| 摘要 |
The invention is dedicated to a compact and lightweight high zoom ratio lens which is configured in 4 lens group zoom system with a deployment of positive, negative, positive, and positive refraction lens groups in order, being approximately 75 degree in shooting angle of view at a wide-angle end, approximately f/3 to 4 at the wide-angle end, and approximately f/6 to 7 at a telephoto end so as to implement an enhanced variable zoom power up to approximately 10. The zoom lens includes first to fourth lens groups each comprised of a plurality of lenses, the lens groups having respective refractive indices of positive, negative, positive, and positive levels in order from the closest to an object. In zooming from a wide-angle end to a telephoto end, the first and second lens groups have a space (air-filled) widened therebetween, the second and third lens groups have a space (air-filled) narrowed therebetween, and the third and fourth lens groups have space (air-filled) narrowed therebetween while the first, third, and fourth lens groups move toward the object, and in focusing, the second lens group alone move, under predetermined conditions.
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