Zoom lens and optical apparatus

Abstract

A zoom lens is equipped with: a first lens group, which is fixed when changing magnification, provided most toward the magnification side; and a second lens group having a positive refractive power, which moves when changing magnification, provided adjacent to the first lens group at the reduction side thereof. The first lens group is constituted essentially by, in order from the magnification side to the reduction side, a front group having a positive refractive power and a rear group having a negative refractive power. Focusing operations are performed by changing the distance between the front group and the rear group. Conditional Formula (1): -0.3 5<=flb / ft<0 related to the focal length flb of the rear group and the focal length ft of the entire lens system at the telephoto end is satisfied.

Description

technical field [0001] The present invention relates to a zoom lens and an optical device, and more specifically, to a zoom lens suitable as a projection optical system used in a projection display device or an imaging optical system used in a digital camera, video camera, etc. And an optical device equipped with the zoom lens. Background technique [0002] Conventionally, cameras in the above-mentioned fields have used an imaging optical system that captures an image of a subject on the magnification side and forms an image on an imaging element on the reduction side. In addition, conventionally, in a projection display device, a projection optical system for projecting an optical image of light modulated by a modulation element disposed on the reduction side toward the enlargement side is used. In such a projection optical system and an imaging optical system, a zoom lens capable of realizing various focal lengths with a single optical system is mainly used. [0003] Amo...

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Problems solved by technology

[0010] However, the F value of the zoom lenses described in Patent Documents 1 to 3 is 4 or more, so it cannot be considered that the F value is small.

In the above-mentioned lens system, the second lens group of the moving group arranged next to the reduction side of the first lens group, which is the fixed group, is set as a negative lens group, so it is difficult to realize the structure of an optical system with a small F value.

In the zoom lens described in Patent Document 4, the size of the optical system is large relative to the focal length, and it cannot be considered that it can meet the demands for miniaturization in recent years.

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