Zoom lens and image pickup apparatus
AssigneeCanon Kabushiki Kaisha
InventorAkihisa Horiuchi
Life of this patent
Estimating the term…
Abstract
A small zoom lens system which realizes a high magnification ratio and high optical performance is disclosed. The zoom lens system comprises, in order from a front side to a rear side, a first lens unit which has a positive power, a second lens unit which has a negative power, a third lens unit which has a positive power, and a fourth lens unit which has a positive power. The second lens unit and the fourth lens unit are moved in an optical axis direction during zooming. The aforementioned object is achieved by specifying the configuration of the second lens unit or specifying an effective diameter of the first or second lens unit.
Claims23
A zoom lens system comprising, in order from a front side to a rear side:
- a first lens unit which has a positive power;
- a second lens unit which has a negative power and consists of at least one negative lens element and a cemented lens formed by cementing a negative lens element to a positive lens element;
- a third lens unit which has a positive power;
- and
- a fourth lens unit which has a positive power,
- wherein said second lens unit and said fourth lens unit are moved in an optical axis direction during zooming, and
- the following condition is satisfied:
- 1.04<|Rs1/Rs2|<1.14
- where Rs1 and Rs2 represent radii of curvature of a front lens surface and a rear lens surface of the negative lens constituting part of the cemented lens in said second lens unit, respectively.
A zoom lens system comprising, in order from a front side to a rear side:
- a first lens unit which has a positive power;
- a second lens unit which has a negative power;
- a third lens unit which has a positive power;
- and
- a fourth lens unit which has a positive power,
- wherein said second lens unit and said fourth lens unit are moved in an optical axis direction during zooming, and
- the following condition is satisfied:
- 6.6<φ1F/fw<8.5
- where φ1F represents an effective diameter of a frontmost surface of said first lens unit, and fw represents a focal length of the entire system at a short focal length end.
A zoom lens system comprising, in order from a front side to a rear side:
- a first lens unit which has a positive power;
- a second lens unit which has a negative power;
- a third lens unit which has a positive power;
- and
- a fourth lens unit which has a positive power,
- wherein said second lens unit and said fourth lens unit are moved in an optical axis direction during zooming, and
- the following condition is satisfied:
- 1.47<φ1F/φ1R<1.77
- where φ1F represents an effective diameter of a frontmost surface of said first lens unit, and φ1R represents an effective diameter of a rearmost surface of said first lens unit.
A zoom lens system comprising, in order from a front side to a rear side:
- a first lens unit which has a positive power;
- a second lens unit which has a negative power;
- a third lens unit which has a positive power;
- and
- a fourth lens unit which has a positive power,
- wherein said second lens unit and said fourth lens unit are moved in an optical axis direction during zooming, and
- the following condition is satisfied:
- 3.2<φ1F/φ2F<4.4
- where φ1F represents an effective diameter of a frontmost surface of said first lens unit, and φ2F represents an effective diameter of a frontmost surface of said second lens unit.
Dependencies are inferred from the claim text.