Patent ID: 8000025
Filing Date: 2011-08-16
Classification: G02B

Abstract:
1. 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, and a fourth lens unit having positive optical power, wherein the first lens unit is composed of three or fewer lens elements, wherein the second lens unit is composed of three lens elements, wherein in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit, the second lens unit, the third lens unit and the fourth lens unit are moved individually along an optical axis such that air spaces between the individual lens units should vary, so that variable magnification is achieved, and wherein the following conditions (2), (a−1) and (b) are satisfied: where, D is a total of an optical axial thickness of each lens unit, ω f f wherein among the three or fewer lens elements constituting the first lens unit and the three lens elements constituting the second lens unit, only the object side surface of the lens element arranged in the center of the second lens unit has a negative radius of curvature.