| 摘要 |
PROBLEM TO BE SOLVED: To provide a compact, low-cost and high-variable power zoom lens which can obtain images of high image quality. SOLUTION: This zoom lens is composed of a first positive lens group Gr1, a second negative lens group Gr2, a third positive lens group Gr3, and a fourth positive lens group Gr4 which are arranged in order from the object side, and second and fourth lens groups Gr2 and Gr4 are moved with first and third lens groups Gr1 and Gr3 fixed at the time of varying the power. The focal length of the first lens group Gr1 and the burden on variable power of the second lens group Gr2 are prescribed by inequalities 2.5<f1/fW<8.0 and 0.7×β34T/β34W <β2T/β2W<2.3×β34T/β34W (where f1, fW,β2W,β2T,β34W, andβ34T are the focal length of the first lens group, the focal length of the entire lens system in the wide angle end, the lateral power of the second lens group in the wide angle end, the lateral power of the second lens group in the telephoto end, the lateral power of third and fourth lens groups in the wide angle end, and the lateral power of third and fourth lens groups in the telephoto end respectively).
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