...The shutter speed you use has to be at a minimum 1/focal length. So if you were shooting on a film camera with a 50mm lens, your shutter speed would need to be at least 1/50s to not introduce camera shake...
If you have a very quiet hand, this need not be the case. I know I can handhold 1/13 when I'm really quiet and position myself firmly, but 1/8 is really hard, harder at that shallow DOF, and anyway ... yes, to handhold slow speeds such as the one used for the photo above is so difficult, it's next to impossible. So the rough rule of thumb that o hey tyler is giving is valid!