# US 2018/0024314 A1 · Zoom lens and image pickup apparatus having the same

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- Number: US 2018/0024314 A1
- Document ID: US20180024314A1
- Status: Published application
- Kind: A1
- Application number: 15/646,492
- Filed: 2017-07-11
- Published: 2018-01-25
- Earliest claimed: 2016-07-19
- Assignees: Canon Kabushiki Kaisha
- Applicants: Canon Kabushiki Kaisha
- Inventors: Yoshihisa Tashiro
- Web page: https://patentgrep.com/patent/US20180024314A1

## CPC

- G02B 9/60: having five components only
- G02B 7/021: {for more than one lens}
- G02B 7/04: with mechanism for focusing or varying magnification
- G02B 13/02: Telephoto objectives, i.e. systems of the type + - in which the distance from the front vertex to the image plane is less than the equivalent focal length
- G02B 13/06: Panoramic objectives; So-called "sky lenses" {including panoramic objectives having reflecting surfaces}
- G02B 15/145113: {arranged +-++-}
- G02B 15/167: having an additional fixed front lens or group of lenses
- G02B 17/00: Systems with reflecting surfaces, with or without refracting elements
- G03B 5/00: Adjustment of optical system relative to image or object surface other than for focusing
- G03B 2205/0046: Movement of one or more optical elements for zooming
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G03B: APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR (optical parts of such apparatus G02B; photosensitive materials or processes for photographic purposes G03C; apparatus for processing exposed photographic materials G03D)

## Abstract

A zoom lens includes, in order from an object side to an image side, first to fifth lens units respectively having positive, negative, positive, positive, and negative refractive powers. The first lens unit does not move for zooming, and each of the distances between the lens units adjacent to each other is changed during zooming. Lateral magnifications β2w and β2t of the second lens unit at a wide angle end and a telephoto end, respectively, lateral magnifications β3w and β3t of the third lens unit at the wide angle end and the telephoto end, respectively, lateral magnifications β4w and β4t of the fourth lens unit at the wide angle end and the telephoto end, respectively, a focal length f5 of the fifth lens unit, and an amount of movement M5 of the fifth lens unit in zooming from the wide angle end to the telephoto end are appropriately set.

## 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 positive refractive power, and a fifth lens unit having a negative refractive power, wherein
the first lens unit does not move for zooming,
each of the distances between the lens units adjacent to each other is changed during zooming, and
when a magnification amount Z2 of the second lens unit, a magnification amount Z3 of the third lens unit, and a magnification amount Z4 of the fourth lens unit are given by
Z2=β2t/β2w,
Z3=β3t/β3w, and
Z4=β4t/β4w,
where β2w and β2t are respectively lateral magnifications of the second lens unit focused at infinity at a wide angle end and a telephoto end, β3w and β3t are respectively lateral magnifications of the third lens unit focused at infinity at the wide angle end and the telephoto end, and β4w and β4t are respectively lateral magnifications of the fourth lens unit focused at infinity at the wide angle end and the telephoto end, the following conditional expressions are satisfied:
2.0<Z2/(Z3×Z4)<5.0, and
0.5<|f5|/M5<2.0
where f5 is a focal length of the fifth lens unit, and M5 is an amount of movement of the fifth lens unit in zooming from the wide angle end to the telephoto end while focused at infinity.

### Claim 2 (depends on 1)

The zoom lens according to claim 1, wherein
the following conditional expression is satisfied:
1.9<f1/fw<2.6
where f1 is a focal length of the first lens unit, and fw is a focal length of the zoom lens at the wide angle end.

### Claim 3 (depends on 1)

The zoom lens according to claim 1, wherein
the following conditional expression is satisfied:
0.6<|f2|/fw<1.4
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 4 (depends on 1)

The zoom lens according to claim 1, wherein
the following conditional expression is satisfied:
1.8<f1/|f2|<3.0
where f1 is a focal length of the first lens unit, and f2 is a focal length of the second lens unit.

### Claim 5 (depends on 1)

The zoom lens according to claim 1, wherein
the following conditional expression is satisfied:
0.1<|f5|/ft<0.6
where ft is a focal length of the zoom lens at the telephoto end.

### Claim 6 (depends on 1)

The zoom lens according to claim 1, wherein
the following conditional expression is satisfied:
0.5<100×(D23t+D34t)/ft<10.0
where D23t is a distance between the second lens unit and the third lens unit focused at infinity at the telephoto end, D34t is a distance between the third lens unit and the fourth lens unit focused at infinity at the telephoto end, and ft is a focal length of the zoom lens at the telephoto end.

### Claim 7 (depends on 1)

The zoom lens according to claim 1, wherein
the third lens unit moves during zooming.

### Claim 8 (depends on 7)

The zoom lens according to claim 7, wherein
the third lens unit is located closer to the object side at the wide angle end than at the telephoto end.

### Claim 9 (depends on 7)

The zoom lens according to claim 7, wherein
the following conditional expression is satisfied:
−1.00<M3/fw<−0.02
where M3 is an amount of movement of the third lens unit in zooming from the wide angle end to the telephoto end, and fw is a focal length of the zoom lens at the wide angle end.

### Claim 10 (depends on 1)

The zoom lens according to claim 1, wherein
the first lens unit includes a reflective member having a reflective surface that bends an optical path.

### Claim 11 (depends on 10)

The zoom lens according to claim 10, wherein
the following conditional expression is satisfied:
0.1<D1/ft<0.6
where D1 is a thickness of the first lens unit, and ft is a focal length of the zoom lens at the telephoto end.

### Claim 12 (depends on 10)

The zoom lens according to claim 10, wherein
the reflective member comprises a prism.

### Claim 13 (depends on 12)

The zoom lens according to claim 12, wherein
the following conditional expression is satisfied:
1.8<Ndpr<2.5
where Ndpr is a refractive index, for d-line, of a material of the prism.

### Claim 14

An image pickup apparatus comprising:
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 positive refractive power, and a fifth lens unit having a negative refractive power, wherein
the first lens unit does not move for zooming,
each of the distances between the lens units adjacent to each other is changed during zooming, and
when a magnification amount Z2 of the second lens unit, a magnification amount Z3 of the third lens unit, and a magnification amount Z4 of the fourth lens unit are given by
Z2=β2t/β2w,
Z3=β3t/β3w, and
Z4=β4t/β4w,
where β2w and β2t are respectively lateral magnifications of the second lens unit focused at infinity at a wide angle end and a telephoto end, β3w and β3t are respectively lateral magnifications of the third lens unit focused at infinity at the wide angle end and the telephoto end, and β4w and β4t are respectively lateral magnifications of the fourth lens unit focused at infinity at the wide angle end and the telephoto end, the following conditional expressions are satisfied:
2.0<Z2/(Z3×Z4)<5.0, and
0.5<|f5|/M5<2.0
where f5 is a focal length of the fifth lens unit, and M5 is an amount of movement of the fifth lens unit in zooming from the wide angle end to the telephoto end while focused at infinity; and
a solid-state image pickup element that receives an image formed by the zoom lens.