Canon EOS 70D Operation Manual - Page 109

When Autofocus Fails Autofocus can fail to achieve focus (viewfinder's focus confirmation light blinks) with certain subjects such as the following: Subjects Difficult to Focus Very low-contrast subjects (Example: Blue sky, solid-color walls, etc.) Subjects in very low light Extremely backlit and reflective subjects (Example: Car with a highly reflective body, etc.) Near and far subjects covered by an AF point (Example: Animal in a cage, etc.) Repetitive patterns (Example: Skyscraper windows, computer keyboards, etc.) In such cases, do either of the following: (1) With One-Shot AF, focus an object at the same distance as the subject and lock the focus before recomposing the shot (p.75). (2) Set the lens focus mode switch to and focus manually (p.110). For subjects difficult to focus during Live View shooting or movie shooting with [u+Tracking], [FlexiZone - Multi], or [FlexiZone - Single], see page 241. 109