| 摘要 |
A zoom lens system comprising a first positive lens unit, a second negative lens unit, a third positive lens unit and a fourth positive lens unit, and configured to change a magnification by moving the first lens unit toward the object side, moving the second lens unit so as to widen an airspace between the first lens unit and the second lens unit, moving the third lens unit so as to narrow an airspace between the second lens unit and the third lens unit. This zoom lens system has a vari-focal ratio of 4.5 or higher, a compact design, a small number of lens elements, a field angle of 65° or larger and high performance over an entire vari-focal range.
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