Wide-angle three-group zoom lens
AssigneeFuji Photo Optical Co., Ltd.
InventorNobuaki Toyama
Life of this patent
Estimating the term…
Abstract
A negative first lens group, a positive second lens group, and a positive third lens group are provided in sequence from an object side of a zoom lens. An aperture is provided in the second group of lenses. At the time of zooming operation, the three groups of lenses independently move over an optical axis X. The second group of lenses is constituted of, in sequence from the object side, a biconvex lens group 2A; a lens group 2B formed by cementing two or more lenses together; an aperture; a lens group 2C formed by cementing together two or more lenses; and a lens group 2D whose convex side is oriented toward the image surface side.
Claims13
A wide-angle three-group zoom lens, comprising:
- a first group of lenses having negative refracting power, a second group of lenses having positive refracting power, and a third group of lenses having positive refracting power, which are provided in sequence from an object side of the zoom lens, wherein zooming is effected by changing intervals between said lens groups;
- and wherein said second group of lenses further comprises, in sequence from said object side, a biconvex lens group 2A, a lens group 2B formed by cementing two or more lenses together, an aperture, a lens group 2C formed by cementing two or more lenses together, and a lens group 2D which has positive refracting power and whose convex side is oriented toward the image surface side.
A wide-angle three-group zoom lens, comprising:
- a first group of lenses having negative refracting power, a second group of lenses having positive refracting power, and a third group of lenses having positive refracting power, which are provided in sequence from an object side of the zoom lens, wherein zooming is effected by changing intervals between said lens groups;
- said second group of lenses further comprises, in sequence from said object side, a biconvex lens group 2A, a lens group 2B formed by cementing three lenses together, an aperture, a lens group 2C formed by cementing together two lenses, and a lens group 2D which has positive refracting power and whose convex side is oriented toward the image surface side;
- wherein conditional equation (1) provided below is satisfied, provided that a combined focal length of said lens group 2A and said lens group 2B is set as f2F and that a combined focal length of said lens group 2C and said lens group 2D is set as f2R, that is, - 0.7 < f 2 F f 2 R < + 0.1 . ( 1 )
Dependencies are inferred from the claim text.