| 摘要 |
The invention concerns a compact optical system that is made up of a reduced number of lens elements with a bendable optical path and so is compatible with miniature image pickup devices used with cellular phones, etc. The image pickup lens of the invention comprises, in order from its object side, a first lens element L101 having negative refracting power, a second lens element L102 having positive refracting power, a stop S1, a third lens element L103 having negative refracting power and a fourth lens element L104 having positive refracting power, and satisfies the following conditions (1) and (2). 50>vd1-vd2>10 (1) 2>f/f3>0.35 (2) Here vd1 is the d-line reference Abbe number of the first lens element, vd2 is the d-line reference Abbe number of the second lens element, f is the focal length of the image pickup lens, and f3 is the composite focal length of the third and fourth lens elements. Between the first and the second lens element there is interposed a reflecting surface.
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