Out of My Depth
The racing season will start again soon, and I’d like to propose some tricks involving conscious creative use of your control over depth of field. You know that there are areas in your pictures that are not sharp because they are too far outside the area where the lens is actually focused; this can be a nuisance in those point and shoot family shots where Annie Mae by the Christmas tree is nice and sharp but Uncle Heinrich closer to the camera has a case of the terminal fuzziness. No doubt the PS camera made the decision and we’ll give it the blame. When you’re shooting for a creative effect, though, you may want to override those auto mode decisions and take control.
Timo Bernard in the first of a pair of RS Spyders; he is quite small in this shot; depth of field gives a pretty clear picture of his car, and the Spyder behind is identifiable.
LEONARD TURNER
A tighter shot causes more blurring of the area of Timo’s car behind him, and the Spyder parked further back is quite blurred.
LEONARD TURNER
Tighter yet, and the rear deck of the car is quite blurred. Note that his face and eyes are the point of focus in all 3 shots.
LEONARD TURNER
Depth of field—how far before and behind the area focused on remains usably sharp—is determined by two things: how close you are to your subject and the size of the f-stop. What does not determine it is the focal length of the lens. If you fill the frame of your viewfinder with anything—say a car—a 500mm and an 18 mm lens both produce the same depth of field, although obviously you won’t be filling the frame with a car during the race with an 18; that’s telephoto turf. To get more front-to-rear sharpness either move back (or zoom out) to produce a smaller image in your viewfinder, or choose a smaller aperture (f-stop) by going to a numerically larger setting.
Generally speaking, you want the car (or other main subject) of the picture to be sharp. Happily, cars are pretty big, so even if you fill half the viewfinder with the front of the car, it will all be acceptably sharp at f8 or above. Light too low to get to f8? Well, there’s a trick here: depth of field is sharp farther behind the point of focus than in front; all other things being equal, if you focus half way down the car facing you, the front is more likely to be out of focus than the rear. Two solutions: first, as the front of the car, closest to you, is more important than the rear, you could focus on the headlights and let the rear be fuzzy. Or, second, you could focus about the level of the windshield—say on the A pillar (about a third of the way back)—to take advantage of the trick; it might get you enough usable depth even at f5.6. Of course, moving back and blowing the image up later can help immensely. Photographing a model car—even a big one—is a different can of worms. Because it’s smaller, the camera is much closer when the frame is filled, and even f22 may not work—that’s why model shots are often easily identified as not the real thing. (There is a workaround, but it’s beyond the scope of this article; let me know if you’re interested).
On the race track in good light, you have choices. With the newer cameras able to record images of excellent quality at iso 1600 and above, you may select a shutter speed of 1/500 to perhaps 1/8000 to stop the action of cars coming toward you. Do you want a sharp lead car filling half the frame with blurred competitors streaming behind? Probably around f5.6-f8. Really blurred, f2.8-f4. Do you want better background detail, say both the car and the “Daytona” on the wall of the banking behind the short infield straight? It’s a long way back; f16, maybe even f22. Adjust to taste.
If the light is low, choices are more limited, but still there. Say it’s twilight, no more to be gained from increasing your iso without grainy results, and your meter is reading f4 at 1/500th (manual metering, of course; you want to read the light coming off the car, not the headlights). Here you can either back away or (more likely) use a wider lens, or you make the choice of keeping either the front of the car or the driver’s face sharp by having the camera focus on the chosen area and let the rest of the image fall where it may.
The rules are the same when working with people; there are times when you want the area before and behind your subject to be sharp to establish an environmental portrait, the individual in his world; there are other times when you will choose the more dramatic route of nearly filling the viewfinder with the person and dropping the background out by using a numerically small f-stop like 2.8 or 4. Always focus on the eyes. It usually doesn’t much matter if the entire person is sharp, as long as the eyes are in perfect focus, and it is common portrait practice to have only that part of the face really sharp. In shots somewhat from the side, where the eyes are not on the same plane of focus, aim for the closer eye and consider going for as little more depth of field.
The infield hairpin at Daytona has a very busy, distracting background. This shot at f5.6 would probably have been better at f4. Even so, note the degree that the following Lexus is out of focus.
f-4.5 gives enough sharpness to cover the entire small-in-the-picture Panoz, blurs the Aston, and is adequate for the “Sebring” sign on the bridge to give a sense of place.
More than filling the frame with the focus on the front of the car, f4.5 causes some (tolerable) blurring of the driver, more of the rear spoiler and close-in Armco.
LEONARD TURNER
It’s really pretty simple then, at least in concept. Play around some with these few tricks, and I’ll bet you get some shots you like! I'm leonardt@pca.org.