IP Library › Granted Patent US 10,739,557
Granted Patent B2
US 10,739,557 · App. 16/120,474 · Granted Aug 11, 2020

Imaging lens and imaging apparatus

Inventor: Takashi Suzuki (Saitama, JP)
Assignee: FUJIFILM Corporation
G02B9/64G02B13/0045G02B5/005G02B13/18G02B27/0025
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Quick Facts
Patent No.
US 10,739,557
App. No.
16/120,474
Granted
Aug 11, 2020
Kind
B2
Abstract

The imaging lens consists of, in order from the object side, a first lens group having a positive power, a second lens group having a negative power, and a third lens group. The first lens group consists of, in order from the object side, a positive front group, a stop, and a positive rear group. The rear group has a cemented lens consisting of a negative lens concave toward the image side and a positive lens convex toward the image side in order from the object side. The second lens group consists of a negative lens. During focusing, only the second lens group moves. The following conditional expression relating to a focal length f2 of the second lens group and focal length f of the whole system is satisfied: 0.8<|f2/f|<5.

Claims (38)

1. An imaging lens consisting of, in order from an object side:

a first lens group that has a positive refractive power;

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

a third lens group that has a refractive power,

wherein the first lens group consists of, in order from the object side, a front group having a positive refractive power, a stop, and a rear group having a positive refractive power,

wherein the front group has at least one negative lens and at least one positive lens,

wherein the rear group has a cemented lens consisting of a negative lens concave toward an image side and a positive lens convex toward the image side in order from the object side,

wherein the second lens group consists of one negative lens,

wherein the third lens group has at least one negative lens and at least one positive lens,

wherein during focusing from an object at infinity to a close-range object, the first lens group and the third lens group remain stationary with respect to an image plane, and the second lens group moves from the object side to the image side, and

wherein assuming that a focal length of the second lens group is f2 and a focal length of the whole system in a state where the object at infinity is in focus is f, Conditional Expression (1) is satisfied,

0.8<| f 2/ f|< 5  (1).

2. The imaging lens according to claim 1 ,

wherein assuming that a focal length of the first lens group is f1, Conditional Expression (2) is satisfied,

0.4< f 1/ f< 1  (2).

3. The imaging lens according to claim 1 , wherein a negative lens is disposed to be closest to the object side in the front group.

4. The imaging lens according to claim 1 ,

wherein assuming that a refractive index of the negative lens of the second lens group at a d line is NdG2 and an Abbe number of the negative lens of the second lens group at the d line is νdG2, Conditional Expressions (3) and (4) are satisfied,

1.55< NdG 2  (3)

30<ν dG 2<65  (4).

5. The imaging lens according to claim 1 , wherein assuming that a focal length of the third lens group is f3, Conditional Expression (5) is satisfied,

| f 2/ f 3|<0.67  (5).

6. The imaging lens according to claim 1 , wherein the third lens group consists of one negative lens and one positive lens.

7. The imaging lens according to claim 1 , wherein the front group consists of a negative lens, which is disposed to be closest to the object side, and a front group sub-lens group which is disposed to be separated by an air gap from the negative lens and has a positive refractive power.

8. The imaging lens according to claim 1 , wherein the third lens group has a positive refractive power.

9. The imaging lens according to claim 1 , wherein the third lens group consists of, in order from the object side, one negative lens and one positive lens.

10. The imaging lens according to claim 1 , wherein the rear group has at least one aspheric surface.

11. The imaging lens according to claim 1 , wherein Conditional Expression (1-1) is satisfied,

1<| f 2/ f|< 4  (1-1).

12. The imaging lens according to claim 2 , wherein Conditional Expression (2-1) is satisfied,

0.5< f 1/ f< 0.9  (2-1).

13. The imaging lens according to claim 4 , wherein Conditional Expression (3-1) is satisfied,

1.55< NdG 2<2  (3-1).

14. The imaging lens according to claim 4 , wherein Conditional Expression (4-1) is satisfied,

32<ν dG 2<62  (4-1).

15. The imaging lens according to claim 5 , wherein Conditional Expression (5-1) is satisfied,

| f 2/ f 3|<0.6  (5-1).

16. An imaging apparatus comprising the imaging lens according to claim 1 .

Assignments (1)
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Sep 4, 2018
From: SUZUKI, TAKASHI
To: FUJIFILM CORPORATION
Reel/Frame 046774/0462 →
Priority Claims (1)
JP 2017-176474 · Sep 14, 2017 · national
Continuity (1)
Related Publication 20190079268A1 · Mar 14, 2019