens according to the fourth example. The zoom lens ZL according to Example 4 includes a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, arranged in order from the object side along the optical axis, A third lens group G3 having a negative refractive power, a fourth lens group G4 having a positive refractive power, a fifth lens group G5 having a negative refractive power, and a sixth lens group G6 having a positive refractive power It is configured with. During 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 second lens group G2 and the third lens group G3 are changed. The distance changes (decreases), the distance between the third lens group G3 and the fourth lens group G4 changes, and the distance between the fourth lens group G4 and the fifth lens group G5 changes (decreases). ing.

  The first lens group G1 is arranged in order from the object side along the optical axis, and includes a positive meniscus lens L11 having a convex surface facing the object side, a negative meniscus lens L12 having a convex surface facing the object side, and a convex surface facing the object side. And a positive cemented lens formed by cementing with the positive meniscus lens L13. The second lens group G2 is arranged in order from the object side along the optical axis, the front group GA that performs image blur correction by shifting in a direction substantially perpendicular to the optical axis, and the second lens group G2 has an image more than the front group GA. The rear group GB is located on the surface I side. The front group GA having negative refractive power is composed of a biconcave negative lens L21. The rear group GB is arranged in order from the object side along the optical axis, a cemented positive lens formed by cementing a negative meniscus lens L22 having a convex surface toward the object side and a positive meniscus lens L23 having a convex surface toward the object side, It comprises a biconcave negative lens L24.

  The third lens group G3 includes a biconvex positive lens L31 arranged in order from the object side along the optical axis, and a negative meniscus lens L32 having a convex surface directed toward the object side. The fourth lens group G4 is formed by joining together a biconvex positive lens L41, a biconvex positive lens L42, and a negative lens L43 having a concave surface facing the object, which are arranged in order from the object side along the optical axis. And a cemented positive lens. The fifth lens group G5 is arranged in order from the object side along the optical axis, and includes a negative meniscus lens L51 having a convex surface facing the object side, a negative lens L52 having a biconcave shape, and a positive lens L53 having a convex surface facing the object side. The zoom lens is configured to move from the image plane I side to the object side along the optical axis during zooming from the wide-angle end state to the telephoto end state. . The sixth lens group G6 includes a biconvex positive lens L61.

  The aperture stop S is disposed between the fourth lens group G4 and the fifth lens group G5, and from the image plane I side along the optical axis during zooming from the wide-angle end state to the telephoto end state. It moves to the object side. Further, focusing from an infinitely distant object to a short distance object (finite distance object) is performed by moving the fourth lens group G4 from the image plane I side to the object side along the optical axis.

Table 4 below shows specifications in the fourth embodiment. Surface numbers 1 to 29 in Table 4 correspond to surfaces 1 to 29 in FIG. 13, and group numbers G1 to G6 in Table 4 correspond to lens groups G1 to G6 in FIG. Further, the axial air gap D5 between the first lens group G1 and the second lens group G2, the axial air gap D12 between the second lens group G2 and the third lens group G3, the third lens group G3 and the fourth lens group. On-axis air gap D16 with G4, on-axis air gap D21 between fourth lens group G4 and aperture stop S, on-axis air gap D22 between aperture stop S and fifth lens group G5, fifth lens group G5 and The axial air gap D27 with respect to the six lens group G6 and the back focus (air conversion length) BF change during zooming.

(Table 4)
[Overall specifications]
Image height = 21.60
Scaling ratio = 2.40
Wide-angle end state Intermediate focal length state Telephoto end state f = 200.00 to 293.26 to 480.00
FNO = 4.1-5.5-6.1
2ω = 12.15-8.25-5.08
TL = 304.76 to 306.48 to 315.01
[Lens data]
Surface number r d nd νd
(First lens group G1)
1 120.266 8.70 70.4 1.48749
2 1207.573 0.20
3 116.457 1.40 37.16 1.834
4 73.308 10.75 81.63 1.497
5 319.318 (D5)
(Second lens group G2)
(Front group GA)
6 -390.292 1.40 35.7 1.90265
7 140.927 3.00
(Back group GB)
8 72.093 1.40 45.29 1.794997
9 49.426 5.77 23.78 1.846660
10 144.667 2.95
11 -555.222 1.40 46.62 1.816000
12 106.906 (D12)
(Third lens group G3)
13 82.313 5.94 59.71 1.607320
14 -221.243 0.58
15 140.875 1.40 47.63 1.795268
16 62.321 (D16)
(Fourth lens group G4)
17 75.194 4.92 64.11 1.51680
18 -520.254 0.20
19 93.562 6.51 67.9 1.59319
20 -80.836 1.40 37.16 1.83400
21 310.334 (D21)
(Variable aperture stop S)
22 ∞ (D22)
(Fifth lens group G5)
23 51.444 1.63 49.61 1.772499
24 33.071 25.43
25 -212.353 1.40 55.52 1.696797
26 51.759 3.00 27.51 1.755199
27 202.381 (D27)
(Sixth lens group G6)
28 16469.671 2.00 64.11 1.516800
29 -169.335 (BF)
[Variable surface interval data]
Wide-angle end state Intermediate focal length state Telephoto end state
f 200.00 293.26 480.00
D5 39.84 65.07 87.63
D12 70.10 31.45 1.50
D16 5.78 22.49 5.61
D21 49.10 1.92 1.98
D22 6.24 42.88 13.34
D27 1.80 10.80 72.96
BF 46.35 46.32 46.42
[Zoom lens group data]
Group number Group first surface Group focal length
G1 1 210.00
G2 6 -86.40
G3 13 301.00
G4 17 113.00
G5 23 -77.00
G6 28 324.34
[Conditional expression values]
Conditional expression (1) f4 / fw = 0.565
Conditional expression (2) (−f2) /fw=0.43
Conditional expression (3) f3 / f1 = 1.43
Conditional expression (4) f3 / (− f2) = 3.48
Conditional expression (5) f3 / ft = 0.63
Conditional expression (6) f3 / (− f5) = 3.91
Conditional expression (7) f1 / (− f5) = 2.73

  Thus, in the present embodiment, it can be seen that all the conditional expressions (1) to (7) are satisfied.

  14 to 16 are graphs showing various aberrations of the zoom lens ZL according to the fourth example. 14A is an aberration diagram at the time of focusing at infinity in the wide-angle end state (f = 200.00 mm), and FIG. 14B is an image blur correction (image when focusing at infinity in the wide-angle end state). It is an aberration diagram when the shift amount of the front group GA of the second lens group G2 which is a shake correction group = 0.2). FIG. 15 is an aberration diagram when focusing on infinity in the intermediate focal length state (f = 293.26 mm). FIG. 16A is an aberration diagram at the time of focusing at infinity in the telephoto end state (f = 480.00 mm), and FIG. 16B is an image blur correction (image when focusing at infinity in the telephoto end state). It is an aberration diagram when the shift amount of the front group GA of the second lens group G2 which is a shake correction group = 0.2). From the aberration diagrams, it can be seen that in the fourth example, various aberrations are well corrected in each focal length state from the wide-angle end state to the telephoto end state, and the optical performance is excellent. As a result, by mounting the zoom lens ZL of the fourth embodiment, excellent optical performance can be secured even in the digital single-lens reflex camera CAM.

  As described above, according to each embodiment, it is possible to realize a zoom lens and an optical apparatus (digital single-lens reflex camera) having good imaging performance.

  In each embodiment, a lens having a weak refractive power (for example, a convex lens) is provided on the front side (object side) of the front group GA of the second lens group G2, and the front group GA is in a direction substantially perpendicular to the optical axis. The image blur correction may be performed by shifting to.

  In each embodiment, at least one of the lens surfaces in the second lens group G2 may be an aspherical surface. Further, at least one of the lens surfaces in the fifth lens group G5 may be an aspherical surface.

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

  In each of the above-described embodiments, the zoom lens mainly has a five-group configuration. However, as described above, the zoom lens can be applied to other group configurations such as a six-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.

  In addition, a single lens group, a plurality of lens groups, or a partial lens group may be moved in the optical axis direction to be a focusing lens group that performs focusing from an object at infinity to a near object. This focusing lens group can be applied to autofocus, and is also suitable for driving a motor for autofocus (using an ultrasonic motor or the like). In particular, the fourth lens group is preferably a focusing lens group.

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

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

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

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

  The zoom lens (variable magnification optical system) of the present embodiment has a magnification ratio of about 2 to 3.

CAM digital SLR camera (optical equipment)
ZL zoom lens G1 first lens group G2 second lens group G3 third lens group G4 fourth lens group G5 fifth lens group S aperture stop I image plane

Claims (16)

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, arranged in order from the object side along the optical axis; A variable power optical system which is substantially composed of five lens groups by a fourth lens group having refractive power and a fifth lens group having negative refractive power,
When 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, and the distance between the fourth lens group and the fifth lens group changes,
A zoom optical system characterized by satisfying the following conditional expression:
0.510 <f4 / fw <0.580
3.25 ≦ f3 / (− f5) <4.30
However,
f3: focal length of the third lens group,
f4: focal length of the fourth lens group,
f5: focal length of the fifth lens group,
fw: focal length in the wide-angle end state of the zoom optical system. 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, arranged in order from the object side along the optical axis; A variable power optical system which is substantially composed of five lens groups by a fourth lens group having refractive power and a fifth lens group having negative refractive power,
When 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, and the distance between the fourth lens group and the fifth lens group changes,
A zoom optical system characterized by satisfying the following conditional expression:
0.510 <f4 / fw <0.580
1.30 <f3 / f1 <3.00
3.20 <f3 / (− f5) <4.30
However,
f1: the focal length of the first lens group,
f3: focal length of the third lens group,
f4: focal length of the fourth lens group,
f5: focal length of the fifth lens group,
fw: focal length in the wide-angle end state of the zoom optical system. 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, arranged in order from the object side along the optical axis; A variable power optical system which is substantially composed of five lens groups by a fourth lens group having refractive power and a fifth lens group having negative refractive power,
When 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, and the distance between the fourth lens group and the fifth lens group changes,
A zoom optical system characterized by satisfying the following conditional expression:
0.510 <f4 / fw <0.580
1.42 ≦ f3 / f1 <3.00
However,
f1: the focal length of the first lens group,
f3: focal length of the third lens group,
f4: focal length of the fourth lens group,
fw: focal length in the wide-angle end state of the zoom optical system. 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, arranged in order from the object side along the optical axis; A variable power optical system which is substantially composed of five lens groups by a fourth lens group having refractive power and a fifth lens group having negative refractive power,
When 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, and the distance between the fourth lens group and the fifth lens group changes,
A zoom optical system characterized by satisfying the following conditional expression:
0.510 <f4 / fw <0.580
2.80 <f3 / (− f2) ≦ 3.18
However,
f2: focal length of the second lens group,
f3: focal length of the third lens group,
f4: focal length of the fourth lens group,
fw: focal length in the wide-angle end state of the zoom optical system. 5. The variable magnification optical system according to claim 1, wherein the following conditional expression is satisfied.
1.10 <f3 / f1 <3.00
However,
f3: focal length of the third lens group,
f1: Focal length of the first lens group. The zoom lens system according to any one of claims 1 to 3, wherein the following conditional expression is satisfied.
2.80 <f3 / (− f2) <3.80
However,
f3: focal length of the third lens group,
f2: focal length of the second lens group. 5. The zoom optical system according to claim 3, wherein the following conditional expression is satisfied.
3.00 <f3 / (− f5) <4.30
However,
f3: focal length of the third lens group,
f5: focal length of the fifth lens group. The most object side lens in the third lens group is a lens having a positive refractive power,
The variable magnification optical system according to claim 1, wherein the following conditional expression is satisfied.
0.50 <f3 / ft <0.70
However,
f3: focal length of the third lens group,
ft: focal length of the zoom optical system in the telephoto end state. When zooming from the wide-angle end state to the telephoto end state, the distance between the second lens group and the third lens group decreases, and the distance between the fourth lens group and the fifth lens group decreases. The variable power optical system according to claim 1, wherein: A diaphragm between the fourth lens group and the fifth lens group;
10. The zoom optical system according to claim 1 , wherein, when zooming from the wide-angle end state to the telephoto end state, the stop moves from the image side to the object side. 11. The variable magnification optical system according to claim 1, wherein at least a part of the second lens group is movable so as to have a component in a direction orthogonal to the optical axis. The variable power optical system according to any one of claims 1 to 11 , wherein focusing from an object at infinity to a finite distance object is performed by moving the fourth lens group along the optical axis. system. The zoom optical system according to any one of claims 1 to 12 , wherein the fifth lens group moves from the image side to the object side when zooming from the wide-angle end state to the telephoto end state. . The variable magnification optical system according to claim 1, wherein the following conditional expression is satisfied.
2.00 <f1 / (− f5) <2.90
However,
f1: the focal length of the first lens group,
f5: focal length of the fifth lens group. An optical apparatus comprising the variable magnification optical system according to any one of claims 1 to 14 . 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 positive refractive power in order from the object side along the optical axis. A variable-power optical system substantially consisting of five lens groups in which a fourth lens group having a negative refractive power and a fifth lens group having a negative refractive power are disposed,
When 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, and the distance between the fourth lens group and the fifth lens group changes,
A variable magnification optical system manufacturing method characterized by satisfying the following conditional expression:
0.510 <f4 / fw <0.580
3.25 ≦ f3 / (− f5) <4.30
However,
f3: focal length of the third lens group,
f4: focal length of the fourth lens group,
f5: focal length of the fifth lens group,
fw: focal length in the wide-angle end state of the zoom optical system.

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