Autofocus can fail to achieve focus (the focus confirmation light <> blinks) with certain subjects such as the following:
- Low-contrast subjects (blue sky, solid-color walls, etc.).
- Subjects in low light.
- Extremely backlit and reflective subjects (car with a reflective body, etc.).
- Overlapping near and far objects (animal in a cage, etc.).
- Lens and/or external AF sensor is dirty
In such cases, do one of the following:
- Focus an object at the same distance as the subject and lock the focus before recomposing.
- Set the lens focus mode switch to <MF> and focus manually.
- Ensure that the lens and any external sensors on the camera are clean. If necessary they may be cleaned with a soft cloth.