Prime lens

A prime lens comprises an aperture, a first lens group and a second lens group. The first lens group is arranged between a first side and the aperture. The first lens group comprises a first lens and a second lens. The first lens is arranged between the first side and the second lens, the first lens and the second lens are two lenses which are closest to the first side and have diopters, and the first lens and the second lens are plastic lenses. The second lens group is arranged between a second side and the aperture. The second lens group comprises a first combined lens and a second combined lens. The aperture partitions the first lens group and the second lens group. 一种定焦镜头，包括一光圈、一第一透镜组以及一第二透镜组。第一透镜组设于一第一侧与光圈之间，第一透镜组包括一第一透镜以及一第二透镜。第一透镜设于第一侧与第二透镜之间，第一透镜及第二透镜为最靠近第一侧的二片具屈光度的透镜，且第一透镜及第二透镜为塑胶透镜。第二透镜组设于一第二侧与光圈之间，第二透镜组包括一第一组合透镜以及一第二组合透镜。光圈区隔第一透镜组及第二透镜组。