When Autofocus Fails; Subjects Difficult To Focus - Canon EOS 5D MARK III Instruction Manual

When Autofocus Fails
Autofocus can fail to achieve focus (viewfinder's focus confirmation light
<O> 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 or 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 on an object at the same distance as the
subject and lock the focus before recomposing (p.67).
(2) Set the lens focus mode switch to <MF> and focus manually (p.111).
[] For €onditions Whe[e AF Can fail t0 achieye focus With [Live mode]t[_ Live
model during Live View shooting Isee page 211
110