| 摘要 |
PURPOSE: A zoom lens is provided, which is easily manufactured in a small size with having a high optical performance by using a plastic lens as a photograph optical system of a camera. CONSTITUTION: A zoom lens includes a first group of lenses(I) having a negative refractive force, a second group of lenses(II) having a positive refractive force and a third group of lenses(III) having a positive refractive force. The first group of lenses(I) includes at least one of plastic lenses and the first, the second and the third groups of lenses(I,II,III) move from the lens side to the tele-side. And, the zoom lens satisfies the following equation: wherein the fw is an overall focus length at the side of lens, the ft is the overall focus length of the tele-side, the f1 is the focus length of the first group of the lenses and the f2 is the focus length of the second group of the lenses.
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