Imaging lens and optical apparatus

Patent metadata

Field	Value
Publication number	US-10852535-B2
Application number	US-201816133038-A
Country	US
Kind code	B2
Filing date	Sep 17, 2018
Priority date	Sep 25, 2017
Publication date	Dec 1, 2020
Grant date	Dec 1, 2020

Abstract

The imaging lens includes at least one negative lens that satisfies predetermined Conditional Expressions (1) to (3) indicating conditions in which dispersion is relatively low and refractive index is high while having a negative rate of change of the refractive index. A positive lens having a largest Abbe number at the d line among positive lenses included in the imaging lens satisfies predetermined Conditional Expressions (4) and (5).

First claim

What is claimed is:

1. An imaging lens in which a plurality of lenses are combined with each other, comprising:
at least one negative lens that satisfies the following Conditional Expressions (1) to (3) in a case where a refractive index at a d line of a negative lens included in the imaging lens is set to nN, an Abbe number at the d line of the negative lens is set to νN, and a rate of change of the refractive index at the d line of the negative lens with respect to a change in temperature at 25° C. is set to dnN/dt,
1.65< nN< 1.75  (1)

45<ν N< 55  (2)

dnN/dt< 0×10 −6 /° C.  (3)

wherein a positive lens having a largest Abbe number at the d line among positive lenses included in the imaging lens satisfies the following Conditional Expressions (4) and (5) in a case where an Abbe number at the d line of the positive lens having a largest Abbe number at the d line is set to νP1, and a partial dispersion ratio of the positive lens having a largest Abbe number at the d line is set to θP1gF,
63<ν P 1  (4)

0.644<θ P 1 gF+ 0.001618×ν P 1  (5).

2. The imaging lens according to claim 1 ,
wherein at least one negative lens among negative lenses that satisfy Conditional Expressions (1) to (3) satisfies the following Conditional Expression (6) in a case where a focal length of the negative lens is set to fN, and a focal length of the whole system during focusing on an infinite object is set to f,
| fN|/f< 10  (6).

3. The imaging lens according to claim 1 , further comprising:
at least one positive lens that satisfies the following Conditional Expressions (7) to (9) in a case where a refractive index at the d line of a positive lens included in the imaging lens is set to nP2, an Abbe number at the d line of the positive lens is set to νP2, and a rate of change of the refractive index at the d line of the positive lens with respect to a change in temperature at 25° C. is set to dnP2/dt,
1.6< nP 2<1.85  (7)

40<ν P 2<60  (8)

6×10 −6 /° C.< dnP 2/ dt   (9).

4. The imaging lens according to claim 3 ,
wherein the positive lens that satisfies Conditional Expressions (7) to (9) satisfies the following Conditional Expression (10), in a case where a focal length of the positive lens is set to fP2, and a focal length of the whole system during focusing on an infinite object is set to f,
fP 2/ f< 15  (10).

5. The imaging lens according to claim 1 ,
wherein the imaging lens is a single-focus lens, and satisfies the following Conditional Expression (11) in a case where a height of a paraxial on-axis light ray on an object-side surface of the negative lens that satisfies Conditional Expressions (1) to (3) is set to HN, and a maximum value of heights of a paraxial on-axis light ray on each lens surface of all lenses included in the imaging lens is set to Hmax,
0.3<| HN/H max|  (11).

6. The imaging lens according to claim 1 ,
wherein the imaging lens has a zooming function, and satisfies the following Conditional Expression (12) in a case where a height of a paraxial on-axis light ray at a telephoto end on an object-side surface of the negative lens that satisfies Conditional Expressions (1) to (3) is set to HNt, a height of a paraxial on-axis light ray at the telephoto end of a surface having a maximum height of a paraxial on-axis light ray at a wide-angle end on each lens surface of all lenses included in the imaging lens is set to Htwm, a height of a paraxial on-axis light ray at the wide-angle end on the object-side surface of the negative lens that satisfies Conditional Expressions (1) to (3) is set to HNw, and a maximum value of heights of a paraxial on-axis light ray at the wide-angle end on each lens surface of all lenses included in the imaging lens is set to Hwwm,
|( HNt/Htwm )/( HNw/Hwwm )|<1.8  (12).

7. The imaging lens according to claim 1 ,
wherein the imaging lens has a zooming function, and satisfies the following Conditional Expression (13) in a case where a height of a paraxial on-axis light ray at a telephoto end on an object-side surface of the negative lens that satisfies Conditional Expressions (1) to (3) is set to HNt, a height of a paraxial on-axis light ray at the telephoto end of a surface having a maximum height of a paraxial on-axis light ray at a wide-angle end on each lens surface of all lenses included in the imaging lens is set to Htwm, a height of a paraxial on-axis light ray at the wide-angle end on the object-side surface of the negative lens that satisfies Conditional Expressions (1) to (3) is set to HNw, and a maximum value of heights of a paraxial on-axis light ray at the wide-angle end on each lens surface of all lenses included in the imaging lens is set to Hwwm,
1.8<|( HNt/Htwm )/( HNw/Hwwm )|  (13).

8. The imaging lens according to claim 1 ,
wherein the negative lens that satisfies Conditional Expressions (1) to (3) satisfies at least one of the following Conditional Expressions (1-1), (2-1), and (3-1),
1.69< nN< 1.71  (1-1)

50<ν N< 52  (2-1)

−2×10 −6 /° C.< dnN/dt<− 1×10 −6 /° C.  (3-1).

9. The imaging lens according to claim 1 ,
wherein the positive lens having a largest Abbe number at the d line among positive lenses included in the imaging lens satisfies at least one of the following Conditional Expressions (4-1) and (5-1),
75<ν P 1<100  (4-1)

0.665<θ P 1 gF+ 0.001618×ν P 1<0.7  (5-1).

10. The imaging lens according to claim 2 ,
wherein a negative lens that satisfies Conditional Expression (6) satisfies the following Conditional Expression (6-1),
0.5<| fN|/f< 5  (6-1).

11. The imaging lens according to claim 3 ,
wherein the positive lens that satisfies Conditional Expressions (7) to (9) satisfies at least one of the following Conditional Expressions (7-1), (8-1), and (9-1),
1.65< nP 2<1.8  (7-1)

42<ν P 2<57  (8-1)

6.5×10 −6 /° C.< dnP 2/ dt< 11×10 −6 /° C.  (9-1).

12. The imaging lens according to claim 4 ,
wherein the positive lens that satisfies Conditional Expressions (7) to (9) satisfies the following Conditional Expression (10-1),
0.2< fP 2/ f< 5  (10-1).

13. The imaging lens according to claim 5 ,
wherein the following Conditional Expression (11-1) is satisfied,
0.49−| HN/H max|<1  (11-1).

14. The imaging lens according to claim 6 ,
wherein the following Conditional Expression (12-1) is satisfied
0.4<|( HNt/Htwm )/( HNw/Hwwm )|<1.5  (12-1).

15. The imaging lens according to claim 7 ,
wherein the following Conditional Expression (13-1) is satisfied
2<|( HNt/Htwm )/( HNw/Hwwm )|<50  (13-1).

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

Assignees

• Fujifilm Corp

Inventors

• Nagatoshi Yukiko
• Miyagishima Shunsuke
• Okada Kazuyoshi
• Tomioka Ukyo
• Yonezawa Masaru
• Shimada Yasutaka

Classifications

• G02B15/146

  having more than five groups · CPC title

• G02B13/04

  Reversed telephoto objectives · CPC title

• G02B9/64

  having more than six components · CPC title

• G02B27/0025 Primary

  for optical correction, e.g. distorsion, aberration · CPC title

• G02B13/0045

  having five or more lenses · CPC title