| 摘要 |
A wide-angle, single focus lens is disclosed that is formed of four lens elements of negative, positive, negative, and positive refractive power, in sequential order from the object side. The first lens element is concave on its object side, the second lens element has at least one surface that is aspheric, and the fourth lens element is convex on its image side and has at least one surface that is aspheric. Specified conditions are preferably satisfied in order to reduce aberrations and provide a bright image while maintaining a short overall lens length.
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