| 摘要 |
A zoom optical system comprises, in order from an object side, a first lens unit having positive refractive power, a second lens unit having positive refractive power, and a third lens unit having negative refractive power. A magnification is changed from a wide-angle position to a telephoto position by moving the lens units toward the object side so as to widen an airspace between the first lens unit and the second lens unit and narrow an airspace between the second lens unit and the third lens unit. The zoom optical system satisfies the following conditions:where fW represents a focal length of the zoom optical system at the wide-angle position, fT represents a focal length of the zoom optical system at the telephoto position, LT represents a distance as measured from a most object side surface to an image surface on an optical axis at the telephoto position, fG1 represents a focal length of the first lens unit, fG2 represents a focal length of the second lens unit, and fG3 represents a focal length of the third lens unit.
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