Camera know-how AF technologies
AF systems use phase- or contrastdetect AF to achieve focus
■ In contrast-detect AF, the lens is moved past the point of focus in its search for the highest contrast, before going back to it. It’s slower than phase-detect AF, and not suited to moving subjects. With phase-detect AF, the incoming light is split into two signals: the camera can tell whether the two images are in phase and therefore in focus. Phasedetect AF can adjust focus between frames, so it is good for moving subjects. Some cameras, like the Fujifilm X-H2S shown here, have hybrid systems: phase-detect for speed and contrast-detect for accuracy.