| 摘要 |
The invention provides a zoom lens system having a zoom ratio as high as about 8 to 12 but is of wide field angle and small size, and is suitable for use on a video camera, said zoom lens system comprising a positive first lens unit L1 which is movable in an orbit, said orbit displaceable toward objet side at the telephoto end position rather than at the wide-angle end position, a negative second lens unit L2 which is movable in an orbit, said orbit displaceable toward the image side at the telephoto end position rather than at the wide-angle end position, a positive third lens unit L3 which is movable in an orbit, said orbit displaceable toward the object side at the telephoto end position rather than at the wide-angle end, and a positive or negative fourth lens unit L4 which is movable, and conforming to2.6<fl/(fWxfT)+E,fra 1/2+EE <6(1)-1.2< beta 2T<-0.7(2)3.2< beta 2T/ beta 2W<8(3)where: fl is the focal length of the first lens unit, fW and fT are the focal lengths of the overall system at the wide-angle and telephoto ends, respectively, and beta 2W and beta 2T are the image-formation magnifications of the second lens unit at the wide-angle and telephoto ends, respectively.
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