| 摘要 |
PURPOSE:To obtain a compact wide-angle zoom lens while improving aberration corrections by satisfying specific condition between the focal length of the whole system and the distance between the wide-angle end and telephoto end of two lens groups. CONSTITUTION:The zoom lens consists of the 1st diverging lens group and the 2nd converging lens group successively from the object side and zooms by varying the air gap between the 1st lens group and the 2nd lens group. The 2nd lens group moves to the object side monotonously and the 1st lens group moves nonlinearly at the same time while maintaining the position of an image surface; when the difference between the distance of the wide-angle end of the 1st lens group from the image surface and the distance of the telephoto end from the image surface is denoted as DELTAL and the focal length of the whole system at the telephoto end is denoted as Ft, the lens is compacted and the negative distortion at the wide-angle end if the expression holds. |
