| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical system having high optical performances capable of favorably correcting various aberrations such as color aberration and the like. <P>SOLUTION: The optical system includes, from an object side to an image side, a first lens group L1 having positive refractive power, an aperture diaphragm SP, and a rear group LR, in which the rear group LR includes a second lens group L2 that moves upon focusing, and the first lens group L1 includes n (where n is an integer of 2 or more) positive lenses and one or more negative lenses. In the optical system, the following factors are each appropriately determined, where i represents an order counted from the object side: a refractive index Ndi (i=1, 2,..., n) and an Abbe number νdi (i=1, 2,..., n) of the material of the i-th positive lens in the first lens group with respect to d-line; the maximum max(νdi) and the minimum min(νdi) of the Abbe number νdi; the minimum min(Ndi) of the refractive index Ndi; a focal length fp of the first lens group; and a focal length f of the whole system. <P>COPYRIGHT: (C)2012,JPO&INPIT |
