Patent ID: 7538957

Claim:
A photographing optical system comprising: a positive lens provided closer to the object side of the system than the intersection (P) of the light axis and a paraxial chief ray; and a negative lens provided closer to the image side of the system than the intersection (P), wherein the positive lens and the negative lens are both formed of materials satisfying the following two conditions when the maximum height of a paraxial marginal ray, passing through a lens surface, from the light axis at a location closer to the object side than the intersection (P) is greater than a maximum height of the paraxial marginal ray, passing through a lens surface, from the light axis at a location closer to the image side than the intersection (P): −0.0015×ν d + 0.6425 <θ gF , and 60 <ν d where νd is the Abbe number and θgF is the partial dispersion ratio.