During production of 2001: A Space Odyssey (1968), together with Geoffrey Unsworth, Stanley Kubrick was able to reinvent and sharpen special effects techniques in cinema of the time. Before the end of production, Unsworth had moved on, leaving his assistant John Alcott in charge.

When the time came for A Clockwork Orange (1972) to be made, Kubrick promoted Alcott to the position of lighting cameraman, the key photographic position.

"A Clockwork Orange employed a darker, more obviously dramatic type of photography," Alcott told AC in 1976. "It was a modern story taking place in an advanced period of the 1980s—although the period was never actually pinpointed in the picture. It called for a really cold, stark style of photography."

The two presented the film in three acts - the ultraviolent beginnings in which Alex (Malcolm McDowell) and his droogs terrorize people and commit crimes - Alex's imprisonment and Ludovico treatment sessions - and the time after Alex is released. The cinematography changes in each of the three parts to represent the atmosphere and emotions of the material and characters. The first chunk has bright colors, dolly shots, lots of lighting, and fluid zooms. The imprisonment is filmed with a cool, flat color palette, long takes, and slow camera movements. The final sequence mimics the first in concept, but is shot flatter to combine the two previous lifestyles Alex experienced and reflect his docile post-Ludovico self.

A writeup from The ASC gives insight into Alcott and Kubrick’s choices for creatively lighting different aspects of the film:

“Partially for the sake of production speed and economy, Kubrick and Alcott primarily relied on practical lamps to light the film. Both the Korova Milkbar and the health farm feature clusters of bare Photoflood bulbs built into futuristic fixtures, while other scenes—such as those set in the prison— feature single bulbs strung simply from the ceiling, or exposed fluorescent tubes glowing brightly. Color temperatures often clash.

To supplement this illumination, Alcott often used very lightweight Lowel 1,000-watt quartz lights bounced off the ceiling or reflective umbrellas. This approach allowed Kubrick to shoot 360-degree pans without concern for hiding cumbersome studio lamps, though larger sources were required for many scenes, such as when Alex and his gang assault an old drunk in a harshly lit underground alley. "I find that the Lowel light has a far greater range of illumination from flood to spot than any other light I know of," Alcott would later note. "In fact, it’s the only light of its kind that gives you a fantastic spot, if you need it, and an absolute overall flood. Also, when you put a flag over most quartz lights you get a double shadow—but not with the Lowels. But then, of course, they were designed by a cameraman."”

Alcott was once quoted during an interview as saying that he had never even wanted to be a cinematographer until meeting and working with Kubrick. Their partnership was successful and influenced much of Kubrick’s work following A Clockwork Orange.

The ASC article further describes the legacy of the Kubrick-Alcott collaboration:

“Tragically, John Alcott died of heart failure at the age of 55 in August of 1986 while vacationing with his family in the south of France. Although Kubrick continued to control every aspect of the cinematography on his films, Alcott made an enduring and distinctive contribution to A Clockwork Orange, as well as Kubrick’s Barry Lyndon (1975) (for which he earned an Academy Award for Best Cinematography, and The Shining (1980)). The use of light in these films is intrinsically linked to Alcott, marking just one of the many contributions he brought to his work with Kubrick.”