| 摘要 |
A zoom lens is provided to obtain favorable light ray aberration, spherical aberration, field curve and distortion aberration. Any one lens constituting a first to a third lens units(110,120,130) is made of an aspherical surface. The aspherical surface is a surface of the first lens facing an object side. An iris diaphragm is positioned between the first lens and the second lens unit. The iris diaphragm moves integrally with the second lens unit in order to maintain a fixed interval with the second lens unit when magnification change operation occurs. When the zoom lens is changed from a wide angle end to a telescopic end, the interval between the first lens unit and the second lens unit is decreased. In this case, the interval between the second lens unit and third lens unit is increased. The third lens unit maintains a fixed interval with the image side.
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