When Autofocus Fails (Manual Focusing) - Canon EOS 30D Instruction Manual

When Autofocus Fails (Manual Focusing)
Autofocus can fail to achieve focus (the focus confirmation light
<.
>
blinks) with certain subjects such as the following:
Subjects difficult to focus
(a) Low-contrast subjects
Example: Blue sky, solid-color walls, etc.
(b) Subjects in low light
(c) Extremely backlit and reflective subjects
Example: Car with a reflective body, etc.
(d) Overlapping near and far objects
Example: Animal in a cage, etc.
(e) Repetitive patterns
Example: Skyscraper windows, computer keyboards, etc.
In such cases, do one of the following:
(1) Focus an object at the same distance as the subject and lock the
focus before recomposing.
(2) Set the lens focus mode switch to <MF> and focus manually.
Manual Focusing
Focusing ring
On the lens, set the focus mode
switch to <MF>.
Focus the subject.
Focus by turning the lens focusing
ring until the subject is in focus in the
viewfinder.
[]] If you press the shutter button halfway during manual focusing, the active
AF point andthe focus confirmation light <e> in the viewfinder will light
when focus is achieved.
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