| 摘要 |
A variable magnification optical system of reduced size and increased zoom ratio is provided. According to one aspect, a positive lens group having positive refractive power which is disposed closest to an object and an end lens group disposed closest to an image are provided. When lens group positions are changed so that the system changes from the wide-angle state to the telephoto state, the positive lens group and the end lens group move toward the object. In this case, a ratio of the moving amount of the positive lens group to that of the end lens group from the wide-angle state to a given state satisfies a particular condition. A simplified barrel structure results when a particular first supporting element for supporting a first lens group which moves along an optical axis and a particular second supporting element for supporting an end lens group located closer to an image than the first lens group are provided. The second supporting element moves integrally with the end lens group along the optical axis. The second supporting element transmits a rotational driving force applied thereto to the first supporting element and moves along the optical axis in accordance with the rotational driving force. The first supporting element moves along the optical axis in accordance with the rotational driving force transmitted thereto via the second supporting element.
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