| 摘要 |
A lens system includes a first lens with positive refractive power and a second lens with positive refractive power, and an image plane. The first lens includes a first surface and a second surface from the object-side to the image-side of the lens system. The lens system satisfies the conditions: D/TTL>1.18; 1.5<F1/F<1.7; 0.15<R2/(F1)2<0.25; wherein, D is a diameter of an effective imaging range of the image plane; TTL is a total length of the lens system, R2 is a radius of curvature of the second surface, F1 is a focal length of the first lens; F is a focal length of the lens system.
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