Imaging lens and electronic apparatus including the same

1. An imaging lens comprising a first lens element, an aperture stop, a second lens element, a third lens element, a fourth lens element and a fifth lens element arranged in order from an object side to an image side along an optical axis of said imaging lens, each of said first lens element, said second lens element, said third lens element, said fourth lens element and said fifth lens element having a refractive power, an object-side surface facing toward the object side, and an image-side surface facing toward the image side, wherein:

said first lens element has a negative refractive power, and said image-side surface of said first lens element has a concave portion in a vicinity of a periphery of said first lens element;

said object-side surface of said second lens element has a convex portion in a vicinity of a periphery of said second lens element, and said image-side surface of said second lens element has a convex portion in a vicinity of the periphery of said second lens element;

said third lens element is made of a plastic material;

said object-side surface of said fourth lens element has a concave portion in a vicinity of the periphery of the fourth lens element, and said image-side surface of said fourth lens element has a convex portion in a vicinity of a periphery of said fourth lens element;

said object-side surface of said fifth lens element has a concave portion in a vicinity of a periphery of said fifth lens element; and

said imaging lens does not include any lens element with refractive power other than said first lens element, said second lens element, said third lens element, said fourth lens element and said fifth lens element, and satisfies 1.5≦(G12+G45)/T3≦5 and T3/G12≦1.1, where G12 represents an air gap length between said first lens element and said second lens element at the optical axis, G45 represents an air gap length between said fourth lens element and said fifth lens element at the optical axis, and T3 represents a thickness of said third lens element at the optical axis,

wherein an Abbe number of said first lens element is smaller than an Abbe number of said fifth lens element.

2. The imaging lens as claimed in claim 1 , further satisfying (G12+G23)/EFL≦3, where G23 represents an air gap length between said second lens element and said third lens element at the optical axis, and EFL represents a system focal length of said imaging lens.

3. The imaging lens as claimed in claim 2 , further satisfying T2/G23≦20, where T2 represents a thickness of said second lens element at the optical axis.

4. The imaging lens as claimed in claim 1 , further satisfying T1/T5≦7.0, where T1 represents a thickness of said first lens element at the optical axis, and T5 represents a thickness of said fifth lens element at the optical axis.

5. The imaging lens as claimed in claim 4 , further satisfying EFL/G23≦100, where EFL represents a system focal length of said imaging lens, and G23 represents an air gap length between said second lens element and said third lens element at the optical axis.

6. The imaging lens as claimed in claim 1 , further satisfying T4/G23≦20, where T4 represents a thickness of said fourth lens element at the optical axis, and G23 represents an air gap length between said second lens element and said third lens element at the optical axis.

7. The imaging lens as claimed in claim 6 , further satisfying 1.0≦ALT/Gaa≦3.0, where ALT represents a sum of thicknesses of said first lens element, said second lens element, said third lens element, said fourth lens element and said fifth lens element at the optical axis, and Gaa represents a sum of four air gap lengths among said first lens element, said second lens element, said third lens element, said fourth lens element and said fifth lens element at the optical axis.

8. The imaging lens as claimed in claim 1 , further satisfying T5/G23≦20, where G23 represents an air gap length between said second lens element and said third lens element at the optical axis, and T5 represents a thickness of said fifth lens element at the optical axis.

9. The imaging lens as claimed in claim 8 , further satisfying (G12+G34)/T3≦20, where G34 represents an air gap length between said third lens element and said fourth lens element at the optical axis.

10. The imaging lens as claimed in claim 1 , further satisfying Gaa/G23≦30, where G23 represents an air gap length between said second lens element and said third lens element at the optical axis, and Gaa represents a sum of four air gap lengths among said first lens element, said second lens element, said third lens element, said fourth lens element and said fifth lens element at the optical axis.

11. The imaging lens as claimed in claim 10 , further satisfying 0.4≦(G34+G45)/T1≦1.7, where G34 represents an air gap length between said third lens element and said fourth lens element at the optical axis, and T1 represents a thickness of said first lens element at the optical axis.

12. The imaging lens as claimed in claim 1 , further satisfying (G12+G45)/T5≦7, where T5 represents a thickness of said fifth lens element at the optical axis.

13. The imaging lens as claimed in claim 12 , further satisfying ALT/G23≦60, where G23 represents an air gap length between said second lens element and said third lens element at the optical axis, and ALT represents a sum of thicknesses of said first lens element, said second lens element, said third lens element, said fourth lens element and said fifth lens element at the optical axis.

14. The imaging lens as claimed in claim 1 , further satisfying T1/G45≦10, where T1 represents a thickness of said first lens element at the optical axis.

15. An electronic apparatus comprising:

a housing; and

an imaging module disposed in said housing, and including an imaging lens as claimed in claim 1 , a barrel on which said imaging lens is disposed, a holder unit on which said barrel is disposed, and an image sensor disposed at the image side of said imaging lens.