A zoom optical system (ZL) comprises, in order from an object: a first lens group (G 1 ) having positive refractive power; an intermediate group (GM) including at least one lens group and having negative refractive power as a whole; an intermediate side lens group (GRP 1 ) having positive refractive power; a subsequent side lens group (GRP 2 ) having positive refractive power; and a subsequent group (GR) including at least one lens group. The subsequent side lens group (GRP 2 ) moves upon focusing. A following conditional expression is satisfied: 2.5< f 1/ fRP 1<5.0 where, f1 denotes a focal length of the first lens group (G 1 ), and fRP1 denotes a focal length of the intermediate side lens group (GRP 1 ).

Description

19 parts

›TECHNICAL FIELD

The present invention relates to a zoom optical system, an optical apparatus using the same and a method for manufacturing the zoom optical system.

›TECHNICAL BACKGROUND

A zoom optical system suitable for photographic cameras, electronic still cameras, video cameras, and the like has conventionally been proposed (see, for example, Patent Document 1). Optical performance of such a conventional zoom optical system has been insufficient.

›PRIOR ARTS LIST

Patent Document

Patent Document 1: Japanese Laid-Open Patent Publication No. H4-293007 (A)

›SUMMARY OF THE INVENTION

A zoom optical system according to the present invention comprises, in order from an object: a first lens group having positive refractive power; an intermediate group including at least one lens group and having negative refractive power as a whole; an intermediate side lens group having positive refractive power; a subsequent side lens group having positive refractive power; and a subsequent group including at least one lens group. Upon zooming, distances between the first lens group and the intermediate group, between the intermediate group and the intermediate side lens group, between the intermediate side lens group and the subsequent side lens group, and between the subsequent side lens group and the subsequent group change. The subsequent side lens group moves upon focusing. A following conditional expression is satisfied:

2.5< f 1/ fRP 1<5.0

where,

f1 denotes a focal length of the first lens group, and

fRP1 denotes a focal length of the intermediate side lens group.

An optical apparatus according to the present invention comprises the zoom optical system described above.

A method for manufacturing a zoom optical system according to the present invention is a method for manufacturing a zoom optical system which comprises, in order from an object: a first lens group having positive refractive power; an intermediate group including at least one lens group and having negative refractive power as a whole; an intermediate side lens group having positive refractive power; a subsequent side lens group having positive refractive power; and a subsequent group including at least one lens group, the method comprising a step of arranging the lens groups in a lens barrel so that: upon zooming, distances between the first lens group and the intermediate group, between the intermediate group and the intermediate side lens group, between the intermediate side lens group and the subsequent side lens group, and between the subsequent side lens group and the subsequent group change; the subsequent side lens group moves upon focusing; and a following conditional expression is satisfied:

2.5< f 1/ fRP 1<5.0

where, f1 denotes a focal length of the first lens group, and fRP1 denotes a focal length of the intermediate side lens group.

›BRIEF DESCRIPTION OF THE DRAWINGS · 1 of 2

FIG. 1 is a diagram illustrating a lens configuration of a zoom optical system according to Example 1 of the present embodiment.

FIG. 2A is a graph showing various aberrations of the zoom optical system according to Example 1 upon focusing on infinity in a wide angle end state, and FIG. 2B is a meridional lateral aberration graph in a case where blur correction is performed for the roll blur of 0.30°.

FIG. 3 is a graph showing various aberrations of the zoom optical system according to Example 1 upon focusing on infinity in an intermediate focal length state.

FIG. 4A is a graph showing various aberrations of the zoom optical system according to Example 1 upon focusing on infinity in a telephoto end state, and FIG. 4B is a meridional lateral aberration graph in a case where blur correction is performed for the roll blur of 0.20°.

FIGS. 5A, 5B, and 5C are graphs showing various aberrations of the zoom optical system according to Example 1 upon focusing on a short distant object, respectively in the wide angle end state, the intermediate focal length state, and the telephoto end state.

FIG. 6 is a diagram illustrating a lens configuration of a zoom optical system according to Example 2 of the present embodiment.

FIG. 7A is a graph showing various aberrations of the zoom optical system according to Example 2 upon focusing on infinity in the wide angle end state, and FIG. 7B is a meridional lateral aberration graph in a case where blur correction is performed for the roll blur of 0.30°.

FIG. 8 is a graph showing various aberrations of the zoom optical system according to Example 2 upon focusing on infinity in the intermediate focal length state.

FIG. 9A is a graph showing various aberrations of the zoom optical system according to Example 2 upon focusing on infinity in the telephoto end state, and FIG. 9B is a meridional lateral aberration graph in a case where blur correction is performed for the roll blur of 0.20°.

FIGS. 10A, 10B, and 10C are graphs showing various aberrations of the zoom optical system according to Example 2 upon focusing on a short distant object, respectively in the wide angle end state, the intermediate focal length state, and the telephoto end state.

FIG. 11 is a diagram illustrating a lens configuration of a zoom optical system according to Example 3 of the present embodiment.

FIG. 12A is a graph showing various aberrations of the zoom optical system according to Example 3 upon focusing on infinity in the wide angle end state, and FIG. 12B is a meridional lateral aberration graph in a case where blur correction is performed for the roll blur of 0.30°.

FIG. 13 is a graph showing various aberrations of the zoom optical system according to Example 3 upon focusing on infinity in the intermediate focal length state.

FIG. 14A is a graph showing various aberrations of the zoom optical system according to Example 3 upon focusing on infinity in the telephoto end state, and FIG. 14B is a meridional lateral aberration graph in a case where blur correction is performed for the roll blur of 0.20°.

FIGS. 15A, 15B, and 15C are graphs showing various aberrations of the zoom optical system according to Example 3 upon focusing on a short distant object, respectively in the wide angle end state, the intermediate focal length state, and the telephoto end state.

FIG. 16 is a diagram illustrating a lens configuration of a zoom optical system according to Example 4 of the present embodiment.

FIG. 17A is a graph showing various aberrations of the zoom optical system according to Example 4 upon focusing on infinity in the wide angle end state, and FIG. 17B is a meridional lateral aberration graph in a case where blur correction is performed for the roll blur of 0.30°.

FIG. 18 is a graph showing various aberrations of the zoom optical system according to Example 4 upon focusing on infinity in the intermediate focal length state.

FIG. 19A is a graph showing various aberrations of the zoom optical system according to Example 4 upon focusing on infinity in the telephoto end state, and FIG. 19B is a meridional lateral aberration graph in a case where blur correction is performed for the roll blur of 0.20°.

FIGS. 20A, 20B, and 20C are graphs showing various aberrations of the zoom optical system according to Example 4 upon focusing on a short distant object, respectively in the wide angle end state, the intermediate focal length state, and the telephoto end state.

FIG. 21 is a diagram illustrating a lens configuration of a zoom optical system according to Example 5 of the present embodiment.

FIG. 22A is a graph showing various aberrations of the zoom optical system according to Example 5 upon focusing on infinity in the wide angle end state, and FIG. 22B is a meridional lateral aberration graph in a case where blur correction is performed for the roll blur of 0.30°.

FIG. 23 is a graph showing various aberrations of the zoom optical system according to Example 5 upon focusing on infinity in the intermediate focal length state.

FIG. 24A is a graph showing various aberrations of the zoom optical system according to Example 5 upon focusing on infinity in the telephoto end state, and FIG. 24B is a meridional lateral aberration graph in a case where blur correction is performed for the roll blur of 0.20°.

FIGS. 25A, 25B, and 25C are graphs showing various aberrations of the zoom optical system according to Example 5 upon focusing on a short distant object, respectively in the wide angle end state, the intermediate focal length state, and the telephoto end state.

FIG. 26 is a diagram illustrating a lens configuration of a zoom optical system according to Example 6 of the present embodiment.

FIG. 27A is a graph showing various aberrations of the zoom optical system according to Example 6 upon focusing on infinity in the wide angle end state, and FIG. 27B is a meridional lateral aberration graph in a case where blur correction is performed for the roll blur of 0.30°.

FIG. 28 is a graph showing various aberrations of the zoom optical system according to Example 6 upon focusing on infinity in the intermediate focal length state.

›BRIEF DESCRIPTION OF THE DRAWINGS · 2 of 2

FIG. 29A is a graph showing various aberrations of the zoom optical system according to Example 6 upon focusing on infinity in the telephoto end state, and FIG. 29B is a meridional lateral aberration graph in a case where blur correction is performed for the roll blur of 0.20°.

FIGS. 30A, 30B, and 30C are graphs showing various aberrations of the zoom optical system according to Example 6 upon focusing on a short distant object, respectively in the wide angle end state, the intermediate focal length state, and the telephoto end state.

FIG. 31 is a diagram illustrating a configuration of a camera comprising the zoom optical system according to the present embodiment.

FIG. 32 is a flowchart illustrating a method for manufacturing the zoom optical system according to the present embodiment.

›DESCRIPTION OF THE EMBODIMENTS · 1 of 3

A zoom optical system and an optical apparatus according to the present embodiment are described below with reference to the drawings. As illustrated in FIG. 1 , a zoom optical system ZL( 1 ) as an example of a zoom optical system (zoom lens) ZL according to the present embodiment comprises, in order from an object: a first lens group G 1 having positive refractive power; an intermediate group GM (second lens group G 2 ) including at least one lens group and having negative refractive power as a whole; an intermediate side lens group GRP 1 (third lens group G 3 ) having positive refractive power; a subsequent side lens group GRP 2 (fourth lens group G 4 ) having positive refractive power; and a subsequent group GR (fifth lens group G 5 ) including at least one lens group. Upon zooming, distances between the first lens group G 1 and the intermediate group GM, between the intermediate group GM and the intermediate side lens group GRP 1 , between the intermediate side lens group GRP 1 and the subsequent side lens group GRP 2 , and between the subsequent side lens group GRP 2 and the subsequent group GR change. The subsequent side lens group GRP 2 moves as a focusing lens group upon focusing.

The zoom optical system ZL according to the present embodiment may also be a zoom optical system ZL( 2 ) illustrated in FIG. 6 , a zoom optical system ZL( 3 ) illustrated in FIG. 11 , a zoom optical system ZL( 4 ) illustrated in FIG. 16 , a zoom optical system ZL( 5 ) illustrated in FIG. 21 , or a zoom optical system ZL( 6 ) illustrated in FIG. 26 . The zoom optical systems ZL( 2 ), ZL( 3 ), and ZL( 4 ) respectively illustrated in FIGS. 6, 11, and 16 have the same configuration as the zoom optical system ZL( 1 ) illustrated in FIG. 1 . In the zoom optical system ZL( 5 ) illustrated in FIG. 21 , the intermediate group GM (second lens group G 2 ), the intermediate side lens group GRP 1 (third lens group G 3 ), and the subsequent side lens group GRP 2 (fourth lens group G 4 ) have the same configurations as those in the zoom optical system ZL( 1 ) illustrated in FIG. 1 . The subsequent group GR consists of the fifth lens group G 5 and a sixth lens group G 6 . In the zoom optical system ZL( 6 ) illustrated in FIG. 26 , the intermediate group GM consists of the second lens group G 2 and the third lens group G 3 , the intermediate side lens group GRP 1 consists of the fourth lens group G 4 , the subsequent side lens group GRP 2 consists of the fifth lens group G 5 , and the subsequent group GR consists of the sixth lens group G 6 .

The zoom optical system ZL according to the present embodiment comprises at least five lens groups, and the distances among the lens groups change upon zooming. Thus, successful aberration correction can be achieved upon zooming. Focusing is performed with the subsequent side lens group GRP 2 serving as the focusing lens group, and thus the focusing lens group can be small and light weight.

An aperture stop is preferably disposed to an object side or an image side of the intermediate side lens group GRP 1 . The aperture stop may be disposed between lenses forming the intermediate side lens group GRP 1 .

The intermediate group GM preferably comprises negative refractive power as a whole from the wide angle end state to the telephoto end state. For example, the intermediate group GM may consist of one lens group having negative refractive power, or may consist of two lens groups each having negative refractive power. For example, the intermediate group GM may consist of two lens groups including, in order from the object, a lens group having positive refractive power and a lens group having negative refractive power, or may consist of two lens groups including, in order from the object, a lens group having negative refractive power and a lens group having positive refractive power.

The subsequent group GR preferably comprises negative or positive refractive power as a whole. For example, the subsequent group GR may consist of one lens group having negative refractive power, or may consist of two lens groups each having negative refractive power.

A plurality of lens groups may be configured to move along the same movement locus upon zooming. Preferably, at least one lens group in the intermediate side lens group GRP 1 and at least one lens group in the subsequent group GR are configured to move along the same movement locus. More preferably, at least one lens group in the first lens group G 1 , at least one lens group in the intermediate side lens group GRP 1 , and at least one lens group in the subsequent group GR are configured to move along the same movement locus.

The zoom optical system ZL according to the present embodiment having the configuration described above satisfies the following conditional expression.

2.5< f 1/ fRP 1<5.0 (1)

where,

f1 denotes a focal length of the first lens group G 1 , and

fRP1 denotes a focal length of the intermediate side lens group GRP 1 .

The conditional expression (1) is for setting an appropriate range of a ratio between the focal lengths of the first lens group G 1 and the intermediate side lens group GRP 1 . Variation of various aberrations including the spherical aberration can be prevented upon zooming when the conditional expression (1) is satisfied.

A value higher than the upper limit value of the conditional expression (1) leads to large refractive power of the intermediate side lens group GRP 1 , rendering variation of various aberrations including the spherical aberration upon zooming difficult to prevent. The effects of the present embodiment can be more effectively guaranteed with the upper limit value of the conditional expression (1) set to be 4.7. To more effectively guarantee the effects of the present embodiment, the upper limit value of the conditional expression (1) is preferably set to be 4.4.

A value lower than the lower limit value of the conditional expression (1) leads to large refractive power of the first lens group G 1 , rendering various aberrations including the spherical aberration upon zooming difficult to correct. The effects of the present embodiment can be more effectively guaranteed with the lower limit value of the conditional expression (1) set to be 2.7. To more effectively guarantee the effects of the present embodiment, the lower limit value of the conditional expression (1) is preferably set to be 2.9.

›DESCRIPTION OF THE EMBODIMENTS · 2 of 3

In the zoom optical system according to the present embodiment, the intermediate group GM preferably comprises a vibration-proof lens group movable to have a component in a direction orthogonal to the optical axis to correct image blur. This effectively prevents the performance from being compromised by camera shake correction.

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

2.9< f 1/(− fMt )<5.5 (2)

where,

fMt denotes a focal length of the intermediate group GM in the telephoto end state.

The conditional expression (2) is for setting an appropriate range of a ratio between the focal lengths of the first lens group G 1 and the intermediate group GM in the telephoto end state. Variation of various aberrations including the spherical aberration can be prevented upon zooming when the conditional expression (2) is satisfied.

A value higher than the upper limit value of the conditional expression (2) leads to large refractive power of the intermediate group GM, rendering variation of various aberrations including the spherical aberration upon zooming difficult to prevent. The effects of the present embodiment can be more effectively guaranteed with the upper limit value of the conditional expression (2) set to be 5.2. To more effectively guarantee the effects of the present embodiment, the upper limit value of the conditional expression (2) is preferably set to be 4.9.

A value lower than the lower limit value of the conditional expression (2) leads to large refractive power of the first lens group G 1 , rendering various aberrations including the spherical aberration upon zooming difficult to correct. The effects of the present embodiment can be more effectively guaranteed with the lower limit value of the conditional expression (2) set to be 3.1. To more effectively guarantee the effects of the present embodiment, the lower limit value of the conditional expression (2) is preferably set to be 3.3.

The zoom optical system according to the present embodiment preferably has a configuration in which the first lens group G 1 moves toward the object upon zooming from the wide angle end state to the telephoto end state. With this configuration, a short total length of the lenses in the wide angle end state can be achieved, whereby a small size of the zoom optical system can be achieved.

The zoom optical system according to the present embodiment preferably comprises the subsequent side lens group GRP 2 having at least one lens having positive refractive power and at least one lens having negative refractive power. With this configuration, variation of various aberrations including the spherical aberration can be prevented upon focusing.

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

0.2< fP /(− fN )<0.8 (3)

where,

fP denotes a focal length of a lens with largest positive refractive power in the subsequent side lens group GRP 2 , and

fN denotes a focal length of a lens with largest negative refractive power in the subsequent side lens group GRP 2 .

The conditional expression (3) is for defining an appropriate range of a ratio between the focal lengths of the lens with the largest positive refractive power in the subsequent side lens group GRP 2 and the lens with the largest negative refractive power in the subsequent side lens group GRP 2 . Variation of various aberrations including the spherical aberration can be prevented upon focusing when the conditional expression (3) is satisfied.

A value higher than the upper limit value of the conditional expression (3) leads to large refractive power of the lens with the largest negative refractive power in the subsequent side lens group GRP 2 , rendering variation of various aberrations including the spherical aberration upon focusing difficult to prevent. The effects of the present embodiment can be more effectively guaranteed with the upper limit value of the conditional expression (3) set to be 0.75. To more effectively guarantee the effects of the present embodiment, the upper limit value of the conditional expression (3) is preferably set to be 0.70.

A value lower than the lower limit value of the conditional expression (3) leads to large refractive power of the lens with the largest positive refractive power in the subsequent side lens group GRP 2 , rendering variation of various aberrations including the spherical aberration upon focusing difficult to prevent. The effects of the present embodiment can be more effectively guaranteed with the lower limit value of the conditional expression (3) set to be 0.25. To more effectively guarantee the effects of the present embodiment, the lower limit value of the conditional expression (3) is preferably set to be 0.30.

The zoom optical system according to the present embodiment preferably comprises the first lens group G 1 including, in order from an object: a 1-1st lens having positive refractive power; a 1-2nd lens having negative refractive power; and a 1-3rd lens having positive refractive power. With this configuration, the spherical aberration and a chromatic aberration can be successfully corrected.

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

0.85< nP/nN< 1.00 (4)

where,

nP denotes a refractive index of a lens with largest positive refractive power in the first lens group G 1 , and

nN denotes a refractive index of a lens with largest negative refractive power in the first lens group G 1 .

The conditional expression (4) is for defining an appropriate range of a ratio between the refractive indices of the lens with the largest positive refractive power in the first lens group G 1 and the lens with the largest negative refractive power in the first lens group G 1 . Various aberrations including the spherical aberration can be successfully corrected when the conditional expression (4) is satisfied.

A value higher than the upper limit value of the conditional expression (4) leads to a small refractive index of the lens with the largest negative refractive power in the first lens group G 1 , rendering various aberrations including the spherical aberration difficult to correct. The effects of the present embodiment can be more effectively guaranteed with the upper limit value of the conditional expression (4) set to be 0.98. To more effectively guarantee the effects of the present embodiment, the upper limit value of the conditional expression (4) is preferably set to be 0.96.

›DESCRIPTION OF THE EMBODIMENTS · 3 of 3

A value lower than the lower limit value of the conditional expression (4) leads to a small refractive index of the lens with the largest positive refractive power in the first lens group G 1 , leading to extremely large spherical aberration that is difficult to correct. The effects of the present embodiment can be more effectively guaranteed with the lower limit value of the conditional expression (4) set to be 0.86. To more effectively guarantee the effects of the present embodiment, the lower limit value of the conditional expression (4) is preferably set to be 0.87.

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

2.25< νP/νN< 2.90 (5)

where,

νP denotes an Abbe number of the lens with the largest positive refractive power in the first lens group G 1 , and

νN denotes an Abbe number of the lens with the largest negative refractive power in the first lens group G 1 .

The conditional expression (5) is for defining an appropriate range of a ratio between the Abbe numbers of the lens with the largest positive refractive power in the first lens group G 1 and the lens with the largest negative refractive power in the first lens group G 1 . The chromatic aberration can be successfully corrected when the conditional expression (5) is satisfied.

A value higher than the upper limit value of the conditional expression (5) leads to a small Abbe number of the lens with the largest negative refractive power in the first lens group G 1 , resulting in an extremely large chromatic aberration that is difficult to correct. The effects of the present embodiment can be more effectively guaranteed with the upper limit value of the conditional expression (5) set to be 2.85. To more effectively guarantee the effects of the present embodiment, the upper limit value of the conditional expression (5) is preferably set to be 2.80.

A value lower than the lower limit value of the conditional expression (5) leads to a small Abbe number of the lens with the largest positive refractive power in the first lens group G 1 , leading to extremely large chromatic aberration that is difficult to correct. The effects of the present embodiment can be more effectively guaranteed with the lower limit value of the conditional expression (5) set to be 2.30. To more effectively guarantee the effects of the present embodiment, the lower limit value of the conditional expression (5) is preferably set to be 2.35.

The optical apparatus according to the present embodiment comprises the zoom optical system with the configuration described above. A camera (optical apparatus) including the zoom optical system ZL is described, as a specific example, with reference to FIG. 31 . This camera 1 is a digital camera including the zoom optical system according to the present embodiment serving as an imaging lens 2 as illustrated in FIG. 31 . In the camera 1 , the imaging lens 2 collects light from an object (subject) (not illustrated), and then the light reaches an image sensor 3 . Thus, an image based on the light from the subject is formed with the image sensor 3 to be stored as a subject image in a memory (not illustrated). In this manner, the photographer can capture an image of the subject with the camera 1 . The camera may be a mirrorless camera, or may be a single lens reflex camera having a quick return mirror.

With the configuration described above, the camera 1 comprising the zoom optical system ZL serving as the imaging lens 2 can have the subsequent side lens group GRP 2 serving as the focusing lens group that is small and light weight, and thus quick and quiet AF (Auto Focus) can be achieved without using a large barrel. Furthermore, with this configuration, variation of aberrations upon zooming from the wide angle end state to the telephoto end state, as well as variation of aberrations upon focusing on a short distant object from an infinite distant object can be successfully prevented, whereby excellent optical performance can be achieved.

Next, a method for manufacturing the zoom optical system ZL described above is described with reference to FIG. 32 . First of all, in order from the object, the first lens group G 1 having positive refractive power, the intermediate group GM including at least one lens group and having negative refractive power, the intermediate side lens group GRP 1 having positive refractive power, the subsequent side lens group GRP 2 having positive refractive power, and the subsequent group GR including at least one lens group are arranged in a barrel (step ST 1 ). The lens groups are arranged in the lens barrel so that, upon zooming, the distances between the first lens group G 1 and the intermediate group GM, between the intermediate group GM and the intermediate side lens group GRP 1 , between the intermediate side lens group GRP 1 and the subsequent side lens group GRP 2 , and between the subsequent side lens group GRP 2 and the subsequent group GR change (step ST 2 ). The lens groups are arranged in the lens barrel so that the subsequent side lens group GRP 2 moves upon focusing (step ST 3 ). The lens groups are arranged in the lens barrel so that at least the conditional expression (1) described above is satisfied (step ST 4 ).

›EXAMPLES

Zoom optical systems (zoom lenses) ZL according to Examples of the present embodiment are described below with reference to the drawings. FIG. 1 , FIG. 6 , FIG. 11 , FIG. 16 , FIG. 21 , and FIG. 26 are cross-sectional views illustrating configurations and refractive power distributions of the zoom optical systems ZL {ZL( 1 ) to ZL( 6 )} according to Examples 1 to 6. In the lower portion of each cross-sectional view of the zoom optical systems ZL( 1 ) to ZL( 6 ), the directions in which the lens groups are moved along the optical axis upon zooming from the wide angle end state (W) to the telephoto end state (T) are shown by arrows. A direction in which the subsequent side lens group GRP 2 serving as the focusing lens group moves upon focusing on a short distant object from infinity is shown by an arrow appended with “focusing”.

In FIGS. 1, 6, 11, 16, 21, and 26 , a combination of a sign G and a number represents each lens group, and a combination of a sign L and a number represents each lens. In each Example, lens groups and the like are each denoted with a combination of the reference sign and numeral independently from other Examples to prevent cumbersomeness due to an excessively wide variety or a large number of signs and numerals. Thus, components in different Examples denoted with the same combination of reference sign and numeral does not necessarily have the same configuration.

Tables 1 to 6 include Table 1 that is a specification table of Example 1, Table 2 that is a specification table of Example 2, Table 3 that is a specification table of Example 3, Table 4 that is a specification table of Example 4, Table 5 that is a specification table of Example 5, and Table 6 that is a specification table of Example 6. In Examples, d-line (wavelength λ=587.6 nm) and g-line (wavelength λ=435.8 nm) are selected as calculation targets of the aberration characteristics.

In Table [Lens specifications], a surface number represents an order of an optical surface from the object side in a traveling direction of a light beam, R represents a radius of curvature of each optical surface (with a surface having the center of curvature position on the image side provided with a positive value), D represents a distance between each optical surface and the next optical surface (or the image surface) on the optical axis, nd represents a refractive index of a material of an optical member with respect to the d-line, and νd represents an Abbe number of the material of the optical member based on the d-line. In the table, object surface represents an object surface, “∞” of the radius of curvature represents a plane or an aperture, (stop S) represents the aperture stop S, and image surface represents an image surface I. The refractive index nd=1.00000 of air is omitted.

Specifically, in Table [Various data], f represents a focal length of the whole zoom lens, FNO represents F number, 2ω represents an angle of view (ω represents a half angle of view (unit: °)), and Ymax represents the maximum image height. TL represents a distance obtained by adding BF to a distance between the lens forefront surface and a lens last surface on the optical axis upon focusing on infinity, and back focus (BF) represents a distance between the lens last surface and the image surface I on the optical axis upon focusing on infinity. These values are provided for each of the zooming states including the wide angle end state (W), the intermediate focal length state (M), and the telephoto end state (T).

Table [Variable distance data] includes surface distances corresponding to surfaces corresponding to surface numbers appended with “variable” in Table [Lens specifications] and the next surface. The surface distances are provided for each of the zooming states including the wide angle end state (W), the intermediate focal length state (M), and the telephoto end state (T) upon focusing on infinity and upon focusing on a short distant object.

Table [Lens group data] includes the group starting surface (surface closest to the object) and the focal length of each of the first to the fifth (or sixth) lens groups.

Table [Conditional expression corresponding value] represents values corresponding to the conditional expressions (1) to (5).

The focal length f, the radius of curvature R, the surface distance D and the other units of length described below as all the specification values, which are generally described with “mm” unless otherwise noted should not be construed in a limiting sense because the optical system proportionally expanded or reduced can have a similar or the same optical performance.

The description on the tables described above commonly applies to all Examples, and thus will not be redundantly given below.

›Examples8

›Example 1 · 1 of 2

Example 1 is described with reference to FIG. 1 , FIGS. 2A and 2B , FIG. 3 , FIGS. 4A and 4B , and FIGS. 5A-5C and Table 1. FIG. 1 is a diagram illustrating a lens configuration of a zoom optical system according to Example 1 of the present embodiment. The zoom optical system ZL( 1 ) according to Example 1 consists of, in order from an object: a first lens group G 1 having positive refractive power; a second lens group G 2 having negative refractive power; a third lens group G 3 having positive refractive power; an aperture stop S; a fourth lens group G 4 having positive refractive power; and a fifth lens group G 5 having negative refractive power. The first to the fifth lens groups G 1 to G 5 each move in a direction indicated by an arrow in FIG. 1 upon zooming from a wide angle end state (W) to a telephoto end state (T). In this Example, the intermediate group GM includes the second lens group G 2 , the intermediate side lens group GRP 1 includes the third lens group G 3 and the aperture stop S, the subsequent side lens group GRP 2 includes the fourth lens group G 4 , and the subsequent group GR includes the fifth lens group G 5 . A sign (+) or (−) provided to a sign of each lens group represents refractive power of the lens group. The same applies to all of Examples described below.

The first lens group G 1 consists of, in order from the object, a positive lens (1-1st lens) L 11 having a biconvex shape and a cemented positive lens consisting of a negative meniscus lens (1-2nd lens) L 12 having a convex surface facing the object and a positive meniscus lens (1-3rd lens) L 13 having a convex surface facing the object.

The second lens group G 2 consists of, in order from the object, a negative meniscus lens L 21 having a convex surface facing the object, a positive meniscus lens L 22 having a convex surface facing the object, and a cemented negative lens consisting of a negative lens L 23 having a biconcave shape and a positive meniscus lens L 24 having a convex surface facing the object.

The third lens group G 3 consists of, in order from the object, a positive lens L 31 having a biconvex shape and a cemented positive lens consisting of a positive lens L 32 having a biconvex shape and a negative lens L 33 having a biconcave shape. The aperture stop S is disposed in the neighborhood of and to the image side of the third lens group G 3 , and integrally moves with the third lens group G 3 upon zooming.

The fourth lens group G 4 consists of a cemented positive lens consisting of a positive lens L 41 having a biconvex shape and a negative meniscus lens L 42 having a concave surface facing the object.

The fifth lens group G 5 consists of, in order from the object, a negative lens L 51 having a biconcave shape, a positive meniscus lens L 52 having a concave surface facing the object, a negative meniscus lens L 53 having a concave surface facing the object, and a positive lens L 54 having a biconvex shape. An image surface I is disposed to the image side of the fifth lens group G 5 .

In the zoom optical system ZL( 1 ) according to Example 1, the fourth lens group G 4 (subsequent side lens group GRP 2 ) moves toward the object upon focusing from a long distant object to a short distant object. In the zoom optical system ZL( 1 ) according to Example 1, the cemented negative lens consisting of the negative lens L 23 and the positive meniscus lens L 24 in the second lens group G 2 serves as a vibration-proof lens group, movable in a direction orthogonal to the optical axis, to be in charge of correcting displacement of the imaging position due to camera shake or the like (image blur on the image surface I).

To correct roll blur of an angle θ with a focal length of the whole system being f and with a lens having a vibration proof coefficient K (the ratio of the image movement amount on the imaging surface to the movement amount of the moving lens group for camera shake correction), a moving lens group for camera shake correction is moved in the direction orthogonal to the optical axis by (f·tan θ)/K. In the wide angle end state in Example 1, the vibration proof coefficient is 0.97 and the focal length is 72.1 (mm), and thus the movement amount of the vibration-proof lens group to correct a roll blur of 0.30° is 0.39 (mm). In the telephoto end state in Example 1, the vibration proof coefficient is 2.01 and the focal length is 292.0 (mm), and thus the movement amount of the vibration-proof lens group to correct a roll blur of 0.20° is 0.51 (mm).

Table 1 below lists specification values of the optical system according to Example 1.

FIG. 2A is a graph showing various aberrations of the zoom optical system according to Example 1 having a vibration-proof function upon focusing on infinity in the wide angle end state, and FIG. 2B is a meridional lateral aberration graph in a case where blur correction is performed for the roll blur of 0.30°. FIG. 3 is a graph showing various aberrations of the zoom optical system according to Example 1 having the vibration proof function upon focusing on infinity in the intermediate focal length state. FIG. 4A is a graph showing various aberrations of the zoom optical system according to Example 1 having a vibration-proof function upon focusing on infinity in the telephoto end state, and FIG. 4B is a meridional lateral aberration graph in a case where blur correction is performed for the roll blur of 0.20°. FIGS. 5A, 5B, and 5C are graphs showing various aberrations of the zoom optical system according to Example 1 upon focusing on a short distant object, respectively in the wide angle end state, the intermediate focal length state, and the telephoto end state.

In the aberration graphs in FIGS. 2A and 2B , FIG. 3 , FIGS. 4A and 4B , and FIGS. 5A-5C , FNO denotes an F number, NA denotes the number of apertures, and Y denotes an image height. The spherical aberration graphs illustrate an F number or the number of apertures corresponding to the maximum aperture, astigmatism graphs and distortion graphs illustrate the maximum image height, and coma aberration graphs illustrate values of image heights. d denotes a d line (wavelength λ=587.6 mu) and g denotes a g line (wavelength λ=435.8 nm). In the astigmatism graphs, a solid line represents a sagittal image surface, and a broken line represents a meridional image surface. In aberration graphs in Examples described below, the same reference signs as in this Example are used, and a redundant description is omitted.

›Example 1 · 2 of 2

It can be seen in these aberration graphs that the zoom optical system according to Example 1 can achieve excellent imaging performance with various aberrations successfully corrected from the wide angle end state to the telephoto end state, and can achieve excellent imaging performance upon focusing on a short distant object.

›Example 2

Example 2 is described with reference to FIG. 6 , FIGS. 7A and 7B , FIG. 8 , FIGS. 9A and 9B , and FIGS. 10A-10C and Table 2. FIG. 6 is a diagram illustrating a lens configuration of a zoom optical system according to Example 2 of the present embodiment. The zoom optical system ZL( 2 ) according to Example 2 consists of, in order from an object: a first lens group G 1 having positive refractive power; a second lens group G 2 having negative refractive power; a third lens group G 3 having positive refractive power; an aperture stop S; a fourth lens group G 4 having positive refractive power; and a fifth lens group G 5 having negative refractive power. The first to the fifth lens groups G 1 to G 5 each move in a direction indicated by an arrow in FIG. 6 upon zooming from a wide angle end state (W) to a telephoto end state (T). In this Example, the intermediate group GM includes the second lens group G 2 , the intermediate side lens group GRP 1 includes the third lens group G 3 and the aperture stop S, the subsequent side lens group GRP 2 includes the fourth lens group G 4 , and the subsequent group GR includes the fifth lens group G 5 .

The second lens group G 2 consists of, in order from the object, a negative meniscus lens L 21 having a convex surface facing the object, a negative meniscus lens L 22 having a concave surface facing the object, a positive meniscus lens L 23 having a convex surface facing the object, and a cemented negative lens consisting of a negative lens L 24 having a biconcave shape and a positive meniscus lens L 25 having a convex surface facing the object.

The fourth lens group G 4 consists of a cemented positive lens consisting of a positive lens L 41 having a biconvex shape and a negative meniscus lens L 42 having a concave surface facing the object.

The fifth lens group G 5 consists of, in order from the object, a negative lens L 51 having a biconcave shape, a positive lens L 52 having a biconvex shape, a negative meniscus lens L 53 having a concave surface facing the object, and a positive lens L 54 having a biconvex shape. An image surface I is disposed to the image side of the fifth lens group G 5 .

In the zoom optical system ZL( 2 ) according to Example 2, the fourth lens group G 4 (subsequent side lens group GRP 2 ) moves toward the object upon focusing from a long distant object to a short distant object. In the zoom optical system ZL( 2 ) according to Example 2, the cemented negative lens consisting of the negative lens L 24 and the positive meniscus lens L 25 in the second lens group G 2 serves as a vibration-proof lens group, movable in a direction orthogonal to the optical axis, to be in charge of correcting displacement of the imaging position due to camera shake or the like (image blur on the image surface I).

To correct roll blur of an angle θ with a focal length of the whole system being f and with a lens having a vibration proof coefficient K (the ratio of the image movement amount on the imaging surface to the movement amount of the moving lens group for camera shake correction), a moving lens group for camera shake correction is moved in the direction orthogonal to the optical axis by (f·tan θ)/K. In the wide angle end state in Example 2, the vibration proof coefficient is 0.97 and the focal length is 72.1 (mm), and thus the movement amount of the vibration-proof lens group to correct a roll blur of 0.30° is 0.39 (mm). In the telephoto end state in Example 2, the vibration proof coefficient is 2.03 and the focal length is 292.0 (mm), and thus the movement amount of the vibration-proof lens group to correct a roll blur of 0.20° is 0.50 (mm).

Table 2 below lists specification values of the optical system according to Example 2.

FIG. 7A is a graph showing various aberrations of the zoom optical system according to Example 2 having a vibration-proof function upon focusing on infinity in the wide angle end state, and FIG. 7B is a meridional lateral aberration graph in a case where blur correction is performed for the roll blur of 0.30°. FIG. 8 is a graph showing various aberrations of the zoom optical system according to Example 2 having a vibration proof function upon focusing on infinity in the intermediate focal length state. FIG. 9A is a graph showing various aberrations of the zoom optical system according to Example 2 having a vibration-proof function upon focusing on infinity in the telephoto end state, and FIG. 9B is a meridional lateral aberration graph in a case where blur correction is performed for the roll blur of 0.20°. FIGS. 10A, 10B, and 10C are graphs showing various aberrations of the zoom optical system according to Example 2 upon focusing on a short distant object, respectively in the wide angle end state, the intermediate focal length state, and the telephoto end state.

It can be seen in these aberration graphs that the zoom optical system according to Example 2 can achieve excellent imaging performance with various aberrations successfully corrected from the wide angle end state to the telephoto end state, and can achieve excellent imaging performance upon focusing on a short distant object.

›Example 3

Example 3 is described with reference to FIG. 11 , FIGS. 12A and 12B , FIG. 13 , FIGS. 14A and 14B , and FIGS. 15A-15C and Table 3. FIG. 11 is a diagram illustrating a lens configuration of a zoom optical system according to Example 3 of the present embodiment. The zoom optical system ZL( 3 ) according to Example 3 consists of, in order from an object: a first lens group G 1 having positive refractive power; a second lens group G 2 having negative refractive power; a third lens group G 3 having positive refractive power; an aperture stop S; a fourth lens group G 4 having positive refractive power; and a fifth lens group G 5 having negative refractive power. The first to the fifth lens groups G 1 to G 5 each move in a direction indicated by an arrow in FIG. 11 upon zooming from a wide angle end state (W) to a telephoto end state (T). In this Example, the intermediate group GM includes the second lens group G 2 , the intermediate side lens group GRP 1 includes the third lens group G 3 and the aperture stop S, the subsequent side lens group GRP 2 includes the fourth lens group G 4 , and the subsequent group GR includes the fifth lens group G 5 .

The fourth lens group G 4 consists of a cemented positive lens consisting of a positive lens L 41 having a biconvex shape and a negative meniscus lens L 42 having a concave surface facing the object.

The fifth lens group G 5 consists of, in order from the object, a negative lens L 51 having a biconcave shape, a negative lens L 52 having a biconcave shape, a positive lens L 53 having a biconvex shape, a negative meniscus lens L 54 having a concave surface facing the object, and a positive meniscus lens L 55 having a convex surface facing the object. An image surface I is disposed to the image side of the fifth lens group G 5 .

In the zoom optical system ZL( 3 ) according to Example 3, the fourth lens group G 4 (subsequent side lens group GRP 2 ) moves toward the object upon focusing from a long distant object to a short distant object. In the zoom optical system ZL( 3 ) according to Example 3, the cemented negative lens consisting of the negative lens L 23 and the positive meniscus lens L 24 in the second lens group G 2 serves as a vibration-proof lens group, movable in a direction orthogonal to the optical axis, to be in charge of correcting displacement of the imaging position due to camera shake or the like (image blur on the image surface I).

To correct roll blur of an angle θ with a focal length of the whole system being f and with a lens having a vibration proof coefficient K (the ratio of the image movement amount on the imaging surface to the movement amount of the moving lens group for camera shake correction), a moving lens group for camera shake correction is moved in the direction orthogonal to the optical axis by (f·tan θ)/K. In the wide angle end state in Example 3, the vibration proof coefficient is 0.96 and the focal length is 72.1 (mm), and thus the movement amount of the vibration-proof lens group to correct a roll blur of 0.30° is 0.39 (mm). In the telephoto end state in Example 3, the vibration proof coefficient is 1.99 and the focal length is 292.0 (mm), and thus the movement amount of the vibration-proof lens group to correct a roll blur of 0.20° is 0.51 (mm).

Table 3 below lists specification values of the optical system according to Example 3.

FIG. 12A is a graph showing various aberrations of the zoom optical system according to Example 3 having a vibration-proof function upon focusing on infinity in the wide angle end state, and FIG. 12B is a meridional lateral aberration graph in a case where blur correction is performed for the roll blur of 0.30°. FIG. 13 is a graph showing various aberrations of the zoom optical system according to Example 3 having a vibration proof function upon focusing on infinity in the intermediate focal length state. FIG. 14A is a graph showing various aberrations of the zoom optical system according to Example 3 having a vibration-proof function upon focusing on infinity in the telephoto end state, and FIG. 14B is a meridional lateral aberration graph in a case where blur correction is performed for the roll blur of 0.20°. FIGS. 15A, 15B, and 15C are graphs showing various aberrations of the zoom optical system according to Example 3 upon focusing on a short distant object, respectively in the wide angle end state, the intermediate focal length state, and the telephoto end state.

It can be seen in these aberration graphs that the zoom optical system according to Example 3 can achieve excellent imaging performance with various aberrations successfully corrected from the wide angle end state to the telephoto end state, and can achieve excellent imaging performance upon focusing on a short distant object.

›Example 4

Example 4 is described with reference to FIG. 16 , FIGS. 17A and 17B , FIG. 18 , FIGS. 19A and 19B , and FIGS. 20A-20C and Table 4. FIG. 16 is a diagram illustrating a lens configuration of a zoom optical system according to Example 4 of the present embodiment. The zoom optical system ZL( 4 ) according to Example 4 consists of, in order from an object: a first lens group G 1 having positive refractive power; a second lens group G 2 having negative refractive power; a third lens group G 3 having positive refractive power; an aperture stop S; a fourth lens group G 4 having positive refractive power; and a fifth lens group G 5 having negative refractive power. The first to the fifth lens groups G 1 to G 5 each move in a direction indicated by an arrow in FIG. 16 upon zooming from a wide angle end state (W) to a telephoto end state (T). In this Example, the intermediate group GM includes the second lens group G 2 , the intermediate side lens group GRP 1 includes the third lens group G 3 and the aperture stop S, the subsequent side lens group GRP 2 includes the fourth lens group G 4 , and the subsequent group GR includes the fifth lens group G 5 .

The fourth lens group G 4 consists of, in order from the object, a positive lens L 41 having a biconvex shape and a negative meniscus lens L 42 having a concave surface facing the object.

The fifth lens group G 5 consists of, in order from the object, a negative meniscus lens L 51 having a convex surface facing the object, a positive meniscus lens L 52 having a concave surface facing the object, a negative meniscus lens L 53 having a concave surface facing the object, and a positive lens L 54 having a biconvex shape. An image surface I is disposed to the image side of the fifth lens group G 5 .

In the zoom optical system ZL( 4 ) according to Example 4, the fourth lens group G 4 (subsequent side lens group GRP 2 ) moves toward the object upon focusing from a long distant object to a short distant object. In the zoom optical system ZL( 4 ) according to Example 4, the cemented negative lens consisting of the negative lens L 23 and the positive meniscus lens L 24 in the second lens group G 2 serves as a vibration-proof lens group, movable in a direction orthogonal to the optical axis, to be in charge of correcting displacement of the imaging position due to camera shake or the like (image blur on the image surface I).

To correct roll blur of an angle θ with a focal length of the whole system being f and with a lens having a vibration proof coefficient K (the ratio of the image movement amount on the imaging surface to the movement amount of the moving lens group for camera shake correction), a moving lens group for camera shake correction is moved in the direction orthogonal to the optical axis by (f·tan θ)/K. In the wide angle end state in Example 4, the vibration proof coefficient is 0.99 and the focal length is 72.1 (mm), and thus the movement amount of the vibration-proof lens group to correct a roll blur of 0.30° is 0.38 (mm). In the telephoto end state in Example 4, the vibration proof coefficient is 2.04 and the focal length is 292.0 (mm), and thus the movement amount of the vibration-proof lens group to correct a roll blur of 0.20° is 0.50 (mm).

Table 4 below lists specification values of the optical system according to Example 4.

FIG. 17A is a graph showing various aberrations of the zoom optical system according to Example 4 having a vibration-proof function upon focusing on infinity in the wide angle end state, and FIG. 17B is a meridional lateral aberration graph in a case where blur correction is performed for the roll blur of 0.30°. FIG. 18 is a graph showing various aberrations of the zoom optical system according to Example 4 having a vibration proof function upon focusing on infinity in the intermediate focal length state. FIG. 19A is a graph showing various aberrations of the zoom optical system according to Example 4 having a vibration-proof function upon focusing on infinity in the telephoto end state, and FIG. 19B is a meridional lateral aberration graph in a case where blur correction is performed for the roll blur of 0.20°. FIGS. 20A, 20B, and 20C are graphs showing various aberrations of the zoom optical system according to Example 4 upon focusing on a short distant object, respectively in the wide angle end state, the intermediate focal length state, and the telephoto end state.

It can be seen in these aberration graphs that the zoom optical system according to Example 4 can achieve excellent imaging performance with various aberrations successfully corrected from the wide angle end state to the telephoto end state, and can achieve excellent imaging performance upon focusing on a short distant object.

›Example 5

Example 5 is described with reference to FIG. 21 , FIGS. 22A and 22B , FIG. 23 , FIGS. 24A and 24B , and FIGS. 25A-25C and Table 5. FIG. 21 is a diagram illustrating a lens configuration of a zoom optical system according to Example 5 of the present embodiment. The zoom optical system ZL( 5 ) according to Example 5 consists of, in order from an object: a first lens group G 1 having positive refractive power; a second lens group G 2 having negative refractive power; a third lens group G 3 having positive refractive power; an aperture stop S; a fourth lens group G 4 having positive refractive power; a fifth lens group G 5 having negative refractive power; and a sixth lens group G 6 having negative refractive power. The first to the sixth lens groups G 1 to G 6 each move in a direction indicated by an arrow in FIG. 21 upon zooming from a wide angle end state (W) to a telephoto end state (T). In this Example, the intermediate group GM includes the second lens group G 2 , the intermediate side lens group GRP 1 includes the third lens group G 3 and the aperture stop S, the subsequent side lens group GRP 2 includes the fourth lens group G 4 , and the subsequent group GR includes the fifth lens group G 5 and the sixth lens group G 6 . The subsequent group GR has negative refractive power as a whole.

The fourth lens group G 4 consists of, in order from the object, a positive lens L 41 having a biconvex shape and a negative meniscus lens L 42 having a concave surface facing the object.

The fifth lens group G 5 consists of, in order from the object, a negative meniscus lens L 51 having a convex surface facing the object and a positive meniscus lens L 52 having a concave surface facing the object.

The sixth lens group G 6 consists of, in order from the object, a negative meniscus lens L 61 having a concave surface facing the object and a positive lens L 62 having a biconvex shape. An image surface I is disposed to the image side of the sixth lens group G 6 .

In the zoom optical system ZL( 5 ) according to Example 5, the fourth lens group G 4 (subsequent side lens group GRP 2 ) moves toward the object upon focusing from a long distant object to a short distant object. In the zoom optical system ZL( 5 ) according to Example 5, the cemented negative lens consisting of the negative lens L 23 and the positive meniscus lens L 24 in the second lens group G 2 serves as a vibration-proof lens group, movable in a direction orthogonal to the optical axis, to be in charge of correcting displacement of the imaging position due to camera shake or the like (image blur on the image surface I).

To correct roll blur of an angle θ with a focal length of the whole system being f and with a lens having a vibration proof coefficient K (the ratio of the image movement amount on the imaging surface to the movement amount of the moving lens group for camera shake correction), a moving lens group for camera shake correction is moved in the direction orthogonal to the optical axis by (f·tan θ)/K. In the wide angle end state in Example 5, the vibration proof coefficient is 1.00 and the focal length is 72.1 (mm), and thus the movement amount of the vibration-proof lens group to correct a roll blur of 0.30° is 0.38 (mm). In the telephoto end state in Example 5, the vibration proof coefficient is 2.07 and the focal length is 292.0 (mm), and thus the movement amount of the vibration-proof lens group to correct a roll blur of 0.20° is 0.49 (mm).

Table 5 below lists specification values of the optical system according to Example 5.

FIG. 22A is a graph showing various aberrations of the zoom optical system according to Example 5 having a vibration-proof function upon focusing on infinity in the wide angle end state, and FIG. 22B is a meridional lateral aberration graph in a case where blur correction is performed for the roll blur of 0.30°. FIG. 23 is a graph showing various aberrations of the zoom optical system according to Example 5 having a vibration proof function upon focusing on infinity in the intermediate focal length state. FIG. 24A is a graph showing various aberrations of the zoom optical system according to Example 5 having a vibration-proof function upon focusing on infinity in the telephoto end state, and FIG. 24B is a meridional lateral aberration graph in a case where blur correction is performed for the roll blur of 0.20°. FIGS. 25A, 25B, and 25C are graphs showing various aberrations of the zoom optical system according to Example 5 upon focusing on a short distant object, respectively in the wide angle end state, the intermediate focal length state, and the telephoto end state.

It can be seen in these aberration graphs that the zoom optical system according to Example 5 can achieve excellent imaging performance with various aberrations successfully corrected from the wide angle end state to the telephoto end state, and can achieve excellent imaging performance upon focusing on a short distant object.

›Example 6 · 1 of 2

Example 6 is described with reference to FIG. 26 , FIGS. 27A and 27B , FIG. 28 , FIGS. 29A and 29B , and FIGS. 30A-30C and Table 6. FIG. 26 is a diagram illustrating a lens configuration of a zoom optical system according to Example 6 of the present embodiment. The zoom optical system ZL( 6 ) according to Example 6 consists of, in order from an object: a first lens group G 1 having positive refractive power; a second lens group G 2 having negative refractive power; a third lens group G 3 having negative refractive power; a fourth lens group G 4 having positive refractive power; an aperture stop S; a fifth lens group G 5 having positive refractive power; and a sixth lens group G 6 having negative refractive power. The first to the sixth lens groups G 1 to G 6 each move in a direction indicated by an arrow in FIG. 26 upon zooming from a wide angle end state (W) to a telephoto end state (T). In this Example, the intermediate group GM includes the second lens group G 2 and the third lens group G 3 , the intermediate side lens group GRP 1 includes the fourth lens group G 4 and the aperture stop S, the subsequent side lens group GRP 2 includes the fifth lens group G 5 , and the subsequent group GR includes the sixth lens group G 6 . The intermediate group GM has negative refractive power as a whole.

The second lens group G 2 consists of, in order from the object, a negative meniscus lens L 21 having a convex surface facing the object and a positive meniscus lens L 22 having a convex surface facing the object.

The third lens group G 3 consists of a cemented negative lens consisting of a negative lens L 31 having a biconcave shape and a positive meniscus lens L 32 having a convex surface facing the object.

The fourth lens group G 4 consists of, in order from the object, a positive lens L 41 having a biconvex shape and a cemented positive lens consisting of a positive lens L 42 having a biconvex shape and a negative lens L 43 having a biconcave shape. The aperture stop S is disposed in the neighborhood of and to the image side of the fourth lens group G 4 , and integrally moves with the fourth lens group G 4 upon zooming.

The fifth lens group G 5 consists of a cemented positive lens consisting of a positive lens L 51 having a biconvex shape and a negative meniscus lens L 52 having a concave surface facing the object.

The sixth lens group G 6 consists of, in order from the object, a negative lens L 61 having a biconcave shape, a positive meniscus lens L 62 having a concave surface facing the object, a negative meniscus lens L 63 having a concave surface facing the object, and a positive lens L 64 having a biconvex shape. An image surface I is disposed to the image side of the sixth lens group G 6 .

In the zoom optical system ZL( 6 ) according to Example 6, the fifth lens group G 5 (subsequent side lens group GRP 2 ) moves toward the object upon focusing from a long distant object to a short distant object. In the zoom optical system ZL( 6 ) according to Example 6, the third lens group G 3 serves as a vibration-proof lens group, movable in a direction orthogonal to the optical axis, to be in charge of correcting displacement of the imaging position due to camera shake or the like (image blur on the image surface I).

To correct roll blur of an angle θ with a focal length of the whole system being f and with a lens having a vibration proof coefficient K (the ratio of the image movement amount on the imaging surface to the movement amount of the moving lens group for camera shake correction), a moving lens group for camera shake correction is moved in the direction orthogonal to the optical axis by (f·tan θ)/K. In the wide angle end state in Example 6, the vibration proof coefficient is 0.97 and the focal length is 72.1 (mm), and thus the movement amount of the vibration-proof lens group to correct a roll blur of 0.30° is 0.39 (mm). In the telephoto end state in Example 6, the vibration proof coefficient is 2.01 and the focal length is 292.0 (mm), and thus the movement amount of the vibration-proof lens group to correct a roll blur of 0.20° is 0.51 (mm).

Table 6 below lists specification values of the optical system according to Example 6.

FIG. 27A is a graph showing various aberrations of the zoom optical system according to Example 6 having a vibration-proof function upon focusing on infinity in the wide angle end state, and FIG. 27B is a meridional lateral aberration graph in a case where blur correction is performed for the roll blur of 0.30°. FIG. 28 is a graph showing various aberrations of the zoom optical system according to Example 6 having a vibration proof function upon focusing on infinity in the intermediate focal length state. FIG. 29A is a graph showing various aberrations of the zoom optical system according to Example 6 having a vibration-proof function upon focusing on infinity in the telephoto end state, and FIG. 29B is a meridional lateral aberration graph in a case where blur correction is performed for the roll blur of 0.20°. FIGS. 30A, 30B, and 30C are graphs showing various aberrations of the zoom optical system according to Example 6 upon focusing on a short distant object, respectively in the wide angle end state, the intermediate focal length state, and the telephoto end state.

It can be seen in these aberration graphs that the zoom optical system according to Example 6 can achieve excellent imaging performance with various aberrations successfully corrected from the wide angle end state to the telephoto end state, and can achieve excellent imaging performance upon focusing on a short distant object.

According to Examples described above, the subsequent side lens group GRP 2 serves as the focusing lens group to achieve a small size and light weight so that quick and quiet AF can be implemented without using a large barrel. Furthermore, a zoom optical system successfully preventing variation of aberrations upon zooming from the wide angle end state to the telephoto end state, as well as variation of aberrations upon focusing on a short distant object from an infinite distant object can be implemented.

›Example 6 · 2 of 2

Examples described above are merely examples of the invention according to the present application. The invention according to the present application is not limited to these examples.

The following configurations can be appropriately employed as long as the optical performance of the zoom optical system according to the present embodiment is not compromised.

Examples of values of the zoom optical system according the present embodiment having five or six lens groups are described above. However, this should not be construed in a limiting sense, and a zoom optical system with other lens group configurations (for example, a configuration with seven lens groups or the like) may be employed. More specifically, the zoom optical system according to the present embodiment may be further provided with a lens or a lens group closest to an object or further provided with a lens or a lens group closest to the image surface. The lens group is a portion comprising at least one lens separated from another lens with a distance varying upon zooming.

The focusing lens group is a portion comprising at least one lens separated from another lens with a distance varying upon focusing. Thus, the focusing lens group may be provided for focusing from an infinite distant object to a short distant object, with a single or a plurality of lens groups or a partial lens group moved in the optical axis direction. The focusing lens group can be applied to auto focus, and is suitable for motor driving for auto focus (using supersonic wave motors, etc.).

The lens surface may be formed to have a spherical surface or a planer surface, or may be formed to have an aspherical surface. The lens surface having a spherical surface or a planer surface features easy lens processing and assembly adjustment, which leads to the processing and assembly adjustment less likely to involve an error compromising the optical performance, and thus is preferable. Furthermore, there is an advantage that a rendering performance is not largely compromised even when the image surface is displaced.

The lens surface having an aspherical surface may be achieved with any one of an aspherical surface formed by grinding, a glass-molded aspherical surface obtained by molding a glass piece into an aspherical shape, and a composite type aspherical surface obtained by providing an aspherical shape resin piece on a glass surface. A lens surface may be a diffractive surface. The lens may be a gradient index lens (GRIN lens) or a plastic lens.

The aperture stop is preferably disposed in the neighborhood of the third or the fourth lens group. Alternatively, the aperture stop may be disposed in the third or the fourth lens group. A lens frame may serve as the aperture stop so that the member serving as the aperture stop needs not to be provided.

The lens surfaces may be provided with an antireflection film comprising high transmittance over a wide range of wavelengths to achieve an excellent optical performance with reduced flare and ghosting and increased contrast. Thus, an excellent optical performance with reduced flare and ghosting and increased contrast can be achieved.

EXPLANATION OF NUMERALS AND CHARACTERS

›Tables in the description — 5

TABLE 1 — [Lens specifications] Surface

	number	R	D	nd	νd
Object	∞
surface
1	443.9646	3.817	1.48749	70.31
2	−469.6963	0.200
3	100.9381	1.700	1.67270	32.19
4	64.8256	8.767	1.49700	81.73
5	2578.1121	Variable
6	189.1236	1.000	1.77250	49.62
7	35.4799	7.123
8	37.2041	2.691	1.80518	25.45
9	57.9432	4.513
10	−64.2854	1.000	1.67003	47.14
11	37.2626	3.500	1.75520	27.57
12	146.7584	Variable
13	107.2202	3.817	1.80610	40.97
14	−71.1994	0.200
15	41.9753	5.272	1.49700	81.73
16	−54.1569	1.000	1.85026	32.35
17	154.3187	1.508
18	∞	Variable			(Aperture
					stop S)
19	104.1819	4.528	1.51680	63.88
20	−28.6539	1.000	1.80100	34.92
21	−53.7161	Variable
22	−120.9949	1.000	1.90366	31.27
23	61.5584	10.276
24	−319.9239	4.049	1.68893	31.16
25	−33.0322	16.448
26	−24.1471	1.000	1.77250	49.62
27	−213.3380	0.200
28	79.7473	3.205	1.71736	29.57
29	−323.3417	BF
Image	∞
surface
[Various data]
Zooming rate 4.05
		W	M	T
	f	72.1	99.9	292.0
	FNO	4.54	4.73	5.88
	2ω	33.60	23.92	8.26
	Ymax	21.60	21.60	21.60
	TL	193.31	211.69	248.31
	BF	38.31	41.11	61.31
[Variable distance data]
				W	M	T
	W	M	T	Short	Short	Short
	Infinity	Infinity	Infinity	distant	distant	distant
d5	2.000	26.394	73.625	2.000	26.394	73.625
d12	41.625	32.810	2.000	41.625	32.810	2.000
d18	21.563	20.201	21.407	20.665	19.062	19.151
d21	2.000	3.362	2.156	2.899	4.501	4.413
[Lens group data]
		Starting	Focal
	Group	surface	length
	G1	1	169.064
	G2	6	−41.090
	G3	13	50.436
	G4	19	100.808
	G5	22	−52.611
	[Conditional expression corresponding value]
	Conditional expression (1) f1/fRP1 = 3.352
	Conditional expression (2) f1/(−fMt) = 4.114
	Conditional expression (3) fP/(−fN) = 0.564
	Conditional expression (4) nP/nN = 0.895
	Conditional expression (5) νP/νN = 2.539

TABLE 2 — [Lens specifications] Surface

	number	R	D	nd	νd
Object	∞
surface
1	524.3080	3.649	1.48749	70.31
2	−473.1509	0.200
3	99.8647	1.700	1.67270	32.19
4	65.5021	8.680	1.49700	81.73
5	1712.5853	Variable
6	93.5170	1.000	1.83400	37.18
7	34.3474	6.920
8	−111.6255	1.000	1.60300	65.44
9	−404.2382	0.200
10	45.6203	2.882	1.84666	23.80
11	103.2990	3.776
12	−66.2945	1.000	1.70000	48.11
13	38.4320	3.453	1.79504	28.69
14	151.5709	Variable
15	101.1563	3.699	1.80400	46.60
16	−81.9293	0.200
17	39.5595	5.119	1.49700	81.73
18	−67.2517	1.000	1.85026	32.35
19	148.7139	1.531
20	∞	Variable			(Aperture
					stop S)
21	99.6360	4.438	1.51680	63.88
22	−28.3755	1.000	1.80610	40.97
23	−55.9883	Variable
24	−69.2441	1.000	1.90366	31.27
25	64.7455	7.965
26	1599.2908	4.469	1.67270	32.19
27	−30.6814	16.326
28	−23.5416	1.000	1.80400	46.60
29	−175.4914	0.343
30	82.8193	3.436	1.67270	32.19
31	−167.6215	BF
Image	∞
surface
[Various data]
Zooming rate 4.05
		W	M	T
	f	72.1	100.0	292.0
	FNO	4.54	4.76	5.88
	2ω	33.58	23.98	8.28
	Ymax	21.60	21.60	21.60
	TL	193.32	210.95	248.32
	BF	38.32	41.61	61.32
[Variable distance data]
				W	M	T
	W	M	T	Short	Short	Short
	Infinity	Infinity	Infinity	distant	distant	distant
d5	2.000	25.989	75.552	2.000	25.989	75.552
d14	43.552	33.897	2.000	43.552	33.897	2.000
d20	21.465	19.956	21.465	20.527	18.788	19.123
d23	2.000	3.509	2.000	2.938	4.677	4.341
[Lens group data]
		Starting	Focal
	Group	surface	length
	G1	1	173.986
	G2	6	−42.714
	G3	15	49.108
	G4	21	106.792
	G5	24	−51.186
	[Conditional expression corresponding value]
	Conditional expression (1) f1/fRP1 = 3.543
	Conditional expression (2) f1/(−fMt) = 4.073
	Conditional expression (3) fP/(−fN) = 0.596
	Conditional expression (4) nP/nN = 0.895
	Conditional expression (5) νP/νN = 2.539

TABLE 3 — [Lens specifications] Surface

	number	R	D	nd	νd
Object	∞
surface
1	394.8396	3.845	1.48749	70.31
2	−543.4808	0.200
3	105.1984	1.700	1.67270	32.19
4	67.0764	8.688	1.49700	81.73
5	3999.3650	Variable
6	187.7927	1.000	1.83481	42.73
7	39.3002	8.392
8	40.6875	2.537	1.84666	23.80
9	61.9560	4.302
10	−65.9607	1.000	1.70000	48.11
11	47.5227	2.966	1.84666	23.80
12	155.3071	Variable
13	100.1220	3.921	1.80400	46.60
14	−71.7118	0.200
15	39.6874	5.409	1.49700	81.73
16	−55.1551	1.000	1.85026	32.35
17	138.4368	1.566
18	∞	Variable			(Aperture
					stop S)
19	90.1287	4.430	1.51680	63.88
20	−29.8148	1.000	1.83400	37.18
21	−56.5509	Variable
22	−89.4853	1.000	1.90366	31.27
23	58.7258	1.623
24	−119.8149	1.000	1.77250	49.62
25	125.4243	2.815
26	86.3318	5.240	1.67270	32.19
27	−30.2745	18.277
28	−22.8447	1.000	1.80400	46.60
29	−60.6486	0.200
30	89.8891	2.703	1.66446	35.87
31	3303.4609	BF
Image	∞
surface
[Various data]
Zooming rate 4.05
		W	M	T
	f	72.1	99.9	292.0
	FNO	4.53	4.71	5.88
	2ω	33.50	23.86	8.24
	Ymax	21.60	21.60	21.60
	TL	193.32	211.55	248.32
	BF	38.32	41.10	61.32
[Variable distance data]
				W	M	T
	W	M	T	Short	Short	Short
	Infinity	Infinity	Infinity	distant	distant	distant
d5	2.000	26.748	74.901	2.000	26.748	74.901
d12	42.901	33.607	2.000	42.901	33.607	2.000
d18	22.086	20.598	21.608	21.186	19.465	19.388
d21	2.000	3.489	2.479	2.900	4.621	4.698
[Lens group data]]
		Starting	Focal
	Group	surface	length
	G1	1	172.579
	G2	6	−42.044
	G3	13	48.716
	G4	19	101.916
	G5	22	−49.748
	[Conditional expression corresponding value]
	Conditional expression (1) f1/fRP1 = 3.543
	Conditional expression (2) f1/(−fMt) = 4.105
	Conditional expression (3) fP/(−fN) = 0.571
	Conditional expression (4) nP/nN = 0.895
	Conditional expression (5) νP/νN = 2.539

TABLE 4 — [Lens specifications] Surface

	number	R	D	nd	νd
Object	∞
surface
1	397.7403	3.807	1.48749	70.31
2	−541.2704	0.200
3	98.5962	1.700	1.67270	32.19
4	64.4142	7.530	1.49700	81.73
5	2167.3548	Variable
6	153.3759	1.000	1.80610	40.97
7	35.8256	8.557
8	37.5306	2.567	1.84666	23.80
9	55.0899	4.528
10	−64.5906	1.000	1.70000	48.11
11	45.3004	3.006	1.84666	23.80
12	146.7719	Variable
13	120.3729	3.847	1.79952	42.09
14	−66.6553	0.200
15	40.5542	5.444	1.49700	81.73
16	−51.5427	1.000	1.85026	32.35
17	136.7432	1.574
18	∞	Variable			(Aperture
					stop S)
19	73.0072	4.267	1.51680	63.88
20	−41.6199	1.157
21	−36.8096	1.000	1.80100	34.92
22	−63.5855	Variable
23	142.7978	1.000	1.90366	31.27
24	39.2858	5.972
25	−32.2173	2.394	1.80518	25.45
26	−25.4336	17.643
27	−22.2559	1.000	1.77250	49.62
28	−60.4849	0.200
29	133.6379	3.767	1.69895	30.13
30	−86.4148	BF
Image	∞
surface
[Various data]
Zooming rate 4.05
		W	M	T
	f	72.1	100.0	292.0
	FNO	4.58	4.77	5.88
	2ω	33.52	23.92	8.28
	Ymax	21.60	21.60	21.60
	TL	193.32	210.92	248.32
	BF	38.32	41.32	62.32
[Variable distance data]
				W	M	T
	W	M	T	Short	Short	Short
	Infinity	Infinity	Infinity	distant	distant	distant
d5	2.000	25.714	72.838	2.000	25.714	72.838
d12	41.838	32.720	2.000	41.838	32.720	2.000
d18	24.804	23.298	24.804	23.943	22.207	22.596
d22	2.000	3.505	2.000	2.861	4.597	4.208
[Lens group data]
		Starting	Focal
	Group	surface	length
	G1	1	166.403
	G2	6	−40.599
	G3	13	52.091
	G4	19	95.393
	G5	23	−58.282
	[Conditional expression corresponding value]
	Conditional expression (1) f1/fRP1 = 3.194
	Conditional expression (2) f1/(−fMt) = 4.099
	Conditional expression (3) fP/(−fN) = 0.468
	Conditional expression (4) nP/nN = 0.895
	Conditional expression (5) νP/νN = 2.539

G1 first lens group	G2 second lens group
G3 third lens group	G4 fourth lens group
G5 fifth lens group	G6 sixth lens group
GM intermediate group	GR subsequent group
GRP1 intermediate side lens group	GRP2 subsequent side lens group
I image surface	S aperture stop

Claims as granted

9 claims

Classifications

10 codes

IPC · International Patent Classification

Section G — Physics

G02B15/20
G02B27/64
G02B15/14
G02B15/173
G02B13/18
G02B13/02
G02B5/00
G02B15/163
G02B9/62
G02B13/00

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Evelyn A Lester

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