Canon 0020C003 Digital Camera User Manual

Autofocus can fail to achieve focus (viewfinder’s focus indicator <o>
blinks) with certain subjects such as the following:
Very low-contrast subjects
(Example: Blue sky, solid-color walls, etc.)
Subjects in very low light
Strongly backlit or reflective subjects
(Example: Car with a highly reflective body, etc.)
Near and distant subjects framed close to an AF point
(Example: Animal in a cage, etc.)
Subjects such as dots of light framed close to an AF point
(Example: Night scenes, etc.)
Repetitive patterns
(Example: Skyscraper windows, computer keyboards, etc.)
In such cases, do either of the following:
(1) With One-Shot AF, focus on an object at the same distance as
the subject and lock the focus before recomposing the shot
(2) Set the lens’s focus mode switch to <MF> and focus manually.
Subjects Difficult to Focus on
Depending on the subject, focus may be achieved by slightly
recomposing the shot and performing AF operation again.
Conditions that make focusing difficult with AF during Live View shooting
or movie shooting are listed on page 224.