| 摘要 |
A zoom lens system is disclosed which includes, in order from an object side to an image side, a first lens unit, a second lens unit, a third lens unit and a fourth lens unit which have a positive, negative, positive and positive optical power, respectively, and at least the first, third and fourth lens units move during zooming so that the distance between the first and second lens units increases, the distance between the second and third lens units decreases and the distance between the third and fourth lens units decreases at the telephoto end compared to the wide-angle end. Then, by appropriately setting lens elements constituting each lens unit and focal lengths of the lens units which move during zooming, the present invention realizes high optical performance over the entire zooming range and entire image area while achieving a desired zoom ratio.
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