Imaging lens and imaging apparatus

Patent metadata

Field	Value
Publication number	US-9519121-B2
Application number	US-201514641915-A
Country	US
Kind code	B2
Filing date	Mar 9, 2015
Priority date	Mar 12, 2014
Publication date	Dec 13, 2016
Grant date	Dec 13, 2016

Abstract

The imaging lens consists essentially of a front group that consist essentially of a negative first lens having a meniscus shape with a convex surface toward the object side, a negative second lens and a positive third lens; a stop; a positive rear group that includes a positive lens and a negative lens. When the focal length of the entire system is f, a half angle of view is ω, and the distance from the object-side surface of the first lens to the imaging plane along the optical axis is L, conditional formula (1) below is satisfied:

0.25<2* f *tan(ω/2)/ L <1.00  (1).

First claim

What is claimed is:

1. An imaging lens, consisting of:
a front group which consists of a negative first lens having a meniscus shape with a convex surface toward the object side, a negative second lens, a point along the optical axis at the image-side surface of which is more toward the object side than points on both ends of the effective diameter of the image-side surface, and a positive third lens;
an aperture stop; and
a rear group which is positive as a whole in this order from the object side, wherein
the rear group consists of one positive lens and one negative lens; and
conditional formula (1) below is satisfied:
0.25<2 *f *tan(ω/2)/ L< 1.00  (1),

where
f: the focal length of the entire system
ω: a half angle of view
L: the distance from the object-side surface of the first lens to the imaging plane along the optical axis (back focus corresponds to an air converted length), and
the conditional formula (2) below is satisfied:
−2.0< f 2/ f <−0.5  (2),

where
f 2 : the focal length of the second lens, and
f: the focal length of the entire system.

2. The imaging lens of claim 1 that satisfies conditional formula (3) below:
1.0< f 3/ f< 3.0  (3),

where
f 3 : the focal length of the third lens, and
f: the focal length of the entire system.

3. The imaging lens of claim 1 that satisfies conditional formula (5) below:
−20.0< fN/fP<− 0.9  (5),

where
fN: the focal length of the negative lens of the rear group,
fP: the focal length of the positive lens of the rear group.

4. The imaging lens of claim 1 that satisfies conditional formula (1-1) below:
0.27<2* f *tan(ω/2)/ L< 1.00  (1-1),

where
f: the focal length of the entire system,
ω: a half angle of view
L: the distance from the object-side surface of the first lens to the imaging plane along the optical axis (the back focus corresponds to an air converted length).

5. The imaging lens of claim 1 that satisfies conditional formula (2-1) below:
−1.9< f 2/ f<− 0.7  (2-1),

where
f 2 : the focal length of the second lens, and
f: the focal length of the entire system.

6. The imaging lens of claim 1 that satisfies conditional formula (3-1) below:
1.0< f 3/ f< 2.7  (3-1),

where
f 3 : the focal length of the third lens, and
f: the focal length of the entire system.

7. The imaging lens of claim 1 that satisfies conditional formula (4-1) below:
d 4/ L< 0.06  (4-1),

where
d 4 : the distance from the second lens to the third lens along the optical axis, and
L: the distance from the object-side surface of the first lens to the imaging plane along the optical axis (the back focus corresponds to an air converted length).

8. The imaging lens of claim 1 that satisfies conditional formula (5-1) below:
−9.0< fN/fP<− 1.0  (5-1),

where
fN: the focal length of the negative lens of the rear group, and
fP: the focal length of the positive lens of the rear group.

9. The imaging lens of claim 1 , wherein the third lens is of a shape with a convex surface toward the object side.

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

11. An imaging lens, consisting of:
a front group which consists of a negative first lens having a meniscus shape with a convex surface toward the object side, a negative second lens, a point along the optical axis at the image-side surface of which is more toward the object side than points on both ends of the effective diameter of the image-side surface, and a positive third lens;
an aperture stop; and
a rear group which is positive as a whole in this order from the object side, wherein
the rear group consists of one positive lens and one negative lens; and
conditional formula (1) below is satisfied:
0.25<2 *f *tan(ω/2)/ L< 1.00  (1),

where
f: the focal length of the entire system
ω: a half angle of view
L: the distance from the object-side surface of the first lens to the imaging plane along the optical axis (back focus corresponds to an air converted length), and
the conditional formula (4) below is satisified:
d4/L<0.07  (4),

where
d 4 : the distance from the second lens to the third lens along the optical axis, and
L: the distance from the object-side surface of the first lens to the imaging plane along the optical axis (the back focus corresponds to an air converted length).

Assignees

• Fujifilm Corp

Inventors

• Yamakawa Hiromitsu

Classifications

• G02B9/04 Primary

  having two components only · CPC title

• G02B13/0045 Primary

  having five or more lenses · CPC title

• G02B13/06

  Panoramic objectives; So-called "sky lenses" {including panoramic objectives having reflecting surfaces} · CPC title

• G02B13/18

  with lenses having one or more non-spherical faces, e.g. for reducing geometrical aberration {(G02B13/002 takes precedence)} · CPC title

• G02B13/00 Primary

  Optical objectives specially designed for the purposes specified below (with variable magnification {in general} G02B15/00) · CPC title