Patent ID: 10151903

Abstract:
A telephoto lens includes, from an object-side to an image-side: a first lens having a positive refractive power, wherein an object-side surface of the first lens is convex, an image-side surface of the first lens is convex; a second lens having a refractive power; a third lens having a refractive power, wherein the third lens includes plastic material, each of an object-side and an image-side surface of the third lens is aspheric; a fourth lens having a refractive power, wherein an object-side surface of the fourth lens is convex, the fourth lens includes plastic material, and each of the object-side and image-side surfaces of the fourth lens is aspheric; wherein, the telephoto lens satisfies: 0.7<TTL/f<0.95, and |f4/f|≥1.2; where TTL is distance from the first lens' object-side surface to an imaging plane; f is effective focal length of the telephoto lens, and f4 is effective focal length of the fourth lens.