High-Speed Continuous Shooting and Predictive AF

The autofocus (AF) technology of Canon's EOS series of SLR cameras debuted in 1987, making an impact on the market for its speed and ease of use. Since that time, Canon has continued to develop and evolve AF technology into a digital camera legacy: from its initial AF with a single focus point at the center of the viewfinder to 3-point AF in 1990, 5-point AF in 1992, and 45-point AF in 1998.

Canon's new Area AF features 19 Cross-Type and 26 Assist AF Points.^*1 While the system includes the same number of 45 focusing points as in conventional Area AF, all 19 selectable points are high-precision cross-type points, in which vertical and horizontal line components of the subject are simultaneously detected by cruciform distance measurement. Vertical lines are detected with professional-class specifications, conforming to the large-diameter lens group of f/2.8-4 distance-measuring light flux. For horizontal line detection, the 26 assist points conform to f/5.6 light flux, effectively assisting the focusing points selected by the photographer and ready at all times to capture subjects adjacent to selected focusing points. This greatly contributes to the faster capture of moving subjects, particularly when shooting continuously with the predictive AI Servo AF at the high speed of approximately 10 frames per second.

This technology was realized through Canon's Area AF precision optical system and unique high-sensitivity new Area AF sensor,^*2 along with the development of sophisticated AF computation algorithms.

*1 AF system with 19 selectable points plus 26 Assist AF Points. This Area AF Sensor, featured in Canon's high-end EOS-1D Mark III/EOS-1Ds Mark III digital SLR cameras, enables continuous shooting with the predictive AI servo AF at speeds up to approximately 10 fps.
*2 High-speed new Area AF sensor. Combines high speed s=true

source: canon.com