He might direct the staging of the actors to walk slightly slow and did not make any big movement to let the camera can get a right focus on their faces and also different size of shots that wide shot, then mid shot, mid close up shot then close up shot, and also the background lighting could brighten up the background to be bright and clear. The focus has been arranged when the actors walking in front of the camera and they will be in different distance from camera, so the focus point would be changed when they have different distance with the camera.