Zoom lens and imaging apparatus

1 . A zoom lens comprising, in order from an object side to an image side: a first lens group that has a positive refractive power; a second lens group that has a negative refractive power; a middle group that includes one or more lens groups; and a final lens group,

wherein the middle group has a positive refractive power as a whole throughout an entire zoom range,

during zooming, a spacing between the first lens group and the second lens group changes, a spacing between the second lens group and the middle group changes, and a spacing between the middle group and the final lens group changes, and

in a case where the middle group includes a plurality of lens groups, all spacings of adjacent lens groups in the middle group change during zooming,

wherein a focal length of the zoom lens in a state where an infinite distance object is in focus at a wide angle end is fw, a focal length of the zoom lens in a state where the infinite distance object is in focus at a telephoto end is ft, and Conditional Expression (1) is satisfied, which is represented by

6< ft/fw< 30  (1),

wherein a back focal length of the zoom lens at an air-equivalent distance in a state where the infinite distance object is in focus at the wide angle end is Bfw, a maximum half angle of view in a state where the infinite distance object is in focus at the wide angle end is ωw, and Conditional Expression (8) is satisfied, which is represented by

0.5< Bfw /( fw ×tan ω w )<1.1  (8),

wherein a central thickness of a lens closest to the object side in the first lens group is d1, a focal length of the first lens group is f1, and Conditional Expression (23) is satisfied, which is represented by

0.01< d 1/ f 1<0.021  (23),

wherein the zoom lens includes a focus group that moves along an optical axis during focusing, a focal length of the focus group is ffoc, and Conditional Expression (31-1) is satisfied, which is represented by

−0.28 <ffoc/ft<− 0.05  (31-1), and

wherein a focal length of the second lens group is f2, a focal length of a lens group closest to the object side in the middle group is f3, and Conditional Expression (41) is satisfied, which is represented by

−0.9< f 2/ f 3<−0.54  (41), and

wherein an Abbe number of a lens closest to the object side in the first lens group based on a d line is vd1, and Conditional Expression (2) is satisfied, which is represented by

29.6< vd 1<50  (2), and

wherein an Abbe number of a lens which is third from the object side in the first lens group based on a d line is vd3, and Conditional Expression (26) is satisfied, which is represented by

70< vd 3<110  (26).

2 . The zoom lens according to claim 1 ,

wherein an Abbe number of a lens which is second from the object side in the first lens group based on a d line is νd2, an Abbe number of a lens which is third from the object side in the first lens group based on the d line is νd3, and Conditional Expression (3) is satisfied, which is represented by

68<( νd 2+ νd 3)/2<98  (3).

3 . The zoom lens according to claim 1 ,

wherein the first lens group consists of, in order from the object side to the image side, a negative lens, a positive lens, and a positive lens.

4 . The zoom lens according to claim 1 ,

wherein the focus group has a negative refractive power.

5 . The zoom lens according to claim 1 ,

wherein the focus group includes a positive lens and a negative lens.

6 . The zoom lens according to claim 1 ,

wherein the focus group consists of a cemented lens in which a positive lens and a negative lens are cemented to each other.

7 . The zoom lens according to claim 1 ,

wherein a lens group which is fourth from the object side in the zoom lens is a focus group that moves along an optical axis during focusing.

8 . The zoom lens according to claim 1 ,

wherein the middle group includes at least one lens group that has a positive refractive power.

9 . The zoom lens according to claim 1 ,

wherein the middle group includes a lens group that has a positive refractive power at a position closest to the object side.

10 . The zoom lens according to claim 1 ,

wherein the middle group includes, successively in order from a position closest to the object side to the image side, a lens group that has a positive refractive power and a lens group that has a negative refractive power.

11 . The zoom lens according to claim 1 ,

wherein all the lens groups move during zooming.

12 . The zoom lens according to claim 1 ,

wherein the zoom lens consists of five lens groups as a whole.

13 . The zoom lens according to claim 1 ,

wherein a lens group closest to the object side in the middle group includes, successively in order from the object side to the image side, a positive lens, a positive lens, and a negative lens.

14 . The zoom lens according to claim 1 ,

wherein a lens group closest to the object side in the middle group includes, successively in order from the image side to the object side, a positive lens, a positive lens, and a negative lens.

15 . The zoom lens according to claim 1 ,

wherein the second lens group consists of, in order from the object side to the image side, a negative lens, a negative lens, a positive lens, and a negative lens.

16 . The zoom lens according to claim 1 ,

wherein an F number in a state where the infinite distance object is in focus at the telephoto end is FNot, and Conditional Expression (4) is satisfied, which is represented by

45<FNot×( ft/fw )<130  (4).

17 . The zoom lens according to claim 1 ,

wherein a sum of a back focal length of the zoom lens at an air-equivalent distance and a distance on an optical axis from a lens surface closest to the object side in the first lens group to a lens surface closest to the image side in the final lens group in a state where the infinite distance object is in focus at the wide angle end is TLw, and Conditional Expression (5) is satisfied, which is represented by

4.5< TLw/fw< 9.5  (5).

18 . The zoom lens according to claim 1 ,

wherein a sum of a back focal length of the zoom lens at an air-equivalent distance and a distance on an optical axis from a lens surface closest to the object side in the first lens group to a lens surface closest to the image side in the final lens group in a state where the infinite distance object is in focus at the telephoto end is TLt, and Conditional Expression (6) is satisfied, which is represented by

0.5< TLt/ft< 1.3  (6).

19 . The zoom lens according to claim 1 ,

wherein a sum of a back focal length of the zoom lens at an air-equivalent distance and a distance on an optical axis from a lens surface closest to the object side in the first lens group to a lens surface closest to the image side in the final lens group in a state where the infinite distance object is in focus at the telephoto end is TLt, a maximum half angle of view in a state where the infinite distance object is in focus at the telephoto end is ωt, and Conditional Expression (7) is satisfied, which is represented by

10< TLt /( ft ×tan ω t )<18  (7).

20 . The zoom lens according to claim 1 ,

wherein a distance on an optical axis from a lens surface closest to the object side in the first lens group to a paraxial entrance pupil position in a state where the infinite distance object is in focus at the wide angle end is Denw, and Conditional Expression (9) is satisfied, which is represented by

1.1<Den w/fw< 1.9  (9).

21 . The zoom lens according to claim 1 ,

wherein a lens group which is fourth from the object side in the zoom lens is set as a fourth lens group,

the fourth lens group moves during at least one of zooming or focusing,

a distance on an optical axis from a lens surface closest to the object side in the fourth lens group to a lens surface closest to the image side in the fourth lens group is DG4,

a sum of a back focal length of the zoom lens at an air-equivalent distance and a distance on an optical axis from a lens surface closest to the object side in the first lens group to a lens surface closest to the image side in the final lens group in a state where the infinite distance object is in focus at the wide angle end is TLw, and

Conditional Expression (10) is satisfied, which is represented by

0.009< DG 4/ TLw< 0.12  (10).

22 . The zoom lens according to claim 1 , wherein

an average value of specific gravities of all lenses in the focus group is Gfave, and

Conditional Expression (11) is satisfied, which is represented by

2.3 <Gfave <5.15  (11).

23 . The zoom lens according to claim 1 , wherein

the focus group includes at least one negative lens,

a specific gravity of the at least one negative lens in the focus group is Gfn, and

Conditional Expression (12) is satisfied, which is represented by

2.4< Gfn< 5.6  (12).

24 . The zoom lens according to claim 1 ,

wherein the zoom lens includes a vibration-proof group that moves in a direction intersecting with an optical axis during image shake correction,

an average value of specific gravities of all lenses in the vibration-proof group is GISave, and

Conditional Expression (13) is satisfied, which is represented by

2.5 <GI Save<5.2  (13).

25 . The zoom lens according to claim 1 ,

wherein the zoom lens includes a vibration-proof group that moves in a direction intersecting with an optical axis during image shake correction,

the vibration-proof group includes at least one positive lens,

a specific gravity of the at least one positive lens in the vibration-proof group is GISp, and

Conditional Expression (14) is satisfied, which is represented by

2.6 <GISp <5  (14).

26 . The zoom lens according to claim 1 , wherein

a net displacement of the first lens group along the optical axis during zooming from the wide angle end to the telephoto end is M1,

a sign of M1 is positive in a case where the first lens group moves from the object side to the image side and is negative in a case where the first lens group moves from the image side to the object side,

a sum of a back focal length of the zoom lens at an air-equivalent distance and a distance on the optical axis from a lens surface closest to the object side in the first lens group to a lens surface closest to the image side in the final lens group in a state where the infinite distance object is in focus at the telephoto end is TLt, and

Conditional Expression (15) is satisfied, which is represented by

0.25<− M 1/ TLt< 0.6  (15).

27 . The zoom lens according to claim 1 , wherein

a net displacement of the second lens group along the optical axis during zooming from the wide angle end to the telephoto end is M2,

a sign of M2 is positive in a case where the second lens group moves from the object side to the image side and is negative in a case where the second lens group moves from the image side to the object side,

a sum of a back focal length of the zoom lens at an air-equivalent distance and a distance on the optical axis from a lens surface closest to the object side in the first lens group to a lens surface closest to the image side in the final lens group in a state where the infinite distance object is in focus at the telephoto end is TLt, and

Conditional Expression (16) is satisfied, which is represented by

0.01<− M 2/ TLt< 0.2  (16).

28 . The zoom lens according to claim 1 ,

wherein a lens group closest to the object side in the middle group is set as a third lens group,

a net displacement of the third lens group along the optical axis during zooming from the wide angle end to the telephoto end is M3,

a sign of M3 is positive in a case where the third lens group moves from the object side to the image side and is negative in a case where the third lens group moves from the image side to the object side,

a sum of a back focal length of the zoom lens at an air-equivalent distance and a distance on the optical axis from a lens surface closest to the object side in the first lens group to a lens surface closest to the image side in the final lens group in a state where the infinite distance object is in focus at the telephoto end is TLt, and

Conditional Expression (17) is satisfied, which is represented by

0.08<− M 3/ TLt< 0.4  (17).

29 . The zoom lens according to claim 1 ,

wherein a lens group which is fourth from the object side in the zoom lens is set as a fourth lens group,

a net displacement of the fourth lens group along the optical axis during zooming from the wide angle end to the telephoto end is M4,

a sign of M4 is positive in a case where the fourth lens group moves from the object side to the image side and is negative in a case where the fourth lens group moves from the image side to the object side,

a sum of a back focal length of the zoom lens at an air-equivalent distance and a distance on the optical axis from a lens surface closest to the object side in the first lens group to a lens surface closest to the image side in the final lens group in a state where the infinite distance object is in focus at the telephoto end is TLt, and

Conditional Expression (18) is satisfied, which is represented by

0.15<− M 4/ TLt< 0.3  (18).

30 . The zoom lens according to claim 1 ,

wherein a lens group which is fifth from the object side in the zoom lens is set as a fifth lens group,

a net displacement of the fifth lens group along the optical axis during zooming from the wide angle end to the telephoto end is M5,

a sign of M5 is positive in a case where the fifth lens group moves from the object side to the image side and is negative in a case where the fifth lens group moves from the image side to the object side,

a sum of a back focal length of the zoom lens at an air-equivalent distance and a distance on the optical axis from a lens surface closest to the object side in the first lens group to a lens surface closest to the image side in the final lens group in a state where the infinite distance object is in focus at the telephoto end is TLt, and

Conditional Expression (19) is satisfied, which is represented by

0.11<− M 5/ TLt< 0.31  (19).

31 . The zoom lens according to claim 1 , wherein

an effective diameter of an object side surface of the lens closest to the object side in the first lens group is ED1, and

Conditional Expression (20) is satisfied, which is represented by

0.022< d 1/ ED 1<0.04  (20).

32 . The zoom lens according to claim 1 , wherein

a distance on an optical axis from a lens surface closest to the object side in the first lens group to a paraxial entrance pupil position in a state where the infinite distance object is in focus at the wide angle end is Denw, and

Conditional Expression (21) is satisfied, which is represented by

0.035< d 1/( Denw ×tan ω w )<0.077  (21).

33 . The zoom lens according to claim 1 , wherein

a central thickness of a lens which is second from the object side in the first lens group is d2,

a paraxial curvature radius of an object side surface of the lens which is second from the object side in the first lens group is R2f,

a paraxial curvature radius of an image side surface of the lens which is second from the object side in the first lens group is R2r, and

Conditional Expression (22) is satisfied, which is represented by

0.06< d 2×(1/ R 2 f− 1/ R 2 r )<0.19  (22).

34 . The zoom lens according to claim 1 , wherein

a distance on an optical axis from a lens surface closest to the object side in the first lens group to a lens surface closest to the image side in the first lens group is DG1, and

Conditional Expression (24) is satisfied, which is represented by

0.06< d 1/ DG 1<0.125  (24).

35 . The zoom lens according to claim 1 ,

wherein an Abbe number of a lens which is second from the object side in the first lens group based on a d line is νd2, and

Conditional Expression (25) is satisfied, which is represented by

75<ν d 2<120  (25).

36 . The zoom lens according to claim 1 ,

wherein a partial dispersion ratio of a lens which is second from the object side in the first lens group between a g line and an F line is θgF2, and

Conditional Expression (27) is satisfied, which is represented by

0.46<θ gF 2<0.62  (27).

37 . The zoom lens according to claim 1 ,

wherein a partial dispersion ratio of a lens which is third from the object side in the first lens group between a g line and an F line is θgF3, and

Conditional Expression (28) is satisfied, which is represented by

0.46<θ gF 3<0.62  (28).

38 . The zoom lens according to claim 1 , wherein

a paraxial curvature radius of a surface having a minimum absolute value of the paraxial curvature radius among object side concave surfaces of lenses in the final lens group is REf,

a focal length of the final lens group is fE, and

Conditional Expression (29) is satisfied, which is represented by

−18 <REf/fE<− 2  (29).

39 . The zoom lens according to claim 1 , wherein

a paraxial curvature radius of a lens surface closest to the object side in the focus group is RfF,

a paraxial curvature radius of a lens surface closest to the image side in the focus group is RfR, and

Conditional Expression (30) is satisfied, which is represented by

1.5< RfF/RfR< 6  (30).

40 . The zoom lens according to claim 1 ,

wherein the zoom lens includes a vibration-proof group that moves in a direction intersecting with an optical axis during image shake correction,

a focal length of the vibration-proof group is fIS, and

Conditional Expression (32) is satisfied, which is represented by

0.01<| fIS/ft|< 0.35  (32).

41 . The zoom lens according to claim 1 , wherein

a focal length of a lens which is second from the object side in the second lens group is fL22, and

Conditional Expression (33) is satisfied, which is represented by

1.4< fL 22/ f 2<7  (33).

42 . The zoom lens according to claim 1 , wherein

a lateral magnification of the focus group in a state where the infinite distance object is in focus at the wide angle end is βfw,

a combined lateral magnification of all lenses closer to the image side than the focus group in a state where the infinite distance object is in focus at the wide angle end is βfRw, and

Conditional Expression (34) is satisfied, which is represented by

−6<(1−β fw 2 )×β fRw 2 <−1  (34).

43 . The zoom lens according to claim 1 , wherein

a lateral magnification of the focus group in a state where the infinite distance object is in focus at the telephoto end is βft,

a combined lateral magnification of all lenses closer to the image side than the focus group in a state where the infinite distance object is in focus at the telephoto end is βfRt, and

Conditional Expression (35) is satisfied, which is represented by

−25<(1−β ft 2 )×β fRt 2 <−6.3  (35).

44 . The zoom lens according to claim 1 ,

wherein the zoom lens includes a vibration-proof group that moves in a direction intersecting with an optical axis during image shake correction,

a lateral magnification of the vibration-proof group in a state where the infinite distance object is in focus at the wide angle end is βISw,

a combined lateral magnification of all lenses closer to the image side than the vibration-proof group in a state where the infinite distance object is in focus at the wide angle end is βISRw, and

Conditional Expression (36) is satisfied, which is represented by

0.75<|(1−β ISw )×β ISRw |<2.5  (36).

45 . The zoom lens according to claim 1 ,

wherein the zoom lens includes a vibration-proof group that moves in a direction intersecting with an optical axis during image shake correction,

a lateral magnification of the vibration-proof group in a state where the infinite distance object is in focus at the telephoto end is βISt,

a combined lateral magnification of all lenses closer to the image side than the vibration-proof group in a state where the infinite distance object is in focus at the telephoto end is βISRt, and

Conditional Expression (37) is satisfied, which is represented by

1.7<|(1−β ISt )×β ISRt |<7  (37).

46 . The zoom lens according to claim 1 , wherein

a lateral magnification of the focus group in a state where the infinite distance object is in focus at the wide angle end is βfw,

a combined lateral magnification of all lenses closer to the image side than the focus group in a state where the infinite distance object is in focus at the wide angle end is βfRw,

a composite focal length of all lenses closer to the image side than the focus group in a state where the infinite distance object is in focus at the wide angle end is ffRw,

a sum of a back focal length of the zoom lens at an air-equivalent distance and a distance on an optical axis from a paraxial exit pupil position to a lens surface closest to the image side in the final lens group in a state where the infinite distance object is in focus at the wide angle end is Dexw,

γ w =(1−β fw 2 )×β fRw 2 , and

BRw={βfw /( ffoc×γw )−1/(β fRw×ffRw )−(1 /Dexw )}, and

Conditional Expression (38) is satisfied, which is represented by

0< |BRw ×( fw ×tan ω w )|<0.25  (38).

47 . The zoom lens according to claim 1 , wherein

a lateral magnification of the focus group in a state where the infinite distance object is in focus at the telephoto end is βft,

a combined lateral magnification of all lenses closer to the image side than the focus group in a state where the infinite distance object is in focus at the telephoto end is βfRt,

a composite focal length of all lenses closer to the image side than the focus group in a state where the infinite distance object is in focus at the telephoto end is ffRt,

a sum of a back focal length of the zoom lens at an air-equivalent distance and a distance on an optical axis from a paraxial exit pupil position to a lens surface closest to the image side in the final lens group in a state where the infinite distance object is in focus at the telephoto end is Dext,

a maximum half angle of view in a state where the infinite distance object is in focus at the telephoto end is ωt,

γ t =(1−β ft 2 )×β fRt 2 , and

BRt={βft /( ffoc×γt )−1/(β fRt×ffRt )−(1 /Dext )}, and

Conditional Expression (39) is satisfied, which is represented by

0 <|BRt ×( ft ×tan ω t )|<0.034  (39).

48 . The zoom lens according to claim 1 , wherein

Conditional Expression (40) is satisfied, which is represented by

−10< f 1/ f 2<−5.6  (40).

49 . The zoom lens according to claim 1 ,

wherein a lens group closest to the object side in the middle group includes five or more lenses.

50 . The zoom lens according to claim 1 ,

wherein the number of lenses included in the focus group is two or less.

51 . The zoom lens according to claim 1 ,

wherein among movement loci of respective lens groups that move during zooming from the wide angle end to the telephoto end, different movement loci are only five.

52 . The zoom lens according to claim 1 ,

wherein a lens group which is fourth from the object side in the zoom lens is set as a fourth lens group,

a net displacement of the fourth lens group along the optical axis during zooming from the wide angle end to the telephoto end is M4,

a net displacement of the final lens group along the optical axis during zooming from the wide angle end to the telephoto end is ME, and

signs of M4 and ME are positive in a case where the fourth lens group and the final lens group move from the object side to the image side and are negative in a case where the fourth lens group and the final lens group move from the image side to the object side, and

Conditional Expression (42) is satisfied, which is represented by

0.9< M 4/ ME< 1.1  (42).

53 . The zoom lens according to claim 1 ,

wherein a focal length of the middle group in a state where the infinite distance object is in focus at the wide angle end is fMw, and

Conditional Expression (43) is satisfied, which is represented by

0.54< fw/fMw< 0.95  (43).

54 . The zoom lens according to claim 1 ,

wherein a focal length of the middle group in a state where the infinite distance object is in focus at the telephoto end is fMt, and

Conditional Expression (44) is satisfied, which is represented by

5.1< ft/fMt< 20  (44).

55 . The zoom lens according to claim 1 , wherein

a net displacement of a lens group adjacent to the object side in the focus group along the optical axis during zooming from the wide angle end to the telephoto end is MfF,

a net displacement of a lens group adjacent to the image side in the focus group along the optical axis during zooming from the wide angle end to the telephoto end is MfR, and

signs of MfF and MfR are positive in a case where the lens groups move from the object side to the image side and are negative in a case where the lens groups move from the image side to the object side, and

Conditional Expression (45) is satisfied, which is represented by

0.9< MfF/MfR< 1.1  (45).

56 . The zoom lens according to claim 1 ,

wherein the zoom lens includes eight or more lens surfaces each having an aspherical shape.

57 . The zoom lens according to claim 1 ,

wherein a lens closest to the image side in the second lens group includes an aspherical surface.

58 . The zoom lens according to claim 1 ,

wherein a lens closest to the object side in the second lens group includes an aspherical surface.

59 . The zoom lens according to claim 1 ,

wherein a lens closest to the image side in a lens group closest to the object side in the middle group includes an aspherical surface.

60 . The zoom lens according to claim 1 ,

wherein a lens closest to the object side in a lens group closest to the object side in the middle group includes an aspherical surface.

61 . The zoom lens according to claim 1 ,

wherein an object side surface of a lens closest to the image side in the second lens group has an aspherical shape by which a refractive power at a position of a maximum effective diameter is weaker than a refractive power near an optical axis.

62 . The zoom lens according to claim 1 ,

wherein an image side surface of a lens closest to the object side in the second lens group has an aspherical shape by which a refractive power at a position of a maximum effective diameter is stronger than a refractive power near an optical axis.

63 . The zoom lens according to claim 1 ,

wherein an object side surface of a lens closest to the image side in a lens group closest to the object side in the middle group has an aspherical shape by which a refractive power at a position of a maximum effective diameter is weaker than a refractive power near an optical axis.

64 . The zoom lens according to claim 1 ,

wherein an image side surface of a lens closest to the object side in a lens group closest to the object side in the middle group has an aspherical shape by which a refractive power at a position of a maximum effective diameter is weaker than a refractive power near an optical axis.

65 . The zoom lens according to claim 1 , wherein

a paraxial curvature radius of an object side surface of a lens closest to the image side in the second lens group is Rc2ef,

a curvature radius of the object side surface of the lens closest to the image side in the second lens group at a position of a maximum effective diameter is Ry2ef, and

Conditional Expression (46) is satisfied, which is represented by

0.1< Rc 2 ef/Ry 2 ef< 0.999  (46).

66 . The zoom lens according to claim 1 , wherein

a paraxial curvature radius of an image side surface of a lens closest to the object side in the second lens group is Rc21r,

a curvature radius of the image side surface of the lens closest to the object side in the second lens group at a position of a maximum effective diameter is Ry21r, and

Conditional Expression (47) is satisfied, which is represented by

1.001< Rc 21 r/Ry 21 r< 4.5  (47).

67 . The zoom lens according to claim 1 , wherein

a paraxial curvature radius of an object side surface of a lens closest to the image side in a lens group closest to the object side in the middle group is Rc3ef,

a curvature radius of the object side surface of the lens closest to the image side in the lens group closest to the object side in the middle group at a position of a maximum effective diameter is Ry3ef, and

Conditional Expression (48) is satisfied, which is represented by

0.1< Rc 3 ef/Ry 3 ef< 0.999  (48).

68 . The zoom lens according to claim 1 , wherein

a paraxial curvature radius of an image side surface of a lens closest to the object side in a lens group closest to the object side in the middle group is Rc31r,

a curvature radius of the image side surface of the lens closest to the object side in the lens group closest to the object side in the middle group at a position of a maximum effective diameter is Ry31r, and

Conditional Expression (49) is satisfied, which is represented by

0< Rc 31 r/Ry 31 r< 0.999  (49).

69 . The zoom lens according to claim 1 , wherein

a paraxial curvature radius of an object side surface of a lens closest to the image side in the second lens group is Rc2ef,

a paraxial curvature radius of an image side surface of a lens closest to the image side in the second lens group is Rc2er,

a curvature radius of the object side surface of the lens closest to the image side in the second lens group at a position of a maximum effective diameter is Ry2ef,

a curvature radius of the image side surface of the lens closest to the image side in the second lens group at the position of the maximum effective diameter is Ry2er, and

Conditional Expression (50) is satisfied, which is represented by

1.05<(1/ Rc 2 ef− 1/ Rc 2 er )/(1/ Ry 2 ef− 1/ Ry 2 er )<5  (50).

70 . The zoom lens according to claim 1 , wherein

a paraxial curvature radius of an object side surface of a lens closest to the object side in the second lens group is Rc21f,

a paraxial curvature radius of an image side surface of the lens closest to the object side in the second lens group is Rc21r,

a curvature radius of the object side surface of the lens closest to the object side in the second lens group at a position of a maximum effective diameter is Ry21f,

a curvature radius of the image side surface of the lens closest to the object side in the second lens group at the position of the maximum effective diameter is Ry21r, and

Conditional Expression (51) is satisfied, which is represented by

0.4<(1/ Rc 21 f− 1/ Rc 21 r )/(1/ Ry 21 f− 1/ Ry 21 r )<0.99  (51).

71 . The zoom lens according to claim 1 , wherein

a paraxial curvature radius of an object side surface of a lens closest to the image side in a lens group closest to the object side in the middle group is Rc3ef,

a paraxial curvature radius of an image side surface of the lens closest to the image side in the lens group closest to the object side in the middle group is Rc3er,

a curvature radius of the object side surface of the lens closest to the image side in the lens group closest to the object side in the middle group at a position of a maximum effective diameter is Ry3ef,

a curvature radius of the image side surface of the lens closest to the image side in the lens group closest to the object side in the middle group at the position of the maximum effective diameter is Ry3er, and

Conditional Expression (52) is satisfied, which is represented by

1.01<(1/ Rc 3 ef− 1/ Rc 3 er )/(1/ Ry 3 ef− 1/ Ry 3 er )<2  (52).

72 . The zoom lens according to claim 1 , wherein

a paraxial curvature radius of an object side surface of a lens closest to the object side in a lens group closest to the object side in the middle group is Rc31f,

a paraxial curvature radius of an image side surface of the lens closest to the object side in the lens group closest to the object side in the middle group is Rc31r,

a curvature radius of the object side surface of the lens closest to the object side in the lens group closest to the object side in the middle group at a position of a maximum effective diameter is Ry31f,

a curvature radius of the image side surface of the lens closest to the object side in the lens group closest to the object side in the middle group at the position of the maximum effective diameter is Ry31r, and

Conditional Expression (53) is satisfied, which is represented by

1.1<(1/ Rc 31 f− 1/ Rc 31 r )/(1/ Ry 31 f− 1/ Ry 31 r )<3  (53).

73 . The zoom lens according to claim 1 ,

wherein Conditional Expression (1-1) is satisfied, which is represented by

7.5< ft/fw< 20  (1-1).

74 . An imaging apparatus comprising the zoom lens according to claim 1 .