| 摘要 |
PURPOSE: To provide a photographing lens composed of two spherical lenses and can be used by the viewing angle of a standard lens having a half viewing angle of 15 deg.-30 deg.. CONSTITUTION: This lens is composed of two spherical lenses arranging a negative meniscus lens 11 whose convex surface confronts the side of an object surface 13 in the front and a positive convex lens 12 in the rear. By representing the radii of curvature of the front and the rear surfaces of the meniscus lens 11 by r1 , r2 , the radius of curvature of the rear surface of the convex lens 12 by r4 , the distance of air gap between two lenses by d2 and the focal distance of two lens system by (f), the conditions: 0.8<|r1 /r2|<2.0, 0.6<|r1 /r4|<2.0, 0.2<|d2 /f|<1.0 are satisfied.
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