It's lens converted for PL Mount by a professional lens technician.Fine adjusted for correct work with cameras PL-mount.Focusing in full range, including infinity.This lens was developed basing on Biotar 2/58 (Carl Zeiss Jena) lens. Focal length:58mmRelative aperture : f/2Frame size:24x36mm.Focusing:from 0.5m to infinity. Focusing in full range, including infinity. On all focal lengths. Filter mount:M49x0,5