Honestly, both lenses were fantastic. There was drift, and with the drift, the Sigma came out behind Sony, but it still comes out ahead of many other prime lenses I regularly use perfectly focused manually with focus zoom -- certainly nothing to disqualify it from real life use. We're talking about really small issues with both lenses.
|Steamin' Mad by ahrensjt|
from Angered Subjects (Street Photography)
|Smile by Olymguy|
from Ultra Asian Indian Female Faces
|Space Shuttle Cockpit- by vbuhay|
from Aircraft Control Stick