Zoom lens and camera with the zoom lens
AssigneeCanon Kabushiki Kaisha
InventorKoji Hoshi
Life of this patent
Estimating the term…
Abstract
A zoom lens includes a first lens unit which does not move for zooming and has positive optical power, a second lens unit having negative optical power, a third lens unit having positive optical power, and a fourth lens unit having positive optical power, these lens unit being arranged in order from the object side to the image side. Due to this simple construction, it is possible to obtain high optical performance over the entire object distance from an object at infinity to a nearby object.
Claims19
A zoom lens comprising in order from an object side to an image side:
- a first lens unit having positive optical power, wherein the first lens unit does not move for zooming and consists of one positive lens and one negative lens arranged in order from the object side to the image side;
- a second lens unit having negative optical power, the second lens unit being movable for zooming;
- a third lens unit having positive optical power, the third lens unit not moving for zooming;
- and
- a fourth lens unit having positive optical power, the fourth lens unit being movable for zooming and consisting of a single positive lens.
A zoom lens comprising in order from an object side to an image side:
- a first lens unit having positive optical power, wherein the first lens unit does not move for zooming and consists of one positive lens and one negative lens;
- a second lens unit having negative optical power, the second lens unit being movable for zooming;
- a third lens unit having positive optical power, the third lens unit not moving for zooming and having at least one negative lens and at least one positive lens;
- and
- a fourth lens unit having positive optical power, the fourth lens unit being movable for zooming,
- wherein the lens surfaces of the lenses of the first lens unit are all spherical surfaces,
- and wherein a refractive index of a material of a positive lens of the first lens unit (1Gn) and a refractive index of a material of a positive lens of the third lens unit nearest to the object side (3Gn) range
- 1.60<1Gn<1.84;
- and 1.67<3Gn<1.89.
A zoom lens comprising in order from an object side to an image side:
- a first lens unit having positive optical power, wherein the first lens unit does not move for zooming and consists of one positive lens and one negative lens;
- a second lens unit having negative optical power, the second lens unit being movable for zooming;
- a third lens unit having positive optical power, the third lens unit not moving for zooming and including a bi-concave negative lens and a bi-convex positive lens adjacent thereto on the object side;
- and
- a fourth lens unit having positive optical power, the fourth lens unit being movable for zooming,
- wherein a thickness of the third lens unit as measured on an optical axis (3BD) and a thickness of the fourth lens unit as measured on an optical axis (4BD) have a relation of
- 0.12<4BD/3BD<0.71.
A zoom lens comprising in order from an object side to an image side:
- a first lens unit having positive optical power, wherein the first lens unit does not move for zooming and consists of one positive lens and one negative lens;
- a second lens unit having negative optical power, the second lens unit being movable for zooming;
- a third lens unit having positive optical power, the third lens unit not moving for zooming;
- and
- a fourth lens unit having positive optical power, the fourth lens unit being movable for zooming, wherein a focal distance of the second lens unit (f2), and a distance between the first lens unit and the third lens unit (LV) have a relation of
- 0.42<|f2|/LV<0.91.
Dependencies are inferred from the claim text.