This 85mm f1.4 lens is rated as one of the sharpest ever made. Photodo.com rates it as a 4.6 out of 5.0. Only the $1700.00 Canon 85mm f1.2 EF rates higher.
The 85mm is regarded as a portrait lens, as it gives life-like perspective on photographs of peoples faces. These lenses tend to be fast to allow the photographer to have a shallow depth of focus and blur the background behind the subject. The low f/no makes them excellent lenses for astrophotography.