Chris Waller , Jun 24, 2011; 10:47 a.m.
There is a rule of thumb which says that the slowest shutter-speed for hand-held shooting is equal to 1/focal length. E.g. for a 50mm lens the slowest hand-held speed would be 1/50, or 1/60, to the nearest actual setting available on the camera. So for a 200mm lens the slowest hand-held speed would be 1/200, or 1/250 to the nearest actual available shutter-speed.