Super wide-angle zoom lens
AssigneeAsahi Kogaku Kogyo Kabushiki Kaisha
InventorsTakashi Enomoto, Takayuki Ito
Life of this patent
Estimating the term…
Abstract
A super wide-angle zoom lens includes at least a negative first lens group and a positive second lens group, in this order from an object side. A zooming operation is carried out by relatively moving the lens groups. When a photographing area is defined by a rectangular area, a boundary of a circular image forming area formed by the zoom lens is at least partially disposed in the rectangular photographing area at the shortest focal length of the zoom lens.
Claims14
A super wide-angle zoom lens comprising at least two lens groups including a first lens group having negative power and a second lens group having positive power, in this order from the object side, wherein a zooming operation is carried out by relatively moving the at least two lens groups, and wherein a photographing area is defined by a rectangular area, at least a part of a boundary of a circular image forming area formed by said zoom lens is disposed in said photographing area at a shortest focal length of said zoom lens, and wherein at a longest focal length, the rectangular photographing area is included within the circular image forming area.
A super wide-angle zoom lens comprising at least two lens groups including a first lens group having negative power and a second lens group having positive power, in this order from the object side, wherein a zooming operation is carried out by relatively moving the at least two lens groups, and wherein a rectangular photographing area is defined, at least a part of a boundary of a circular image forming area formed by said zoom lens is disposed in said photographing area at a shortest focal length of said zoom lens, wherein said first lens group having a negative power comprises a negative first lens element, a negative second lens element, and a third lens subgroup, in this order from the object side, wherein at a longest focal length, the rectangular photographing area is included within the circular image forming area, and wherein said zoom lens satisfies the following condition:
- 0.5<f.sub.1-2 /f.sub.1 <0.9
- wherein:
- f.sub.1-2 represents a resultant focal length of said first and second lens elements of said first lens group, and f.sub.1 represents a focal length of said first lens element of said first lens group.
A super wide-angle zoom lens comprising at least two lens groups including a first lens group having negative power and a second lens group having positive power, in this order from the object side, wherein a zooming operation is carried out by relatively moving the at least two lens groups, and wherein a photographing area is defined, at least a part of a boundary of a circular image forming area formed by said zoom lens is disposed in said photographing area at a shortest focal length of said zoom lens, and wherein a portion of said photographing area is outside of said image forming area.
A super wide-angle zoom lens comprising at least two lens groups including a first lens group having negative power and a second lens group having positive power, in this order from the object side, wherein a zooming operation is carried out by relatively moving the at least two lens groups, and wherein a photographing area is defined, at least a part of a boundary of a circular image forming area formed by said zoom lens is disposed in said photographing area at a shortest focal length of said zoom lens, wherein said first lens group having a negative power comprises a negative first lens element, a negative second lens element, and a third lens subgroup, in this order from the object side, wherein a portion of said photographing area is outside of said image forming area, and wherein said zoom lens satisfies the following condition:
- 0.5<f.sub.1-2 /f.sub.1 <0.9
- wherein:
- f.sub.1-2 represents a resultant focal length of said first and second lens elements of said first lens group, and
- f.sub.1 represents a focal length of said first lens element of said first lens group.
Dependencies are inferred from the claim text.