IMAGING LENS AND IMAGING APPARATUS

• US 20100046094A1
• Filed: 08/20/2009
• Published: 02/25/2010
• Est. Priority Date: 08/21/2008
• Status: Active Grant

• Current Assignee: Nanchang Ofilm Optical-Electronic Tech Company Limited
• Original Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Inventors: Asami, Taro
• Granted Patent: US 8,054,562 B2
• Time in Patent Office: Days
• US Class Current: 359/739
• CPC Class Codes: G02B 13/16 for use in conjunction with image converters or intensifiers , or for use with projectors, e.g. objectives for projection TV
• CPC Class Codes: G02B 9/62 having six components only

Abstract

Disclosed is an imaging lens having a small F number, a wide angle of view, and a low manufacturing cost and capable of obtaining a high-quality image.

An imaging lens includes a first lens having a negative power and including a concave surface facing an image side, a second lens having a positive power, an aperture diaphragm, a third lens having a negative power, an aperture diaphragm, a fourth lens having a positive power, a fifth lens having a positive power and including a convex surface facing the image side, and a sixth lens having a negative power arranged in this order from an object side. When the curvature radius of an image-side surface of the third lens is R3r and the curvature radius of an object-side surface of the fourth lens is R4f, the imaging lens satisfies the following Conditional expression:

|R3r/R4f|<1.0.

Claims

1. An imaging lens comprising:

a first lens that is made of glass, has a negative power and includes a concave surface facing an image side;

a second lens having a positive power;

a third lens having a negative power;

a fourth lens having a positive power;

a fifth lens that has a positive power and includes a convex surface facing the image side;

a sixth lens having a negative power; and

a stop positioned in rear of the second lens or the third lens,

wherein the first to sixth lenses are arranged in this order from an object side, and

when the curvature radius of an image-side surface of the third lens is R3r and the curvature radius of an object-side surface of the fourth lens is R4f, the imaging lens satisfies the following conditional expression;

|R3r/R4f|<

1.0.

3. The imaging lens according to claim 1,

wherein the third lens is a biconcave lens.

4. The imaging lens according to claim 1,

wherein, when the focal length of the entire lens system is f and a composite focal length from the third lens to the sixth lens is f3456, the imaging lens satisfies the following conditional expression:

f3456/f>

0.8.

5. The imaging lens according to claim 1,

wherein, when the focal length of the entire lens system is f and the focal length of the fifth lens is f5, the imaging lens satisfies the following conditional expression:

0.6<

f5/f<

1.2.

6. The imaging lens according to claim 1,

wherein, when the focal length of the entire lens system is f and the focal length of the sixth lens is f6, the imaging lens satisfies the following conditional expression:

−

2.0<

f6/f<

−

0.6.

7. The imaging lens according to claim 1,

wherein, when the focal length of the entire lens system is f and the focal length of the third lens is f3, the imaging lens satisfies the following conditional expression:

−

1.5<

f3/f<

−

0.5.

8. The imaging lens according to claim 1,

wherein, when the focal length of the entire lens system is f and the curvature radius of an image-side surface of the fourth lens is R9, the imaging lens satisfies the following conditional expression:

−

1.2<

R9/f<

−

0.5.

9. The imaging lens according to claim 1,

wherein, when the focal length of the fourth lens is f4 and the focal length of the fifth lens is f5, the imaging lens satisfies the following conditional expression:

0.5<

f4/f5<

1.5.

10. The imaging lens according to claim 1,

wherein the Abbe number of the second lens with respect to the d-line is greater than 32.

11. The imaging lens according to claim 1,

wherein the Abbe number of the fourth lens with respect to the d-line is equal to or greater than 35,

the Abbe number of the fifth lens with respect to the d-line is equal to or greater than 35, and

the Abbe number of the sixth lens with respect to the d-line is equal to or less than 30.

12. The imaging lens according to claim 1,

wherein the Abbe number of the first lens with respect to the d-line is equal to or greater than 40.

13. An imaging apparatus comprising the imaging lens according to claim 1.

2. An imaging lens comprising:

a first lens that has a negative power and includes a concave surface facing an image side;

a second lens having a positive power;

a third lens having a negative power;

a fourth lens having a positive power;

a fifth lens that has a positive power and includes a convex surface facing the image side;

a sixth lens having a negative power; and

a stop positioned in rear of the second lens or the third lens,

wherein the first to sixth lenses are arranged in this order from an object side, and

each of the lenses is a single lens.