ZOOM LENS, OPTICAL APPARATUS WITH THE ZOOM LENS, AND METHOD OF MANUFACTURING ZOOM LENS

• US 20110149412A1
• Filed: 07/13/2009
• Published: 06/23/2011
• Est. Priority Date: 08/12/2008
• Status: Active Grant

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Sato, Susumu
• Granted Patent: US 8,503,094 B2
• Time in Patent Office: Days
• US Class Current: 359/683
• CPC Class Codes: G02B 15/145121 arranged +-+-+

Abstract

A zoom lens ZL, which is mounted on an electronic still camera 1 or the like, is composed of, in order from the object side, a first lens unit G1 having a positive refractive power, a second lens unit G2 having a negative refractive power, a third lens unit G3 having a positive refractive power, a fourth lens unit G4 having a negative refractive power, and a fifth lens unit G5 having a positive refractive power. The first lens unit G1 has, in order from the object side, a negative meniscus lens with a convex surface on the object side, and a positive lens, and the second lens unit G2 has, in order from the object side, a negative meniscus lens with a convex surface on the object side, a biconcave lens, and a positive lens. The zoom lens satisfies a condition of the following expression:

0.005<(−f2)×f3/(f1²)<0.023,

• • where f1, f2, and f3 are the respective focal lengths of the first, second, and third lens units G1, G2, and G3.

Claims

1. A zoom lens comprising, in order from the object side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit having a positive refractive power, a fourth lens unit having a negative refractive power, and a fifth lens unit having a positive refractive power,

wherein the first lens unit has a negative lens and a positive lens in order from the object side,

wherein the second lens unit has an object-side negative lens, an image-side negative lens, and a positive lens in order from the object side,

the zoom lens satisfying a condition of the following expression:

0.005<

(−

f2)×

f3/(f1²)<

0.023,

where f1 is the focal length of the first lens unit, f2 the focal length of the second lens unit, and f3 the focal length of the third lens unit.

2. The zoom lens according to claim 1, wherein at least one of the negative lens and the object-side negative lens is a negative meniscus lens with a convex surface on the object side.

3. The zoom lens according to claim 1, wherein the image-side negative lens is of a biconcave shape.

4. The zoom lens according to claim 1, satisfying a condition of the following expression:

0.050<

(−

f2)/f1<

0.140.

5. The zoom lens according to claim 1, satisfying a condition of the following expression:

0.57<

f5/f1<

1.30,

where f5 is the focal length of the fifth lens unit.

6. The zoom lens according to claim 1, satisfying a condition of the following expression:

1.85<

n11<

2.30,

where n11 is a refractive index of a medium of the negative lens at the d-line.

7. The zoom lens according to claim 1, wherein the first lens unit is composed of a cemented lens of the negative lens and the positive lens, and wherein the second lens unit is configured so that all the lenses are arranged with an air space in between.

8. The zoom lens according to claim 1, satisfying a condition of the following expression:

0.10<

f3/(−

f4)<

0.45,

where f3 is the focal length of the third lens unit and f4 the focal length of the fourth lens unit.

9. The zoom lens according to claim 1, wherein an object-side lens surface of the object-side negative lens consists of an aspherical surface, and

wherein at least one of lens surfaces of the positive lens in the second lens unit consists of an aspherical surface.

10. The zoom lens according to claim 1, wherein at least one of the second lens unit and the third lens unit is configured so that at least a part thereof moves so as to have a component in a substantially perpendicular direction to the optical axis.

11. The zoom lens according to claim 1, wherein the fifth lens unit is configured as a positive lens in which an object-side lens surface has a convex shape on the object side and has a smaller radius of curvature than an image-side lens surface, and

wherein during focusing with a photographing object at a finite distance, the fifth lens unit moves along the optical axis toward the object.

12. The zoom lens according to claim 1, wherein with a photographing object at infinity and during change of a lens position state from a wide-angle end state to a telephoto end state,

the first lens unit and the third lens unit move toward the object, and

the second lens unit moves along the optical axis toward an image from the wide-angle end state to a predetermined intermediate focal length state and moves along the optical axis toward the object from the predetermined intermediate focal length state to the telephoto end state.

13. The zoom lens according to claim 1, wherein the third lens unit has, in order from the object side,

a negative meniscus lens with a convex surface on the object side, and

a biconvex lens with an image-side lens surface of an aspherical surface, and

wherein the fourth lens unit has a negative meniscus lens with a convex surface on the object side.

14. The zoom lens according to claim 1, wherein the third lens unit has, in order from the object side,

a positive lens with an object-side lens surface of an aspherical surface of a convex shape on the object side,

a negative meniscus lens with a convex surface on the object side, and

a biconvex lens with an image-side lens surface of an aspherical surface, and

wherein the fourth lens unit has a negative meniscus lens with a convex surface on the object side.

15. An optical apparatus comprising the zoom lens as set forth in claim 1.

16. A method of manufacturing a zoom lens comprising, in order from the object side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit having a positive refractive power, a fourth lens unit having a negative refractive power, and a fifth lens unit having a positive refractive power,

the method comprising:

arranging a negative lens and a positive lens in order from the object side, in the first lens unit; and

arranging an object-side negative lens with an object-side lens surface of an aspherical surface, an image-side negative lens, and a positive lens with at least one aspherical surface, in order from the object side, in the second lens unit.

17. The method of manufacturing the zoom lens according to claim 16, satisfying a condition of the following expression:

0.005<

(−

f2)×

f3/(f1²)<

0.023,

where f1 is the focal length of the first lens unit, f2 the focal length of the second lens unit, and f3 the focal length of the third lens unit.

18. The method of manufacturing the zoom lens according to claim 16, wherein at least one of the negative lens and the object-side negative lens is a negative meniscus lens with a convex surface on the object side.

19. The method of manufacturing the zoom lens according to claim 16, wherein the image-side negative lens is of a biconcave shape.

20. The method of manufacturing the zoom lens according to claim 16, satisfying a condition of the following expression:

0.050<

(−

f2)/f1<

0.140.

21. The method of manufacturing the zoom lens according to claim 16, satisfying a condition of the following expression:

0.57<

f5/f1<

1.30,

where f5 is the focal length of the fifth lens unit.

22. The method of manufacturing the zoom lens according to claim 16, satisfying a condition of the following expression:

1.85<

n11<

2.30,

where n11 is a refractive index of a medium of the negative lens at the d-line.

23. The method of manufacturing the zoom lens according to claim 16, wherein the first lens unit is composed of a cemented lens of the negative lens and the positive lens, and wherein the second lens unit is configured so that all the lenses are arranged with an air space in between.

24. The method of manufacturing the zoom lens according to claim 16, satisfying a condition of the following expression:

0.10<

f3/(−

f4)<

0.45,

where f3 is the focal length of the third lens unit and f4 the focal length of the fourth lens unit.

25. The method of manufacturing the zoom lens according to claim 16, wherein at least one of the second lens unit and the third lens unit is configured so that at least a part thereof moves so as to have a component in a substantially perpendicular direction to the optical axis.

26. The method of manufacturing the zoom lens according to claim 16, wherein the fifth lens unit is configured as a positive lens in which an object-side lens surface has a convex shape on the object side and has a smaller radius of curvature than an image-side lens surface, and

wherein during focusing with a photographing object at a finite distance, the fifth lens unit moves along the optical axis toward the object.

27. The method of manufacturing the zoom lens according to claim 16, wherein with a photographing object at infinity and during magnification variation from a wide-angle end state to a telephoto end state,

the first lens unit and the third lens unit move toward the object, and

the second lens unit moves along the optical axis toward an image from the wide-angle end state to a predetermined intermediate focal length state and moves along the optical axis toward the object from the predetermined intermediate focal length state to the telephoto end state.

28. The method of manufacturing the zoom lens according to claim 16, wherein the third lens unit has, in order from the object side, a negative meniscus lens with a convex surface on the object side, and a biconvex lens with an image-side lens surface of an aspherical surface, and

wherein the fourth lens unit has a negative meniscus lens with a convex surface on the object side.

29. The method of manufacturing the zoom lens according to claim 16, wherein the third lens unit has, in order from the object side, a positive lens with an object-side lens surface of an aspherical surface of a convex shape on the object side, a negative meniscus lens with a convex surface on the object side, and a biconvex lens with an image-side lens surface of an aspherical surface, and

wherein the fourth lens unit has a negative meniscus lens with a convex surface on the object side.