Brent Stirton is driven by a passion to help others. Whether photographing sex workers in Ukraine or rangers on the front lines of the fight against illegal wildlife poaching, Stirton uses his photographic gift to tell these stories in a way that makes us take notice. We spoke with Stirton for our new series “Through the Lens,” where we get to know the photographers behind the unforgettable images showcased on National Geographic.

What was the first picture you made that mattered to you?

The first picture that mattered to me was probably shot in 1994 during the run-up to the first democratic South African election. I had been shooting images for less than six months at that stage. I remember I was in a crowd that was quite agitated—a police dog bit one of the people in the crowd, and they were reacting. This kid was right in front of me, and he immediately tapped into the anger of the crowd. I remember realizing how powerful unity could be and how ridiculous it seemed that a small minority had been able to hold back that collective anger for such a long time. It’s not a great image, but it had some emotion, and for the first time I could sense the potential of that in photography.

View Images WEST BENGAL, INDIA: Legally blind Indian boys with albinism are photographed at the Vivekananda Mission Ashram boarding school in India. Albinism often leads to blindness due to a lack of pigment in the eyes. Photograph by Brent Stirton, Getty Images Reportage

View Images KRYVYI RIH, UKRAINE: Maria, a drug addict and sex worker, entertains a client in a room she rents. Maria uses drugs on a daily basis and has clients every week but remains HIV negative. She claims she needs the money to support herself, her habit, and her nine-year-old daughter. 2011. Photograph by Brent Stirton, Getty Images Reportage

View Images RIFIJI, SELOUS, TANZANIA: Yusuf Shabani Difika, 41, lost both his arms to a lion attack on a fishing trip in the region of Selous National Park, Tanzania, 4 March 2013. The attack occured in the evening in 2005. The lion attacked Yusuf and his arms were shredded beyond recovery as he attempted to fend off the lion. Photograph by Brent Stirton, Getty Images Reportage for National Geographic Magazine.

If you weren’t a photographer, what would you be?

If I wasn’t a photographer, I’d probably want to be a professional soldier, a military paramedic at the highest possible level.

Who is your greatest influence?

My greatest influence is an ever present fear of failure, but in terms of photographers, James Nachtwey, Sebastião Salgado, and Nick Nichols were inside my head from early on. These days, Yuri Kozyrev, Alex Majoli, Paul Nicklen, Edward Burtynsky, Moises Saman, Helmut Newton, Steven Klein. The list goes on.

View Images NZARA, SOUTH SUDAN: Michael Oryem, 29, is a recently defected Lord's Resistance Army fighter whose former L.R.A group is involved in the poaching of ivory in Garamba National Park in the Democratic Republic of the Congo (DRC). Photograph by Brent Stirton, Getty Images Reportage for National Geographic

View Images OL PEJETA CONSERVANCY, KENYA: A four-man antipoaching team permanently guards a northern white rhino on Ol Pejeta Conservancy in Kenya in July 2011. Only three northern white rhinos remain in the world. Photograph by Brent Stirton, Getty Images Reportage for National Geographic

What fuels your passion for photography?

My passion is fueled by the fact that I constantly meet better people than myself in the course of my job, and those people inevitably need and deserve help. I’m often in a position to highlight that need—not doing so would be cowardly. I think this job often has moments where your character is tested. I guess having a sense of self-respect means always trying to make the right move. I don’t always succeed, that’s for sure.

View Images KONO DISTRICT, SIERRA LEONE: A 12-year-old victim of the Revolutionary United Front (RUF) was taken from her village at ten and forced into sexual servitude. When she attempted to escape, they used battery acid to burn off her breast as an example to the other slaves. PHOTOGRAPH BY BRENT STIRTON, GETTY IMAGES REPORTAGE

What is the perfect photograph?

A perfect photograph for me is something that transcends its time. Truly remarkable pictures endure as part of the consciousness of our civilization. In the kind of work that gets done at National Geographic, it’s an image that reminds us of what it means to be commonly human and all the connection that entails. On a personal note, I know that when I am in a situation when a good image is possible, it always makes me nervous. That happens because it’s a moment of responsibility made manifest—I have to be good enough to see it when it passes in front of me. If I blink, I’ll miss it and always remember that moment with a bitter taste in my mouth.

View Images WEST BENGAL, INDIA: Blind girls Sonia, 12, and Anita Singh, 5, accompany their parents during a rainstorm while they work in the fields of their rural Indian village in October 2013. Photograph by Brent Stirton, Getty Images Reportage

View Images A Congolese conservation ranger stands at the edge of a new lava field, working out which way his patrol will move through the area. The foreground shows luminous sulphur deposits that have been forced to the surface. Virunga has three active volcanoes, including Nyiragongo, home to the world’s largest lava lake. The latest volcano is only a few years old. Photograph by Brent Stirton, Getty Images Reportage

What is your most treasured possession in the field?

My most treasured possession in the field is my light meter and my camera. Nothing happens without those. Second would be my fixer and an inexhaustible supply of patience. The fixer I can usually make happen ...

View Images AMBOSELI, KENYA: Undercover Kenya Wildlife Services rangers de-tusk a bull elephant in 2011. The elephant was killed by a single spear stroke close to the spine, which penetrated deeply enough to cause massive internal bleeding. Photograph by Brent Stirton, Getty Images Reportage for National Geographic

View Images RUMANGABO, NORTH KIVU, DRC: A funeral is held for ICCN (Institut Congolais pour la Conservation de la Nature) ranger Theodore Mbusa Matofali, 27, after a car accident left him dead from head injuries. Over 150 ICCN rangers have died in the course of their duties in Virunga National Park, most as a result of conflict. Photograph by Brent Stirton, Getty Images Reportage for National Geographic

What is the most important advice you can give emerging photographers?

My advice to emerging photographers is to find what you love and have faith in it since you are going to spend a lot of time pursuing that, and it's not always going to love you back. Go for overwhelming passion—that, for me, is the greatest luxury I can imagine in this profession.

View Images LAKE MURRAY, WESTERN PROVINCE, PAPUA NEW GUINEA: Kids enjoy the lake in Kubut village in 2009. Photograph by Brent Stirton, Getty Images Reportage