This appealing lens, the first wide-angle zoom in the world to offer an aspherical element, covers an angle of view from 84° to 63 °. The aspherical s

This appealing lens, the first wide-angle zoom in the world to offer an aspherical element, covers an angle of view from 84° to 63 °. The aspherical surface of its first element minimizes barrel distortion at short focal lengths and effectively controls curvature of field (an error which affects image quality by fall-off of sharpness towards the edges), coma, astigmatism, and lateral chromatic aberration. The optical performance of this lens virtually exceeds the performance of a fixed focal length lens.