Patent attributes
A wide angle of view optical system, suitable for monitor cameras such as an in-vehicle camera and a security camera, having a reduced optical entire length and aberration correction for forming an optical image on light-receiving surfaces of an imaging element having a first lens having a negative optical power and a group of lenses each having a positive optical power, which are serially disposed from an object side. The first lens comprises at least one aspherical surface, and has a concave surface centered around an optical axis in vicinity of the optical axis on an image-side surface thereof. Further, an optical entire length T in millimeters (mm) of the entire system, a half angle of view θ, and a focal distance ftot of the entire system, also in millimeters, satisfy the conditional expressions.