Usage patterns
〈事〉が焦点となるfor something to become the main focus/issue
This issue became the focal point of the meeting.
〈事〉に焦点を置くto place the focus on something
This research places its focus on environmental issues.
焦点がぼやけるfor the focus to become blurry
When I moved the lens, the focus became blurry.
Expressions
焦点を絞るnarrow the focus; focus attention; concentrate; zero in