Imaging lens and imaging apparatus

Patent metadata

Field	Value
Publication number	US-9470873-B2
Application number	US-201414569865-A
Country	US
Kind code	B2
Filing date	Dec 15, 2014
Priority date	Dec 18, 2013
Publication date	Oct 18, 2016
Grant date	Oct 18, 2016

Abstract

The imaging lens substantially consists of a first lens group having a positive refractive power and a second lens group having a positive refractive power, in which the entire second lens group moves along the optical axis to perform focusing. In the imaging lens, the first lens group comprises a positive first lens, a negative second lens, a negative third lens, a positive fourth lens, and a positive fifth lens in this order from the object side. When the Abbe number of the second lens with respect to the d-line is νd2 and the Abbe number of the third lens with respect to the d-line is νd3, conditional formula (1) below is satisfied:

2.0<ν d 2/ν d 3  (1).

First claim

What is claimed is:

1. An imaging lens substantially consisting of a first lens group having a positive refractive power and a second lens group having a positive refractive power in this order from the object side, wherein
focusing is performed by moving the entirety of the second lens group along the optical axis;
the first lens group comprises a first lens having a positive refractive power which is disposed on the most-object side, a second lens having a negative refractive power which is disposed next to the first lens on the image side, a third lens having a negative refractive power which is disposed next to the second lens on the image side, a fourth lens having a positive refractive power which is disposed next to the third lens on the image side, and a fifth lens having a positive refractive power which is disposed next to the fourth lens on the image side; and
the imaging lens satisfies conditional formula (1):
2.0<ν d 2/ν d 3  (1),

where
νd2: the Abbe number of the second lens with respect to the d-line, and
νd3: the Abbe number of the third lens with respect to the d-line.

2. The imaging lens of claim 1 , wherein an aperture stop is disposed between the first lens group and the second lens group.

3. The imaging lens of claim 1 , wherein the first lens group comprises the first lens having a positive refractive power which is disposed on the most-object side, the second lens having a negative refractive power which is disposed next to the first lens on the image side, the third lens having a negative refractive power which is disposed next to the second lens on the image side, the fourth lens having a positive refractive power which is disposed next to the third lens on the image side, the fifth lens having a positive refractive power which is disposed next to the fourth lens on the image side, a sixth lens having a negative refractive power which is disposed next to the fifth lens on the image side, a seventh lens having a negative refractive power which is disposed next to the sixth lens on the image side, an eighth lens having a positive refractive power which is disposed next to the seventh lens on the image side, and a ninth lens having a positive refractive power which is disposed next to the eighth lens on the image side.

4. The imaging lens of claim 1 that satisfies conditional formula (2) below:
1.0< FA/FB< 8.0  (2), where

FA: the focal length of the first lens group, and
FB: the focal length of the second lens group.

5. The imaging lens of claim 1 , wherein the first lens group comprises the first lens which is disposed on the most-object side; and
the imaging lens satisfies conditional formula (3) below:
1< f 1/ f< 6  (3),

where
f1: the focal length of the first lens, and
f: the focal length of the entire system.

6. The imaging lens of claim 1 , wherein the most-image-side lens of the second lens group has a positive refractive power; and
the imaging lens satisfies conditional formula (4) below:
0.5<( RLF+RLB )/( RLF−RLB )<3.0  (4),

where
RLF: the radius of curvature of the object-side surface of the most-image-side lens of the second lens group, and
RLB: the radius of curvature of the image-side surface of the most-image-side lens of the second lens group.

7. The imaging lens of claim 1 , wherein a lens which is second from the most-image side in the second lens group has a positive refractive power; and
the imaging lens satisfies conditional formula (5) below:
0.3<( RL 2 F+RL 2 B )/( RL 2 F−RL 2 B )<3.0  (5),

where
RL2F: the radius of curvature of the object-side surface of the lens which is second from the most-image side in the second lens group, and
RL2B: the radius of curvature of the image-side surface of the lens which is second from the most-image side in the second lens group.

8. The imaging lens of claim 1 , wherein both the most-image-side lens of the second lens group and the lens which is second from the most-image side in the second lens group are lenses with convex surfaces toward the image side.

9. The imaging lens of claim 1 , wherein the most-image-side lens in the first lens group is a positive meniscus lens with a convex surface toward the image side.

10. An imaging apparatus comprising:
the imaging lens of claim 1 .

Assignees

• Fujifilm Corp

Inventors

• Asami Taro

Classifications

• G02B9/06 Primary

  two + components · CPC title

• G02B9/64

  having more than six components · CPC title

• G02B15/161

  Physics · mapped topic

• G02B15/1421 Primary

  the first group being positive · CPC title

• G02B13/006

  at least one element being a compound optical element, e.g. cemented elements · CPC title