Patent ID: 7639433

Claim:
A fixed-focus lens comprising: a first lens disposed between an object side and an image side and having a negative refractive power; a second lens disposed between the first lens and the image side and having a positive refractive power; a cemented lens disposed between the second lens and the image side, and consisting of a third lens and a fourth lens arranged in sequence from the object side to the image side, one of the third lens and the fourth lens having a positive refractive power, and the other of the third lens and the fourth lens having a negative refractive power; an aperture stop disposed between the fourth lens and the image side; and a fifth lens disposed between the aperture stop and the image side and having a positive refractive power, wherein each of the first, second, third, fourth, and fifth lens is a spherical lens, an effective focal length of the fixed-focus lens is f, an axial distance between a surface of the first lens facing the object side and a surface of the third lens facing the object side is d, and 2.1<d/f<2.9.