Zoom lens system and image pickup apparatus including the same

A zoom lens system, comprising, in order of from an object side toward an image side:

• a first lens unit with a negative refractive power;
• a second lens unit with a positive refractive power;
• and
• a third lens unit with the positive refractive power,
• the first lens unit, the second lens unit, and the third lens unit moving to perform zooming,
• wherein the first lens unit includes a first lens element with the negative refractive power, and a second lens element with the positive refractive power in order of from the object side toward the image side, and
• wherein when a refractive index of a material of the first lens element is N11, an Abbe number of a material of the second lens element is ν12, and the radii of curvatures of lens surfaces of the first lens element on the object side and the image side are R11a and R11b, respectively, the following conditions are satisfied:
• 1.81<N11;
• ν12<20.0;
• and
• 0<(R11a+R11b)/(R11a−R11b)≦1.0.