Patent ID: 8675100

Claim:
A zoom lens system, in order from an object side to an image side, comprising a first lens unit having positive optical power, a second lens unit having negative optical power, a third lens unit having positive optical power, a fourth lens unit having negative optical power, and a fifth lens unit having positive optical power, wherein the third lens unit includes at least one lens element having positive optical power and at least one lens element having negative optical power, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, at least the first lens unit, the second lens unit, and the third lens unit are individually moved along an optical axis so that air spaces between the respective lens units vary, thereby performing magnification change, in focusing from an infinity in-focus condition to a close-object in-focus condition, a lens unit positioned on the image side relative to an aperture diaphragm is moved along the optical axis, and the following conditions are satisfied: 8.1 <f G1/Ir <10.4 Z=f t /f W ≧9.0 where f G1 is a composite focal length of the first lens unit, Ir is a value represented by the following equation: Ir=f T ×tan(ω T ), ω T is a half view angle (°) at a telephoto limit, f T is a focal length of the entire system at a telephoto limit, and f W is a focal length of the entire system at a wide-angle limit.