Zoom lens and image pickup apparatus including the same

Patent metadata

Field	Value
Publication number	US-2016131879-A1
Application number	US-201514929631-A
Country	US
Kind code	A1
Filing date	Nov 2, 2015
Priority date	Nov 6, 2014
Publication date	May 12, 2016
Grant date	—

Abstract

A zoom lens, includes, in order from an object side: a positive first lens unit; a negative second lens unit; and a rear lens group that includes at least two lens units and is positive as a whole over an entire zoom range, intervals between adjacent lens units changing during zooming. The second lens unit includes at least two negative lenses successively arranged including a first negative lens arranged closest to the object side and a second negative lens, an object-side surface of the first negative lens includes an aspherical surface having a positive aspherical surface amount; and an image-side surface of the first negative lens and surfaces of the second negative lens include a surface having an aspherical surface having a positive aspherical surface amount and a surface having an aspherical surface having a negative aspherical surface amount.

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 lens group that includes at least two lens units and has a positive refractive power over an entire zoom range, the zoom lens being configured such that intervals between adjacent lens units changes during zooming, the second lens unit comprising, at least two successively arranged negative lenses, the at least two successively arranged negative lenses including a first negative lens arranged closest to the object side and a second negative lens, wherein an object-side lens surface of the first negative lens comprises an aspherical lens surface having a positive aspherical surface amount; and
of an image-side lens surface of the first negative lens, an object-side lens surface of the second negative lens, and an image-side lens surface of the second negative lens, at least one lens surface comprises an aspherical lens surface having a positive aspherical surface amount and at least one lens surface comprises an aspherical lens surface having a negative aspherical surface amount.

2 . A zoom lens according to claim 1 , wherein the following conditional expression is satisfied:
0.15 <Dasp/BLD 2<0.60 where Dasp represents a distance on an optical axis from the lens surface of the second lens unit closest to the object side to a lens surface of the aspherical lens surfaces included in the second lens unit, which is closest to the image side, and BLD2 represents a distance on the optical axis from the lens surface of the second lens unit closest to the object side to a lens surface of the second lens unit closest to the image side.

3 . A zoom lens according to claim 1 , wherein the second lens unit comprises at least three negative lenses and at least two positive lenses.

4 . A zoom lens according to claim 1 , wherein the following conditional expression is satisfied:
4.0< f 1 /fw< 8.0 where f1 represents a focal length of the first lens unit, and fw represents a focal length of the zoom lens at a wide angle end.

5 . A zoom lens according to claim 1 , wherein the following conditional expression is satisfied:
0.60<| f 2|/ fw< 1.10
where f2 represents a focal length of the second lens unit, and fw represents a focal length of the zoom lens at a wide angle end.

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

7 . A zoom lens according to claim 6 , wherein, during zooming from a wide angle end to a telephoto end, the first lens unit, the third lens unit, the fourth lens unit, and the fifth lens unit are configured to move to the object side, and the second lens unit is configured to move to the object side and then move to the image side.

8 . A zoom lens according to claim 6 , wherein, during zooming from a wide angle end to a telephoto end, the first lens unit, the third lens unit, the fourth lens unit, and the fifth lens unit are configured to move to the object side, and the second lens unit is configured to move to the image side and then move to the object side.

9 . A zoom lens according to claim 6 , wherein, during zooming from a wide angle end to a telephoto end, the first lens unit, the third lens unit, the fourth lens unit, and the fifth lens unit are configured to move to the object side, and the second lens unit is configured to monotonically move to the object side.

10 . A zoom lens according to claim 1 ,
wherein the rear lens group consists of, in order from the object side to the image side, 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, and wherein all of the lens units are configured to move to the object side during zooming from a wide angle end to a telephoto end.

11 . A zoom lens according to claim 1 ,
wherein the rear lens group consists of a third lens unit having a positive refractive power and a fourth lens unit having a negative refractive power, and wherein all of the lens units are configured to move to the object side during zooming from a wide angle end to a telephoto end.

12 . 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; and
a rear lens group that includes at least two lens units and has a positive refractive power over an entire zoom range,
the zoom lens being configured such that intervals between adjacent lens units changes during zooming,
the second lens unit comprising, at least two successively arranged negative lenses, the at least two successively arranged negative lenses including a first negative lens arranged closest to the object side and a second negative lens,
wherein an object-side lens surface of the first negative lens comprises an aspherical lens surface having a positive aspherical surface amount; and
of an image-side lens surface of the first negative lens, an object-side lens surface of the second negative lens, and an image-side lens surface of the second negative lens, at least one lens surface comprises an aspherical lens surface having a positive aspherical surface amount and at least one lens surface comprises an aspherical lens surface having a negative aspherical surface amount; and

an image pickup element configured to receive an image formed by the zoom lens.

Assignees

• Canon Kk

Inventors

• Sugita Shigenobu

Classifications

• G02B13/009

  having zoom function · 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

• G02B13/002

  having at least one aspherical surface · CPC title

• G02B15/143105 Primary

  arranged +-+ · CPC title