Every weekend through the summer, big-budget movies compete for dominance at the box office. On movie sets, a quieter sort of contest is taking place as a handful of companies are angling to have their digital movie cameras used to capture the action, supplanting the traditional 35-millimeter film camera.

Many of this summer’s most prominent releases have relied on digital movie cameras, including “Superman Returns” from Warner Brothers, “Click” from Sony Pictures and “Miami Vice,” a Universal Pictures offering that opens Friday.

But while the changeover to digital filmmaking has long been predicted, these companies are encountering an unusual degree of resistance from producers, directors and cinematographers. A majority of feature films are still shot with film cameras and some well-known directors, including Steven Spielberg and M. Night Shyamalan, have been vocal about their intention to continue shooting on film.

“People involved with big-budget features are usually risk-averse,” said Marker Karahadian, the president of Plus8 Digital, a company in Burbank, Calif., that rents digital cameras. “Delays are very costly when you’ve got stars on the set, and that means no trailblazing.” Mr. Karahadian’s company supplied six digital cameras made by Thomson Grass Valley for “Miami Vice.”

Unlike the market for consumer digital photography, the market for professional digital movie cameras is relatively small: the major American studios released only 194 films in 2005, according to the Motion Picture Association of America. And while Panavision and Thomson Grass Valley, both based in California, have an early edge, many new cameras are on the way, from established companies like the ARRI Group of Germany and a start-up, Red Digital Cinema.

Digital cinematography first appeared as a faint spot on Hollywood’s radar in 1999, when George Lucas announced his plan to shoot “Star Wars: Episode II” with a new kind of digital camera adapted from Sony Electronics’ television news cameras. The Lucas experiment, released in 2002, persuaded a few directors to dabble with digital cameras, but it was not until this year that the roster of movies using digital photography began to grow.

“We’ve reached what may be looked at, five years from now, as a tipping point in the use of digital cameras,” said Curtis Clark, a cinematographer who is chairman of the American Society of Cinematographers’ technology committee.

Manufacturers have promoted the potential cost savings of the new technology. Digital cameras eliminate the need to buy and develop film, and the need later to scan that film into a computer, add digital special effects or adjust the color. Robert L. Beitcher, Panavision’s chief executive, estimates that even though renting his company’s Genesis digital camera at a typical rate of about $3,000 a day is nearly twice as expensive as renting a film camera, they can help save about $600,000 on film costs and processing in a big-budget feature.

But producers and cinematographers say that cutting production budgets is not the main motivation for switching to digital moviemaking.

“It saves a little money, but that was not the driving force,” said Dean Devlin, the producer of “Flyboys,” a $60 million World War I picture being released in September, which used the Genesis camera.

Rather, Mr. Devlin said the main advantage was the ability to shoot for nearly an hour during airborne dogfight sequences, with the camera mounted on a replica biplane or a helicopter and linked to a digital tape deck. Tony Bill, the movie’s director, estimated that a film camera would have been limited to shooting takes perhaps five minutes long, before requiring a new load of film.

Others are gravitating toward the digital cameras because of their aesthetic qualities. Dion Beebe, the cinematographer for “Miami Vice,” said that he and the director, Michael Mann, chose a camera from Thomson Grass Valley called the Viper to create a particular look for the movie.

“We made use of the Viper’s amazing depth of field,” Mr. Beebe said. “You’re seeing clearly from two inches to infinity.”

But Mr. Beebe says that film cameras are still superior to their digital brethren for capturing bright sunlight in a more nuanced way, and other cinematographers acknowledge that digital cameras do not have the resolution found in film.

Dean Semler, who shot “Click” and “Apocalypto,” a Mayan historical adventure movie directed by Mel Gibson, said he was impressed by the Panavision camera’s sensitivity in low-light situations when he was in the Mexican jungle. Some cinematographers may hold out for higher-resolution digital cameras, Mr. Semler said, but then added: “I’m looking at my images, and it doesn’t matter. It looks fabulous on the screen to me.”

Still, executives at Panavision and Thomson Grass Valley are not expecting an abrupt fade-out for celluloid. The bulk of Panavision’s $233 million in 2005 revenue came from renting film cameras and accessories to movie and television producers. Panavision does not sell its cameras. (The company is controlled by the investor Ronald O. Perelman, who is in the midst of taking it private, Mr. Beitcher, the chief executive, said.)

“We’ve got 1,000 film cameras in our warehouse, and we expect to be renting them for a long time,” Mr. Beitcher said.

Thomson Grass Valley is a division of Thomson, the French-based media products and services company, and is a corporate sister to Technicolor, which develops film for motion pictures.

“It’s not our job to push the market,” said Mark Chiolis, senior marketing manager for Thomson Grass Valley. “It’s our job to provide tool sets for the market to select from. If you like the look of film, shoot film.” Thomson Grass Valley and Panavision also face a cattle call of new digital movie cameras, some being sold for much lower prices. Red Digital Cinema, founded by Jim Jannard, a billionaire who started the sunglasses company Oakley, is developing a higher-resolution digital camera that will sell for $17,500.

“For the cost of a few days’ rental of their products, you can own ours,” said Ted Schilowitz, a Red Digital executive.

Mr. Karahadian, the camera rental entrepreneur, has five cameras from Red Digital on order. Complicating the market for digital cameras, he said, is their quicker path to obsolescence, and the small size of the feature film and television market in Hollywood, which does not support the cost efficiencies of high-volume manufacturing .

But camera companies like Panavision, which was founded in 1953 and supplied lenses for films like “Lawrence of Arabia” and “Ben-Hur,” may have no choice but to wade into the swift waters of digital competition.

“We don’t envision developing or building a new film camera,” Mr. Beitcher said.