| 摘要 |
PROBLEM TO BE SOLVED: To reduce the fluctuation of various kinds of aberration from an infinite distance to a close distance of a photographing magnification of about 0.15. SOLUTION: The lens is constituted of a 1st lens group G1 whose refractive power is positive, a 2nd lens group G2 whose refractive power is positive or negative, and a 3rd lens group G3 whose refractive power is positive in order from an object side, and at focusing, the 1st lens group G1 is fixed, and the 2nd lens group G2 and the 3rd lens group G3 are moved along an optical axis A, and the moving speed of the 3rd lens group G3 is made higher than that of the 2nd lens group G2.
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