Zoom lens, optical apparatus, and method for manufacturing zoom lens
AssigneeNikon Corporation
InventorsNorio Murayama, Sayako Yamamoto
Life of this patent
Estimating the term…
Abstract
The present invention provides a zoom lens ZL comprising a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, and a fourth lens group G4 having positive refractive power, the first lens group G1 including a negative meniscus lens L11 and a positive meniscus lens L12, the second lens group G2 including a negative meniscus lens L21, a biconcave negative lens L22 and a positive meniscus lens L23, and the fourth lens group G4 including one positive lens L41, and the refractive indexes of at least three lenses in the zoom lens ZL being greater than 1.9.
Claims19
A zoom lens comprising, in order from an object:
- a first lens group having positive refractive power;
- a second lens group having negative refractive power, a third lens group having positive refractive power;
- and a fourth lens group having positive refractive power,
- a distance between the first lens group and the second lens group, a distance between the second lens group and the third lens group, and a distance between the third lens group and the fourth lens group changing respectively upon zooming from a wide-angle end state to a telephoto end state,
- the first lens group including, in order from the object, a negative lens and a positive meniscus lens having a convex surface facing the object,
- the second lens group including, in order from the object, a first negative lens, a second negative lens, and a positive meniscus lens having a convex surface facing the object,
- the fourth lens group including one positive lens, and
- the following conditional expressions being satisfied:
- 1.90<Nd11<2.50
- 1.90<Nda<2.50
- 1.86<Ndb<2.50
- where Nd11 denotes a refractive index of the negative lens closest to the object in the first lens group, Nda denotes a refractive index of the lens closest to the abject out of at least two lenses in the second lens group, the third lens group and the fourth lens group, and Ndb denotes a refractive index of the lens closer to an image than the lens closest to the object out of the at least two lenses.
A method for manufacturing a zoom lens by disposing, in order from an object, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a fourth lens group having positive refractive power,
- a distance between the first lens group and the second lens group, a distance between the second lens group and the third lens group, and a distance between the third lens group and the fourth lens group changing respectively upon zooming from a wide-angle end state to a telephoto end state,
- the first lens group including, in order from the object, a negative lens and a positive meniscus lens having a convex surface facing the object,
- the second lens group including, in order from the object, a first negative lens, a second negative lens, and a positive meniscus lens having a convex surface facing the object,
- the fourth lens group including one positive lens, and
- the following conditional expressions being satisfied:
- 1.90<Nd11<2.50
- 1.90<Nda<2.50
- 1.86<Ndb<2.50
- where Nd11 denotes a refractive index of the negative lens closest to the object in the first lens group, Nda denotes a refractive index of the lens closest to the object out of at least two lenses in the second lens group, the third lens group and the fourth lens group, and Ndb denotes a refractive index of the lens closer to an image than the lens closest to the object out of the at least two lenses.
Dependencies are inferred from the claim text.