This 135mm full-frame F1.8 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 F1.8 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.