TELEVISION OBJECTIVE WITH DISCRETE CHANGING OF FOCAL LENGTH Russian patent published in 1995 - IPC

FIELD: instrument engineering. SUBSTANCE: objective has four components
motionless positive component, the fourth negative motionless component, the second negative and the third positive components mounted for having capability of introduction into beam pass. Positive motionless component is made in form of positive meniscus turned with its concavity to image, biconvex lens, biconcave lens and positive meniscus turned with its concavity to the image. The second negative component has to be double-glued lens formed by positive meniscus and biconcave lens; positive meniscus is turned to image with its concavity. The third component has negative meniscus-shaped lens turned with its concavity to the image. The lens is turned to the image with its concavity and is glued of biconcave and biconvex lenses. The third component has also positive lens which is glued of negative meniscus turned with its concavity to the image and biconcave lens. Motionless negative fourth component is glued of positive and negative menisci turned with their convexity to the image, and negative single meniscus turned with its concavity to the image. Focal lengths of the components correspond to the relations given in the description of the invention. EFFECT: improved efficiency. 2 dwg