The four main components of a slide projector are an incandescent or halogen light bulb, a condenser system consisting of a convex lens or mirror between the light source and object holder, a slide holder, and a focusing lens. Typically, a mounted frame of developed, positive film is held in a position within the projector so that when projected light shines through, it produces an image that can be focused onto a screen. Autofocus by Ceal Floyer (born 1968) consists of a slide projector that is simply turned on and pointed at a wall. There are no slides to display, and the projector endlessly cycles through the empty slide carrier, focusing imageless, projected light anew each time on the wall. As with Zen for Film, Autofocus’s absence of image draws attention to the materiality of display, created by the laboring machine, the appropriate white-walled or white-screened setting, and human attention linked with the time of perception. —LS

Image: Courtesy the artist and Lisson Galley, London. © Artists Rights Society (ARS), New York / VG Bild-Kunst, Bonn.