| 摘要 |
A zoom leas includes a first lens unit of a negative optical power and a second and third lens unit each of a positive optical power. The second lens unit consists of a first and second lens sub unit, each of a positive optical power arranged respectively on an object side and an image side. Zooming is effected by moving the lens units such that the distance between the first and second lens unit is smaller at a telephoto end than at a wide-angle end and that the distance between the second and third lens unit is larger. Focusing is effected by moving the second lens sub unit or the third lens unit where, when focusing on an object at infinity, the distance between the first lens sub unit and the second lens sub unit and the focal length of the entire system satisfy a predetermined condition.
|
