ZOOM LENS AND OPTICAL APPARATUS INCLUDING THE SAME

• US 20090185283A1
• Filed: 01/16/2009
• Published: 07/23/2009
• Est. Priority Date: 01/18/2008
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Maetaki, Satoshi
• Granted Patent: US 7,679,838 B2
• Time in Patent Office: Days
• US Class Current: 359/689
• CPC Class Codes: G02B 15/143507 arranged -++

Abstract

A zoom lens includes a first lens unit having a negative refractive power and a second lens unit having a positive refractive power, which are arranged in order from the object side to the image side. The zoom lens performs zooming by changing a distance between the lens units. The first lens unit includes a compound optical element including a lens element and a resin layer having optical characteristics different from optical characteristics of the lens element, the resin layer being laminated on the lens element. An Abbe number νdg of a material of the lens element, an Abbe number νdj of a material of the resin layer, and an anomalous partial dispersion ratio ΔθgFj of the material of the resin layer are adequately set.

Claims

1. A zoom lens comprising:

a first lens unit having a negative refractive power; and

a second lens unit having a positive refractive power,

wherein the first lens unit and the second lens unit are arranged in order from the object side to the image side,

wherein the zoom lens performs zooming by changing a distance between the lens units,

wherein the first lens unit includes a compound optical element including a lens element and a resin layer having optical characteristics different from optical characteristics of the lens element, the resin layer being laminated on the lens element, and

wherein the following conditions are satisfied;

31<

|ν

dg−

ν

dj|

26>

ν

dj

0.10>

|Δ

θ

gFj|

where ν

dg is an Abbe number of a material of the lens element, and ν

dj and Δ

θ

gFj are an Abbe number and an anomalous partial dispersion ratio, respectively, of a material of the resin layer.

2. The zoom lens according to claim 1, wherein the anomalous partial dispersion ratio Δ

θ

gFj of the material of the resin layer satisfies the following condition;

−

0.10<

Δ

θ

gFj<

0.038.

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

fg/fj<

0

where fg is a focal length of the lens element in the air and fj is a focal length of the resin layer in the air.

4. The zoom lens according to claim 1, wherein at least one surface of the lens element has an aspherical shape.

5. The zoom lens according to claim 1, wherein at least one surface of the resin layer has an aspherical shape.

6. The zoom lens according to claim 1, wherein the lens element is formed by molding a glass material.

7. The zoom lens according to claim 1, further comprising an ultraviolet absorption film positioned on the object side of the resin layer.

8. The zoom lens according to claim 1, wherein the resin layer is disposed on the image side of the lens element.

9. The zoom lens according to claim 1, further comprising a third lens unit having a positive refractive power, the third lens unit being positioned on the image side of the second lens unit and moving independently of the first and second lens units during zooming.

10. An optical apparatus comprising:

the zoom lens according to claim 1; and

an image pickup element which receives an image formed by the zoom lens.