IMAGING OPTICAL SYSTEM, AND ELECTRONIC IMAGING DEVICE INCORPORATING IT

摘要

PROBLEM TO BE SOLVED: To provide a zoom lens which is made small and thin by reducing the number of the constituents of the optical system, and provide an electronic imaging device incorporating it. SOLUTION: In an imaging optical system having a positive lens group, a negative lens group, and a diaphragm, the positive lens group is placed at the object side of the diaphragm and has a cemented lens formed by cementing lenses. When a straight line expressed by Nd=α×νd+β(α=-0.017) is set in an orthogonal coordinate system of the abscissa axis of Nd and ordinate axis ofνd, Nd andνd of at least one lens composing the cemented lens are contained both in the area set by the straight line showing the lower limit of the extent of the following conditional expression (1) and the straight line showing the upper limit and in the area set by the following conditional expression (2) and (3): 1.45<β<2.15... (1), 1.58