| 摘要 |
A wide angle zoom lens system. A first lens group has a positive refractive power, while a second lens group has a negative refractive power. The distance between the first lens group and the second lens group is changed during zooming. The first lens group includes a front group having a negative refractive power and a rear group having a positive refractive power. The front group includes a meniscus lens which is concave toward the object and has a negative refractive power, and the rear group includes at least four lenses which have positive or negative refractive powers, wherein 4.5<|fF/fW |<13; 0.005<|K/fF |<0.07; and 20<|(fbWxfF)/fW |<100 where fF is the focal length of the front group of the first lens group, fW is the focal length of the zoom lens at a wide angle position, K is the distance along an optical axis from the surface of the lens closest to the image plane to a rear principal point in the first lens group; and fbW is the back focus distance at the wide angle position.
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