Patent ID: 7123422

Claim:
A zoom lens system comprising: a first lens group having positive refractive power; a second lens group having negative refractive power; and a third lens group having positive refractive power; said first-third lens groups being provided in a row in order from an object; wherein, when a state of lens group positions varies from a wide-angle end state to a telephoto end state, a distance between the first lens group and the second lens group varies; and a distance between the second lens group and the third lens group varies; and the third lens group including a front lens group with positive refractive power located to an object side and a rear lens group with negative refractive power located to an image side, a space between the front lens group and the rear lens group being the largest in the third lens group; the front lens group including an aperture stop and a diffractive optical surface; an incident angle of a principal ray reaching a maximum image height to the diffractive optical surface being ten degrees or less; and the following conditional expression being satisfied: 0.3 <R/fw< 5.0 where R denotes a radius of curvature of the object side surface of a positive lens located to the image side of the aperture stop and fw denotes the focal length of the zoom lens system in the wide-angle end state.