Patent ID: 8654456
Filing Date: 2014-02-18
Classification: G02B

Abstract:
1. A photographic optical system having a plurality of lens units, in order from an object side to an image side and arranged along an optical axis thereof, comprising: a first lens unit having a positive refractive power; a second lens unit having a positive or negative refractive power; and a third lens unit having a positive or negative refractive power, wherein the first lens unit consists of a first lens sub-unit having a positive refractive power and a second lens sub-unit having a positive or negative refractive power with a largest air space provided therebetween, wherein the first lens unit further includes a diffractive optical element and an aspheric surface, wherein the second lens unit is configured to move along the optical axis to effect focusing, and wherein, when L is a length on the optical axis from a lens surface furthest on the object side of the first lens sub-unit to an image plane of the entire photographic optical system, d