Zoom lens and optical equipment using the same
First Claim
Patent Images
1. A zoom lens, comprising in sequence from an object side to an image side:
- a first lens unit having a positive optical power;
a second lens unit having a negative optical power;
a third lens unit having a positive optical power; and
a fourth lens unit having a negative optical power, wherein said first, second, third, and fourth lens units move to the object side along an optical axis in zooming from the wide angle end to the telephoto end, wherein said fourth lens unit has a diffractive optical surface located on an object side surface of an optical element of said fourth lens unit, wherein the lens units comprising the zoom lens are only said first, second, third, and fourth lens units, and wherein the shape of the surface closest to the image side in said fourth lens unit is convex to the image side.
1 Assignment
0 Petitions
Accused Products
Abstract
A zoom lens includes a first lens unit having a positive optical power, a second lens unit having a negative optical power, a third lens unit having a positive optical power, and a fourth lens unit having a negative optical power in sequence from an object side. The zoom lens executes zooming by moving all the four lens units on an optical axis. At least one of the four lens units has at least one diffractive optical surface. By this arrangement, the size of the zoom lens can be easily reduced while securing a desired variable power ratio and correcting lateral chromatic aberration that is varied by zooming.
16 Citations
31 Claims
-
1. A zoom lens, comprising in sequence from an object side to an image side:
-
a first lens unit having a positive optical power;
a second lens unit having a negative optical power;
a third lens unit having a positive optical power; and
a fourth lens unit having a negative optical power, wherein said first, second, third, and fourth lens units move to the object side along an optical axis in zooming from the wide angle end to the telephoto end, wherein said fourth lens unit has a diffractive optical surface located on an object side surface of an optical element of said fourth lens unit, wherein the lens units comprising the zoom lens are only said first, second, third, and fourth lens units, and wherein the shape of the surface closest to the image side in said fourth lens unit is convex to the image side. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
an optical-equipment element; and
a zoom lens according to claim 1, said zoom lens being connected to said optical-equipment element.
-
-
13. A zoom lens according to claim 1, wherein said fourth lens unit has a diffractive optical surface.
-
14. A zoom lens according to claim 1, wherein said diffractive optical surface is provided with the effect of an aspherical surface by changing the pitch of said diffractive optical surface.
-
15. A zoom lens, comprising in sequence from an object side to an image side:
-
a first lens unit having a positive optical power;
a second lens unit having a negative optical power;
a third lens unit having a positive optical power; and
a fourth lens unit having a negative optical power, wherein said first, second, third, and fourth lens units move to the object side along an optical axis in zooming from the wide angle end to the telephoto end, said fourth lens unit has a diffractive optical surface located on an object side surface of an optical element of said fourth lens unit, wherein the lens units comprising the zoom lens are only said first, second, third, and fourth lens units, and wherein the only lenses of said first lens unit are a negative lens whose concave surface faces the object side and a positive lens in sequence from the object side to the image side. - View Dependent Claims (16)
-
-
17. A zoom lens, comprising in sequence from an object side to an image side:
-
a first lens unit having a positive optical power;
a second lens unit having a negative optical power;
a third lens unit having a positive optical power; and
a fourth lens unit having a negative optical power, wherein said first, second, third, and fourth lens units move to the object side along an optical axis in zooming from the wide angle end to the telephoto end, wherein said first lens unit has a diffractive optical surface located on a surface other than a lens surface closest to the object side of said first lens unit, wherein the lens units comprising the zoom lens are only said first, second, third, and fourth lens units, and wherein said second lens unit has only one lens element, which is a biconcave negative lens element. - View Dependent Claims (18, 19, 20, 21, 22, 23)
-
-
24. A zoom lens, comprising in sequence from an object side to an image side:
-
a first lens unit having a positive optical power;
a second lens unit having a negative optical power;
a third lens unit having a positive optical power; and
a fourth lens unit having a negative optical power, wherein said first, second, third, and fourth lens units move to the object side along an optical axis in zooming from the wide angle end to the telephoto end, wherein said fourth lens unit has a diffractive optical surface located on an object side surface of an optical element of said fourth lens unit, wherein the lens units comprising the zoom lens are only said first, second, third, and fourth lens units, and wherein the zoom lens further comprises an aperture stop, and said aperture stop moves with said second lens unit as a unit in zooming. - View Dependent Claims (25)
-
-
26. A zoom lens, comprising in sequence from an object side to an image side:
-
a first lens unit having a positive optical power;
a second lens unit having a negative optical power;
a third lens unit having a positive optical power; and
a fourth lens unit having a negative optical power, wherein said first, second, third, and fourth lens units move to the object side along an optical axis in zooming from the wide angle end to the telephoto end, wherein said fourth lens unit has a diffractive optical surface located on an object side surface of an optical element of said fourth lens unit, wherein the lens units comprising the zoom lens are only said first, second, third, and fourth lens units, and wherein said second lens unit has only one lens element, which is a negative lens element. - View Dependent Claims (27)
-
-
28. A zoom lens, comprising in sequence from an object side to an image side:
-
a first lens unit having a positive optical power;
a second lens unit having a negative optical power;
a third lens unit having a positive optical power; and
a fourth lens unit having a negative optical power, wherein said first, second, third, and fourth lens units move to the object side along an optical axis so that the interval between said first lens unit and said fourth lens unit decreases, in zooming from the wide angle end to the telephoto end, wherein said fourth lens unit has a diffractive optical surface located on an object side surface of an optical element of said fourth lens unit, wherein the lens units comprising the zoom lens are only said first, second, third, and fourth lens units, and wherein said fourth lens unit comprises three lenses. - View Dependent Claims (29)
-
-
30. A zoom lens, comprising in sequence from an object side to an image side:
-
a first lens unit having a positive optical power;
a second lens unit having a negative optical power;
a third lens unit having a positive optical power; and
a fourth lens unit having a negative optical power, wherein said first, second, third, and fourth lens units move to the object side along an optical axis in zooming from the wide angle end to the telephoto end, wherein said fourth lens unit has a diffractive optical surface located on an object side surface of an optical element of said fourth lens unit, wherein the lens units comprising the zoom lens are only said first, second, third, and fourth lens units, and wherein said fourth lens unit comprises a positive lens and two negative lenses. - View Dependent Claims (31)
-
Specification