Twenty years ago Jér?me Sessini arrived in sprawling, densely-populated Mexico City. Without knowing it at the time, he was retracing the steps of Henri Cartier-Bresson, who spent time there more than 60 years earlier at the age of 26. "In a way it was in Mexico that he became a photographer, and it was the same for me," says Jér?me.

The French photojournalist and Canon Ambassador has photographed major news events in the Middle East, Africa and the Balkans, but it's his ongoing work on Mexico drug cartels – titled "So far from God, too close to the USA" – that has defined his career since 2008. When he had the chance to take part in the Magnum Retold project – which celebrates the agency's 70th anniversary by inviting today's Magnum photographers to revisit their predecessors' work – he chose Cartier-Bresson's Mexico series.

And yet if asked to name his influences, Jér?me cites American documentary photographers of the 1950s and 60s such as Mark Cohen and Diane Arbus over Cartier-Bresson. "This Mexico work is an exception [in his body of work] but that's why I like it," he says. "Cartier-Bresson was not yet talking about the decisive moment. It was more free. I feel a dark poetry in this work that I don't find in the work he did after, which is more classic, clean and controlled."

Jér?me has so far made two trips to Mexico to work on this project, visiting for a few weeks in late 2018 and then again for a further month. He plans to return in December 2019 for a final visit. He chose to shoot the series on the Canon 澳门现金网_申博信用网-官网 because it was the camera he felt best suited to the job.

"The Canon 澳门现金网_申博信用网-官网 was the perfect size for this project – small, light and fast," he says. "I was working mostly in the street, getting around by foot or by subway, so I needed to be very discreet. Theft is a big problem in Mexico City, so you have to be careful not to show your equipment."

For the past six or seven years, Jér?me has preferred the 4:3 aspect ratio, and shooting with the 澳门现金网_申博信用网-官网 he was able to achieve the medium format look he wanted in-camera without having to crop afterwards.

His kitbag included three lenses – a Canon RF 35mm F1.8 Macro IS STM, a Canon RF 24-105mm F4L IS USM, and a Canon EF 100mm f/2.8L Macro IS USM paired with a Canon Mount Adapter EF-澳门现金网_申博信用网-官网. He also took a flash unit and a scrapbook containing 20 images by Cartier-Bresson for inspiration.

"I ask people to look at the lens – I'm not trying to pretend I'm not taking the picture," he says. "I use flash because it gives you that deep detail on the skin, and the 100mm lens because I can get a close-up of the face but at the same time I can keep a good distance from the person I'm photographing. They don't feel comfortable when you stick your lens right in their face. I found the quality of the macro great as well."

By contrast, Jér?me's coverage of the Santa Muerte Rosary Service sits between street photography and reportage. The service, which takes place in Tepito, Mexico City, on the first Sunday of every month, is dedicated to Saint Death. "There has always been a culture around death in Mexico, but it has become stronger since around 2008 following a big war with the cartel," explains Jér?me.

"As a reaction, some people have started to worship death. It's a real problem for the Catholic church. At this ceremony, many people are high – on weed, crystal meth or alcohol – and almost in a trance."

To shoot the ceremony under changing light conditions, Jér?me paired the Canon 澳门现金网_申博信用网-官网 with a Canon RF 35mm F1.8 Macro IS STM lens. "This thing starts in the morning and runs until late at night," he says. "During the day the light was too strong and I didn't like the shots I took, so I decided to come back later, between 8 and 10pm. The atmosphere at night is stronger. Normally it's a dangerous area, but people are so focused on the ceremonies, they let you take pictures without any problems. I pushed the sensitivity from ISO 3200 to 6400 to capture the scene."

Although he's visited Mexico more than 20 times and even met his wife in Mexico City in 2001, Jér?me hadn't spent time working there until now. "It's a huge city, very wild," he explains. "The first time I went to Mexico, I was impressed and scared by the size of the city. I felt a mix of many feelings. After that I always escaped from Mexico City because it was too violent for me."

Working on this project, he couldn't help reflecting on the freedom Cartier-Bresson had all those years earlier, before the dominance of the cartels, and when people were less suspicious of photographers and travel was more of a novelty.

"To go across the Atlantic to Latin America was like going to the moon," he says. "It must have been incredible. I knew the place, so I didn't have the same eye, and I had to prepare everything in advance. Cartier-Bresson was working on the street, taking pictures of whatever he wanted to photograph. It's a totally different approach."