| 摘要 |
PURPOSE:To photograph an object at a long distance more vividly by placing a lens system having a negative power before a photographic lens system to correct the focus for photographing of the object at a long distance. CONSTITUTION:For the purpose of photographing vividly an object at a long distance in an auto-focus lens shutter camera, a fixed-focus lens shutter camera, or the like, the light from the object in the inifinity is refracted by an attachment lens L1 having a weak negative power to form a virtual image of the object in the infinity in a position P of the farthest photographic distance of the camera, and this virtual image is focused onto a film surface F by a photographic lens system L2 of the camera to photograph the object in the infinity vividly. In this case, since a plano-concave and plano-convex lenses different in refractive index are stuck to each other, refractive indexes and radiuses of curvature of stuck faces of them are selected properly to determine the focal length of the whole of the system. |
