mmm… nice creamy background…

There’s a common misconception that, when shooting sports on sunny days, an f/5.6 lens of a given focal length is just as good as an f/2.8 lens of the same focal length. That’s certainly true in terms of exposure, of course; when you can get shutter speeds of 1/1000th or faster even at f/8, who cares, right?

But the real technical issue here, once you can get an adequate shutter speed, is depth of field and subject isolation. Cluttered, relatively in-focus backgrounds are death for good sports photos, traditionally conceived: anything drawing the eye away from the subject is bad. Look at a professional sports photo and invariably you will see a strong subject and a blurred-out, indistinct background, with nothing to distract from the action. Look at an amateur photo - even one capturing good action - and you will often see a distracting background. In my opinion this is one of the main telltales separating the pros from the rest (assuming all is equal regarding composition and exposure).

This is also why, to capture a shot of some action happening all the way across the field, having something like a 400/2.8 lens is way better than using an 80-200/2.8 lens, like the one I use, and cropping the frame down. The longer focal length of the 400mm will result in much shallower depth of field and stronger subject isolation compared to the 200mm cropped down. Since I’m not a pro and I can’t afford to drop $8,500 for a 400/2.8 (or $4,000 for a 300/2.8, for that matter), I have to make do with the latter technique, and that ruins some photos sometimes:

This one would have been way better if the players on the sideline had been thrown more out of focus - either if the play had happened closer to me (and thus the sideline had been further from the plane of focus), or if I’d had a longer lens (thus giving a much shallower depth of field).

In general, I’ve taken to stopping down to f/3.5 or f/4 if the light is good, to get enough depth of field to keep two players in focus (and to avoid the problem I’ve had before where the disc and a player’s hands are in focus, but not his or her face), and because, like any lens, the 80-200/2.8 is a bit sharper when stopped down. At these apertures the background is generally out of focus enough to not be distracting, unless, as above, the action is far away from me, in which case I’ll sometimes be quick enough on my feet to open back up to f/2.8 before taking the shot.

To me, in terms of sports photography, subject isolation is the biggest reason to upgrade to a wide-aperture lens… shutter speed is secondary. Granted, I almost exclusively shoot Ultimate Frisbee outdoors during the daytime, when light is plentiful; shutter speed is a real consideration for indoor sports shooters.

This entry was posted on Tuesday, October 7th, 2008 at 12:04 pm and is filed under Sports, Technique. You can follow any responses to this entry through the RSS 2.0 feed. Responses are currently closed, but you can trackback from your own site.