Zoom lens and image pickup apparatus including the same

Patent metadata

Field	Value
Publication number	US-11073684-B2
Application number	US-201715838935-A
Country	US
Kind code	B2
Filing date	Dec 12, 2017
Priority date	Dec 13, 2016
Publication date	Jul 27, 2021
Grant date	Jul 27, 2021

Abstract

A zoom lens includes 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 which includes at least one lens unit and has a positive refractive power as a whole. Distances between the adjacent lens units change during zooming. The rear lens group includes a lens P 1 that has a positive refractive power and moves at image stabilization so as to have a component perpendicular to the optical axis. The shape factor SFP 1 of the lens P 1 , a curvature radius R 1 P 1 of a lens surface of the lens P 1 on the object side, and a curvature radius R 2 P 1 of a lens surface of the lens P 1 on the image side are appropriately determined.

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 which includes at least one lens unit and has a positive refractive power as a whole,
wherein:
intervals between adjacent lens units are changed during zooming,
interval between the first lens unit and the second lens unit is longer at a telephoto end than at a wide angle end,
interval between the second lens unit and the rear lens group is a shorter at a telephoto end than a wide angle end,
the rear lens group includes a lens P 1 that has a positive refractive power and moves for image stabilization so as to have a component perpendicular to an optical axis,
a surface of the lens P 1 on the object side and a surface of the lens P 1 on the image side are both in contact with air,
the lens P 1 is a lens disposed at most object side in the rear lens group, and
the following conditional expression is satisfied:
−2.5< SFP 1≤−0.844

where SFP 1 is a shape factor of the lens P 1 which is expressed by SFP 1 =(R 2 P 1 +R 1 P 1 )/(R 2 P 1 −R 1 P 1 ), R 1 P 1 is a curvature radius of a lens surface of the lens P 1 on the object side while R 2 P 1 is a curvature radius of a lens surface of the lens P 1 on the image side,
wherein the rear lens group includes in order from the object side to the image side: a third lens unit having a positive refractive power; a fourth lens group having a positive refractive power; and a fifth lens group having a positive refractive power, and
wherein the third lens unit is composed of one positive lens, which is the lens P 1 .

2. The zoom lens according to claim 1 , wherein the following conditional expression is satisfied:
0.01<β st/βsw< 3.20

where βsw is a lateral magnification of a composite system of the second lens unit to the lens P 1 at a wide-angle end and βst is a lateral magnification of the composite system of the second lens unit to the lens P 1 at a telephoto end.

3. The zoom lens according to claim 1 , wherein
the following conditional expression is satisfied:
1.8< D 23 w/D 23 t< 20.0

where D 23 w is a distance between the second and third lens units on the optical axis at the wide-angle end and D 23 t is a distance between the second and third lens units on the optical axis at the telephoto end.

4. The zoom lens according to claim 1 , wherein
the following conditional expression is satisfied:
1.0<|−β Pw|< 25.0

where βfP is a lateral magnification of the lens P 1 at the wide-angle end.

5. The zoom lens according to claim 1 , wherein
the following conditional expression is satisfied:
1.1< fP/fRt <4.8

where fP is a focal length of the lens P 1 and fRt is a focal length of the rear lens group at the telephoto end.

6. The zoom lens according to claim 1 , wherein
the following conditional expression is satisfied:
0.7< fRt/fw <2.0

where fRt is a focal length of the rear lens group at the telephoto end and fw is a focal length of the zoom lens at the wide-angle end.

7. The zoom lens according to claim 1 , wherein
the following conditional expression is satisfied:
0.5<(1−β Pt )□β Rt< 1.8

where βPt is a lateral magnification of the lens P 1 at the telephoto end and βRt is a lateral magnification of an optical system provided on the image side of the lens P 1 at the telephoto end.

8. The zoom lens according to claim 1 , wherein the following conditional expressions are satisfied:
1.45< nP< 1.75
45.0<ν P< 100.0

where nP and νP are a refractive power and an Abbe number of a material of the lens P 1 for the d-line, respectively.

9. An image pickup apparatus comprising a zoom lens and an image pickup element receiving an image formed by the zoom lens,
wherein the zoom lens includes 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 at least one lens unit,
wherein the zoom lens includes a rear lens group having a positive refractive power as a whole, and distances between adjacent lens units change during zooming,
wherein:
interval between the first lens unit and the second lens unit is longer at a telephoto end than at a wide angle end,
interval between the second lens unit and the rear lens group is a shorter at a telephoto end than a wide angle end,
the rear lens group includes a lens P 1 that has a positive refractive power and moves at image stabilization so as to have a component perpendicular to an optical axis,
the lens P 1 is a lens disposed at most object side in the rear lens group, and
a surface of the lens P 1 on the object side and a surface of the lens P 1 on the image side are both in contact with air,

wherein the following conditional expression is satisfied:
−2.5< SFP 1≤−0.844

where SFP 1 is a shape factor of the lens P 1 which is expressed by SFP 1 =(R 2 P 1 +R 1 P 1 )/(R 2 P 1 −R 1 P 1 ), R 1 P 1 is a curvature radius of a lens surface of the lens P 1 on the object side while R 2 P 1 is a curvature radius of a lens surface of the lens P 1 on the image side,
wherein the rear lens group includes in order from the object side to the image side: a third lens unit having a positive refractive power; a fourth lens group having a positive refractive power; and a fifth lens group having a positive refractive power, and
wherein the third lens unit is composed of one positive lens, which is the lens P 1 .

10. 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 which includes at least one lens unit and has a positive refractive power as a whole,
wherein:
intervals between adjacent lens units are changed during zooming,
interval between the first lens unit and the second lens unit is longer at a telephoto end than at a wide angle end,
interval between the second lens unit and the rear lens group is a shorter at a telephoto end than a wide angle end,
the rear lens group includes in order from the object side to the image side: a third lens unit having a positive refractive power; a fourth lens group having a positive refractive power; and a fifth lens group having a positive refractive power, or, the rear lens group includes in order from the object side to the image side: a third lens unit having a positive refractive power; a fourth lens group having a negative refractive power; and a fifth lens group having a positive refractive power, and
the third lens unit is composed of a lens P 1 that has a positive refractive power and moves for image stabilization so as to have a component perpendicular to an optical axis,
a surface of the lens P 1 on the object side and a surface of the lens P 1 on the image side are both in contact with air,
the lens P 1 is a lens disposed at most object side in the rear lens group, and
the following conditional expression is satisfied:
−2.5< SFP 1<−0.5

where SFP 1 is a shape factor of the lens P 1 which is expressed by SFP 1 =(R 2 P 1 +R 1 P 1 )/(R 2 P 1 −R 1 P 1 ), R 1 P 1 is a curvature radius of a lens surface of the lens P 1 on the object side while R 2 P 1 is a curvature radius of a lens surface of the lens P 1 on the image side.

11. 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

Assignees

• Canon Kk

Inventors

• Saito Shinichiro

Classifications

• G02B27/0025

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

• G02B15/173

  arranged +-+ · CPC title

• G02B15/143105 Primary

  arranged +-+ · CPC title

• G02B13/18

  with lenses having one or more non-spherical faces, e.g. for reducing geometrical aberration {(G02B13/002 takes precedence)} · CPC title

• G02B27/646

  compensating for small deviations, e.g. due to vibration or shake (movement of one or more optical elements for control of motion blur in cameras, projectors or printers G03B2205/0007; image stabilisation in cameras peculiar to the presence or use of an electronic image sensor H04N23/68) · CPC title