Patent ID: 7502179

Claim:
A fixed-focus lens, comprising: a first lens group, having a negative refractive power, and comprising a first lens, a second lens and a third lens arranged in sequence from an object side to an image side, wherein the first lens is an aspheric lens; a second lens group, disposed between the first lens group and the image side and having a positive refractive power, the second lens group comprising two lenses arranged from the object side to the image side; and a third lens group, disposed between the second lens group and the image side and having a positive refractive power, the third lens group comprising six lenses arranged from the object side to the image side, wherein refractive powers of the lenses of the third lens group in sequence from the object side to the image side are negative, positive, negative, positive, positive and positive, wherein F is an effective focal length of the fixed-focus lens, F 1 is an effective focal length of the first lens group, F 2 is an effective focal length of the second lens group, F 3 is an effective focal length of the third lens group, and 0.2<|F 1 |/F<3, 0.5<F 2 /F<3, and 0.5<F 3 /F<3.5.