| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a zoom lens and an optical device including the same, which provides satisfactorily high optical performance even when a solid state imaging device with high variable power ratio including many pixels is used. <P>SOLUTION: A zoom lens comprises, from the object side in order: a first lens group having a positive refractive power, which is immovable in an optical direction for varying power and focusing; a second lens group having a negative refractive power, which has a function of varying power; a third lens group having a positive refractive power; and a fourth lens group having a positive refractive power, which has a correcting function of an image plane which varies due to variation of power and a focusing function. The first lens group includes one or more negative lens and plural positive lens. Abbe number ν- of material for one negative lens in the first lens group, a partial dispersion ratio Pgf-, average Abbe number ν+ of the material for plural positive lenses in the first lens group, a focal distance of the first lens group f1 and a focal distance f1 N of negative lens in the first lens group are appropriately set respectively. <P>COPYRIGHT: (C)2012,JPO&INPIT |
