PRACTICE: PORTRAITS & OTHER STILL PHOTOS

Still photos are best taken using the one-shot autofocus mode, which ensures that a focus lock has been achieved before the exposure begins. The usual focus point requirements of contrast and strong lighting still apply, although one needs to ensure there is very little subject motion.

For portraits, the eye is the best focus point—both because this is a standard and because it has good contrast. Although the central autofocus sensor is usually most sensitive, the most accurate focusing is achieved using the off-center focus points for off-center subjects. If one were to instead use the central AF point to achieve a focus lock (prior to recomposing for an off-center subject), the focus distance will always be behind the actual subject distance—and this error increases for closer subjects. Accurate focus is especially important for portraits because these typically have a shallow depth of field.

Since the most common type of AF sensor is the vertical line sensor, it may also be worth considering whether your focus point contains primarily vertical or horizontal contrast. In low-light conditions, one may be able to achieve a focus lock not otherwise possible by rotating the camera 90° during autofocus.
In the example to the left, the stairs are comprised primarily of horizontal lines. If one were to focus near the back of the foreground stairs (to maximize apparent depth of field using the hyperfocal distance), one could avoid a failed autofocus by first orienting their camera in landscape mode during autofocus. Afterwards one could rotate the camera back to portrait orientation during the exposure, if so desired.

Note that the emphasis in this tutorial has been on *how* to focus — not necessarily *where* to focus. For further reading on this topic please visit the tutorials on depth of field and the hyperfocal distance.