| 摘要 |
PROBLEM TO BE SOLVED: To obtain a small, high-performance and high variable power zoom lens and to provide an imaging unit using the same. SOLUTION: This zoom lens consists of a front group of negative refractive power and a rear group of positive refractive power, arranged in this order from the object side, and the power is varied by changing the interval of the principal points of the front group and the rear group. The front group consists of an Fa group of positive refractive power and an Fb group of negative refractive power, arranged in this order from the object side, and the interval of the Fa group and the Fb group is changed, when the power is varied. The rear group consists of an Ra group of positive refractive power and an Rb group of positive refractive power, arranged in this order from the object side; and the interval of the Ra group and Rb group is changed, when the power is varied. When the power of the entire lens system is varied from the wide-angle end to the telephoto end, the Fb group, the Ra group and the Rb group are moved relative to the image surface of the entire lens system, and after the Rb group has moved toward the image side, then its moving direction is reversed toward the object side; and the Ra group moves at least from the wide-angle end toward the object side, until the movement of the Rb group is reversed.
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