Understanding Optical Stabilization » Flowers DOF 2.8 and 16
And here’s a pair of shots I made while I was working on a piece about the Sigma 120-300mm f2.8 at 300mm. The top image is shot wide open at F2.8 @ 1/4000. This is much faster then the reciprocal of the focal length, so it is sharp on the focal plane, but the flowers even a few inches behind are soft. Stopping down to f16 gives us much more depth of field, but to keep it properly exposed, our shutter speed is 1/125–below the reciprocal of the 300mm focal length. Activating Optical Stabilization allows us to make this shot and keep it sharp and free of camera shake without having to haul a tripod along!