Not keeping an eye on the shutter speed

The rule of thumb for handholding is to set a shutter speed equivalent to (or faster than) one divided by the focal length you’re shooting at, so that’s 1/50 sec when shooting at 50mm, 1/400 sec at 400mm and so on. But your hit rate may vary when it comes to keeping a lens still at these shutter speeds. Vibration Reduction (VR) lenses make a difference at slower speeds, but will have no effect on any subject movement.

If in doubt, use a shutter speed that’s twice as fast – you may need to increase the ISO, but better to have a sharp, grainy shot than a blurred one. If your subject is moving, you might have to go even faster – even if you’re able to eliminate camera shake, if the shutter speed isn’t fast enough to ‘freeze’ the movement, your subject will end up looking blurred.