His friend and colleague Peter Magubane paid tribute to Khumalo on Monday (October 22).
"He loved his work. You know, we have lost a great man in our photographic world," Magubane said.
Khumalo's career as a photographer mirrored the rise in Nelson Mandela's political career and Alf Khumalo photographed many of the historic events in which Mandela played a key role. These include the 1956-1961 Treason Trial and the Rivonia Trial.
In 1996, an assignment turned into a photo-call when Nelson Mandela pulled Khumalo out from behind his camera to face the cameras himself - and Alf Khumalo was filmed and photographed between then British Prime Minister John Major, and South Africa's President at the time, Nelson Mandela.
The spontaneous gesture and break with protocol was typical of Mandela, even in his time as head of state.
For Khumalo, this moment was just one of many that underscored his unusually close relationship with his favourite subject.
The photographer was born in 1930 and started taking pictures in Johannesburg in the 1950s, focusing both on his people's struggle for freedom, and on the private life of its most famous leader.
"We were close, I'd known him for years, and when Mandela was in jail I used to supply him with photographs of his family, of his wife, of the children as they were growing, so that he could assess as to how much they've grown," Khumalo explained in a 2009 interview.
Khumalo turned his house in Soweto into a museum of his work, even if the walls can hold only a tiny fraction of the moments in South African history that he captured on film in a career spanning more than half a decade.
His photographs include Winnie Mandela outside the courthouse during her husband's trial, causing a provocation by wearing Xhosa traditional dress; Mandela and Winnie with their baby daughter Zindzi, just a few months before Mandela went into hiding and was subsequently found and arrested in 1963; and many key leaders and moments in South Africa's struggle for freedom, from the Sharpeville Massacre in 1960 to the Soweto Uprising in 1976.
More of Khumalo's photos are on display in Mandela's former house in 8115 Orlando West, Soweto, where Mandela lived with Winnie and their daughters until 1963.
The house is now a museum, and a few years ago Khumalo agreed to give Reuters Television a guided tour of the place that he once visited as a family friend. All the photographs displayed on the walls were taken here by Alf Khumalo and give a rare insight into the private lives of the Mandelas before and after Nelson Mandela's arrest.
Khumalo also founded a school for aspiring photographers. Never one to seek fame or recognition for himself, he took pictures of South Africa's history as it unfolded because he wanted to hold its architects accountable; and even in the free South Africa that Mandela helped to bring about, Khumalo hoped that future photographers would do the same.