When does the “Decisive Moment” Happen?
Many great photographs were made in this manner, though not out of sheer luck. Usually, they’re pre-composed, i.e. the photographer was ready and waiting for the magic to happen. Whether a breaching whale or a baby staring directly at the camera, once you miss that fleeting moment, it’s gone forever. So important was the idea of the “Decisive Moment” that the great street photographer Henri Cartier-Bresson wrote an entire book describing it!

Anatomy of the “Jaws” Image
Note the determined look on the man’s face, which is not incongruous with the background image painted on the wall of the building. You’ll agree that this juxtaposition makes the photograph. Was it planned? Not at all. But I had to be ready for it if it happened! Therefore, for this kind of street photography to be a success, there’s obviously more involved than just being in the right place at the right time. You need to pick a location, a background or setting with which to work. Then you hope something magical happens.

I choose this mural and shot several images as people passed by. I got lucky with this particular guy, who looks so determined and in a hurry. The fact that his jaw resembles that of the mural skull was an added bonus! I shot the image from my car window with a Canon Rebel XT DSLR with a 28-135mm lens zoomed all the way out. The photo is uncropped. I decided ahead of time that I wanted the mural in focus rather than the passersby, since I didn’t necessarily want the people to be recognizable. Therefore I switched the lens to manual focus and preset it for the mural. (The fact that I was using a zoom forced me to use critical focusing, as a long zoom’s depth of field can be very shallow.) To further blur the person, I used a relatively slow shutter speed, 1/30 second.

Now, you can try just the opposite in your own experimentation with such photojournalistic street photography. Pre-focus on something closer in order to get the passersby crisp, which will cause the background to blur (assuming you’re using a zoom). Either is acceptable. If you’re shooting close to your subject (a la Gary Winogrand), perhaps you can just shoot with a wide angle lens. This way, everything from maybe four feet to infinity will be in focus.

Cartier-Bresson, Doisneau, and Brassai
Many great photographs were made by pre-composing a scene, then shooting at the decisive moment. For further illustration (and much better examples of the genre than I can provide), please see the works of master photographers Henri Cartier-Bresson, Robert Doisneau, and Brassai. As you look at their imagery, notice how much of the composition is provided by the background, as opposed to the supposed “subject.” Realize that a true artistic composition is just that, a whole composed of lesser parts. Would my photo of the walking man be of any interest at all if not for the background? Would the background hold its own as a still life? Probably not.

Finding Your Own Way To Shooting the “Decisive Moment”
The photographers mentioned above are famous for capturing street scenes in imaginative and highly artistic ways. Studying their work can help add a new dimension to your own photography.

Realize that while emulation may be a sincere form of praise, people who practice specific techniques (as these folks do a la Cartier-Bresson) may achieve sadly derivative results. It’s really best to study the masters then find your own way. It’s been said that photography is like writing. Everybody can do it, but almost nobody should. If you want something more than a snapshot, concentrate on composition. You’ll also notice that very few of the examples I’ve shown are in color. That’s because black and white adds artistic abstraction to almost any image; color tends to make almost everything look snapshoddy.