Patent ID: 7057831

Claim:
An optical system, in which a maximum height from an optical axis of a passing point of a paraxial marginal ray on a lens surface that is located on a front side of a point P is larger than a maximum height from the optical axis of a passing point of the paraxial marginal ray on a lens surface that is located on a rear side of the point P, the point P being a point where a paraxial chief ray crosses the optical axis, the optical system comprising: a refractive optical element having refractive surfaces on a light-incident side and a light-emergent side, the refractive optical element being formed of a solid material that satisfies the following conditions: νd<30 θgd<−3.333×10 −3 ·νd+ 1.40 θ gF <−2.615×10 −3 ·νd+ 0.67 where νd represents an Abbe's number, and θgd and θgF represent partial dispersion ratios, wherein the refractive optical element has a negative optical power in a case where the refractive optical element is located on the front side of the point P, and the refractive optical element has a positive optical power in a case where the refractive optical element is located on the rear side of the point P.