Canon EOS 550D Instruction Manual page 28

Using AF to Focus
Shooting conditions which can make focusing diffJcuJt:
® Low-contrast subjects such as the blue sky and solid-color, fiat
surfaces.
® Subjects in low light.
® Stripes and other patterns where there is contrast only in the
horizontal direction.
® Under a light source whose brightness, color, or pattern keeps
changing.
® Night scenes or points of light.
® Under fluorescent lighting or when the image flickers.
® Extremely small subjects.
® Subjects at the edge of the picture.
® Subjects strongly reflecting light.
® The AF point covers both a near and faraway subject (such as an
animaJ in a cage).
® Subjects which keep moving within the AF point and cannot keep
still due to camera shake or subject blur.
® A subject approaching or moving away from the camera.
® Autofocusing while the subject is way out of focus.
® Soft focus effect is applied with a soft focus lens.
® A speciaJ effects fiJter is used.
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