Both Uses of

focus

in

The Witch of Blackbird Pond

Only when he had wrung the last dregs of light from the sunset, and the shadows reached across the water and fell upon his book, would he reluctantly raise his head and become aware of the ship again. When that moment came, Kit made sure that his eyes, blinking half blindly from his book, would focus on her gay, silk-clad figure nearby.
p. 18.2 *

focus = look

Rachel Wood's eyes focused for the first time on the three trunk bearers.
p. 31.2

focused = looked and concentrated

Definitions:

(1) (focus as in: Turn your focus to question #2.)
verb: to concentrate, look at, or pay attention to

noun: the act of concentration, or the ability to concentrate

(to concentrate is to direct attention or effort towards a single thing)
(2) (focus as in: The focus of our study is...)
where attention is concentrated or directed
(3) (focus as in: bring into focus; or out of focus)
a state where something has come into view or can be seen clearly; or an adjustment made to permit a clear view
(4) (focus as with technical usage)
technical usage typically involves some sense of center or concentration such as:
- physics — a point where things come together such as the point where light rays meet
- geometry — a fixed reference point (as of a parabola)
- geology — the point of origin of an earthquake
See a comprehensive dictionary for other less common meanings.
(5) (meaning too rare to warrant focus)