Zoom lens and image pickup apparatus including same

Patent metadata

Field	Value
Publication number	US-2018348481-A1
Application number	US-201815985320-A
Country	US
Kind code	A1
Filing date	May 21, 2018
Priority date	May 31, 2017
Publication date	Dec 6, 2018
Grant date	—

Abstract

A zoom lens including a first lens unit that has a positive refractive power, a second lens unit that has a negative refractive power, and at least one lens unit, in which the first lens unit, the second lens unit, and at least one lens unit are disposed from an object side to an image side in the above order. The first lens unit is formed of a single piece of lens element, and the zoom lens includes a positive lens on a side closest to an image. An Abbe number of the positive lens, back focuses at a wide angle end and a telescopic end, and focal lengths of the zoom lens at the wide angle end and the telescopic end are each set appropriately.

First claim

What is claimed is:

1 . A zoom lens comprising:
a first lens unit that has a positive refractive power; a second lens unit that has a negative refractive power; and at least one lens unit, wherein the first lens unit, the second lens unit, and the at least one lens unit are disposed from an object side to an image side in an order of the first lens unit, the second lens unit, and the at least one lens unit, wherein a distance between lens units that are adjacent to each other changes when zooming, wherein the first lens unit is formed of a single piece of lens element, wherein the zoom lens includes a positive lens on a side closest to an image, and wherein the following conditional expressions
15.0<ν dp< 30.0

0.96<( skt/skw )/( ft/fw )<2.0

are satisfied, where νdp is an Abbe number of the positive lens, skw is back focus at a wide angle end, skt is back focus at a telescopic end, fw is focal length of the zoom lens at the wide angle end, and ft is focal length of the zoom lens at the telescopic end.

2 . The zoom lens according to claim 1 ,
wherein a conditional expression
3.0< f 1 /f 2<6.0

is satisfied, where f1 is a focal length of the first lens unit and f2 is a focal length of the second lens unit.

3 . The zoom lens according to claim 1 ,
wherein a conditional expression
0.5< fp/fw< 2.5

is satisfied, where fp is a focal length of the positive lens.

4 . The zoom lens according to claim 1 ,
wherein a conditional expression
2.0< f 1 /fw< 7.4

is satisfied, where f1 is a focal length of the first lens unit.

5 . The zoom lens according to claim 1 ,
wherein a conditional expression
0.32< f 2 /ft< 0.50

is satisfied, where f2 is a focal length of the second lens unit.

6 . The zoom lens according to claim 1 ,
wherein a conditional expression
3.0< lw/fw< 6.0

is satisfied, where lw is a distance from a surface of the zoom lens on a side closest to an object to an image plane on an optical axis at the wide angle end.

7 . The zoom lens according to claim 1 ,
wherein a conditional expression
0.161< t 1 /fw< 0.285

is satisfied, where t1 is a distance along an optical axis from a surface of the first lens unit on a side closest to an object to a surface of the first lens unit on the side closest to the image.

8 . The zoom lens according to claim 1 ,
wherein the at least one lens unit includes a third lens unit that has a positive refractive power, a fourth lens unit that has a positive refractive power, a fifth lens unit that has a positive refractive power, a sixth lens unit that has a negative refractive power, and a seventh lens unit that has a positive refractive power.

9 . An image pickup apparatus comprising:
a zoom lens; and an image pickup element that receives light of an image formed by the zoom lens, wherein the zoom lens includes a first lens unit that has a positive refractive power, a second lens unit that has a negative refractive power, and at least one lens unit, wherein the first lens unit, the second lens unit, and the at least one lens unit are disposed from an object side to an image side in an order of the first lens unit, the second lens unit, and the at least one lens unit, wherein a distance between lens units that are adjacent to each other changes when zooming, wherein the first lens unit is formed of a single piece of lens element, wherein the zoom lens includes a positive lens on a side closest to an image, wherein the zoom lens includes a positive lens on a side closest to an image, wherein the following conditional expressions
15.0<ν dp< 30.0

0.96<( skt/skw )/( ft/fw )<2.0

are satisfied, where νdp is an Abbe number of the positive lens, skw is back focus at a wide angle end, skt is back focus at a telescopic end, fw is focal length of the zoom lens at the wide angle end, and ft is focal length of the zoom lens at the telescopic end.

10 . The image pickup apparatus according to claim 9 ,
wherein a conditional expression
3.0< f 1/ f 2<6.0

is satisfied, where f1 is a focal length of the first lens unit and f2 is a focal length of the second lens unit.

11 . The image pickup apparatus according to claim 9 ,
wherein a conditional expression
0.5< fp/fw< 2.5

is satisfied, where fp is a focal length of the positive lens.

12 . The image pickup apparatus according to claim 9 ,
wherein a conditional expression
2.0< f 1/ fw< 7.4

is satisfied, where f1 is a focal length of the first lens unit.

13 . The image pickup apparatus according to claim 9 ,
wherein a conditional expression
0.32< f 2/ ft< 0.50

is satisfied, where f2 is a focal length of the second lens unit.

14 . The image pickup apparatus according to claim 9 ,
wherein a conditional expression
3.0< lw/fw< 6.0

is satisfied, where lw is a distance from a surface of the zoom lens on a side closest to an object to an image plane on an optical axis at the wide angle end.

15 . The image pickup apparatus according to claim 9 ,
wherein a conditional expression
0.161< t 1/ fw< 0.285

is satisfied, where t1 is a distance along an optical axis from a surface of the first lens unit on a side closest to an object to a surface of the first lens unit on the side closest to the image.

16 . The image pickup apparatus according to claim 9 ,
wherein the at least one lens unit includes a third lens unit that has a positive refractive power, a fourth lens unit that has a positive refractive power, a fifth lens unit that has a positive refractive power, a sixth lens unit that has a negative refractive power, and a seventh lens unit that has a positive refractive power.

Assignees

• Canon Kk

Inventors

• Iwamoto Shunji

Classifications

• H04N23/69

  Control of means for changing angle of the field of view, e.g. optical zoom objectives or electronic zooming · CPC title

• H04N23/55

  Optical parts specially adapted for electronic image sensors; Mounting thereof · CPC title

• H04N23/698

  for achieving an enlarged field of view, e.g. panoramic image capture · CPC title

• G02B13/02

  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 · CPC title

• G02B13/06

  Panoramic objectives; So-called "sky lenses" {including panoramic objectives having reflecting surfaces} · CPC title