| 摘要 |
PROBLEM TO BE SOLVED: To provide a rear focus system zoom lens capable of attaining the miniaturization of the whole lens system by further miniaturizing a prism without damaging the optical performance. SOLUTION: The zoom lens is provided with a 1st lens group GR1 to a 5th lens group GR 5 having positive, negative, positive, positive and negative refractive power, respectively, in this order from an object side, and zooming is performed by shifting the 2nd lens group GR2 and the 4th lens group GR4. Besides, the 1st lens group GR1 is provided with a front lens group having negative refractive power, an optical member for deflecting the optical path and a rear lens group having positive refractive power in this order from the object side. Further, by constituting the zoom lens so that a condition of 1.0<β5<1.9 is satisfied provided that the image forming magnification of the 5th lens group GR5 when the distance to an object is infinite is expressed byβ5, the focal distance of the lens positioned closer to the object can be shortened, the effective diameter of the 1st lens group GR1 can be made smaller, and the optical member (for example, prism P1) is made thinner in shape. COPYRIGHT: (C)2005,JPO&NCIPI
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