| 摘要 |
PROBLEM TO BE SOLVED: To provide a thin, high performance intermediate telephoto zoom lens system of a deformation gauss type for an SLR camera by appropriately setting the power position of each lens (group) and selecting an appropriate glass material. SOLUTION: The intermediate telephoto lens system comprises, in order from the object side, a front group with positive power, diaphragm, and a rear group with positive power. The front group includes, in order from the object side, a first lens L1 with positive power, a second lens L2 with positive power and a third lens L3 with negative power. The rear group includes, in order from the object side, a fourth lens L4 with negative power, a cemented lens serving as a fifth lens L5 with positive power, and a sixth lens L6 with positive power. The intermediate telephoto lens system satisfies following conditional formula: (1) 2.0<f/f<SB>12</SB><3.0, wherein f is the focal distance of the entire system and f<SB>12</SB>is the composite focal distance of the first and second lenses. COPYRIGHT: (C)2008,JPO&INPIT
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