| 摘要 |
PROBLEM TO BE SOLVED: To provide a large-sized aperture medium telephoto lens configured, such that an actuator for performing focusing can be housed inside a lens barrel, high performance level is exhibited, even when focusing, and various aberrations are corrected satisfactorily. SOLUTION: The large-sized aperture medium telephoto lens includes, in the order starting from the object side, a first lens group L1 having positive refractive power as a whole, and a second lens group L2 having a positive refractive power as a whole; the first lens group L1 includes a 1a-th lens group L1a, having a positive refractive power and a 1b-th lens group L1b. The 1a-the lens group L1a includes, in the order starting from the object side, at least two positive lenses, and a lens component having negative refractive power and having a lens surface in which the lens face closest to an image is concave in shape as going toward the side of the image. The 1b-th lens group L1b has a lens component, in which the lens face on the object side is concave as going toward the object side. In focusing from an infinity object to a proximity object, the second lens group L2 moves in the direction of an optical axis toward the object side, and satisfies a predetermined conditional expression. COPYRIGHT: (C)2011,JPO&INPIT |
