The EOS-1Ds Mark III incorporates new Canon AF technologies that bring about improvement in key performance areas. The extraordinary 45-point high-density area AF system provides not only the industry's largest continuous AF coverage area, but also the greatest range of control over focusing point selection. The focusing point can be selected automatically by the camera (based on high-speed microcomputer analysis of image content), or users can manually select any of the 19 high precision cross-type AF points, which can be complemented by 26 additional Assist Points for fast, accurate focusing.
A separate processing unit devoted solely to autofocus calculation is a key in the EOS-1Ds Mark III's superb AF performance. The One-Shot AF mode is ideal for more static subjects. The camera rapidly selects the optimum focusing point, and the subject is instantly brought into focus even if it is off-center. The AI Servo AF mode is excellent for moving subjects. Aided by a the camera's outstanding new AF sensor and powerful processing abilities, it precisely tracks subject movement, even when shooting continuously at 5 fps. Even with erratic or rapid subject movement, the photographer can concentrate solely on image composition.
New Custom Functions aid the photographer in choosing default focusing points, as well as changing the size of a manually-selected AF point, making this not only the fastest, but also the most customizable AF system on the planet.