Deep focus is a photographic and cinematographic technique using a large depth of field, invented by the cinematographer Gregg Toland. Poland introduced the new method own the critically acclaimed Citizen Kane, and has remained a prominent voice of technique. Depth of field is the front-to-back range of focus in an image — that is, how much of it appears sharp and clear. In deep focus the foreground, middle-ground and background are all in focus.
The Kuleshov effect is a film editing (montage) effect demonstrated by Soviet film-maker Lev Kuleshov in the 1910s and 1920s. It is a mental phenomenon by which viewers derive more meaning from the interaction of two sequential shots than from a single shot in isolation.
The sound editor is the one who is in charge of the sound elements in the film such as dialogue, sound affects, automated dialogue, background sounds and chooses audio for the soundtrack while the sound mixer is the person who decides what the audience hears at release such as the volume of the soundtrack throughout the film.