Sally Mann explains why, aged 74, she has finally switched from 10x8in sheet film to using a digital camera

Sally Mann, the 74-year-old photographer renowned for her large-format, black-and-white images, has made a creative pivot that she describes as her "Wizard of Oz moment"; she's finally shooting digital, and in color.

In a candid conversation on BBC Radio 4's Desert Island Discs, Mann revealed she's currently working on a new body of work in the Mississippi Delta using a digital camera paired with a 1940s lens that "doesn't handle light very well, so there's this little glow to everything".

This marks a dramatic shift for a photographer who's spent decades hauling an 8x10in Deardorf sheet-film view camera that, in her words, "lives in my car". Yet this landmark transition wasn't driven by technological fascination or creative experimentation but by something a little more mundane.

"The film is now so expensive. I hate spending that much money on each shot," Mann explained. "You're always second-guessing yourself, saying, 'Is that good enough? Is that really worth $12?' But with digital, you just shoot, and if you don't like it, boom, gone off your computer."

She's not complaining, though. "I'm just loving it," she said, her excitement palpable. "Color is so easy and so much fun. You can't take a bad picture because of the gorgeous lyricism and dreamlike quality of the light down there."

Darkroom as refuge

Her switch to digital, however, has done nothing to dent her characteristic work ethic. When asked about retirement, she was emphatic: "Oh no. I'm a workhorse. I'm a peasant. I just put on the harness every day." Her advice to aspiring photographers was equally direct: "Put on the harness every day and pull. You just have to do it and do it and do it and do it. It's the 10,000 hours."

Mann has a new exhibition coming up at Gagosian gallery, featuring decades of photographs of her husband Larry, including intimate shots of his experience with muscular dystrophy. The couple have been married for 55 years.

Yet no matter how much new, acclaimed work she creates, her Immediate Family series, which were taken between 1984 and 1991, continues to attract unwanted headlines. In January last year, some of these images were seized from a gallery in Texas by local officials.

The atmospheric photographs of her three children on their remote Virginia farm – sometimes nude, exploring themes of childhood, mortality and innocence – has drawn both critical acclaim and fierce criticism. Referring to the new Gagosian show, she said: "I do hope that the work is viewed in its entirety as a whole. I don't want to be always known just for the family pictures. There's so much more and more to come."

At 74, working with new tools and new vision, she appears determined to prove that point.