US 2006/0152815 A1 · Zoom lens and imaging system incorporating it

Abstract

The invention relates to a small-format yet high-performance two units or three units type zoom lens with a negative unit at the front, which has a zoom ratio of about 3, an angle of view of as wide as 60° at the wide-angle end and high image-formation capability, and is much less susceptible to chromatic blurring, with a compact lens barrel. The zoom lens comprises a first lens unit G1 of negative refracting power and a second lens unit G2 of positive power, wherein zooming is implemented by varying the space between the lens units. The first lens unit G1 is made up of one negative lens L11 and one positive lens L12, two in all, and satisfies specific conditions with respect to their refractive index and Abbe constant.

Claims24

Dependent claims

A zoom lens comprising, in order from an object side to an image side thereof,

a first lens unit of negative refracting power, and
a second lens unit of positive refracting power, with a space between both the lens units varied for zooming, wherein:
the first lens unit consists of, in order from an object side thereof, one negative lens L11 and one positive lens L12, and satisfies the following conditions:
1.6800<nd1<2.3000 (1)
1.7000<nd2<2.3000 (2)
30.0<νd2<50.0 (3)
0.0<nd2−nd1<0.5 (4)
where
νd2 is an Abbe constant of the positive lens in the first lens unit,
nd1 is a refractive index of the negative lens in the first lens unit, and
nd2 is a refracting index of the positive lens in the first lens unit.

8 more elements

A zoom lens comprising, in order from an object side to an image side thereof,

a first lens unit of negative refracting power,
a second lens unit of positive refracting power, and
a third lens unit of positive refracting power, with a space between adjacent lens units varied for zooming, wherein:
the first lens unit consists of, in order from an object side thereof, one negative lens and one positive lens,
the second lens unit comprises two positive lenses and one negative lens,
the third lens unit consists of one positive lens, and
the zoom lens satisfies the following condition:
(Σd1+Σd2+Σd3)/ft<0.64 (14)
where
Σd1 is an axial thickness of the first lens unit from a lens surface nearest to an object side thereof to a lens surface nearest to an image side thereof,
Σd2 is an axial thickness of the second lens unit from a lens surface nearest to an object side thereof to a lens surface nearest to an image side thereof,
Σd3 is an axial thickness of the third lens unit from a lens surface nearest to an object side thereof to a lens surface nearest to an image side thereof, and
ft is a focal length of a whole zoom lens system at the telephoto end.

10 more elements

Dependencies are inferred from the claim text.

Zoom lens and imaging system incorporating it

Life of this patent

Zoom lens and imaging system incorporating it

Life of this patent

Abstract

Claims24