AGFA 307 - Manual (Page 39)

Special Focusing Situations
In special focusing situations, it may be difficult or impossible for the
camera to focus accurately — you may have to use focus lock or
manual focus.
If two subjects at different distances overlap in the focus frame.
If a subject composed of alternating light and dark lines completely
fills the focus frame.
If the subject within the focus frame is very bright, or low contrast.