Patent ID: 7301578

Claim:
A super-wide-angle optical system, for forming an optical image of an object on an image pickup surface of an image sensing device that converts the optical image into an electrical signal, comprising, in order from an object side: a first negative lens having a meniscus shape convex to the object side; a second negative lens positioned next to the first negative lens; and a positive lens positioned on an image side with respect to the first and second negative lenses, having an aspherical surface, wherein at least one of four lens surfaces of the first and second negative lenses is an aspherical surface, and wherein the following condition is fulfilled: 0.05<( TL×Yd )/{ f ×tan(Ψ d )}<3.5 where Ψd represents a maximum half field angle, Yd represents a maximum image height (mm), TL represents a on-axis length (mm) from the lens surface in the closest position to the object and an imaging position, and f represents a focal length (mm) of the entire optical system.