AF System

AF System
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.