Patent ID: 7692870

Claim:
A zoom lens comprising, in order from an object side to an image-plane side: a first lens group having a positive refractive power; a second lens group having a negative refractive power; a third lens group having a positive refractive power; a fourth lens group having a negative refractive power; and a fifth lens group having a positive refractive power, wherein, during a change of a lens zoom position from a maximum wide angle state to a maximum telephoto state, at least the second lens group moves toward an image side, the third lens group moves toward an object side, and the fourth lens group is fixed in an optical-axis direction, an aperture stop is disposed near the object side of the third lens group, and the following conditional expressions (1) and (2) are satisfied: 0.05 <f 2/ f 4<0.3, and (1) 0.1<Δ3/ ft< 0.2, (2) where f 2 is a focal length of the second lens group, f 4 is a focal length of the fourth lens group, Δ 3 is an amount of movement of the third lens group during the change of the lens zoom position from the maximum wide angle state to the maximum telephoto state, and ft is a focal length of a whole lens system at the maximum telephoto state.