Zoom lens
AssigneeKonica Corporation
InventorsNobuyoshi Mori, Masae Sato
Life of this patent
Estimating the term…
Abstract
A zoom lens includes, in the order named from an object side: a first lens group having a positive focal length; a second lens group having a negative focal length; and a third lens group having a positive focal length. A magnification is changed by moving said second and third lens groups in an optical axis direction of said zoom lens, and satisfies the following condition, 3.0<Lt/(L{square root over (Z)})<6.0 where Lt represents a distance between a lens surface closest to the object side of said first lens group and an image plane, L represents a diagonal length of the image plane, and Z represents a variable magnification ratio showing a ratio of a focal length at a wide angle end to a focal length at a telephoto end.
Claims36
A zoom lens, comprising:
- a plurality of lens groups, wherein the plurality of lens groups consists of, in the order named from an object side:
- (a) a first lens group having a positive focal length;
- (b) a second lens group having a negative focal length and at least one positive lens;
- and
- (c) a third lens group having a positive focal length,
- wherein a magnification is changed by moving said second and third lens groups in an optical axis direction of said zoom lens, and wherein the following condition is satisfied,
- 3.0<Lt/(LZ)<6.0
- where Lt represents a distance between a lens surface closest to the object side of said first lens group and an image plane, L represents a diagonal length of the image plane, and Z represents a variable magnification ratio showing a ratio of a focal length at a wide angle end to a focal length at a telephoto end.
A digital still camera, comprising:
- an image sensor for changing optical information to an electrical signal;
- and
- a zoom lens comprising a plurality of lens groups, wherein the plurality of lens groups consists of, in the order named from an object side:
- (a) a first lens group having a positive focal length;
- (b) a second lens group having a negative focal length and at least one positive lens;
- and
- (c) a third lens group having a positive focal length, wherein a magnification is changed by moving said second and third lens groups in an optical axis direction of said zoom lens, and wherein the following condition is satisfied,
- 3.0<Lt/(LZ)<6.0
- where Lt represents a distance between a lens surface closest to the object side of said first lens group and an image plane, L represents a diagonal length of the image plane, and Z represents a variable magnification ratio showing a ratio of a focal length at a wide angle end to a focal length at a telephoto end.
A video camera, comprising:
- an image sensor for changing optical information to an electrical signal;
- and
- a zoom lens comprising, in the order named from an object side:
- (a) a first lens group having a positive focal length,
- (b) a second lens group having a negative focal length and comprising at least one positive lens;
- and
- (c) a third lens group having a positive focal length,
- wherein a magnification is changed by moving said second and third lens groups in an optical axis direction of said zoom lens, and wherein the following condition is satisfied,
- 3.0<Lt/(LZ)<6.0
- where Lt represents a distance between a lens surface closest to the object side of said first lens group and an image plane, L represents a diagonal length of the image plane, and Z represents a variable magnification ratio showing a ratio of a focal length at a wide angle end to a focal length at a telephoto end.
Dependencies are inferred from the claim text.