Canon’s AF (auto focus) sensors have won renown for their sensitivity and precision. EOS Digital SLRs can use selected focus points to support AF all the way to f/2.8*. AF remains effective in extremely low-light conditions, with a required brightness range of only EV-0.5 to EV18 on entry-level models.
AF points are positioned to provide a wide field of view for optimal focusing control, particularly with 'rule of thirds' compositions.
Depending on model, AF modes are selectable between:
One-Shot AF - single shot auto focus
AI Servo AF – automatic tracking of a subject approaching or receding at speeds up to 50 kph, from up to 8 metres** away
AI Focus AF – switches automatically between One-Shot AF and AI Servo AF modes based on subject movement, available on selected EOS models.
*Centre AF point sensitive to vertical lines to f/2.8.
**Approx. shooting distance when using an EF 300mm f/2.8L IS USM lens.