| 摘要 |
A zoom lens system includes, in order from an object side to an image side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit having a positive refractive power, and a fourth lens unit having a positive refractive power. The third lens unit is stationary and the second and fourth lens units move along an optical axis during zooming. The fourth lens unit consists of a cemented lens in which a positive lens element and a negative lens element are cemented together. The zoom lens system satisfies the following conditional expression: 7.5<|R42|/TD4<20.0 where R42 denotes a radius of curvature of a cemented surface of the cemented lens, and TD4 denotes a thickness of the fourth lens unit along the optical axis.
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