Large F1.8 maximum aperture.

7-blade circular aperture creates beautiful defocused bokeh and great in low light.

Aspherical element controls spherical aberration and chroma.

Double-Gauss configuration suppresses field curvature & distortion

Metal mount adds solid durability as well as a sophisticated feel

Fast DC motor focus actuator system drives all lens groups

Personally I recommend this more for stills than video because of the internal motor.

If you are going to record video with this lens I'd highly recommend you have an external recording device.