ZOOM LENS AND IMAGE PICKUP APPARATUS

• US 20200132974A1
• Filed: 10/21/2019
• Published: 04/30/2020
• Est. Priority Date: 10/24/2018
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Kimura, Kohei, Hatada, Takahiro
• Granted Patent: US 11,314,064 B2
• Time in Patent Office: Days
• CPC Class Codes: G02B 15/144113 arranged +-++
• CPC Class Codes: G02B 15/1461 the first group being positive
• CPC Class Codes: G02B 15/16 with interdependent non-linearly related movements between one lens or lens group, and another lens or lens group G02B15/22 takes precedence
• CPC Class Codes: G02B 27/646 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 Class Codes: H04N 23/69 Control of means for changing angle of the field of view, e.g. optical zoom objectives or electronic zooming

Abstract

Provided is a zoom lens including, in order from an object side to an image side, a positive first lens unit, a negative second lens unit, a positive third lens unit, a positive fourth lens unit and a rear lens group consisting of at least one lens unit. An interval between each pair of adjacent lens units is changed during zooming. The rear lens group includes a negative N-th lens unit configured to move during focusing. The second lens unit and the third lens unit are configured to move during zooming. A focal length of the second lens unit, a focal length of the third lens unit, a focal length of the fourth lens unit, a lateral magnification of the fourth lens unit at a wide angle end and a lateral magnification of the fourth lens unit at a telephoto end are appropriately set.

Claims

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;

a third lens unit having a positive refractive power;

a fourth lens unit having a positive refractive power; and

a rear lens group consisting of at least one lens unit,

wherein an interval between each pair of adjacent lens units is changed during zooming,

wherein the rear lens group includes an N-th lens unit having a negative refractive power, which is configured to move during focusing,

wherein the second lens unit and the third lens unit are configured to move during zooming, and

wherein the following conditional expressions are satisfied;

0.2<

f2²/(f3×

f4)<

1.0; and

2.0<

β

4t/β

4w<

10.0,

where f2 represents a focal length of the second lens unit, f3 represents a focal length of the third lens unit, f4 represents a focal length of the fourth lens unit, β

4w represents a lateral magnification of the fourth lens unit at a wide angle end, and β

4t represents a lateral magnification of the fourth lens unit at a telephoto end.

2. The zoom lens according to claim 1, wherein the following conditional expression is satisfied:

−

5.0<

ff/fw<

−

1.0,

where “

ff”

represents a focal length of the N-th lens unit, and “

fw”

represents a focal length of the zoom lens at the wide angle end.

3. The zoom lens according to claim 1, wherein the following conditional expression is satisfied:

−

1.5<

f2/fw<

−

0.5,

where “

f2”

represents a focal length of the second lens unit, and “

fw”

represents a focal length of the zoom lens at the wide angle end.

4. The zoom lens according to claim 1, wherein the following conditional expression is satisfied:

2.0<

f1/fw<

10.0,

where “

f1”

represents a focal length of the first lens unit, and “

fw”

represents a focal length of the zoom lens at the wide angle end.

5. The zoom lens according to claim 1, wherein the following conditional expression is satisfied:

0.1<

f4/ft<

0.7,

where “

ft”

represents a focal length of the zoom lens at the telephoto end.

6. The zoom lens according to claim 1,

wherein the rear lens group includes at least one lens unit arranged on the image side of the N-th lens unit, and

wherein the following conditional expression is satisfied:

−

10.0<

frw/skw<

−

1.0,

where “

frw”

represents a combined focal length of the at least one lens unit arranged on the image side of the N-th lens unit at the wide angle end, and “

skw”

represents a distance on an optical axis from a last lens surface to an image plane at the wide angle end.

7. The zoom lens according to claim 1, wherein the following conditional expression is satisfied:

−

7.0<

(Rf2+Rf1)/(Rf2−

Rf1)<

−

0.5,

where Rf1 represents a curvature radius of a lens surface closest to the object side in the N-th lens unit, and Rf2 represents a curvature radius of a lens surface closest to the image side in the N-th lens unit.

8. The zoom lens according to claim 1, wherein the following conditional expression is satisfied:

−

7.0<

(1−

β

ft²)×

β

rt²<

−

1.0,

where “

β

ft”

represents a lateral magnification of the N-th lens unit at the telephoto end, and “

β

rt”

represents a combined lateral magnification of a lens unit arranged on the image side of the N-th lens unit at the telephoto end.

9. The zoom lens according to claim 1, wherein the following conditional expression is satisfied:

3.0<

TTDw/skw<

20.0,

where “

skw”

represents a distance from a last lens surface to an image plane at the wide angle end, and TTDw represents a distance on an optical axis from a lens surface closest to the object side to the image plane at the wide angle end.

10. The zoom lens according to claim 1, wherein the following conditional expression is satisfied:

0.3<

m3/m4<

1.0,

where m3 represents a movement amount of the third lens unit during zooming from the wide angle end to the telephoto end, and m4 represents a movement amount of the fourth lens unit during zooming from the wide angle end to the telephoto end.

11. The zoom lens according to claim 1, wherein the N-th lens unit consists of two or less lenses.

12. The zoom lens according to claim 1, wherein the rear lens group consists of:

a fifth lens unit, which is the N-th lens unit; and

a sixth lens unit having a positive refractive power, which is arranged on the image side of the fifth lens unit.

13. The zoom lens according to claim 1, wherein the rear lens group consists of:

a fifth lens unit, which is the N-th lens unit; and

a sixth lens unit having a negative refractive power, which is arranged on the image side of the fifth lens unit.

14. The zoom lens according to claim 1, wherein the rear lens group consists of, in order from the object side to the image side:

a fifth lens unit, which is the N-th lens unit;

a sixth lens unit having a negative refractive power; and

a seventh lens unit having a positive refractive power.

15. An image pickup apparatus comprising:

a zoom lens; and

an image pickup element configured to receive light of 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;

a third lens unit having a positive refractive power;

a fourth lens unit having a positive refractive power; and

a rear lens group consisting of at least one lens unit,

wherein an interval between each pair of adjacent lens units is changed during zooming,

wherein the rear lens group includes an N-th lens unit having a negative refractive power, which is configured to move during focusing,

wherein the second lens unit and the third lens unit are configured to move during zooming, and

wherein the following conditional expressions are satisfied;

0.2<

f2²/(f3×

f4)<

1.0; and

2.0<

β

4t/β

4w<

10.0,

where f2 represents a focal length of the second lens unit, f3 represents a focal length of the third lens unit, f4 represents a focal length of the fourth lens unit, β

4w represents a lateral magnification of the fourth lens unit at a wide angle end, and β

4t represents a lateral magnification of the fourth lens unit at a telephoto end.