| 摘要 |
<P>PROBLEM TO BE SOLVED: To achieve a zoom lens that has an inner focus system, is small in the amount of movement of focus groups, has a small size and high performance, has 36.8 degrees or more in half angle of view at a wide angle end, has a variable power ratio of 2.8 times to approximately 5 times, and also has resolution corresponding to an imaging element that has 500-million to 1000-million pixels. <P>SOLUTION: The zoom lens comprises, in order from an object side, a positive first lens group I, negative second and third lens groups II and III, positive fourth and fifth lens groups IV and V, and an aperture diaphragm S between the third and fourth lens groups. To vary power from a wide angle end to a telephoto end, an interval between the first and second lens groups increases, the interval between the second and third lens groups increases, the interval between the third and fourth lens groups decreases, and the interval between the fourth and fifth lens groups decreases. The third lens group is composed of a single negative meniscus lens the concave face of which is oriented toward the object side. Focusing is carried out by the movement of the third lens group in the direction of an optical axis. The zoom lens satisfies predetermined conditional expressions relating to the lens shape and focal distance of the third group. <P>COPYRIGHT: (C)2013,JPO&INPIT |
