| 摘要 |
PURPOSE:To obtain a photographic lens having a long back-focal distance, whose comatic flare in each direction of the outside of an axis, and each aberration is corrected satisfactorily, by constituting said lens of six groups and seven pieces, and setting it to a prescribed condition. CONSTITUTION:a titled lens is constituted of six groups and seven pieces of the first group lens and the second group lens of positive meniscus lenses, respectively, the third group lens of a negative meniscus lens, the fourth group lens of a cemented meniscus lens of a negative lens sand a positive lens, the fifth group lens of a positive meniscus lens, and the sixth group lens of a positive lens, in order from an object side, and set to a condition of an expression. In this regard, (f), (fi), (fi-j), (ri) ad (ni) denote a focal distance of the whole system, a focal distance of each lens successively from the object side, a composite focal distance of the lens system extending from the i-th lens to the j-th lens, a radius of curvature of each surface successively from the object side, and a refractive index of each lens successively from the object side, respectively.
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