A close-up is a photograph, or a shot in a film, where the camera is very near what it is showing. You often see a face filling the whole picture, or a small thing — a hand, a ring, an insect — looking large. Film people set it against a wide shot, where you see a whole room or street. In everyday talk people also say “a close-up of…” when they mean a very near look, even with no camera there, but the home meaning is the camera one. You can write close-up or closeup; the hyphen is common.