| 摘要 |
Projection lens systems for use in projection televisions are provided. The lens systems include a strong positive element which provides a majority of the power of the lens, a strong negative unit which provides most of the correction for the field curvature of the lens system, and four weak meniscus aspherical elements, two on each side of the positive element. By means of this arrangement, the lens system achieves a semi-field of view of approximately 40 degrees at a f-number of about 1.0 or less. The lens systems are used to minimize the size of projection television sets since their semi-field of view of approximately 40 degrees substantially matches the maximum numerical aperture of about 0.65 of projection screens used in such sets.
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