Document Type and Number:
Japanese Patent JPS50110630
Kind Code:
A
Abstract:
A projection lens system comprises a positive meniscus lens G1 (as numbered consecutively from front to rear) convex to the front, a biconcave lens G2, a biconvex lens G3, a positive meniscus lens G4 convex to the front, and a biconcave lens G5. The projection lens system is designed to be well matched with the halogen lamp of cold mirror type in which the distance to the secondary focus is short by using a negative lens at the rear end thereof, making the Petzval sum small, locating the entrance pupil as near to the aperture as possible and shortening the back focal distance. The image surface is made flat and spherical aberration and astigmatism are well corrected. The high order comatic flares are markedly reduced and an image of high sharpness and contrast can be obtained thereby. Further, the radii of curvature of all the surfaces in the lens system are made not smaller than 0.68f so that the lenses can be manufactured at a low cost.
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Application Number:
JP1602374A
Publication Date:
August 30, 1975
Filing Date:
February 08, 1974
Export Citation:
International Classes:
G02B9/60; G02B13/24; (IPC1-7): G02B9/60