Patent ID: 7643219
Filing Date: 2010-01-05
Classification: G02B

Abstract:
1. A zoom lens comprising, in order from an object side thereof: a first lens unit having a positive refracting power; a second lens unit having a negative refracting power; and a rear group having a positive refracting power that comprises at least one lens unit, a lens unit located closest to the object side in the rear group being a third lens unit having a positive refracting power, wherein the zoom lens comprises an aperture stop disposed closer to an image side than the second lens unit and closer to the object side than a lens surface closest to the image side in the third lens unit, during zooming from a wide angle end to a telephoto end in a state in which the zoom lens is focused on an object at a farthest distance, a distance between the first lens unit and the second lens unit is larger at the telephoto end than at the wide angle end, a distance between the second lens unit and the third lens unit is smaller at the telephoto end than at the wide angle end, the first lens unit is located closer to the object side at the telephoto end than at the wide angle end, the second lens unit starts to move toward the object side at an intermediate point in zooming from the wide angle end to the telephoto end and thereafter reverses its moving direction to move toward the image side, the aperture stop is located closer to the object side at the telephoto end than at the wide angle end, the third lens unit is located closer to the object side at the telephoto end than at the wide angle end, and the zoom lens satisfies the following conditions: where, f t is a focal length of the entire zoom lens system at the telephoto end, S 1 t is an actual distance on the optical axis from a lens surface located closest to the object side in the first lens unit to an image plane at the telephoto end, S 2 w is an actual distance on the optical axis from a lens surface located closest to the object side in the second lens unit to the image plane at the wide angle end, S 2 t is an actual distance on the optical axis from the lens surface located closest to the object side in the second lens unit to the image plane at the telephoto end, S 2 m1 is an actual distance on the optical axis from the lens surface located closest to the object side in the second lens unit to the image plane at a first intermediate zoom position, which is defined as a zoom position at which the second lens unit starts to move toward the object side, and S 2 m2 is an actual distance on the optical axis from the lens surface located closest to the object side in the second lens unit to the image plane at a second intermediate zoom position, which is defined as a zoom position at which the second lens unit reverses its moving direction from movement toward the object side to movement toward the image side.