David Douglas Duncan, who died in 2018 aged 102, came to think of himself as the luckiest photographer alive. In February 1956 he travelled from his home in the United States to Cannes in the hope of photographing the world’s most famous artist, Pablo Picasso.

Duncan had been a distinguished photojournalist with the US marines in the Korean war; his fellow photographer, Robert Capa, had suggested to him during that conflict that somebody should knock on Picasso’s door and persuade him to let them take pictures of him as he worked. Duncan did just that.

He was either very charming, or he arrived at a good moment. Picasso’s wife Jacqueline opened the door when Duncan knocked, and 10 minutes after he had explained his mission he was taking his first portrait of Picasso, who was soaping himself in the bathtub. For many years after that Duncan was permitted to come and go pretty much as he pleased at Picasso’s various homes. Picasso never asked him to take a particular picture, and never posed for him, but he also never said that anything was off limits. His rule was, “You take pictures, I paint.”

Thousands of photographs resulted from that collaboration; in some, Picasso dances in front of a painting, or tries on a mask. But many, like this one taken at the house in Cannes in 1957, offer an intimate corrective to some of the volatile mythology of the artist. Picasso sits in his high-ceilinged studio, surrounded by all the material and detritus of his making, as if he is just one element among many on a canvas. Jacqueline is nearby reading the paper.

The scene appears one of enormous ease and relaxation. Looking hard at Picasso, lost in concentration, you might think of him tinkering or pottering – verbs that too rarely attach themselves to creative genius.

Picasso Through the Lens of David Douglas Duncan runs until 28 February at Hauser & Wirth, Gstaad