| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an imaging lens comprising four lenses, which has various aberrations corrected well though it is made smaller in size than the conventional type one; and to provide an imaging unit and a personal digital assistant which are equipped with the same. Ž<P>SOLUTION: A conditional expression (1) is prepared to appropriately achieve shortening of the entire length of the imaging lens and correction of the aberration by appropriately setting a synthetic focal length of a first lens and a second lens. By making a value f12/f less than an upper limit of the conditional expression (1), the positive synthetic focal length of the first lens and the second lens is properly maintained, and the shortening of the entire length of the lens is achieved. Meanwhile, by making the value f12/f more than a lower limit thereof, the positive synthetic focal length of the first and second lenses does not get too large, and high order spherical aberration and coma aberration are prevented from occurring. More desirably, such a value may be in a range of a following expression. (1) 1.15<f12/f<1.75. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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