Howard L. Bingham, a photographer who took an estimated one million pictures of Muhammad Ali over more than 50 years while becoming one of the boxer’s closest friends, died on Thursday in Marina del Rey, Calif. He was 77.

Harlan Werner, his friend and agent, confirmed the death but did not specify the cause.

In 1962, Mr. Bingham was working for The Los Angeles Sentinel, an African-American newspaper, when he met Ali at a news conference to announce a coming fight. Mr. Bingham took a few shots of the brash, rising boxer and left.

But afterward he spotted Ali, then known as Cassius Clay, and his brother, Rudy, on a street corner.

“I asked them if they wanted a ride someplace because it looked like they were waiting for a bus, and they said no,” Mr. Bingham said in “Muhammad Ali: His Life and Times” (1991), an oral biography by Thomas Hauser. “They were just watching the girls go by. So I asked if they’d like to take a ride with me.”