| 摘要 |
PURPOSE:To realize a compact constitution while holding manufacturing precision easily, by using >=4 lens groups, moving the 1st and the 2nd lens groups independently for zooming, and giving the 2nd lens group image-formation magnifications including unmagnification. CONSTITUTION:This zoom lens system consists of four lens groups, i.e. the 1st positive lens group of lenses R1-R5, the 2nd negative lens group of lenses R6- R10, the 3rd positive lens group of R11-R15, and the 4th positive lens group of R17-R25 from an objective side. For zooming, the 1st and the 2nd lens groups are moved independently of each other. Therefore, the 2nd lens group of R6- R10 is fixed during zooming, so the manufacturing precision is held high. Further, the image-formation magnefications of the 2nd lens group of R6-R10 includes unmagnification in a zooming area, so the compact structure is realized. |
