| 摘要 |
The invention provides a high-performance, bright and compact triplet that has a zoom ratio of about 1.05 with an wide field angle, said triplet comprising, in order from the object side, a first lens L1 consisting of a positive single lens of glass in a meniscus form convex on the object side, a second lens L2 located with an air separation between it and said first lens L1 and consisting of a negative single lens of glass, a third lens L3 located with an air separation between it and said second lens L2 and consisting of a positive single lens of glass in a double-convex form, and an aperture stop S located on the image side of said third lens, at least two of said first to third lenses having aspherical surfaces, and conforming to the following conditions n1>1.6, n3>1.6 wherein n1 and n3 are the refractive indices of said first and third lenses, respectively.
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