| 摘要 |
<P>PROBLEM TO BE SOLVED: To obtain a zoom lens system with a short total lens length, which is light weight, easily manufactured at small expense and has spherical aberration corrected well. <P>SOLUTION: The zoom lens system is composed of: a first lens group with positive refractive power; a second lens group with negative refractive power; a third lens group with positive refractive power; and a fourth lens group, in this order from an object side. In this case, the third lens group is composed of: a positive single lens; a doublet lens of a positive lens and a negative lens positioned in this order from the object side with negative refractive power as a whole; and a positive single lens, in this order from the object side and the next conditional expressions (1) and (2) are satisfied. (1) -0.5<G3Fmw<-0.15 and (2) 0.35<(R2+R1)/(R2-R1)<0.65 where G3Fmw represents lateral magnification of the positive single lens on the object side in the third lens group at infinite distance focusing in a short focal distance end, R2 represents curvature radius of a surface on an image side of the positive single lens on the object side in the third lens group, and R1 represents curvature radius of a surface on the object side of the positive single lens on the object side in the third lens group. <P>COPYRIGHT: (C)2013,JPO&INPIT |
