Sony SAL85F28 Specification Guide (en)

Excellent Contrast Reproduction
Precision optical design to provide high contrast from image center to periphery.
Smooth Backgrounds
The combination of large F2.8 aperture and circular aperture design delivers smooth, natural 
defocusing effects
SAM (Smooth Autofocus Motor)
Autofocus signals received from the camera body control a motor built into the lens. The internal 
motor directly drives the focusing group for smooth autofocus operation.