| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a zoom lens having a high zoom ratio, favorably correcting chromatic aberrations in the entire zoom range from a wide-angle end to a telephoto end, having high optical performance in the entire zoom range and, even when there is a change in environment temperature, having little focus variation, and an image pickup apparatus including the same. <P>SOLUTION: A zoom lens includes, in order from an object side: a positive first lens group which does not move during variation in power; a negative second lens group U2 which moves in the optical axis direction with variation in power; a negative third lens group U3 which moves in the optical axis direction with variation in power and correcting fluctuation in an image surface caused by the variation in power; and a positive fourth lens group which does not move during variation in power. The fourth lens group includes, in order from the object side, a positive 4a lens group and a positive 4b lens group that are spaced at a largest air gap in the group. Abbe numbers, partial dispersion ratios, and temperature change coefficients of refractive index of lens materials constituting the third lens group, the 4a lens group, and the 4b lens group are appropriately set. <P>COPYRIGHT: (C)2013,JPO&INPIT |
