Zoom lens and imaging apparatus
The zoom lens consists of, in order from an object side: a first lens group that remains stationary during zooming and has a positive refractive power; at least two movable lens groups that are moved during zooming; and a final lens group that remains stationary during zooming and has a positive refractive power. The first lens group consists of, in order from the object side, a first-a lens group that remains stationary during focusing and has a negative refractive power, a first-b lens group that is moved during focusing and has a positive refractive power, and a first-c lens group that remains stationary during focusing and has a positive refractive power. The first-a lens group consists of, in order from the object side, a first lens that has a negative refractive power, a second lens that is convex toward the object side and has a positive refractive power, and a third lens that has a negative refractive power. At least one of the first lens or the third lens satisfies a predetermined conditional expression, and the entire system satisfies the other predetermined conditional expressions.
1. A zoom lens consisting of, in order from an object side:
a first lens group that remains stationary with respect to an image plane during zooming and has a positive refractive power;
at least two movable lens groups that are moved by changing distances between the movable lens groups and adjacent groups in a direction of an optical axis during zooming; and
a final lens group that remains stationary with respect to the image plane during zooming and has a positive refractive power,
wherein the first lens group consists of, in order from the object side, a first-a lens group that has a negative refractive power and remains stationary with respect to the image plane during focusing, a first-b lens group that has a positive refractive power and is moved by changing a distance in the direction of the optical axis between the first-b lens group and an adjacent lens group during focusing, and a first-c lens group that has a positive refractive power and remains stationary with respect to the image plane during focusing,
wherein the first-a lens group consists of, in order from the object side, a first lens that has a negative refractive power, a second lens that is convex toward the object side and has a positive refractive power, and a third lens that has a negative refractive power,
wherein assuming that a specific gravity of the lens having the negative refractive power in the first-a lens group is Gv1an and an Abbe number of the lens having the negative refractive power in the first-a lens group at a d line is Nud1an, at least one of the first lens or the third lens satisfies Conditional Expression (1),
0.03< Gv 1 an/Nud 1 an< 0.06 (1),
and
wherein assuming that a focal length of the first-c lens group is f1c and a focal length of the first lens group is f1, Conditional Expression (2) is satisfied
0.8< f 1 c/f 1<1 (2).
2. The zoom lens according to claim 1 ,
wherein assuming that a focal length of the first-a lens group is f1a and a focal length of the first-b lens group is f1b, Conditional Expression (3) is satisfied
−0.9< f 1 a/f 1 b<− 0.5 (3).
3. The zoom lens according to claim 1 ,
wherein assuming that a focal length of the first-a lens group is f1a, Conditional Expression (4) is satisfied
−1.5< f 1 a/f 1<−0.8 (4).
4. The zoom lens according to claim 1 ,
wherein assuming that a focal length of the first lens is f1a1 and a focal length of the first-a lens group is f1a, Conditional Expression (5) is satisfied
0.9< f 1 a 1/ f 1 a< 1.9 (5).
5. The zoom lens according to claim 1 ,
wherein assuming that an average value of dn/dt as a temperature coefficient of a refractive index of the lens having the negative refractive power in the first-a lens group at the d line is G1an_ave_dn, Conditional Expression (6) is satisfied
−1.5< G 1 an _ ave _ dn< 3.8 (6).
6. The zoom lens according to claim 1 ,
wherein the at least two movable lens groups consist of, in order from the object side, a second lens group that has a negative refractive power and a third lens group that has a positive refractive power.
7. The zoom lens according to claim 1 ,
wherein the at least two movable lens groups consist of, in order from the object side, a second lens group that has a positive refractive power, a third lens group that has a negative refractive power, and a fourth lens group that has a negative refractive power.
8. The zoom lens according to claim 1 ,
wherein at least one lens of the first lens and the third lens satisfies Conditional Expression (1-1)
0.032< Gv 1 an/Nud 1 an< 0.045 (1-1).
9. The zoom lens according to claim 1 ,
wherein Conditional Expression (2-1) is satisfied
0.9< f 1 c/f 1<0.96 (2-1).
10. The zoom lens according to claim 2 ,
wherein Conditional Expression (3-1) is satisfied
−0.79< f 1 a/f 1 b<− 0.67 (3-1).
11. The zoom lens according to claim 3 ,
wherein Conditional Expression (4-1) is satisfied
−1.2< f 1 a/f 1<−1 (4-1).
12. The zoom lens according to claim 4 ,
wherein Conditional Expression (5-1) is satisfied
1.02< f 1 a 1/ f 1 a< 1.63 (5-1).
13. The zoom lens according to claim 5 ,
wherein Conditional Expression (6-1) is satisfied
−1< G 1 an _ ave _ dn< 3 (6-1).
14. An imaging apparatus comprising the zoom lens according to claim 1 .