This 135mm full-frame F 1.8 lens delivers extremely narrow depth of field and breathtaking g Master bokeh. It employs a new state-of-the-art optical design which maintains high corner-to-corner resolution throughout the focus range, even at F 1.8 maximum aperture, using an XA, super ED and ED glass elements along with four XD linear focus motors to drive two focus groups for fast, quiet and precise autofocus.