At the South by Southwest music and film festival, cinematographer Lan Bui aimed his Nikon D800 camera at Southern rock band the Statesboro Revue, shooting a live musicvideo for Warner Music. Nikon co-sponsored the event to showcase its new DSLR (digital single-lens reflex) camera to the SXSW crowd of indie filmmakers and trendsetters.

“The camera performed as expected from a next generation DSLR video camera,” says Bui. “Beautiful images with a tiny form factor. The new features Nikon put into the camera made it great to shoot with.”

Until now, Canon was the only game in town for filmmakers wanting a DSLR camera that can shoot high-def video. With the introduction of the Nikon D800, Canon is facing real competition in this hot production space for the first time.

How hot? “When the Canon 5D Mark II came out, it transformed our business,” says Karen McHugh, the official ‘personal shopper’ for ASC cinematographers at Samy’s Camera in Los Angeles. “We’ve already sold thousands and thousands of the Mark II.”

In fact, Chuck Westfall, Canon technical adviser for professional imaging, reports that the company sold 7.3 million DSLR cameras in 2011 and projects 9 million DSLRs will be sold this year. That’s part of a larger shift in the camera market as consumers drop film for digital, but the 5D’s HD video capabilities helped drive buyers to Canon.

Will the Nikon D800 ignite DSLR wars? “Quite possibly,” says McHugh, who reports that she’s observed a “big battle” between proponents of the Mark III and D800 on an online filmmaker forum. “I think Nikon has given Canon a run for its money this go-round with the D800. And it is most definitely good for the market to have competition.”

Among still photographers, Nikon has earned legions of loyalists for its high-quality lenses, but until now, there’s been no Nikon DSLR to rival Canon’s.

Both companies came out with DSLRs four years ago, aimed at photojournalists who needed to shoot video as well as stills, but neither expected video on DSLRs to drive a big market.

But professional filmmakers began to embrace DSLRs. Cinematographer Robert Primes, who conducted a large-scale technical evaluation of single-chip cameras, said two factors account for the popularity of DSLRs. “They’re very cheap,” he says, referring to the typical $3,000 to $4,000 price tag. Also, “They’re small and inconspicuous so someone holding them doesn’t look like they’re shooting a movie. It costs almost nothing to run and you get a dozen angles.”

Canon paid attention. Crucially, they added well known cinematographers, including Russell Carpenter, Gale Tattersall, Shane Hurlbut and Rodney Charters, as well as photojournalist Vincent Laforet, to their “Explorers of Light” initiative, begun in the mid 1990s for “photographic education and inspiration.” EOL contributors are under contract to Canon USA, and are paid for teaching seminars or product training events. These cinematographers played a key role in creating the buzz for Canon DSLRs, which they used in their productions.

Laforet, one of the first to use the Canon 5D Mark II, made the short video “Reverie,” put it up on YouTube and got 2 million hits in the first week. “I owe a lot to the DSLR revolution,” says Laforet, who now shoots commercials, is working on his first feature film and has joned the DGA.

Charters also pioneered use of DSLRs, by adding them to the mix on Fox’s hit series “24.”

“We found it extraordinary that it had capable speed and the resolution was pretty interesting,” Charters said. “All kinds of TV shows then jumped on it, and we use DSLRs pretty extensively to do background plate capture on “Nashville,” the TV pilot I’m now shooting.”

More recently Hurlbut shot Navy SEAL action-adventure pic “Act of Valor” largely with Canon 5D Mark IIs. He says “‘Act of Valor’ shows everyone it’s absolutely possible to take a Canon 5D image and put it on a 60-foot screen. Everyone said it was impossible, but the game is over.”

As a result of all this, said filmmaker Stu Maschwitz, “Nikon got lapped by Canon.” But Maschwitz, author of a popular book on digital filmmaking, said “The D800 is clearly showing they’re back and want to take it (filmmaking) seriously.”

Nikon isn’t new to the DSLR market. They offered a DSLR camera, the D90, some four years ago. Matthew Bennett used it to shoot a short in New York’s subway, showing it could be used inconspicuously and in low light. Nikon followed up with the D5000 and D7000. Sony and Panasonic also offer DSLRs, the Alpha NEX-7 and Lumix G-1 respectively. But most of those models were limited to 720p video, and none were marketed to adventurous cinematographers as the Canon was.

Nikon put its D800 in the hands of cinematographer Anthony Arendt who shot “Joy Ride,” showcasing the camera’s ability to shoot an action-packed sequence in very low light. “I’ve shot with all of Canon’s DSLR line-up,” says Arendt. “And I’m excited about the Nikon.”