| 摘要 |
A large aperture wide-angle lens includes, arranged in order from the object side, a first lens group having negative refractive power, a second lens group having positive refractive power, a stop, a third lens group having positive refractive power, and a fourth lens group having negative refractive power. The first lens group is formed of one lens element, and the second lens group is formed of one or two lens elements. Each of the third and fourth lens groups includes at least one aspheric surface and each may be formed of two lens components that are lens elements. The wide-angle lens preferably satisfies specified conditions related to f-number, focal length and back focal length of the wide-angle lens, focal lengths of the first and fourth lens groups, maximum image height at the image surface, and indexes of refraction and Abbe numbers of particular lens elements.
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