Possessing magnification change optical system and the image pickup device

摘要

PROBLEM TO BE SOLVED: To provide a variable power optical system whose entire length value is made to be small as compared with image height and then whose aberration is satisfactorily corrected.;SOLUTION: The variable power optical system includes, in order from an object side: a first lens group having negative refractive power; a second lens group having positive refractive power; a third lens group having negative refractive power; and a fourth lens group having positive refractive power. The first lens group comprises, in order from the object side, one negative lens and one positive lens with air space. The variable power optical system satisfies following conditional expressions (1), (2) and (3). The conditional expression (1): 1.75≤Nd1g≤2.50, the conditional expression (2): 15≤Vd1g≤43 and the conditional expression (3): 3≤VdN-VdP≤28, wherein Nd1g is a refractive index of each of the lenses constituting the first lens group for a d-line, Vd1g is an Abbe number of each of the lenses constituting the first lens group for the d-line, VdN is an Abbe number of the negative lens in the first lens group for the d-line, and VdP is an Abbe number of the positive lens in the first lens group for the d-line.;COPYRIGHT: (C)2011,JPO&INPIT