One of the most enduring film sequences of Jacqueline du Pré is of the cellist on a train heading to Gatwick airport. Her face transfused with joy, she’s singing a French folk song and accompanying herself, pizzicato, on the cello. The director responsible for that footage, Christopher Nupen, who has died at the age of 88, made no fewer than six films, including compilations, involving Du Pré, and no one was more successful in capturing her infectiously uncontainable pleasure in performing.

A series of other pioneering, psychologically probing films made early in his career featured Daniel Barenboim – Du Pré’s husband and playing partner – and several friends, among them Vladimir Ashkenazy and John Williams, all at that time electrifying the London music scene.

Later he was to film other young talents such as the pianists Evgeny Kissin and Daniil Trifonov, as well as more established artists such as Murray Perahia, Nathan Milstein and Isaac Stern. There were also distinguished composer portraits such as those of Respighi, Sibelius and Schubert. His film We Want the Light (2004) is a sensitive, acutely observed exploration of the subject of the Jews and German music, reflecting more broadly on the role of music in human experience.

After spending five years in BBC Radio, in 1966 he was offered a job in the music department of BBC Television by Huw Wheldon. Acting on the suggestion of the young Barenboim, whom he had befriended, he proposed a film about a performance by Barenboim and Ashkenazy of Mozart’s Concerto for Two Pianos, K365, at a concert with the English Chamber Orchestra. He was given a budget to shoot and edit a nine-minute introduction to the concert, itself to be directed by Brian Large. With the film editor Peter Heelas and cameraman David Findlay he established a team that would work fruitfully together for more than 40 years.

Double Concerto, as their first enterprise was called, was unconventionally edited as a documentary incorporating a complete performance, combining both 35mm film and the 16mm used by the new generation of silent, hand-held cameras, flagrantly outstripping the commission of a nine-minute introduction to a concert. Despite the consternation engendered on the sixth floor of Television Centre when it was broadcast in 1966, the film was a prize-winning success.

His working relationship with Ashkenazy was henceforth to prove one of the longest and most productive of his career. It began with a radio study of Scriabin under the title Prometheus: Bringer of Fire, and continued with some two dozen films for television of the pianist in a range of repertory including Beethoven, Chopin, Schumann and Rachmaninov. Perhaps the most notable of them was the first, which attempted to emulate the success of Double Concerto by filming Ashkenazy as he moved home from London to Reykjavik.

The logistics of the project imposed a greater strain on BBC bureaucracy than it could bear, so Nupen, along with Findlay and Heelas, resigned in 1968 to set up their own company, Allegro Films. It produced Vladimir Ashkenazy: The Vital Juices Are Russian, and all his more than 70 subsequent films, many transmitted on various broadcasting platforms including the BBC and Channel 4.

Immediately grasping the potential of filming a scheduled performance of Schubert’s Trout Quintet by Barenboim and a group of friends (Itzhak Perlman on the violin, Pinchas Zukerman on viola, Du Pré and Zubin Mehta, returning to the double bass for the first time for many years), he asked for, and received, permission to place cameras, discreetly concealed in tongue-and-groove hides, on the stage of the Queen Elizabeth Hall alongside the artists. The Trout (1969) again defied convention, first by being shot live, without a single retake, and second by its inclusion of footage showing the artists going about their professional lives, engaging in high-spirited offstage antics.

The following year he recorded a similarly spellbinding performance in The Ghost (1970), of Beethoven’s Piano Trio Op 70, No 1, given that name, featuring Barenboim, Zukerman and Du Pré. Nupen had a gift for putting artists completely at ease and securing portraits of them that caught the essence of their musical personality. For the 250th anniversary of Beethoven’s birth in 2020 he repackaged other films he had made in 1970, including footage not broadcast at the time. The resulting 13-part series for EuroArts, Barenboim on Beethoven, included the Fourth Piano Concerto, with the New Philharmonia Orchestra conducted by Sir Adrian Boult.

Doing justice to the onstage performance was only part of the challenge for Nupen: crucial was what happened, he once said, in the cutting room, “where a film can either come alive or drain away into the quicksands of film editing”. From the early 1980s, too, he developed a habit of placing his subject out of vision, so that their words or playing could resonate with images reflecting their spiritual lives and artistic aspirations.

Born in Johannesburg, Christopher was the son of Claire (nee Meikle) and to Eiulf Peter Nupen, a lawyer of Norwegian birth who, known as Buster Nupen, became a celebrated South African Test cricketer as an off-spinner. Although his parents were music lovers, his father playing the Norwegian folk-fiddle in his youth, Christopher himself had no musical education as a young child.

Inspired by the sounds of Enrico Caruso, Beniamino Gigli and Giuseppe de Luca emanating from the mahogany radio-gramophone acquired by his father, he took singing lessons and began to immerse himself, via recordings, in the operatic repertoire. A visiting Italian company brought Gigli and Tito Gobbi to Johannesburg for the first time and the boy soprano was thrilled to be introduced to the two singers.

When the Sadler’s Wells Theatre Ballet visited Johannesburg in 1954, the 19-year-old befriended the choreographer Kenneth MacMillan and the dancer Margaret Hill, taking the opportunity to mix with artists backstage and honing his skills at identifying with their concerns and winning their trust.

After studying law at Cape Town University, he took a job in a merchant bank, which happily for him required a four-year study period in London. Having determined to attend the postwar reopening of the Vienna State Opera in November 1955, he managed to muster the fare for a third-class overnight train with no upholstering and a restricted-view seat at the back of a stalls circle box.

By mistake he found himself in the guest of honour box allocated to Lotte Lehmann. His ingratiating charm earned him a signed photograph and an invitation to lunch with the diva.

A deep friendship developed that Nupen believed affected the entire course of his life. Recounting the episode more than six decades later in his thoughtful autobiography, Listening Through the Lens (2019), he revealed that his relationship with the 67-year-old soprano had also been a sexual one.

Lehmann, appalled that Nupen was working in a bank, advised him to apply to the BBC. Appointed studio manager to the features department of the BBC Third Programme, one of his earliest assignments was to produce sound effects for a broadcast of Louis MacNeice’s translation of Goethe’s Faust. “I was everything from the Miller of Hell to a barking black dog,” he later recalled.

No more affecting tribute was paid to Nupen’s ability to capture memorable but otherwise evanescent events for posterity than that of Du Pré. “When we played the Trout,” she recalled, “it would have evaporated, as all concerts do, but Christopher Nupen saw a film in it and suddenly there was a statement of our happiness for ever, and when I see the film it gives me back something of that feeling which will always be so precious to me.”

Listening Through the Lens was also the title of the 90-minute documentary looking back at the films he made between 1966 and 2017, and it was shown on BBC Four in 2021.

His first wife, Diana Baikie, initially a colleague at BBC Radio, died in 1979. Five years later he embarked on a relationship with Caroline Percival, and they married in 1999. She survives him, along with his stepson Matthew, a film-maker and producer.

• Christopher Nupen, music documentary film-maker, born 30 September 1934; died 19 February 2023