Canon EOS Rebel T6i W Instruction Manual page 231

k Shooting Movies
When you press the shutter button halfway to autofocus during movie
shooting, the following phenomena may occur.
• Focus may become far off momentarily.
• The brightness of the recorded movie may change.
• The recorded movie may be momentarily still.
• The movie may record the lens operation noise.
• You cannot shoot still photos when focus is not achieved, such as when
the subject is moving.
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