Zoom lens and imaging apparatus

1. A zoom lens consisting of, in order from an object side to an image side:

a first lens group that remains stationary with respect to an image plane during zooming and has a positive refractive power;

a middle group that consists of two or more movable lens groups moving along an optical axis by changing a distance between groups adjacent to each other during zooming; and

a subsequent group that has a lens group including a stop at a position closest to the object side,

wherein at least two movable lens groups in the middle group each have a negative refractive power,

wherein the at least one movable lens group having the negative refractive power in the middle group includes at least one LN lens which is a negative lens, and

wherein assuming that

a refractive index of the LN lens at a d line is Ndn,

an Abbe number of the LN lens based on the d line is νdn, and

a partial dispersion ratio of the LN lens between a g line and an F line is θgFn,

the LN lens satisfies Conditional Expressions (1), (2), (3), and (4) represented by

1.72< Ndn< 1.8  (1),

43<ν dn< 57  (2),

0.6355<θ gFn+ 0.001625×ν dn< 0.66  (3), and

2.21< Ndn+ 0.01×ν dn   (4).

2. The zoom lens according to claim 1 ,

wherein the movable lens group, which has the negative refractive power in the middle group, closer to the object side than the movable lens group, which has the negative refractive power and is closest to the image side in the middle group, includes the LN lens, and

wherein assuming that

a focal length of the movable lens group which has the negative refractive power in the middle group and includes the LN lens, which has a strongest negative refractive power among the LN lenses, which are included in the movable lens group having the negative refractive power in the middle group and being located to be closer to the object side than the movable lens group, which has the negative refractive power and is closest to the image side in the middle group, is fA, and

a focal length of the movable lens group, which has the negative refractive power and is closest to the image side in the middle group, is fB,

Conditional Expression (5) is satisfied, which is represented by

0.6< fB/fA< 4.5  (5).

3. The zoom lens according to claim 2 , wherein Conditional Expression (5-1) is satisfied, which is represented by

2< fB/fA< 4  (5-1).

4. The zoom lens according to claim 1 ,

wherein the movable lens group, which has the negative refractive power in the middle group, closer to the object side than the movable lens group, which has the negative refractive power and is closest to the image side in the middle group, includes the LN lens, and

wherein assuming that

a focal length of the movable lens group which has the negative refractive power in the middle group and includes the LN lens, which has a strongest negative refractive power among the LN lenses, which are included in the movable lens group having the negative refractive power in the middle group and being located to be closer to the object side than the movable lens group, which has the negative refractive power and is closest to the image side in the middle group, is fA, and

a focal length of the LN lens, which has the strongest negative refractive power, among the LN lenses, which are included in the movable lens group having the negative refractive power in the middle group, is fLNm,

Conditional Expression (6) is satisfied, which is represented by

0.5 <fLNm/fA< 40  (6).

5. The zoom lens according to claim 4 , wherein Conditional Expression (6-1) is satisfied, which is represented by

0.5 <fLNm/fA< 4  (6-1).

6. The zoom lens according to claim 1 , wherein the at least one movable lens group in the middle group includes a cemented lens in which at least one LN lens and at least one positive lens are cemented.

7. The zoom lens according to claim 6 , wherein assuming that

an Abbe number of the at least one LN lens of the cemented lens based on the d line is νdcn, and

an Abbe number of at least one positive lens of the cemented lens based on the d line is νdcp,

at least one of the cemented lenses satisfies Conditional Expression (7) represented by

18<ν dcn−νdcp< 35  (7).

8. The zoom lens according to claim 1 , wherein the movable lens group having the strongest negative refractive power among the movable lens groups having the negative refractive powers in the middle group includes the LN lens.

9. The zoom lens according to claim 1 , wherein focusing is performed by moving at least a part of lenses in the first lens group along the optical axis.

10. The zoom lens according to claim 1 , wherein the movable lens group closest to the image side in the middle group has a negative refractive power.

11. The zoom lens according to claim 10 ,

wherein the middle group consists of the two movable lens groups having the negative refractive powers, and

wherein the subsequent group consists of a lens group which remains stationary with respect to the image plane during zooming and has a positive refractive power.

12. The zoom lens according to claim 10 ,

wherein the middle group consists of the two movable lens groups having the negative refractive powers, and

wherein the subsequent group consists of, in order from the object side to the image side, a lens group, which moves along the optical axis by changing a distance between the groups adjacent to each other during zooming and has a positive refractive power, and a lens group which remains stationary with respect to the image plane during zooming and has a positive refractive power.

13. The zoom lens according to claim 10 ,

wherein the middle group consists of, in order from the object side to the image side, the movable lens group having a positive refractive power and the two movable lens groups having the negative refractive powers, and

wherein the subsequent group consists of a lens group which remains stationary with respect to the image plane during zooming and has a positive refractive power.

14. The zoom lens according to claim 10 ,

wherein the middle group consists of the three movable lens groups having the negative refractive powers, and

wherein the subsequent group consists of a lens group which remains stationary with respect to the image plane during zooming and has a refractive power.

15. The zoom lens according to claim 10 ,

wherein the middle group consists of the four movable lens groups having the negative refractive powers, and

wherein the subsequent group consists of a lens group which remains stationary with respect to the image plane during zooming and has a positive refractive power.

16. The zoom lens according to claim 1 , wherein the LN lens further satisfies Conditional Expression (2-1) represented by

45<ν dn< 55  (2-1).

17. The zoom lens according to claim 1 , wherein the LN lens further satisfies Conditional Expression (3-1) represented by

0.637<θ gFn+ 0.001625×ν dn< 0.65  (3-1).

18. The zoom lens according to claim 1 , wherein the LN lens further satisfies Conditional Expression (4-1) represented by

2.21< Ndn+ 0.01×ν dn< 2.33  (4-1).

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