Zoom lens, optical apparatus and method for manufacturing the zoom lens
AssigneeNikon Corporation
InventorSaburo Masugi
Life of this patent
Estimating the term…
Abstract
A zoom lens (ZL) comprises, in order from an object: a first lens group (G1) having negative refractive power; an aperture stop (S); a second lens group (G2) having positive refractive power; a third lens group (G3) having negative refractive power; and a fourth lens group (G4) having positive refractive power. In this zoom lens (ZL), upon zooming from a wide angle end state to a telephoto end state, a distance between the aperture stop (S) and the first lens group (G1), a distance between the aperture stop (S) and the second lens group (G2), and a distance between the aperture stop (S) and the third lens group (G3) are changed and the aperture stop (S) is moved in an optical axis direction.
Claims18
A zoom lens comprising, in order from an object:
- a first lens group having negative refractive power;
- an aperture stop;
- a second lens group having positive refractive power;
- a third lens group having negative refractive power;
- and a fourth lens group having positive refractive power, wherein
- upon zooming from a wide angle end state to a telephoto end state, a distance between the aperture stop and the first lens group, a distance between the aperture stop and the second lens group, and a distance between the aperture stop and the third lens group are changed and the aperture stop is moved in an optical axis direction, and a following conditional expression is satisfied:
- 1.12<TLw/TLt<1.30
- where,
- TLw denotes a total length of the zoom lens in the wide angle end state, and
- TLt denotes a total length of the zoom lens in the telephoto end state.
A zoom lens comprising, in order from an object:
- a first lens group having negative refractive power and comprising at least two lenses, wherein the lens that is second closest to the object in the first lens group is a negative lens;
- an aperture stop;
- a second lens group having positive refractive power;
- a third lens group having negative refractive power;
- and a fourth lens group having positive refractive power, wherein
- upon zooming from a wide angle end state to a telephoto end state, a distance between the aperture stop and the first lens group, a distance between the aperture stop and the second lens group, and a distance between the aperture stop and the third lens group are changed and the aperture stop is moved in an optical axis direction, and a following conditional expression is satisfied:
- −0.10<(Rn2+Rn1)/(Rn2−Rn1)<1.00
- where,
- Rn1 denotes a radius of curvature of an object-side surface of the negative lens that is second closest to the object in the first lens group, and
- Rn2 denotes a radius of curvature of an image-side surface of the negative lens that is second closest to the object in the first lens group.
A method for manufacturing a zoom lens including, in order from an object:
- a first lens group having negative refractive power;
- an aperture stop;
- a second lens group having positive refractive power;
- a third lens group having negative refractive power;
- and a fourth lens group having positive refractive power, the method comprising:
- arranging the first to the fourth lens groups and the aperture stop within a lens barrel in such a manner that, upon zooming from a wide angle end state to a telephoto end state, a distance between the aperture stop and the first lens group, a distance between the aperture stop and the second lens group, and a distance between the aperture stop and the third lens group are changed and the aperture stop is moved in an optical axis direction,
- further comprising one or more of the following features A and B, wherein
- the feature A comprises satisfying a following conditional expression:
- 1.12<TLw/TLt<1.30
- where,
- TLw denotes a total length of the zoom lens in the wide angle end state, and
- TLt denotes a total length of the zoom lens in the telephoto end state, and
- the feature B comprises that the first lens group includes at least two lenses, wherein the lens that is second closest to the object in the first lens group is a negative lens, and satisfying a following conditional expression:
- −0.10<(Rn2+Rn1)/(Rn2−Rn1)<1.00
- where,
- Rn1 denotes a radius of curvature of an object-side surface of the negative lens that is second closest to the object in the first lens group, and
- Rn2 denotes a radius of curvature of an image-side surface of the negative lens that is second closest to the object in the first lens group.
Dependencies are inferred from the claim text.