“Behind every portrait there’s a life story. It’s important not just to take photographs but also to include the name, the location – to break the aesthetic.”

In a break during the installation of a new display of her work at The Photographers’ Gallery, South African photographer Zanele Muholi is holding forth ardently about the lives of the black lesbian women and trans men she portrays, showing me their portraits alongside their harrowing testimonies of homophobic violence, ‘curative’ rape and extreme prejudice from the medical, religious, legal and political worlds.

Zanele Muholi, Vredehoek, 2012

Muholi calls herself not an artist but a “visual activist” whose role is to bear and share witness, to honour victims and survivors, document hate crimes and sexual violence, challenge stigmatisation and silencing and expose failures in the criminal justice system.

“Fine artists deal with finery,” she tells me, “but I deal with painful material. I’m an artist who uses visuals for activism to deal with the many political issues that affect human beings.”

Her work combines two different kinds of rigour: that of a portrait artist representing a subject with humanity and honesty; and that of a humanitarian creating a historical record. It’s clear that she sees the two as indivisible.

The Photographers’ Gallery showcase of Muholi’s work is part of a broader exhibition honouring the four shortlistees of the prestigious Deutsche Borse Photography Prize, which is awarded to a photographer of any nationality for a specific body of work presented as an exhibition or publication.