FOCUS ON THE MOVE
Master the art of finding focus in busy urban environments
Focusing on a moving subject takes a significant amount of practice if sharp images are to be achieved on a reliable basis – that is, successful shots are captured on every shoot, not sporadically or by chance. The situation is complicated further when you are also in motion, when engaged in shooting a street scene for example. It is advisable that on such shoots the photographer finds a place to stand and observe the scene passing before them. If this is not possible however, a workable solution is required. This has to cater for an ‘average’ scenario, since every scene is continually changing.
The key challenge of street and documentary photography is the need for discretion, in combination with the erratic movement of multiple elements around and in front of the subject. These make holding the camera to the eye and effectively locking on with autofocus impractical in many cases. Street photographers require a method of estimating focus distance and depth of field, so that they can wait until the subject moves to within a predetermined area before taking a shot. Such traditional strategies are well established and offer the repeatable sharpness characteristics we desire. They also work with any photographic equipment, meaning that no photographer employing them will be limited by the AF speed of their camera or lenses, the performance of which may vary greatly between pro-grade and entry-level gear. This is noticeable where obstructions are regularly crossing the subject, which can lead AF systems to lose focus unless locked between shots. Techniques such as zone focusing provide a means of confidently assessing when an object will be in focus, without having to look through a viewfinder or at a Live View image. With experience this can be judged by eye alone, opening up many opportunities for images of people and events, which are likely to be disturbed by raising a camera to the eye.
The main considerations when using a non-visual focusing method such as this are subject movement and your ability to compensate for this with ease. By remaining stationary yourself you reduce the speed of distance change between the camera and subject, streamlining the focusing process. If your lens lacks a distance scale, as many modern optics do, pre-focus at an estimated distance, turn off AF and keep the lens set, moving yourself instead of re-focusing.