| 摘要 |
A lens system includes a first, a second and a third lenses, and an image plane. The lens system satisfies the formulae: FB/TTL>0.30; G1R2/F1>19.54; and D1/D2<1.62. FB denotes a distance between a nearest point of an image-side surface of the third lens relative to the image plane and the image plane, TTL denotes the total track length of the lens system, G1R2 denotes the curvature radius of the vertex of an image-side surface of the first lens, F1 denotes the focal length of the first lens. D1 denotes an orthogonal distance between a farthest point of an image-side surface of the second lens relative to an optical axis of the lens system and a central point of the image-side surface of the second lens, along a direction substantially perpendicular to the optical axis. D2 denotes an orthogonal distance between the farthest point and the central point along the optical axis.
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