| 摘要 |
A retrofocus lens system comprises a first lens group having a negative power, a second lens group having a positive power, and a third lens group having a positive power. The first lens group includes a first lens, a meniscus-shaped second lens having a negative power and a convex surface facing the large conjugate side, a third lens having a negative power, and a fourth lens. The second lens group includes a fifth lens having a positive power. The third lens group includes a sixth lens having a negative power, both surfaces of which are concave, a seventh lens having a positive power, both surfaces of which are convex, an eighth lens having a positive power, both surfaces of which are convex, and a ninth lens having a positive axial power. The system satisfies 0.9<f2/f3<1.8, 1.5<|f1|/f<2.7, |f4|/f>30, and f5/f>6, where f is a focal distance of the whole lens system, |f1| is an absolute value of a focal distance of the first lens group, f2 is a focal distance of the second lens group, f3 is a focal distance of the third lens group, |f4| is an absolute value of a focal distance of the first lens, and f5 is an axial focal distance of the ninth lens.
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