| 摘要 |
PURPOSE: A zoom lens system with a high zoom ratio is provided to be capable of having a high zoom ratio of more than 3.5 and of being compacted. CONSTITUTION: When viewed from the object side, a first lens group with a positive refractive power, a second lens group with a positive refractive power and a third lens group with a negative refractive power are arranged on a common optical axis. The first lens group includes a first lens(11) with a negative refractive power, a second lens(12) whit a positive refractive power a third lens(13) with a positive refractive power. The second lens group includes a fourth biconcave lens(21) with a negative refractive power, a fifth biconvex lens(22) which is cemented to the fourth lens(21) and has a positive refractive power, a sixth lens(23) which has a positive refractive power, a seventh meniscus lens(24) which is cemented to the sixth lens and has a negative refractive power an eighth lens(25) which has a positive refractive power and a convex surface facing the image side. The third lens group includes a ninth lens(31) which has a positive refractive power and a convex surface facing the image side, a tenth lens(32) which is cemented to the ninth lens(31) and has a negative refractive power and a concave surface facing the object side and an eleventh meniscus lens(33) which has a negative refractive power and a convex surface facing the image side.
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