Depth of field can be defined to mean the size of the area of sharpness in front of and behind the focal point of sharp focus. There are three elements that effect Depth of field: aperture, focal length and the distance from the subject.
Depth of field in films is important in influencing the image in a film and altering meaning and intention for the better.

Shallow depth of focus describes a small area or part of the image in focus, where things away from the main subject become blurry. Subjects shot with a shallow depth of focus almost leap from their background, taking on a 3D effect.

Deep focus or a large depth of field is used to describe an image that has a deeper field, therefore the region of acceptable sharpness has a lower drop off rate, meaning more of the image is kept sharp and clear. Larger depths of field are most commonly used to depict landscapes where the whole image is seen clearly.

Depth of field in Moonlight

The scene in which Chiron reconnect with Kevin as an adult utilises a shallow depth focus, the camera focuses solely on the subject and everything surrounding looks blurred. James Laxton chooses to do this to depict the raw and threatening experience Chiron is having. The use of a shallow depth focus amplified the significance of Chirons first encounter with Kevin after growing up, the way the camera focuses of Kevin’s face and blocks out any distractions the audience that Chiron has a overwhelming and all-consuming connection with Kevin. The way the camera adopts the perspective of both Chiron seeing Kevin, and Kevin seeing Chiron, tells the audience that the magnitude and significance of this first sight is reciprocated between both parties.

The shallows depth of this shot separates this scene from the rest, the close up and intimate nature of the shot signifies how Chiron feels a deep and complicated connection with Kevin, unlike any connection he has with anyone else. This is proven in James Laxton’s choice to also utilise a shallow depth focus depicting a younger Chiron and his mother earlier in the movie.

The use of a shallow depth focus in this scene between Chiron and his addict mother differentiates from the effect a shallow depth focus has later in the movie between Chiron and Kevin. Whilst the shallow depth focus allows the audience to feel a more detailed presence with the characters, this is now used to encapsulate the abandonment Chiron feels from his mother. Instead of a raw and emotional connection, the audience is left to feel every imperfection Chirons mother presents to him.
By focusing just on the subject, and in context of the mistreatment and torment Chirons mother enforces on her only son, the audience is left to digest the reality of the shot and what it suggests about the never-ending maternal trauma Chiron endures.