| 摘要 |
PROBLEM TO BE SOLVED: To obtain a projection zoom lens having a wide angle, a high magnification ratio and high resolution. SOLUTION: In the order starting from the magnification side of the projection zoom lens system, five lens groups G<SB>1</SB>to G<SB>5</SB>are arranged. The fourth lens group G<SB>4</SB>includes, in the order starting from the magnification side, a negative lens L<SB>8</SB>having at least one aspheric surface, a positive lens L<SB>9</SB>, a negative lens L<SB>10</SB>concave toward the magnification side, a positive lens L<SB>11</SB>convex toward the reduction side, and a positive lens L<SB>12</SB>. The fifth lens group G<SB>5</SB>is formed of one lens L<SB>13</SB>and is configured so that the ratio of the focal length f<SB>5</SB>of the fifth lens group with respect to the focal length f<SB>W</SB>of the system as a whole at a wide-angle end lies within a numerical range of 3 to 8. COPYRIGHT: (C)2010,JPO&INPIT
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