For everything to be blur-free, the slowest shutter speed you can shoot if you’re hand-held is “one over the focal length of the lens”. So for a 200mm lens, 1/200 second. For a 50mm lens, 1/50 second (there are some of you who are going to argue that cropped sensors – less than full-frame – are even worse. We could have that technical argument all day but bottom line, it’s the same). There are ways to get around that: shoot with a tripod or monopod. Have VR (vibration reduction) lenses or cameras. But even if the subject is not moving, that’s your limit.
If you’re trying for tack-sharp focus, think again. Double that speed, at least. To reach that high speed, you may need to compromise on your ISO setting. I’m shooting hockey action next week with my 70-200mm lens. Indoor lighting in an arena is awful. I expect I’ll be shooting at ISO 1600 or 3200, 1/1000 sec at f/2.8.
If the subject is moving, it’s a whole new ballgame. Or, by the way, if you’re moving. Sometimes you have to go a whole lot further. Picture a racing motorcycle coming right at you at 200 miles/hour. Good luck. Even if your autofocus is up to it, are you? What you need to do in that circumstance is manually focus on a point and when the racing bike hits that point, trip the shutter. Right. Good luck with that. The solution in that circumstance is to use your fastest cycle rate – in the D300 it’s 6 frames/second or 8 if you have an external battery. Hold down the shutter release just before the bike reaches the pre-focused point and pray.
So what about that same motorcycle travelling across your lens? Even with a high shutter speed, you’re not going to get the shot unless you pan with the bike. And never stop moving, even after you’ve released the shutter (trust me. I know, after the shot, who cares? But if you don’t, you’ll be bringing your camera to a stop just at the point of release. Follow through, like a golfer or a skeet shooter.
OK, now as I said, does everything have to be unblurred? Not necessarily. In fact, you give the impression of motion when the background has a motion blur to it. The trick is to pan the camera with the moving subject. Believe it or not, I’ve gotten pretty good images shooting a 200mm lens at 1/30 second. Pan smoothly – keep some part of your subject in the same place in your viewfinder – let’s say the driver’s door of that car or the wheel of the bike. This takes practice, lots of practice. Go out on the road and shoot at cars going by (Watch them slow down if you dress in black or dark blue when you do this. They think that’s a radar gun!). Think about what you want to accomplish in advance and try it!