Two heavyweight presences – photographer Sebastião Salgado and film-maker Wim Wenders – come together for this profoundly moving meditation on photography, environment, and human experience; all disguised, only superficially, as a biographical profile of Salgado himself. In simple terms, this film takes us from Salgado’s boyhood in Brazil, though his early years as a struggling photography in Paris and his increasingly ambitious project-based work, and finally to his retreat from front-line photojournalism to rainforest conservation back on the family farm on Brazil’s Atlantic coast.

Wenders co-directs here with Salgado’s son Juliano Ribeiro Salgado, and what emerges is an intriguing hybrid which derives part of its interest from intra-family tension. Footage shot by Juliano gives an unrivalled insight into Salgado’s working methods, attempting to get pictures of walruses in the Arctic, or bonding with otherwise utterly isolated tribal peoples in New Guinea. Wenders conducts extensive interviews with the photographer, with Salgado looming through giant translucent images of his best known pictures. Wenders’ method is a generous one, allowing us to follow Salgado’s own journey, both geographic and spiritual as well as artistic and intellectual.

As his work takes on bigger scope, and broader themes, it’s hard to contend with Salgado’s own notion that it’s all connected – at least initially – by a concern for humanity, and the photographer’s own instinct for befriending and empathising with his subjects – “the salt of the earth”, as he calls them. What becomes apparent, however, that repeated exposure to war and carnage took its toll: the aftermath of the Rwandan massacre in the mid-1990s, and the migrations across Congo, meant that Salgado came to the end of a road, photographically speaking. His subsequent focus on the natural world is an unmistakeable evidence of a retreat from such horrors.

The film’s unsung hero is Salgado’s wife Lélia who, it becomes apparent, contributes equally to the ambitious projects: editing, organising and generally making them happen. She also is responsible, it seems, for the inspiration behind Instituto Terra, the rainforest foundation the pair founded, and which triggered the epic Genesis undertaking, designed to record what remains of pre-modern Earth. But Salt of the Earth’s main focus is Salgado himself: a humane, articulate presence whose photography remains stunning to look at, whatever the context. And this film does it full justice.