# US 10,310,240 B2 · Zoom lens and image pickup apparatus including the same

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- Number: US 10,310,240 B2
- Document ID: US10310240B2
- Status: Granted
- Kind: B2
- Application number: 15/346,186
- Filed: 2016-11-08
- Published: 2017-05-18
- Granted: 2019-06-04
- Earliest claimed: 2015-11-13
- Assignees: Canon Kabushiki Kaisha
- Applicants: Canon Kabushiki Kaisha
- Inventors: Shin Kuwashiro
- Web page: https://patentgrep.com/patent/US10310240B2

## CPC

- G02B 15/173: arranged +-+
- G02B 5/005: {Diaphragms (for cameras G03B9/02)}
- G02B 15/145105: {arranged +-+--}
- G02B 15/145121: {arranged +-+-+}
- G02B 15/28: arranged +-+
- G02B 27/0025: {for optical correction, e.g. distorsion, aberration}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

A zoom lens includes, in order from an object side to an image 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 rear unit including at least one lens unit. In the zoom lens, the locus of movement, the focal length, the amount of displacement during zooming, and the shapes of lens surfaces are appropriately set for each lens unit.

## Claims

### Claim 1

A zoom lens comprising, in order from an object side to an image 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 rear lens group including at least one lens unit, wherein
the first lens unit does not move for zooming,
during zooming from a wide angle end to a telephoto end, each of the third lens unit and the fourth lens unit moves toward the object side, and an interval between each adjacent two of the lens units varies, and
the zoom lens satisfies the following conditional expressions:
0.1<f3/|m3|<0.9,
−1.4<f4/|m4|<−0.1, and
1.5<(R2a+R1a)/(R2a−R1a)<30.0,
where f3 is a focal length of the third lens unit, f4 is a focal length of the fourth lens unit, m3 is an amount of displacement of the third lens unit in the zooming from the wide angle end to the telephoto end, m4 is an amount of displacement of the fourth lens unit in the zooming from the wide angle end to the telephoto end, R1a is a radius of curvature of a lens surface nearest to the object side in the first lens unit, and R2a is a radius of curvature of a lens surface nearest to the image side in the first lens unit.

### Claim 2 (depends on 1)

The zoom lens according to claim 1, wherein
the zoom lens satisfies the following conditional expression:
20.0<f1/D1<200.0,
where f1 is a focal length of the first lens unit L1, and D1 is a thickness of the first lens unit on an optical axis.

### Claim 3 (depends on 1)

The zoom lens according to claim 1, wherein
the first lens unit consists of a single positive lens, and
the zoom lens satisfies the following conditional expressions:
1.50<nd11a<1.80, and
45.0<νd11a<75.0,
where nd11a and νd11a are respectively a refractive index and an Abbe number of a material of the positive lens of the first lens unit.

### Claim 4 (depends on 1)

The zoom lens according to claim 1, wherein
the zoom lens satisfies the following conditional expression:
−3.6<f2/fw<−2.0,
where f2 is a focal length of the second lens unit, and fw is a focal length of the zoom lens at the wide angle end.

### Claim 5 (depends on 1)

The zoom lens according to claim 1, wherein
the second lens unit includes, in order from the object side to the image side, a negative lens, a negative lens, a negative lens, and a positive lens, and
the zoom lens satisfies the following conditional expressions:
1.85<nd24a<2.00, and
14.0<νd24a<22.0,
where nd24a and νd24a are respectively a refractive index and an Abbe number of a material of the positive lens of the second lens unit.

### Claim 6 (depends on 1)

The zoom lens according to claim 1, wherein
the third lens unit includes a plurality of positive lenses, and
the zoom lens satisfies the following conditional expression:
65.0<νd3a,
where νd3a is an average Abbe number of materials of the positive lenses in the third lens unit.

### Claim 7 (depends on 1)

The zoom lens according to claim 1, wherein
the third lens unit includes a plurality of positive lenses, and
at least two of the positive lenses of the third lens unit are formed from a material satisfying the following conditional expression:
0.010<θgF−(0.644−0.00168×νd)<0.070,
where νd is an Abbe number of the material, and θgF is a partial dispersion ratio of the material.

### Claim 8 (depends on 1)

The zoom lens according to claim 1, wherein
during zooming from the wide angle end to the telephoto end, the second lens unit moves toward the image side and then toward the object side, and
the zoom lens satisfies the following conditional expression:
0.5<m2/ft<1.3,
where m2 is a distance between positions of the second lens unit on an optical axis during the zooming from the wide angle end to the telephoto end, one of the positions being closest to the object and the other position being closest to the image, and ft is a focal length of the zoom lens at the telephoto end.

### Claim 9 (depends on 1)

The zoom lens according to claim 1, wherein
the fourth lens unit moves toward the image side to focus from infinity to close-up.

### Claim 10 (depends on 1)

The zoom lens according to claim 1, wherein
the rear lens group consists of a fifth lens unit having a positive refractive power.

### Claim 11 (depends on 1)

The zoom lens according to claim 1, wherein
the rear lens group consists of, in order from the object side to the image side, a fifth lens unit having a negative refractive power and a sixth lens unit having a positive refractive power.

### Claim 12 (depends on 1)

An image pickup apparatus, comprising:
the zoom lens according to claim 1; and
an image pickup element configured to receive an image formed by the zoom lens.

### Claim 13

A zoom lens comprising, in order from an object side to an image 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 rear group including at least one lens unit, wherein
the first lens unit does not move for zooming,
each of the third lens unit and the fourth lens unit moves toward the object side during zooming from a wide angle end to a telephoto end, thereby varying an interval between each adjacent two of the lens units during the zooming,
the third lens unit includes a plurality of positive lenses, and
the zoom lens satisfies the following conditional expressions:
0.1<f3/|m3|<0.9,
−1.4<f4/|m4|<−0.1, and
1.5<(R2a+R1a)/(R2a-R1a)<30.0,
where f3 is a focal length of the third lens unit, f4 is a focal length of the fourth lens unit, m3 is an amount of displacement of the third lens unit in the zooming from the wide angle end to the telephoto end, m4 is an amount of displacement of the fourth lens unit in the zooming from the wide angle end to the telephoto end, R1a is a radius of curvature of a lens surface nearest to the object side in the first lens unit, and R2a is a radius of curvature of a lens surface nearest to the image side in the first lens unit, and
wherein at least two of the positive lenses of the third lens unit are formed from a material satisfying the following conditional expression:
0.010<θgF−(0.644−0.00168×νd)<0.070,
where νd is an Abbe number of the material, and θgF is a partial dispersion ratio of the material.

### Claim 14

A zoom lens comprising, in order from an object side to an image 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 rear group including at least one lens unit, wherein
the first lens unit does not move for zooming,
each of the third lens unit and the fourth lens unit moves toward the object side during zooming from a wide angle end to a telephoto end, thereby varying an interval between each adjacent two of the lens units during the zooming, and
the zoom lens satisfies the following conditional expressions:
0.1<f3/|m3|<0.9,
−1.4<f4/|m4|<−0.1,
1.5<(R2a+R1a)/(R2a−R1a)<30.0, and
0.5<m2/ft<1.3,
where f3 is a focal length of the third lens unit, f4 is a focal length of the fourth lens unit, m3 is an amount of displacement of the third lens unit in the zooming from the wide angle end to the telephoto end, m4 is an amount of displacement of the fourth lens unit in the zooming from the wide angle end to the telephoto end, R1a is a radius of curvature of a lens surface nearest to the object side in the first lens unit, R2a is a radius of curvature of a lens surface nearest to the image side in the first lens unit, m2 is a distance between positions of the second lens unit on an optical axis during the zooming from the wide angle end to the telephoto end, one of the positions being closest to the object and the other position being closest to the image, and ft is a focal length of the zoom lens at the telephoto end.