Multi Point Autofocus, commonly abbreviated to MPAF, is an advanced autofocus system found on many modern cameras that uses multiple focus detection points distributed across the image frame to measure subject distance and determine focus, rather than relying solely on a single central focus point as earlier and more basic autofocus systems did. By sampling focus information from several different locations within the frame simultaneously, multi point autofocus systems are able to make more intelligent and reliable focus decisions across a broader range of shooting situations and subject positions than single point systems, significantly improving the overall accuracy and consistency of autofocus performance in real world photography.
In its fully automatic mode, a multi point autofocus system analyses the distance information gathered from all available focus points across the frame and applies a focusing algorithm to determine the most appropriate focus distance for the scene. Most systems are programmed to prioritise the closest subject within the frame on the assumption that this is most likely to be the intended subject, though more sophisticated algorithms also consider subject size, contrast, colour, and movement to make more nuanced and contextually appropriate focusing decisions. The result is a system that can reliably focus on subjects positioned anywhere within the active focus point area of the frame without requiring the photographer to first centre the subject, acquire focus, and then recompose - a limitation that the single central focus point approach imposed on compositional freedom.
A particularly valuable feature of many multi point autofocus implementations is the ability for the photographer to manually select a specific focus point or zone from the available array, directing the camera's autofocus to operate exclusively from that chosen position rather than making an automatic selection across all points. This manual point selection capability gives the photographer precise control over exactly where in the frame the camera focuses, allowing them to set the active focus point to correspond to the typical position of their subject in the frame without needing to recompose after focusing. A photographer who regularly shoots portraits with the subject positioned to the left of the frame, for example, can select a focus point in the left portion of the frame and compose and shoot directly without the additional step of centring, focusing, and recomposing that would otherwise be required.
The number and distribution of focus points available in multi point autofocus systems has increased dramatically over successive generations of camera technology, from the modest arrays of five to eleven points found in cameras of the late 1990s and early 2000s through to the densely packed arrays of dozens, hundreds, or even thousands of focus points covering the majority of the frame area in modern mirrorless cameras. This expansion in focus point coverage and density has been accompanied by the development of increasingly sophisticated subject tracking, face detection, eye detection, and artificial intelligence based subject recognition algorithms that leverage the wide area focus coverage to maintain accurate focus on moving subjects across the full frame with a reliability and precision that earlier systems could not approach.