Zoom lens and image pickup apparatus having the same

Patent metadata

Field	Value
Publication number	US-2016349492-A1
Application number	US-201615165215-A
Country	US
Kind code	A1
Filing date	May 26, 2016
Priority date	May 28, 2015
Publication date	Dec 1, 2016
Grant date	—

Abstract

A zoom lens has a first positive lens unit having a positive refractive power, a second positive lens unit arranged adjacent to the first positive lens unit on its image side, a third positive lens unit arranged adjacent to the second positive lens unit on its image side, and a front lens group arranged on the object side of the first positive lens unit. Appropriate conditions concerning the refractive power of the front lens group, the focal length of the second positive lens unit, and the focal length of the zoom lens at the wide angle end are given.

First claim

What is claimed is:

1 . A zoom lens comprising a first positive lens unit having a positive refractive power, a second positive lens unit having a positive refractive power arranged adjacent to the first positive lens unit on its image side, and a third positive lens unit having a positive refractive power arranged adjacent to the second positive lens unit on its image side, the distances between the adjacent lens units varying during at least one of zooming and focusing, wherein
the zoom lens includes a front lens group including at least one lens unit provided on the object side of the first positive lens unit, the combined focal length of the front lens group at the wide angle end is negative, the second positive lens unit moves along the optical axis toward the image side during focusing from infinity to a short distance, and the zoom lens satisfies the following conditions:
1.5< fp 2/ fw< 10.0 and
1.0<|β p 2 w|,

where fp2 is a focal length of the second positive lens unit, fw is a focal length of the zoom lens at the wide angle end, and βp2w is a lateral magnification of the second positive lens unit in a state in which the zoom lens is focused at infinity at the wide angle end.

2 . A zoom lens according to claim 1 , wherein the zoom lens satisfies the following condition:
0.55< fp 2/ fp 3<5.00, where fp3 is the focal length of the third positive lens unit.

3 . A zoom lens according to claim 1 , wherein the zoom lens satisfies the following condition:
0.2< fw/fpw< 1.0, where fpw is a focal length of a combined lens system composed of the first positive lens unit, the second positive lens unit, and the third positive lens unit at the wide angle end.

4 . A zoom lens according to claim 1 , further comprising a rear lens group including at least one lens unit on the image side of the third positive lens unit, and the zoom lens satisfies the following condition:
1.0<| frw/fpw|, where frw is a focal length of the rear lens group at the wide angle end, fpw is a focal length of a combined lens system composed of the first positive lens unit, the second positive lens unit, and the third positive lens unit at the wide angle end.

5 . A zoom lens according to claim 1 , wherein the zoom lens satisfies the following condition:
1.0<|β p 2 t|,
where βp2t is a lateral magnification of the second positive lens unit in the state in which the zoom lens is focused at infinity at the telephoto end.

6 . A zoom lens according to claim 1 , wherein during zooming, the second positive lens unit and the third positive lens unit move in such a way that a distance between the second positive lens unit and the third positive lens unit on the optical axis is larger at the telephoto end than at the wide angle end.

7 . A zoom lens according to claim 1 , wherein during zooming, the first positive lens unit and the second positive lens unit move in such a way that a distance between the first positive lens unit and the second positive lens unit on the optical axis is smaller at the telephoto end than at the wide angle end.

8 . A zoom lens according to claim 1 , wherein a combined focal length of a lens system on the object side of the second positive lens unit at the wide angle end is negative.

9 . A zoom lens according to claim 1 , wherein the zoom lens satisfies the following condition:
2.0< fp 1/ fw< 40.0, where fp1 is a focal length of the first positive lens unit.

10 . A zoom lens according to claim 1 , wherein the zoom lens satisfies the following condition:
1.1<|β p 1 w|,
where βp1w is a lateral magnification of the first positive lens unit in a state in which the zoom lens is focused at infinity at the wide angle end.

11 . A zoom lens according to claim 1 , wherein the zoom lens satisfies the following conditions:
−4.0< ff 1/ fw<− 0.5, and
−6.0< ff 2/ fw<− 0.5,
where ff1 is a focal length of the front lens group at the wide angle end, ff2 is the combined focal length of the front lens group, the first positive lens unit and the second positive lens unit at the wide angle end.

12 . A zoom lens according to claim 1 , wherein the zoom lens consists of 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, a fifth lens unit having a positive refractive power, a sixth lens unit having a negative refractive power, and a seventh lens unit having a positive refractive power, which are arranged in order from the object side to the image side, wherein the lens units move during zooming, the third lens unit is the first positive lens unit, the fourth lens unit is the second positive lens unit, and the fifth lens unit is the third positive lens unit.

13 . A zoom lens according to claim 1 , wherein the zoom lens consists of a first lens unit having a negative refractive power, a second lens unit having a positive refractive power, a third lens unit having a positive refractive power, a fourth lens unit having a positive refractive power, a fifth lens unit having a negative refractive power, and a sixth lens unit having a positive refractive power, which are arranged in order from the object side to the image side, wherein the lens units move during zooming, the second lens unit is the first positive lens unit, the third lens unit is the second positive lens unit, and the fourth lens unit is the third positive lens unit.

14 . An image pickup apparatus comprising:
a zoom lens, and an image sensor configured to receive an image formed by the zoom lens, wherein the zoom lens comprises a first positive lens unit having a positive refractive power, a second positive lens unit having a positive refractive power arranged adjacent to the first positive lens unit on its image side, and a lens unit having a positive refractive power arranged adjacent to the second positive lens unit on its image side, the distances between the adjacent lens units varying during at least one of zooming and focusing, wherein the zoom lens includes a front lens group including at least one lens unit provided on the object side of the first positive lens unit, the combined focal length of the front lens group at the wide angle end is negative, the second positive lens unit moves along the optical axis toward the image side during focusing from infinity to a short distance, and the zoom lens satisfies the following conditions:
1.5< fp 2/ fw< 10.0 and
1.0<|β p 2 w|,

where fp2 is a focal length of the second positive lens unit, fw is a focal length of the zoom lens at the wide angle end, and βp2w is a lateral magnification of the second positive lens unit in a state in which the zoom lens is focused at infinity at the wide angle end.

Assignees

• Canon Kk

Inventors

• Maetaki Satoshi

Classifications

• G02B15/22 Primary

  with movable lens means specially adapted for focusing at close distances · CPC title

• G02B15/1461 Primary

  the first group being positive · CPC title

• G02B15/1465

  the first group being negative · CPC title