Patent ID: 8542447

Claim:
A photographic optical system comprising, along an optical axis thereof and arranged in order from an object side to an image side: 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, focusing being performed by moving the second lens unit in a direction parallel to the optical axis, wherein at least one diffractive optical element and at least one optical element made of solid material are provided closer to the object side than a position where a paraxial chief ray intersects the optical axis, and wherein, when a focal length obtained by only a diffraction component of the diffractive optical element is denoted by fDOE, a focal length of the optical element made of solid material is denoted by fNL, a focal length of the first lens unit is denoted by f 1 , and a relative anomalous partial dispersion of a material forming the optical element made of solid material is denoted by ΔθgF NL , the following conditions are satisfied: 10 <f DOE× fNL/f 1 2 <600 0.0272 <ΔθgF NL <0.3000.