| 摘要 |
A zoom lens system, in order from an object side to an image side, comprising: a negative first lens unit; a positive second lens unit; a negative third lens unit; and a positive fourth lens unit, wherein the first, second and third lens units move along an optical axis in zooming, the third lens unit moves along the optical axis in focusing, and the conditions: 2.5≦|(1−(β3T)2)×(β4T)2|≦7.0 and 0.5≦BfW/fW≦4.0 (β3T: a lateral magnification of the third lens unit at an infinite object point distance at the telephoto limit, β4T: a lateral magnification of the fourth lens unit at an infinite object point distance at the telephoto limit, BfW: a back focal length of the zoom lens system at the wide-angle limit, fW: a focal length of the zoom lens system at the wide-angle limit) are satisfied. |
