| 摘要 |
PURPOSE: A zoom lens is provided to be compact and yield high optical quality by shortening the distance between the surface of the lens closest to the object side and the image field as well as increasing the effective diameter of the first lens in the first lens group using only three lens groups. CONSTITUTION: The zoom lens zoom lens includes three lens groups(I,II,III), and has a zoom ratio of about 3.0:1 and a high overall aberration quality. The first lens group(I), in the order of proximity to the object side, has an overall positive refractive power, the second lens group(II) has an overall negative refractive power, and the third lens group(III) has an overall positive refractive power. The second and the third lens groups(II,III) move along an optical axis when zooming from a wide-angle position to a telephoto position. The zoom lens system satisfies the following conditions: 2.0<.beta.2 (T)/.beta.3 (T)<2.5, -0.7<.beta.3 (T)<-0.4 where: .beta.2 (T) represents magnification of the second lens group at a telephoto position; and .beta.3 (T) represents magnification of the third lens group at a telephoto position.
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