John Lennon and Yoko Ono, photographed by Bob Gruen at the Fillmore East in New York City, August 1972.
The history of rock and roll couldn't be documented without Bob Gruen's photographs; he has taken some of music's most iconic images.
Gruen, who has photographed thousands of bands over nearly five decades, become friends with many of his subjects. He says he has never seen it as a job: "Yeah, I wasn't there on assignment. I was there 'cause I wanted to be there," he told Anthony Mason.
His new book, "Rock Seen," is not just a collection of his work - he says it's also "a family album of my life."
Credit: copyright Bob Gruen / bobgruen.com