Patent ID: 8363332

Claim:
A zoom lens system comprising the following lens units arranged along an optical axis and in order from an object side: a first lens unit having a positive refracting power; a second lens unit having a negative refracting power; a third lens unit having a positive refracting power; a fourth lens unit having a negative refracting power; and a fifth lens unit having a positive refracting power, wherein the fourth lens unit comprises the following lenses arranged in order from the object side: a 4a lens having a negative refracting power; a 4b lens having a positive refracting power; and a 4c lens having a negative refracting power, the zoom lens system satisfying a condition of the following expression: −1.00<((1 /r 4 BR 2)×(− f 4))<4.00, where r4BR2 is a radius of curvature of an image-side lens surface of the 4b lens and f4 is a focal length of the fourth lens unit.