| 摘要 |
PURPOSE:To obtain a variable power lens for copying, having the variable power ratio of two times or more such as 1.4X-0.6X, which is made small in size and low in cost, while taking an easy assembly into consideration, by including a half view angle 30 deg. class, and also constituting said lens of five groups and seven pieces. CONSTITUTION:A first lens group (a first lens) and a third lens group (a seventh lens) consist of one piece of negative meniscus lens whose concave surface is faced to the side of an object to be photographed and an image side, respectively, and a second lens group consists of three groups and five pieces wwhich places a conjugated lens consisting of negative meniscus lenses (a third and a fifth lenses) whose concave surfaces are faced to the center, and positive meniscus lenses (a second and a sixth lenses) whose concave surfaces are faced to the center in the same way, in both its outsides, centering around a positive biconvex lens (a fourth lens), and the whole system consists of five groups and seven pieces. Also, in a variable power lens for copying constituted in this way, it is constituted so as to satisfy the conditions required by the equations shown. Also, as for the variabble power lens for copying, the shape of each lens is symmetrical.
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