In 1955, a nineteen-year-old Dennis Hopper appeared in Rebel Without a Cause, the film that abetted the precocious James Dean’s meteoric rise, but it was Hopper that went on to live his life as a Hollywood rebel. He forged his name as a rambunctious actor and visionary director in extraordinary films such as Easy Rider, Apocalypse Now, and Blue Velvet, but the man born in Dodge City, Kansas, was also an admired and avid photographer.

Hopper took around 18,000 pictures with his trusty Nikon F – a gift from his wife – and it was the only one that he ever used during the 1960s. These images were exhibited in 1970, at the Fort Worth Art Center in Texas, but were boxed up and essentially forgotten in the following decades. However, after Hopper’s death in 2010, the vintage photographs that lay hidden in some fusty basement boxes were rediscovered. As a result, over 400 of these tender, insightful images will form part of an exhibition – Dennis Hopper: The Lost Album at London’s Royal Academy of Arts.

Taken from 1961-67, when he was effectively blacklisted by Hollywood studios, the photos are both a document of Hopper’s private and intimate experiences but also signify a wider '60s America, in all its freewheeling abandon and raw independence. Hopper used photography as a creative outlet during the time he was under contract with Warner Brothers, when he was seemingly artistically shackled, and logically, he put the camera away in 1967 when beginning to write Easy Rider.

The show's curator, Petra Giloy-Hirtz, believes that the exhibition will change perceptions of Hopper. "He's not only a great actor and writer and director, he's a wonderful photographer and a very serious and dedicated one," she said. "When you walk around, the sixties really flash before your eyes. This show is about one of the most vivid and inspiring epochs in our past history. The world was on fire, an expression Hopper uses, with art, with music and with love."

Though while Hopper took memorable portraits of his contemporary artistic luminaries: Paul Newman, Robert Rauschenberg, Andy Warhol, Jane Fonda and many other actors, artists, poets and musicians, his work that captured countercultural movements is more enduring. Be it the the Hells Angels or hippie festivals, free speech or beat movements, Hopper was in the right place at the right time. There was more weighty content too: the 1965 march from Selma to Montgomery at the height of the African-American Civil Rights Movement, where he accompanied Martin Luther King, proof that the man was no dilettante – he was a bona fide cultural figure.

While his work may not be technically flawless, Hopper was fleet-of-foot as a disciple of Tri-X, the fast film created by Kodak in the mid-1950s, which allowed him to shoot without the weighty accessories of a flash and light metre. Through his lens, a snapshot of sixties Americana is revealed, with stimulating shades of Henri Cartier-Bresson’s decisive moment.