Lens system, wide-angle lens, optical apparatus equipped with lens system, and method for manufacturing lens system

• US 8,503,110 B2
• Filed: 09/07/2010
• Issued: 08/06/2013
• Est. Priority Date: 09/09/2009
• Status: Active Grant

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Oshita, Koichi
• Primary Examiner(s): Sugarman, Scott J
• Application Number:
  US13/395,234
• Publication Number:
  US 20120170135A1
• Time in Patent Office: 1,064 Days
• Field of Search: 359749-753
• US Class Current: 359/753
• CPC Class Codes: G02B 13/06 Panoramic objectives; So-called "sky lenses" including panoramic objectives having reflecting surfaces

Abstract

With comprising, in order from an object side: a first lens L1 constructed by a negative meniscus lens having a convex surface facing the object side; a cemented lens component CL1 having positive refractive power as a whole constructed by a second lens L2 having positive refractive power and a third lens L3 having negative refractive power; a fourth lens L4 having negative refractive power; a fifth lens L5 having positive refractive power; and a sixth lens L6 having positive refractive power, and the following expression being satisfied:
0.01<d2/(−f1)<0.15
where d2 denotes a distance along an optical axis between the first lens and the second lens, and f1 denotes a focal length of the first lens, a compact lens system having superb optical performance with correcting various aberrations, a wide-angle lens, an optical apparatus equipped therewith, and a method for manufacturing the lens system are provided.

Claims

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

a first lens constructed by a negative meniscus lens having a convex surface facing the object side;

a cemented lens component having positive refractive power as a whole constructed by a second lens having positive refractive power cemented with a third lens having negative refractive power;

a fourth lens having negative refractive power;

a fifth lens having positive refractive power; and

a sixth lens having positive refractive power, and

the following conditional expression being satisfied;

0.01<

d2/(−

f1)<

0.15

where d2 denotes a distance along an optical axis between the first lens and the second lens, and f1 denotes a focal length of the first lens.

2. The lens system according to claim 1, wherein the following conditional expression is satisfied:

−

5<

(r2+r1)/(r2−

r1)<

−

2

where r1 denotes a radius of curvature of the object side lens surface of the first lens, and r2 denotes a radius of curvature of the image side lens surface of the first lens.

3. The lens system according to claim 1, wherein an aperture stop is disposed between the cemented lens component and the fourth lens.

4. The lens system according to claim 1, wherein the following conditional expression is satisfied:

0.0<

fb/fa<

1.2

where fa denotes a focal length at d-line of a front lens group composed of the first lens and the cemented lens component, and fb denotes a focal length at d-line of a rear lens group composed of the fourth lens, the fifth lens and the sixth lens.

5. The lens system according to claim 1, wherein the following conditional expression is satisfied:

−

0.25<

(rb+r3)/(rb−

r3)<

0.00

where rb denotes a radius of curvature of the image side lens surface of the fifth lens, and r3 denotes a radius of curvature of the object side lens surface of the second lens.

6. The lens system according to claim 1, wherein the following conditional expression is satisfied:

0.7<

D/f<

1.2

where D denotes a distance along the optical axis between the object side lens surface of the first lens and the image side lens surface of the sixth lens, and f denotes a focal length of the lens system.

7. The lens system according to claim 1, wherein at least one lens surface of the sixth lens is an aspherical surface.

8. The lens system according to claim 1, wherein the fourth lens is cemented with the fifth lens.

9. A wide-angle lens having a configuration of the lens system according to claim 1.

10. An optical apparatus equipped with the lens system according to claim 1.

11. A method for manufacturing a lens system comprising steps of:

disposing, in order from an object side, a first lens constructed by a negative meniscus lens having a convex surface facing the object side, a cemented lens component constructed by a second lens having positive refractive power cemented with a third lens having negative refractive power, a fourth lens having negative refractive power, a fifth lens having positive refractive power, and a sixth lens having positive refractive power; and

disposing each lens with satisfying the following conditional expression;

0.01<

d2/(−

f1)<

0.15

where d2 denotes a distance along the optical axis between the first lens and the second lens, and f1 denotes a focal length at d-line of the first lens.

12. The method according to claim 11, further comprising a step of:

disposing each lens with satisfying the following conditional expression;

−

5<

(r2+r1)/(r2−

r1)<

−

2

where r1 denotes a radius of curvature of the object side lens surface of the first lens, and r2 denotes a radius of curvature of the image side lens surface of the first lens.

13. The method according to claim 11, further comprising a step of:

disposing an aperture stop between the cemented lens component and the fourth lens.

14. The method according to claim 11, further comprising a step of:

disposing each lens with satisfying the following conditional expression;

0.0<

fb/fa<

1.2

where fa denotes a focal length at d-line of a front lens group composed of the first lens and the cemented lens component, and fb denotes a focal length at d-line of a rear lens group composed of the fourth lens, the fifth lens and the sixth lens.

15. The method according to claim 11, further comprising a step of:

disposing each lens with satisfying the following conditional expression;

−

0.25<

(rb+r3)/(rb−

r3)<

0.00

where rb denotes a radius of curvature of the image side lens surface of the fifth lens, and r3 denotes a radius of curvature of the object side lens surface of the second lens.

16. The method according to claim 11, further comprising a step of:

disposing each lens with satisfying the following conditional expression;

0.7<

D/f<

1.2

where D denotes a distance along the optical axis between the object side lens surface of the first lens and the image side lens surface of the sixth lens, and f denotes a focal length of the lens system.