| 摘要 |
A large aperture, medium telephoto lens system is disclosed which is composed of a front group GF that comprises, in order from the object side, at least two positive lens elements having a strong convex surface directed toward the object and a negative lens having a strong concave surface directed toward the image and which has a positive overall refractive power, and a rear group GR with a surface SR1 which is the closest to the object being convex toward the object and which the a positive overall refractive power, with only the rear group GR being moved along the optical axis to perform focusing operations.
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