I just use an Arriflex 2C motion picture camera and place myself 10 feet from the model. I then set the focus on the lens for five feet and then slowly walk toward the model while shooting 24 frames per second. Once I reach the model I stop the camera and send the 400 ft roll of film to be processed. Then I scan through the 6400 frames to find the one where the model is in best focus.
Costly, but the results are good.
Best,
-Tim