Patent ID: 7522347

Claim:
A zoom optical system comprising; a lens group A having one negative lens component at the most object side, and a lens group B arranged adjacent to the lens group A, where a distance on the optical axis between the lens group A and the lens group B is changed for magnification purpose, wherein the negative lens component is a cemented lens consisting of a positive lens L AP and a negative lens L AN , and when in a rectangular coordinate system in which a horizontal axis is expressed by νdp and an vertical axis is expressed by θgFp, a straight line expressed by θgFp=αp×νdp+βp (αp=−0.00163) is set up, ν dp and θgFp of the positive lens L AP are included in both of a domain which is specified by a straight line at a lower limit of the following condition (1) and a straight line at an upper limit of the following condition (1), and a domain which is specified by the following condition (2) 0.6400<βp<0.9000 (1) 3<ν dp<27 (2) here, θ gFp is a ratio of a partial dispersion (ng−nF)/(nF−nC) of the positive lens L AP ; ν d p is Abbe number (nd−1)/(nF−nC) of the positive lens L AP ; nd is refractive index to d line; nC is refractive index to C line; nF is refractive index to F line; and ng is refractive index to g line.