Mobile device and optical imaging lens thereof

An optical imaging lens, sequentially from an object side to an image side, comprising an aperture stop, first, second, third, fourth and fifth lens elements, each of the first, second, third, fourth and fifth lens elements having an object-side surface facing toward the object side and an image-side surface facing toward the image side, wherein:

• the image-side surface of the first lens element comprises a concave portion in a vicinity of a periphery of the first lens element;
• the second lens element is made of a plastic material;
• the third lens element is made of a plastic material, has negative refracting power, and the object-side surface of the third lens element has a concave portion in a vicinity of an optical axis;
• the object-side surface of the fourth lens element comprises a concave portion in a vicinity of a periphery of the fourth lens element;
• the object-side surface of the fifth lens element comprises a concave portion in a vicinity of the optical axis;
• the fifth lens element is made of a plastic material;
• and
• the optical imaging lens as a whole has only the five lens elements having refracting power,
• wherein an effective focal length of the optical imaging lens is EFL, a largest air gap among the four air gaps from the first lens element to the fifth lens element along the optical axis is Gmax, and EFL and Gmax satisfy the equation:
• 7.50≤EFL/Gmax.