A zoom lens includes a first lens group and a second lens group disposed between the first lens group and an image side. The first lens group has three lenses. Refractive powers of the three lenses arranged from an object side to the image side are respectively negative, negative, and positive. The second lens group has five lenses. Refractive powers of the five lenses arranged from the object side to the image side are respectively positive, negative, positive, negative, and positive. Effective focal lengths (EFL) of the first and the second groups are respectively f1 and f2. The EFL of the zoom lens is fw when the zoom lens is switched to a wide end. The zoom lens satisfies −2.8