Star filter is one of camera filters, as the center of light emitting, include 2 lines, 4 lines, 6 lines, 8 lines, 16 lines...
Star filters turn point light sources and specular highlights into stars. Commonly seen star filters can generate four to sixteen points stars. A star filter consists of two glasses. The top one is rotatable and has a grid etched into the glass surface. The following image is a four-point star filter. The etched grid is easily seen. The distance between two parallel etched lines is an important factor. More precisely, the wider the distance, the fewer number of stars. This distance can be 1mm to 4mm. The 2mm version is the most common one. Some star filters can even create variable star shapes. That is, in the case of 4-point star, the two etched lines do not have to be perpendicular to each other, and can be rotated to form any desired angle.
Picturn shown is 37mm, 8 lines. We'd like to supply other size filters as per your requested.