Patent ID: 8064145

Claim:
An optical system including a front lens group, a stop, and a rear lens group, which are arranged successively in order from the object side toward the image side, wherein: the front lens group includes a refractive optical element and a solid material element having a refractive action, the solid material element formed on at least one transmissive surface of the refractive optical element, the rear lens group includes a diffractive optical element, and the following conditional expressions are satisfied: vd< 60, dn/dg <0.50, 0.01 <|fn/fd|< 0.80, and either θ gF <(−1.665×10 −7 ·vd 3 +5.213×10 −5 ·vd 2 −5.656×10 −3 ·vd+ 0.700) or θ gF >(−1.665×10 −7 ·vd 3 +5.213×10 −5 ·vd 2 −5.656×10 −3 ·vd+ 0.755), where vd is an Abbe number of a solid material of the solid material element with respect to the d line, dn and dg are respectively a thickness of the solid material element and a thickness of the refractive optical element when measured on the optical axis, fd and fn are respectively a focal length of a diffractive optical portion of the diffractive optical element and a focal length of the solid material element in air, and θgF is a partial dispersion ratio of the solid material with respect to the g line and the F line.