| 摘要 |
PROBLEM TO BE SOLVED: To obtain a zoom lens which has strong durability when it is installed in an imaging apparatus though it is thinned while maintaining excellent optical performance, is prevented from spoiling permeability in a rectangular prism and achieves the reduction of cost. SOLUTION: The zoom lens is equipped with a first lens group GR1, a second lens group GR2, a diaphragm St, a third lens group GR3, and a fourth lens group GR4 in order from an object side. The first and the third lens groups GR1 and GR3 are fixed groups, and the second and the fourth lens groups GR2 and GR4 are movable groups. The zoom lens has the rectangular prism LP in the first lens group GR1, and satisfies conditions (1) 1.71<N<SB>P</SB><1.80, (2)ν<SB>P</SB>>30 and (3) 1.4<D<SB>2-6</SB>/f<SB>W</SB><1.9. Provided that N<SB>P</SB>shows the refractive index of the rectangular prism LP on a d-line,ν<SB>P</SB>shows the Abbe number of the rectangular prism LP on the d-line, D<SB>2-6</SB>shows a distance on an optical axis from the image side surface of a first lens to the object side surface of a second lens in the first lens group, and f<SB>W</SB>shows the focal distance of the entire system at a wide angle end. COPYRIGHT: (C)2008,JPO&INPIT
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