| 摘要 |
PURPOSE:To expand a power variation range by varying the refracting power of a lens group while holding the image formation position of the whole system at a constant position and shifting the focal length variable range of the whole system by power variation. CONSTITUTION:The focal length (f) of the whole system is V.fR, where V is afocal power and fR is the focal length of an image formation system 14. In general, the afocal power is varied variously to vary the focal length (f) of the whole system. Further, the focal length f' of the whole system is varied to V.fR' by varying the focal length fR of the image formation system 14 to fR' to shift the focal length variable range of the whose system. The focal length of this image formation system is varied by using a transparent elastic body such as silicone rubber for two hatched lenses in a front lens group 141 and a rear lens group 142, and controlling the lens shapes of those lenses and varying them in refracting power. |
