Zoom lens, image pickup apparatus including the zoom lens, and image pickup system including the zoom lens

Patent metadata

Field	Value
Publication number	US-2018299652-A1
Application number	US-201815952725-A
Country	US
Kind code	A1
Filing date	Apr 13, 2018
Priority date	Apr 17, 2017
Publication date	Oct 18, 2018
Grant date	—

Abstract

Provided is 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, and a rear unit including at least one lens unit, in which the second lens unit is configured to move during zooming, an interval between each pair of adjacent lens units is changed during zooming, the rear unit has a positive refractive power over an entire zoom range, and the first lens unit includes a diffraction surface formed at a cemented surface of two optical elements cemented to each other. A focal length of the first lens unit, an amount of movement of the second lens unit during zooming from a wide angle end to a telephoto end and a back focus at the wide angle end are appropriately set.

First claim

What is claimed is:

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; and a rear unit including at least one lens unit, wherein the second lens unit is configured to move during zooming, wherein an interval between each pair of adjacent lens units is changed during zooming, wherein the rear unit has a positive refractive power over an entire zoom range, wherein the first lens unit includes a diffraction surface formed at a cemented surface of two optical elements cemented to each other, and wherein the following conditional expressions are satisfied:
1.00< f 1/ m 2<1.75; and
0.05< BFw/f 1<0.15,

where f 1 represents a focal length of the first lens unit, m 2 represents an amount of movement of the second lens unit during zooming from a wide angle end to a telephoto end, and BFw represents a back focus at the wide angle end.

2 . A zoom lens according to claim 1 , wherein the following conditional expression is satisfied:
−9.0< f 1/ f 2<−3.0,

where f 2 represents a focal length of the second lens unit.

3 . A zoom lens according to claim 1 , wherein the following conditional expression is satisfied:
0.95< TDt/TDw< 1.20,
where TDw represents a total lens length at the wide angle end, and TDt represents a total lens length at the telephoto end.

4 . A zoom lens according to claim 1 , wherein the following conditional expression is satisfied:
20.0 <fdoe/f 1<500.0,
where fdoe represents a focal length of the diffraction surface.

5 . A zoom lens according to claim 1 ,
wherein the first lens unit includes, in order from the object side to the image side, a negative lens G 11 and a positive lens G 12 , which are cemented to each other, and a positive lens G 13 , and wherein the diffraction surface is formed at a cemented surface of the negative lens G 11 and the positive lens G 12 .

6 . A zoom lens according to claim 1 ,
wherein the first lens unit includes a plurality of positive lenses, and wherein the following conditional expression is satisfied:
nd 1 p> 1.55,

where nd 1 p represents a minimum value among refractive indices of materials of the plurality of positive lenses.

7 . A zoom lens according to claim 1 ,
wherein the rear unit includes, in order from the object side to the image side, a third lens unit having a positive refractive power, a fourth lens unit, and a fifth lens unit, wherein the third lens unit is configured to move during zooming from the wide angle end to the telephoto end, and wherein the fourth lens unit is configured to move to correct an image plane position along with the zooming.

8 . A zoom lens according to claim 1 , wherein the following conditional expression is satisfied:
−3.0< f 2/ fw<− 0.4,

where f 2 represents a focal length of the second lens unit, and fw represents a focal length of an entire system of the zoom lens at the wide angle end.

9 . A zoom lens according to claim 1 , wherein the following conditional expression is satisfied:
0.1< f 1/ ft< 1.5
where ft represents a focal length of an entire system of the zoom lens at the telephoto end.

10 . A zoom lens according to claim 1 , wherein the following conditional expression is satisfied:
1.35< f 1/ m 2<1.65.

11 . A zoom lens according to claim 1 , wherein the following conditional expression is satisfied:
0.05< BFw/f 1<0.13.

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

13 . An image pickup apparatus according to claim 12 , wherein the following conditional expression is satisfied:
0.015< Y/TDt< 0.100,
where TDt represents a total lens length at the telephoto end, and Y represents a maximum image height.

14 . An image pickup apparatus according to claim 12 , further comprising a corrector configured to electrically correct an aberration of the zoom lens.

15 . An image pickup system, comprising:
the zoom lens of claim 1 ; and a control unit configured to control the zoom lens during zooming.

16 . An image pickup system according to claim 15 ,
wherein the control unit is formed as a separate member from the zoom lens, and wherein the image pickup system further comprises a transmitter configured to transmit a control signal for controlling the zoom lens.

17 . An image pickup system according to claim 15 ,
wherein the control unit is formed as a separate member from the zoom lens, and wherein the image pickup system further comprises an operation unit for use in operation of the zoom lens.

18 . An image pickup system according to claim 15 , further comprising a display configured to display information related to zooming of the zoom lens.

Assignees

• Canon Kk

Inventors

• Inomoto Yu

Classifications

• G02B13/02 Primary

  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

• G02B9/64

  having more than six components · CPC title

• G02B15/16 Primary

  with interdependent non-linearly related movements between one lens or lens group, and another lens or lens group (G02B15/22 takes precedence) · CPC title

• G02B27/4211

  correcting chromatic aberrations (G02B27/0056, G02B27/4222, G02B27/4227 take precedence) · CPC title

• G02B27/0025

  for optical correction, e.g. distorsion, aberration · CPC title