Zoom lens, and imaging apparatus incorporating the same

Patent metadata

Field	Value
Publication number	US-9500841-B2
Application number	US-201213486926-A
Country	US
Kind code	B2
Filing date	Jun 1, 2012
Priority date	Jun 3, 2011
Publication date	Nov 22, 2016
Grant date	Nov 22, 2016

Abstract

The zoom lens comprises, from an object side, a first lens group, a second lens group that includes an aperture stop moving integrally therewith, a third lens group, and a fourth lens group having, respectively, negative, positive, negative, and positive refracting power, and during zooming from a wide-angle end to a telephoto end, a spacing between the first and second lens groups becomes narrow, between the second and third lens groups changes, and between the third and fourth lens groups grows wide, and the first lens group includes a first lens having negative refracting power, a second lens having a reflective surface for bending a light ray coming out of an object and a third lens having positive refracting power, and in said second lens group, a most image-plane-side surface of a lens having negative refracting power is configured in a concave shape on an image plane side.

First claim

What is claimed is:

1. A zoom lens, comprising:
in order from an object side:
a first lens group having negative refracting power,
a second lens group that includes an aperture stop moving integrally therewith and has positive refracting power,
a third lens group having negative refracting power, and
a fourth lens group having positive refracting power; during zooming from a wide-angle end to a telephoto end,
the first lens group is fixed in position, the second lens group and the third lens group move toward the object side only, and the fourth lens group moves,
a spacing between the first lens group and the second lens group becomes narrow,
a spacing between the second lens group and the third lens group changes, and
a spacing between the third lens group and the fourth lens group grows wide;

wherein the first lens group consists of:
a first lens having negative refracting power,
an optical element having a reflective surface for bending a light ray coming out of an object, and
a second lens having positive refracting power, wherein the second lens having positive refracting power is a singlet positive lens;

wherein the second lens group comprises:
a cemented meniscus lens component concave to an image side including a positive lens element convex to the object side and a negative lens element concave to the image side, and
a positive lens component,
wherein the cemented meniscus lens component in the second lens group has the positive lens element positioned on the object side and the negative lens element positioned on the image side;

wherein the first lens in the first lens group is a bi-concave lens having an object-side surface concave to the object side, and the first lens in the first lens group satisfies the following Conditions (8) and (11):
−0.5<( R 11 F+R 11 R )/( R 11 F−R 11 R )<1.0  (8)

−0.5 < M 4/ M 2<−0.01  (11)

where R 11 F is a radius of curvature of the object-side surface of the first lens in the first lens group,
R 11 R is a radius of curvature of an image-side surface of the first lens in the first lens group,
M 2 is an amount of movement of the second lens group from the wide-angle end to the telephoto end upon focusing on an infinite object point, and
M 4 is an amount of movement of the fourth lens group from the wide-angle end to the telephoto end upon focusing on the infinite object point.

2. The zoom lens according to claim 1 , wherein the first lens in the first lens group satisfies the following Condition:
−0.5<( R 11 F+R 11 R )/( R 11 F−R 11 R )≦0.739

where R 11 F is a radius of curvature of the object-side surface of the first lens in the first lens group, and
R 11 R is a radius of curvature of an image-side surface of the first lens in the first lens group.

3. The zoom lens according to claim 1 , which satisfies the following Condition (1):
0.095 ≦ fw/f 13<1.0  (1)

where f 13 is a focal length of said second lens in said first lens group, and
fw is a focal length of the whole system at the wide-angle end upon focusing on an infinite object point.

4. The zoom lens according to claim 1 , which satisfies the following Condition (2):
0.438 ≦ft/f 13<3.0  (2)

where f 13 is a focal length of said second lens in said first lens group, and
ft is a focal length of the whole system at the telephoto end upon focusing on an infinite object point.

5. The zoom lens according to claim 1 , which satisfies the following Condition (3):
−3.0 <fw/f 11<−0.41  (3)

where f 11 is a focal length of said first lens in said first lens group, and
fw is a focal length of the whole system at the wide-angle end upon focusing on an infinite object point.

6. The zoom lens according to claim 1 , which satisfies the following Condition (4):
−9.0 <ft/f 11≦−2.318  (4)

where f 11 is a focal length of said first lens in said first lens group, and
ft is a focal length of the whole system at the telephoto end upon focusing on an infinite object point.

7. The zoom lens according to claim 1 , which satisfies the following Condition (5):
−0.6 <f 11 /f 13≦−0.159  (5)

where f 11 is a focal length of said first lens in said first lens group, and
f 13 is a focal length of said second lens in said first lens group.

8. The zoom lens according to claim 1 , which satisfies the following Condition (6):
0.0181<1/ν13−1/ν11<0.05  (6)

where ν 11 is an Abbe constant of a medium of said first lens in said first lens group, and
ν 13 is an Abbe constant of a medium of said second lens in said first lens group.

9. The zoom lens according to claim 1 , which satisfies the following Condition (7):
−1.50 <ff 1 /f 1<−0.20  (7)

where f 1 is a combined focal length of said first lens group, and
ff 1 is a front focal position of said first lens group.

10. The zoom lens according to claim 1 , wherein the second lens group includes an additional positive lens component.

11. The zoom lens according to claim 1 , which satisfies the following Condition:
−0.5<( R 11 F+R 11 R )/( R 11 F−R 11 R )≦0.668.

12. A zoom lens, comprising:
in order from an object side:
a first lens group having negative refracting power,
a second lens group that includes an aperture stop moving integrally therewith and has positive refracting power,
a third lens group having negative refracting power, and
a fourth lens group having positive refracting power; during zooming from a wide-angle end to a telephoto end,
the first lens group is fixed in position, the second lens group and the third lens group move toward the object side only, and the fourth lens group moves,
a spacing between the first lens group and the second lens group becomes narrow,
a spacing between the second lens group and the third lens group changes, and
a spacing between the third lens group and the fourth lens group grows wide;

wherein the first lens group consists of:
a first lens having negative refracting power,
an optical element having a reflective surface for bending a light ray coming out of an object, and
a second lens having positive refracting power, wherein the second lens having positive refracting power is a singlet positive lens;

wherein the second lens group, comprises:
in order from the object side:
a positive lens element convex to the object side,
a positive lens element convex to the object side, and
a negative lens element concave to an image side;

wherein the first lens in the first lens group is a bi-concave lens having an object-side surface concave to the object side, and the first lens in the first lens group satisfies the following Conditions (8) and (11):
−0.5<( R 11 F+R 11 R )/( R 11 F−R 11 R )<1.0  (8)

−0.5 < M 4/ M 2<−0.01  (11)

where R 11 F is a radius of curvature of the object-side surface of the first lens in the first lens group,
R 11 R is a radius of curvature of an image-side surface of the first lens in the first lens group,
M 2 is an amount of movement of the second lens group from the wide-angle end to the telephoto end upon focusing on an infinite object point, and
M 4 is an amount of movement of the fourth lens group from the wide-angle end to the telephoto end upon focusing on the infinite object point.

13. The zoom lens according to claim 12 , wherein the first lens in the first lens group satisfies the following Condition:
−0.5<( R 11 F+R 11 R )/( R 11 F−R 11 R )≦0.739

where R 11 F is a radius of curvature of an object-side surface of the first lens in the first lens group, and
R 11 R is a radius of curvature of an image-side surface of the first lens in the first lens group.

14. The zoom lens ac

Assignees

• Ichikawa Keisuke
• Ono Kenji
• Olympus Corp

Inventors

• Ichikawa Keisuke
• Ono Kenji

Classifications

• G02B15/177 Primary

  having a negative front lens or group of lenses · CPC title

• G02B15/144511 Primary

  arranged -+-+ · CPC title