| 摘要 |
PROBLEM TO BE SOLVED: To provide a large-aperture, wide-angle zoom lens which has little distortion aberration and offers high performance.SOLUTION: A zoom lens comprises a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a third lens group G3 having a positive refractive power arranged in order from the object side to the image side. In zooming from the wide angle end to the telephoto end, the magnification is changed by moving the second lens group G2 toward the object side along the optical axis and the correction of an image plane associated with the zooming is made by moving the first lens group G1 along the optical axis. The first lens group G1 comprises three negative lenses and one positive lens. A focal length fw of the entire system at the wide angle end and a focal length f1 of the first lens group G1 are determined such that a value of f1/fw is within a predetermined range. |
