Granted Patent B2

US 12,222,479 · App. 18/450,713 · Granted Feb 11, 2025

Inventors: Daiki Kawamura (Saitama, JP); Taiga Noda (Saitama, JP)

Assignee: FUJIFILM Corporation

G02B15/145121G02B9/60H04N23/55

Abstract

Claims (45)

1. A zoom lens comprising, as lens groups, only five lens groups consisting of, 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 third lens group that has a positive refractive power;

a fourth lens group that has a negative refractive power; and

a fifth lens group that has a positive refractive power,

wherein an aperture stop is disposed between a lens surface closest to the image side in the second lens group and a lens surface closest to the object side in the fourth lens group,

wherein during zooming, by changing all distances between lens groups adjacent to each other in a direction of an optical axis, at least the first lens group, the second lens group, the third lens group, and the fourth lens group move along the optical axis, and the fifth lens group remains stationary with respect to an image plane,

wherein only the fourth lens group moves along the optical axis during focusing from an object at infinity to a close-range object,

wherein the first lens group consists of, in order from the object side to the image side, a first lens having a negative refractive power, a second lens having a positive refractive power, and a third lens having a positive refractive power,

wherein the second lens group consists of, in order from the object side to the image side, a first negative lens of which an image side surface is concave, a second negative lens of which an object side surface is concave, a positive lens, and a third negative lens of which an object side surface is concave,

wherein

a focal length of the first lens group is f1,

a focal length of the fifth lens group is f5,

a refractive index of the second lens in the first lens group at a d line is Nd2,

a back focal length at an air conversion distance in a state where the object at infinity is in focus at a wide-angle end is BFw,

a focal length of the zoom lens in the state where the object at infinity is in focus at the wide-angle end is fw,

a maximum half angle of view in the state where the object at infinity is in focus at the wide-angle end is ωw,

a focal length of the second lens group is f2,

a focal length of the third lens group is f3, and

a focal length of the fourth lens group is f4,

Conditional Expressions (1-4), (2), (3-3), (12), (14), and (15-3) are satisfied, which are represented by

0.621≤ f 1/ f 5<1.8  (1-4),

−0.7< f 4/ f 5<−0.1  (2),

1.711≤ Nd 2<1.96  (3-3),

0.5< BFw /( fw ×tan|ω w |)<1.6  (12),

−1.3< f 2/ f 3<−0.4  (14), and

−5.845≤ f 1/ f 2<−3  (15-3).

2. The zoom lens according to claim 1 , wherein

a sum of a distance on the optical axis from a lens surface closest to the object side to a lens surface closest to the image side and the back focal length at the air conversion distance in the state where the object at infinity is in focus at the wide-angle end is TLw,

Conditional Expression (4) is satisfied, which is represented by

0.07< BFw/TLw< 0.25  (4).

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

−0.64< f 4/ f 5<−0.15  (2-1).

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

−0.58< f 4/ f 5<−0.2  (2-2).

5. The zoom lens according to claim 4 , wherein Conditional Expression (17) is satisfied, which is represented by

0.2< f 2/ f 4<0.8  (17).

6. The zoom lens according to claim 5 , wherein Conditional Expression (14-1) is satisfied, which is represented by

−1.1< f 2/ f 3<−0.5  (14-1).

7. The zoom lens according to claim 6 , wherein

an Abbe number of the first lens in the first lens group based on the d line is νd1,

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

15<ν d 1<26  (20).

8. An imaging apparatus comprising the zoom lens according to claim 7 .

Assignments (1)

Priority Claims (1)

Continuity (3)

References Cited (35)