How do I find the right motion blur/depth of field trade off in sports photography?

Question

I could be wrong but when doing sports photography I'm always thinking about the following trade off:

• A fast shutter speed to freeze the action.
• A small(er) aperture to increase DOF and thus counter focusing errors due to the fast action.

What would you consider to be optimal settings in ideal circumstances. And what compromises would you make if conditions are sub-optimal (less light). Compromises would be: slower shutter speed, larger aperture, higher ISO.

What I'm aiming for are sharp images of people running around in games such as soccer or ultimate frisbee.

Answer 1

The effect you are going for or story you want to tell with your photograph will play a big part in what shutter speed/depth of field you use.

• If you are photographing a Formula 1 race you might want to show the cars as a blur against the stands. In that case you want a slower shutter speed.
• If you want to highlight the loneliness of a batsman at the crease then a tight depth of field might work to make the fielding team out of focus.

The possibilities are endless.

If you've decided that you want to see sharp images of the participants in the sport then you need a fast shutter speed to capture this regardless of the light levels. You'd then have to decide whether you wanted a higher ISO (and increased graininess) to keep the aperture the same or were happy with a wider aperture (and hence smaller depth of field).

Answer 2

Addressing the depth of field question: with a 200mm lens, unless you are quite distant from the athletes, you should be able to isolate them from the background. And unless you are very close, you should have sufficient depth of field at f/5.6 or f/8 to easily get them in focus.

With a 200mm lens at f/5.6

• at 20 meters, you'll have 2 meters depth of field
• at 10 meters, you'll have 0.5m
• at 5 meters, you'll have 0.1m

Depth of field calculator

As you get closer to the action, your depth of field will be reduced, making it harder to nail focus; at the same time, being closer to you, the athletes will be moving faster through the frame, so you'll possibly need a faster shutter speed. So if you are quite close, it may be helpful to position yourself so the action is coming directly at you rather then across the frame - that way there is less apparent motion so less blur.

Answer 3

Assuming you're using a telephoto lens of 200mm or more...

Under artificial light you're almost always going to shoot wide open. Even with a fast lens like a f/2.8 or f/4.0 you'll struggle to get enough light in, so it's a case of shoot wide open and depth of field be damned.

Depending on the lens in good light, probably one stop down from wide open would be optimal, taking the edge of any aberrations whilst still leaving a fast shutter speed available. I wouldn't stop down past f/5.6 unless I had a very good reason to.

You generally only want the depth of field to make up for focus errors, in sports photography you usually isolate the individual, including others for context, so it's not a problem to have just one person in focus (unlike, for example group portraits). The background tends to be unimportant, and in any case you'll never get a sharp background with a telephoto lens at any aperture (nor would you want to).

Answer 4

You might also want to think of using a slower shutter speed and trying to pan the camera with the subject. If you do it right the background will blur but the subject will be sharp. It is easiest with something moving in a straight line that you can predict. The trick with this is to just find something you can practice on and do it over and over trying to catch a good one.

Answer 5

When capturing fast moving action, it is always about the shutter speed. In low light you never have enough, so you shoot wide open and expect that AF inaccuracies will relegate some shots to the Recycle Bin. You can mitigate focus issues somewhat by pre-focusing on spots ahead of the action and then operating the shutter when the action moves to that spot. Of course this requires a good working knowledge of the sport you are shooting and even the particular tendencies of the participants. Learning the exact way your camera's AF focus system functions will also help reduce the number of shots with missed focus. Being able to, for instance, quickly switch from Servo (continuous focus) to One Shot (locked focus) without taking your eye from the viewfinder, and knowing when to use each is invaluable. And the actual target areas for each of those little squares in your viewfinder may surprise you (please see this entry at Andre's Blog).

The shallow depth of field usually works to your advantage when shooting sports by helping to isolate the subject from the surrounding players and distracting backgrounds. Even when shooting in bright sunlight, using too much DoF allows your subject to get lost in their surroundings. Selectively focusing only on one or two participants draws the viewer's eye to that spot in the frame.