| 摘要 |
PROBLEM TO BE SOLVED: To provide a zoom lens which has high aperture and zoom ratios, is small and lightweight as a whole system and achieves high optical performance.SOLUTION: A zoom lens comprises, in an order from an object side to an image side: a first lens group U1 which has positive refractive power; a variable power system having at least two lenses or more which move along an optical axis when zooming; and a rear lens group LR. In the zoom lens, a distance between neighboring lens groups is varied when zooming. The variable power system has, in the order from the object side to the image side: a second lens group U2 having negative refractive power; and a third lens group U3 having the negative refractive power. The second lens group moves to the image side when zooming from a wide angle end to a telephoto end. The variable power system also has an aperture diaphragm at a position closer to the image side than the second lens group. In the zoom lens, a focal length f1 of the first lens group, the focal length f2 of the second lens group, an imaging magnification ratio β2w of the second lens group, a distance L12w between the first lens group and the second lens group on an optical axis, and a length L1Sw along the optical axis from a lens surface closest to the image side in the first lens group to the aperture diaphragm at a wide angle end satisfy a specific conditional equation.SELECTED DRAWING: Figure 1 |
