| 摘要 |
PURPOSE:To make the whole lens length less than about 2.2 times a focal distance on he zooming position of a telephotographic end at 1.2F number brightness by forming four lens groups consisting of positive, negative, negative and positive lens groups from the object side, constituting the 4th lens group by two lens groups and satisfying these lens groups with specific conditional formulas. CONSTITUTION:The 1st lens group I has positive refractive power to be used for focusing, the 2nd lens group II has negative refractive power and a power modifying function, the 3rd lens group III has negative refractive power to compensate an image surface varied by the power modification, and the 4th lens group IVhas two lens groups consisting of the 41-th lens group IV1 and the 42-th lens group IV2; the 41-th lens group IV1 is constituted of 4 lenses consisting of the 411-th-the 414-th lenses, the 42-th lens groups is constituted of the 421-th-423-th lenses and these lenses are constituted so as to satisfy specific conditional formulas. |
