| 摘要 |
A telephoto objective lens consisting of a positive front lens group and a negative rear lens group which is divided into sub-groups, the rear one being movable for focusing and the front one remaining stationary, thereby the weight of the complete objective is minimized. As the front lens group consists of only one positive and only one negative lens element, since the provision for focusing is made at such lens, this objective lens tends to produce aberrations of which the spherical and comatic aberrations are particularly deteriorated. According to the invention, therefore, the frontmost surface and rearmost surface of the front lens group and the rearmost surfce of the movable sub-group are specified in radius of curvature to achieve good stability of correction of the aberrations throughout the focusing range.
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