| 摘要 |
PURPOSE:To reduce the size and weight of a titled lens by making effective use of spherical shapes and determining respective focal lengths so as to satisfy specific conditions. CONSTITUTION:This lens is constituted, successively from an object side, of a 1st lens which is a negative single lens convex on the object side, a 2nd lens which is a negative single lens convex on an image side, a 3rd lens which is a positive single lens, 4th lens and 5th lenses which are two pieces of positive single lenses, a 6th lens which is a negative single lens, and two pieces of 7th lens and 8th lens the combined focal length of which is positive. The lens satisfies the conditions expressed by the equations. In the equations, fw is the focal length of the entire system at a wide angle end; f1, f2, f3, f4, f5 respectively denote the combined focal length of the 1st lens and the 2nd lens, the focal length of the 3rd lens, the combined focal length of the 4th lens and the 5th lens, the focal length of the 6th lens, and the combined focal length of the 7th lens and the 8th lens. The zoom lens of 8-elements constitution for a video camera which has about 1.5 F-number, about 2-times zoom ratio, is compact and has good performance is thereby obtd. and the considerable reduction in the size and weight thereof is attained.
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