| 摘要 |
A small zoom lens makes possible short distance focusing with a high zoom ratio and high performance using a simple lens barrel. A focusing second lens unit moves along the optical axis during focusing to the short distance object; a first lens unit is adjacent to and on the object side of the focusing lens unit; and a third lens unit is adjacent to and on the image side of the focusing lens unit. The second unit lens and the third lens unit move integrally together during zooming between a maximum wide-angle state and a maximum telephoto state. The focusing lens unit moves in conjunction with and relative to the second and third lens units. The first or the third lens unit has a positive focal length and the other has a negative focal length. Additionally, the first and third lens units satisfies the following condition:-0.6<(fa +fb)/(fa-fb)<0.4where fa=focal length of the first lens unit, and fb=focal length of the third lens unit.
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