| 摘要 |
PURPOSE: A zoom lens is provided to obtain a lens low in cost and small in size and weight, while achieving a high optical performance. CONSTITUTION: A zoom lens comprises the first lens unit(10) constituted by the first lens(11) made up of a plastic material, and which has a meniscus object side surface and an aspheric upper surface, and the second lens(12) having concave side surfaces, wherein the first lens unit has a positive refractive power; the second lens unit(30) constituted by the third lens(31) having a positive meniscus object side surface and the fourth lens(32) having a negative meniscus object side surface, wherein the second lens unit has a negative refractive power; and an iris diaphragm(20) interposed between the first lens unit and the second lens unit so as to adjust the amount of light incidence from the first lens unit. The first lens unit and the second lens unit move toward the object so as to reduce the spacing between two units, and two or more plastic lenses are employed from among four lenses, upon variation of power from the wide-angle end and the telephoto end.
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