If I'm not mistaken, the trick to getting the focus from end to end is the adjustment of the aperture of the camera. I couldn't tell you what the aperture setting should be for a given distance and depth, but I do know that the smaller the aperture, the greater the depth of field/focus. The you have to adjust the shutter speed to maintain the correct exposure, without going so slow as to blur the picture from movement. Of course, if you have a tripod and a remote shutter release, or if you have great professional lighting, you will have a wider range of adjustment.
Now about that knife.... BEAUTIFUL!