Patent ID: 8792187

Claim:
An imaging lens having an object side and an imaging side, the imaging lens comprising: a first plastic lens element that is biconvex, has a positive focusing power, and an object-side surface facing the object side; a second plastic lens element that is biconcave and has a negative focusing power and an abbe number not greater than 30, said second plastic lens element being adjacent to said first plastic lens element; a third plastic lens element that has a positive focusing power and a convex imaging-side surface facing toward the imaging side, said third plastic lens element being adjacent to said second plastic lens element; a fourth plastic lens element that has an imaging-side surface facing toward the imaging side with a concave area in a vicinity of an optical axis of said fourth plastic lens element, said fourth plastic lens element being adjacent to said third plastic lens element; an aperture stop disposed between said first and said second plastic lens elements; and an imaging plane disposed at the imaging side, wherein said imaging lens further satisfies the optical conditions of: 0.7<f 1 /f≦1.1, wherein f represents a focal length of said imaging lens and f 1 represents a focal length of said first plastic lens element, and TL/f<1.5, wherein TL represents a distance between said object-side surface of said first plastic lens element and said imaging plane, and wherein said imaging lens does not include any lens element with focusing power other than said first, second, third, and fourth plastic lens elements.