To provide a zoom lens system having high optical performance by using a
diffractive optical element, the system includes a first group having
positive power, a second group having negative power, and a third group
having positive power. When zooming from a wide-angle end state to a
telephoto end state, a distance between the first group and the second
group and a distance between the second group and the third group vary.
The third group is composed of a front group having positive power
locating to the object side of the largest space in the third group and a
rear group having negative power locating to an image side of the space.
The front group includes an aperture stop and a diffractive optical
surface. An incident angle of a principal ray reaching the maximum image
height to the diffractive optical surface is ten degrees or less. Given
condition is satisfied.