Patent ID: 7375900
Filing Date: 2008-05-20
Classification: G02B

Abstract:
1. A variable power optical system for forming an optical image of a subject on an image pickup surface of an image pickup device, comprising: a plurality of lens groups; wherein a first lens group of the plurality of lens groups which is the most nearest to the subject has a negative refractive power, wherein the first lens group includes: a reflective optical element for bending a light path; and an only lens which is provided on a subject side of the reflective optical element and consists of a single negative lens, wherein an axial distance between the first lens group and the image pickup surface changes when varying a power of the variable power optical system, and a refractive index and an Abbe number of the negative lens satisfy the following relationship: wherein: Nd is the refractive index at d-line of the negative lens; νd is the Abbe number of the negative lens.