| 摘要 |
An intermediate telephoto lens system includes a first lens group and a second lens group. The first lens group includes a first lens element, a second lens element, a third lens element, an aperture stop, cemented lens elements constituted by a fourth lens element and a fifth lens element, and a sixth lens element. The second lens group includes a seventh lens element and an eighth lens element. Upon focusing, only the first lens group moves along the optical axis. The intermediate telephoto lens system satisfies the following condition: (nu'1-1+nu'1-2)/2>102 . . . (1); nu'1-1: the dispersion ratio of the first lens element; nu'1-2: the dispersion ratio of the second lens element; nu'=(nd-1)/(ng-nF); nd: the refractive index of the d-line for each lens element; ng: the refractive index of the g-line for each lens element n the refractive index of the F-line for each lens element.
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