| 摘要 |
PURPOSE:To improve the balance in performance from the unmagnification to reduction or from the unmagnification to magnification of a lens system, by introducing asymmetry to the lens system for copying. CONSTITUTION:A lens system consists of the 1st lens of a biconvex positive lens, the 2nd lens of a biconcave negative lens, a stop, the 3rd lens of a biconcave negative lens, and the 4th lens of a biconvex positive lens, successively from an object side in the case of using said system from the variable powers from the unmagnification to reduction and successively from an imaging plane side in the case of using the same for variable powers from the unmagnification to magnification, and the shape of the lens system satisfies the condition 4 for asymmetry. Here, q1+q2+q3+q4=0 holds for a symmetrical lens system, but with this lens system, the asymmetrical type of the lens system wherein said value has a slight negative value is incorporated. The balance in the performance of the lens system from the unmagnification to reduction or from the unmagnification to magnification is thus improved. |
