(CNN)In 1960, Curt Gunther was an established sports photographer. A young boxer named Cassius Clay was heading to the Olympics, unknown by most outside his hometown of Louisville, Kentucky, and some avid followers of the sport.
Previously unseen photos show young Muhammad Ali at home
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It was probably about then, says Curt Gunther's son, Steve, that two paths crossed, with the young boxer setting out on his history-making course and the photographer setting out to chronicle that course in images.
For decades, Curt Gunther stood by Ali's side both in and out of the ring, capturing the knockout punches that made news, and the candid moments that made up home life for a man who championed his sport and his beliefs.
Personal photographs of Muhammad Ali, rarely seen by the public, are some of the thousands of archives handed down from Curt Gunther to his son before the elder Gunther died in 1991.
"My dad just lived to get the shot," says Steve Gunther, who lives in California.
It is these snapshots that rarely saw the light of day that Steve Gunther wants the world to see as part of the joint legacy left by his father and, now, Ali.
"Though my father did publish a lot of his work, he was more concerned with getting 'the shot' than hustling up jobs or marketing himself, so there are thousands of photos in his archive," says the late photographer's son, who is working on restoring many of these historic images.
Curt Gunther died at age 72, before digital cameras revolutionized the field of photography.
"My poor dad struggled with his Nikon F camera his whole life," says Gunther. "He shot all these photos of celebrities the old-fashioned way before there were good zoom lenses, or auto-focus. He never got to experience the easy way of shooting."
Curt Gunther came to the United States from Germany as a young man in 1938 to pursue his passion for photography. Over the decades he became a success by any standard, sought after by many high-profile athletes and celebrities of the time. He was the official photographer for the Beatles' 1964 summer tour in the United States.
But it was the sports world, and in particular Muhammad Ali, that focused Curt Gunther's attention.
The elder Gunther "shot most of Ali's fights from beginning to end," says his son. "The first fight my dad shot with Ali was in Los Angeles, Ali versus Archie Moore in November 1962."
Away from the spotlight, Curt Gunther and Muhammad Ali were friends.
Steve Gunther recalls as a boy accompanying his father on the road with Ali, where they spent hours with Ali outside the media frenzy that followed him.
"When I got older, I would help my dad on shoots. He would get so nervous before Ali's fights, worried he would miss 'the shot,' so he would light up a cigarette to calm his nerves," says Steve Gunther, remembering being in the champ's hotel suite with his father before one of Ali's fights.
"And I'd say to him, 'Dad, you can't smoke in Ali's suite!' Then when the fight was over, my dad would turn to me and say, 'did you get the shot?' "
Steve Gunther followed in his father's professional footsteps, and he remembers Ali being a photographer's dream.
"Ali would ham it up for the cameras," Gunther says. "He liked to act like he was going to punch the camera. It was probably enjoyable for him and definitely helped the photographers."
The last time Steve Gunther saw Ali was about 32 years ago, but the memories, he says, will last a lifetime.
"I was never impressed with celebrities, but Muhammad Ali is the most amazing human being I have ever met," says Gunther. "The vibe he emanated made you shiver. He had a palpable energy that just filled the room.
"I remember Ali saying, 'If you do more good deeds than bad deeds, then you'll go to heaven.' I think he's in heaven now."