US 8,830,592 B2Granted

Zoom lens, imaging apparatus, and method for manufacturing zoom lens

AssigneeNikon Corporation

InventorsHaruo Sato, Issei Tanaka

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Abstract

A zoom lens including, from an object: a front group having negative power; and a rear group having positive power, the rear group including, from the object, a positive lens, a negative lens having a concave surface facing the object, a cemented positive lens constructed by a negative lens and a positive lens, and a cemented lens constructed by a positive lens and a negative lens, the rear group further including a focusing group disposed to the object side of the positive lens La for focusing from infinity to a close object by moving from the object side to an image side, a distance between the front group and the rear group being varied thereby zooming from a wide-angle end state to a telephoto end state, and given condition being satisfied, thereby providing a downsized zoom lens having wide angle of view and excellent optical performance with fewer lenses.

Claims29

Dependent claims

A zoom lens comprising, in order from an object side:

a front lens group having negative refractive power;
and
a rear lens group having positive refractive power,
the front lens group including, in order from the object side, an aspherical lens component Ga that has negative refractive power and a shape that the negative refractive power becomes smaller toward the periphery, and an aspherical lens component Gb that has positive refractive power and a shape that the positive refractive power turns to negative refractive power toward the periphery or has negative refractive power and a shape that the negative refractive becomes stronger toward the periphery,
a distance between the front lens group and the rear lens group being varied thereby carrying out zooming from a wide-angle end state to a telephoto end state,
the following conditional expression being satisfied:
0.0406≦(−Fa)/|Fb|<0.650
where Fa denotes a focal length of the aspherical lens component Ga in the front lens group, and Fb denotes a focal length of the aspherical lens component Gb in the front lens group.

5 more elements

A method for manufacturing a zoom lens including, in order from an object side, a front lens group having negative refractive power, and a rear lens group having positive refractive power, the method comprising steps of:

disposing, in order from the object side, an aspherical lens component Ga that has negative refractive power and the negative refractive power becomes weaker toward periphery, and an aspherical lens component Gb that has positive refractive power and the positive refractive power varies to negative toward periphery, or has negative refractive power and the negative refractive power becomes strong toward periphery into the front lens group;
disposing the aspherical lens component Ga and the aspherical lens component Gb with satisfying the following conditional expression:
0.0406≦(−Fa)/|Fb|<0.650
where Fa denotes a focal length of the aspherical lens component Ga in the front lens group, and Fb denotes a focal length of the aspherical lens component Gb in the front lens group;
and
making an arrangement so as to carry out zooming by varying a distance between the front lens group and the rear lens group.

3 more elements

Dependencies are inferred from the claim text.

Facts

Application: 13/166,631Filed 22 Jun 2011
Priority: JP 2010-14294123 Jun 2010
Published: US 2011/0317278 A129 Dec 2011
Granted: 9 Sep 2014
Term ends: Not estimatedThe source records don’t support an estimate.

Classification8 codes

G02B 13/04
Optical objectives specially designed for the purposes specified below: reversed telephoto objectives
G02B 1/11
Optical coatings produced by application to, or surface treatment of, optical elements: anti-reflection coatings
G02B 15/177
With interdependent non-linearly related movements between one lens or lens group, and another lens or lens group: having a negative front lens or…
G02B 27/0018
Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00: with means for preventing ghost images