ZOOM LENS AND OPTICAL APPARATUS HAVING THE SAME

摘要

Provided is a zoom lens having, in order from an object: a first lens group (G1) having positive refractive power; a second lens group (G2) having negative refractive power; and a third lens group (G3) having positive refractive power. The first lens group (G1) and the third lens group (G3) respectively move toward the object upon zooming from the wide-angle end state to the telephoto end state. The first lens group (G1) includes a diffraction optical element (DOE) in which two optical elements, constituted by optical materials of which refractive index difference at the d-line is 0.45 or less, are cemented and a diffraction optical surface (corresponding to the optical surface with the radius of curvature R8 in FIG. 1) on which diffraction grating grooves are formed, exists on the interface of the two optical elements. The zoom lens satisfies the following conditional expressions: 0.05<φ1/ft<1.00, and 3.0<φd/y<10.0, where φ1 denotes an effective diameter of a surface closest to the object in the first lens group (G1), ft denotes a focal length of the zoom lens (ZL) in the telephoto end state, φd denotes an effective diameter of the diffraction optical surface, and y denotes a maximum image height of the zoom lens (ZL).

主权项

1. A zoom lens comprising, in order from an object:
a first lens group having positive refractive power; a second lens group having negative refractive power; and a third lens group having positive refractive power, the first lens group and the third lens group respectively moving toward the object upon zooming from a wide-angle end state to a telephoto end state, the first lens group including a diffraction optical element in which two optical elements, constituted by optical materials of which refractive index difference at the d-line is 0.45 or less, are cemented and a diffraction optical surface on which diffraction grating grooves are formed exists on the interface of the two optical elements, and the following conditional expressions being satisfied:
0.05<φ1/ft<1.003.0<φd/y<10.0 where φ1 denotes an effective diameter of an optical surface closest to the object in the first lens group, ft denotes a focal length of the zoom lens in the telephoto end state, φd denotes an effective diameter of the diffraction optical surface, and y denotes a maximum image height of the zoom lens.