| 摘要 |
A compact zoom lens is provided to obtain a high magnification ratio as well as telecentric characteristics and high optical performance. A first lens group(100-1), a second lens group(110-1), and a third lens group(120-1) which are arranged in orders from an object side. The first lens group has a negative refractive index. The second lens group has a positive refractive index and an iris. The third lens has a positive refractive index. The first, second, and third lens groups are moved in a process for changing a magnification from a wide-angle stage to a telescopic stage. The second lens group includes a cemented lens including a double-faced convex lens having a positive refractive index and a meniscus lens having an upper convex surface and a negative refractive index. The second group lens further includes a meniscus lens having a convex surface to the object side and a negative refractive index.
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