| 摘要 |
PURPOSE:To obtain a zoom lens whose aberration has been corrected satisfactorily by constituting so that a lens system formed by placing a relay lens system, following a variable power system consisting of a focusing part, a variator part and a compensator part having refractive powers of positive, negative and positive, respectively, in order from an object side satisfies prescribed conditions. CONSTITUTION:A relay lens system IV following a focuing part I , a variator part II and a compensator part III consists of the first group lens IVa which contains lens components of positive and negative and is positive as a whole, the second group lens IVb of a positive lens component, the third group lens IVc of a negative meniscus lens whose convex surface is faced to an image side, and the fourth group lens IVd of positive. This lens is made to satisfy conditions of an expression I and an expression II, and in the expressions, f4a, f4, f4c, and f4bcd denote a focal distance of the first group lens VIa of the relay lens system VI, a focal distance of the third group lens VIc of the relay lens system VI, and a composite focal distance of a relay lens system VI, a focal distance of the second, the third and the fourth group lenses VIb, VIc and VId of the relay lens system VI.
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