ZOOM LENS AND IMAGING APPARATUS

• US 20180299643A1
• Filed: 06/21/2018
• Published: 10/18/2018
• Est. Priority Date: 01/27/2016
• Status: Active Grant

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Inventors: YONEZAWA, Masaru, IKEDA, Shinkichi
• Granted Patent: US 10,620,399 B2
• Time in Patent Office: Days
• CPC Class Codes: G02B 13/002 having at least one aspherical surface
• CPC Class Codes: G02B 13/009 having zoom function
• CPC Class Codes: G02B 13/18 with lenses having one or more non-spherical faces, e.g. for reducing geometrical aberration G02B13/002 takes precedence
• CPC Class Codes: G02B 15/14 by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective
• CPC Class Codes: G02B 15/144109 arranged +--+
• CPC Class Codes: G02B 15/16 with interdependent non-linearly related movements between one lens or lens group, and another lens or lens group G02B15/22 takes precedence
• CPC Class Codes: G02B 15/167 having an additional fixed front lens or group of lenses
• CPC Class Codes: G02B 15/20 having an additional movable lens or lens group for varying the objective focal length
• CPC Class Codes: G02B 5/005 Diaphragms for cameras G03B9/02
• CPC Class Codes: G02B 7/10 by relative axial movement of several lenses, e.g. of varifocal objective lens
• CPC Class Codes: G02B 9/34 having four components only
• CPC Class Codes: G02B 9/62 having six components only

Abstract

Provided are a zoom lens which can be configured to have a small size while ensuring a high zoom ratio and has high optical performance by satisfactorily correcting chromatic aberration, and an imaging apparatus including the zoom lens. The zoom lens consists of, in order from the object side, a first lens group G1 that has a positive refractive power and remains stationary during zooming, a plurality of movable lens groups that move during zooming; and a final lens group Ge that has a positive refractive power and remains stationary during zooming. At least one movable lens group has a negative refractive power. The movable lens group, which is closest to the object side and has a negative refractive power, has two or more negative lenses, and satisfies predetermined conditional expressions.

Claims

1. A zoom lens comprising, in order from an object side:

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

a plurality of movable lens groups that move by changing distances between groups adjacent to each other in a direction of an optical axis during zooming; and

a final lens group that has a positive refractive power and remains stationary with respect to the image plane during zooming,

wherein in the plurality of movable lens groups, at least two movable lens group all have a negative refractive power,

wherein in a case where the movable lens group which is closest to the object side and has a negative refractive power is set as a front side negative lens group, the front side negative lens group has two or more negative lenses,

wherein in a case where the movable lens group which is closest to an image side and has a negative refractive power is set as a rear side negative lens group, the rear side negative lens group includes a negative lens and a positive lens, and wherein all Conditional Expressions (1) to (3), (5) and (6) are satisfied,

2.395<

NF2+0.012×

vF2<

2.495  

 

(1),

−

35<

vF1−

vF2<

−

16  

 

(2),

and

0.12<

NF1−

NF2<

0.34  

 

(3),

2.395<

NRn+0.012×

vRn<

2.495  

 

(5),

and

25<

vRn−

vRp<

35  

 

(6),

where NF2 is a refractive index of a second negative lens from the object side in the front side negative lens group at the d line,

vF2 is an Abbe number of the second negative lens from the object side in the front side negative lens group at the d line,

vF1 is an Abbe number of a negative lens closest to the object side in the front side negative lens group at the d line,

NF1 is a refractive index of the negative lens closest to the object side in the front side negative lens group at the d line,

NRn is a refractive index of the negative lens of the rear side negative lens group at the d line,

vRn is an Abbe number of the negative lens of the rear side negative lens group at the d line, and

vRp is an Abbe number of the positive lens of the rear side negative lens group at the d line.

2. The zoom lens according to claim 1, wherein Conditional Expression (4) is satisfied,

0.93<

fF2/fGNF<

1.1  

 

(4),

where fF2 is a focal length of the second negative lens from the object side in the front side negative lens group, and

fGNF is a focal length of the front side negative lens group.

3. The zoom lens according to claim 1, wherein Conditional Expression (7) is satisfied,

0.35<

fRn/fGNR<

0.51  

 

(7),

where fRn is a focal length of the negative lens of the rear side negative lens group, and

fGNR is a focal length of the rear side negative lens group.

4. The zoom lens according to claim 2, wherein Conditional Expression (7) is satisfied,

0.35<

fRn/fGNR<

0.51  

 

(7),

where fRn is a focal length of the negative lens of the rear side negative lens group, and

fGNR is a focal length of the rear side negative lens group.

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

2.395<

NF2+0.012×

vF2<

2.455  

 

(1-1)

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

2.395<

NF2+0.012×

vF2<

2.455  

 

(1-1)

7. The zoom lens according to claim 3, wherein Conditional Expression (1-1) is satisfied.

2.395<

NF2+0.012×

vF2<

2.455  

 

(1-1)

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

2.395<

NF2+0.012×

vF2<

2.455  

 

(1-1)

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

−

33<

vF1−

vF2<

−

18  

 

(2-1)

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

−

33<

vF1−

vF2<

−

18  

 

(2-1)

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

−

33<

vF1−

vF2<

−

18  

 

(2-1)

12. The zoom lens according to claim 1, wherein Conditional Expression (3-1) is satisfied.

0.13<

NF1−

NF2<

0.31  

 

(3-1)

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

0.94<

fF2/fGNF<

1.05  

 

(4-1),

where fF2 is a focal length of the second negative lens from the object side in the front side negative lens group, and

fGNF is a focal length of the front side negative lens group.

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

2.395<

NRn+0.012×

vRn2<

2.455  

 

(5-1)

15. The zoom lens according to claim 1, wherein Conditional Expression (6-1) is satisfied.

27<

vRn−

vRp<

30  

 

(6-1)

16. The zoom lens according to claim 1, wherein Conditional Expression (7-1) is satisfied,

0.37<

fRn/fGNR<

0.48  

 

(7-1),

where fRn is a focal length of the negative lens of the rear side negative lens group, and

fGNR is a focal length of the rear side negative lens group.

17. The zoom lens according to claim 1, wherein the plurality of movable lens groups includes a lens group having a negative refractive power and a lens group having a negative refractive power.

18. The zoom lens according to claim 1, wherein the plurality of movable lens groups includes, in order from the object side, a lens group having a positive refractive power, a lens group having a negative refractive power, and a lens group having a negative refractive power.

19. The zoom lens according to claim 1, wherein the plurality of movable lens groups includes, in order from the object side, a lens group having a negative refractive power, a lens group having a positive refractive power, and a lens group having a negative refractive power.

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