| 摘要 |
PROBLEM TO BE SOLVED: To reduce the fluctuation of various aberrations from an infinite distance to a short distance. SOLUTION: The telephoto lens is composed of a 1st lens group G1 with positive refracting power, a 2nd lens group G2 with negative refracting power, and a 3rd lens group G3 with positive or negative refracting power in order from the object side; and the 1st lens group G1 is composed of at least two positive lenses L1 and L2 and one negative lens L3, the 2nd lens group G2 is composed of a negative lens L4 and a positive lens L5 in order from the object side, and the 3rd lens group G3 is composed of a positive lens L6 and a negative lens L7 in order from the object side. This is telephoto lens is put in focus from an infinite distance to a short distance by moving the 2nd lens group G2 toward an image plane on the optical axis and the positive lens L6 in the 3rd lens group G3 toward the object on the optical axis.
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