Canon EOS 80D - Manual (Page 190)

Focusing with AF (AF Method)
188
Shooting Conditions that Make Focusing Difficult
 Low-contrast subjects such as the blue sky, solid-color flat surfaces
or when highlight or shadow details are lost.
 Subjects in low light.
 Stripes and other patterns where there is contrast only in the
horizontal direction.
 Subjects with repetitive patterns (Example: Skyscraper windows,
computer keyboards, etc.).
 Fine lines and subject outlines.
 Under a light source whose brightness, color, or pattern keeps
changing.
 Night scenes or points of light.
 The image flickers under fluorescent or LED lighting.
 Extremely small subjects.
 Subjects at the edge of the picture.
 Strongly backlit or reflective subjects (Example: Cars with highly
reflective bodies, etc.).
 The AF point covers both near and distant subjects (Example:
Animal in a cage, etc.).
 Subjects that keep moving within the AF point and cannot keep still
due to camera shake or subject blur.
 Performing AF when the subject is very far out of focus.
 Soft focus effect is applied with a soft focus lens.
 A special effect filter is used.
 Noise (dots of light, banding, etc.) appears on the screen during AF.