| 摘要 |
PURPOSE:To move a lens system with small driving force and to improve its delineation performance from infinite distance to the closest distance by moving the 3rd lens group and the 4th lens group in an optical-axis direction for focusing and satisfying inequalities I and II. CONSTITUTION:The photographic lens consists of the 1st lens group I with positive refracting power, the 2nd lens group II composed of a single negative meniscus lens having the convex surface on an object surface, the 3rd lens group IIIcomposed of at least one negative lens and one positive lens, the 4th lens group IVcomposed of at least one positive lens, and the 5th lens group l composed of at least one negative or positive lens. The 3rd lens group III and the 4th lens group IV are moved in the optical axis direction to peform focusing and the inequalities I and II hold. |
