| 摘要 |
PROBLEM TO BE SOLVED: To provide a zoom lens with small size and high performance, capable of attaining high speed of AF operation and downsizing of a drive system required for the AF operation, and achieving a half field angle of 36.8 degrees or more at a wide angle end, a variable power ratio of approximately 2.8 times to 5 times and a resolution sufficient for an image sensor having 5 million to over 10 million pixels.SOLUTION: A zoom lens is arranged with a positive first lens group G1, a negative second lens group G2, a negative third lens group G3, a positive fourth lens group G4 and a positive fifth lens group G5 in this order from an object side along an optical axis, and performs focusing by the third lens group G3. In the zoom lens, the following conditional expressions (1) and (2): (1) 15<&ngr;d3g-&ngr;d2g<35 and (2) 0.15<nd2g-nd3g<0.35 are satisfied, where &ngr;d2g represents an average Abbe number of the second lens group; &ngr;d3g represents an average Abbe number of the third lens group; nd2g represents an average refractive index of d lines of the second lens group; and nd3g represents an average refractive index of d lines of the third lens group. |
