By Jessica Herndon, Film Writer

LOS ANGELES (AP) --

For more than a decade, cinematographer Wally Pfister brought director Christopher Nolan's cinematic visions to life. Now, he's the one calling the shots.

His directorial debut, the new sci-fi mystery "Transcendence," has many elements of a Nolan blockbuster — eye-popping visual effects, a mind-bending story and an A-list lead in Johnny Depp. All of those things translate into high expectations for Pfister, who jokingly likens his newly christened director's seat to an "electric chair."

In the film releasing Friday, the mind of Depp's terminally ill scientist, Will Caster, is uploaded into a computer after his death, spawning an eerily unruly machine. At the heart of the story is the disrupted relationship of Will and his wife, Evelyn, played by Rebecca Hall.

"Transcendence," which was executive-produced by Nolan and written by first-time screenwriter Jack Paglen, hooked Pfister because of the emotional weight put on the study of husband and wife and the increasing reliance on technology. "We start to wonder where it's all going to go," he says.

"We are dependent on technology. It's got us," affirmed Depp in a recent joint interview to promote the film.

Depp, 50, first met Pfister, 52, when they worked on Paul McCartney's 2012 video for his romantic ballad "My Valentine," in which Depp and Natalie Portman starred and Pfister was the director of photography.

"I was immediately intrigued and curious from (the) initial reading," says Depp of "Transcendence."

"So many things come into my mind as far as the dangers of technology. Say I'm suddenly holding a gun," Depp illustrates, lifting his left hand as his formidable engagement ring with Amber Heard sparkles. "The gun is not inherently bad. It's a tool. It's what we do with it. I think it's the same with technology."

For his first directing gig, Pfister, who's worked on everything from "Memento" to "The Dark Knight Rises," swayed from doing a big action film.

"I'd done a lot as a cinematographer," he says. "What was important was telling some sort of character-driven story. Exploring human emotion. That is the logical reason to jump from visual storytelling to narrative."

Nolan will also release a thought-provoking sci-fi film this year: the time travel-focused "Interstellar," out in November. But Pfister assures he's not in competition with his long-time collaborator. "Chris is an old friend," he says. "He has been incredibly supportive of my move into this."

The two filmmakers even shared crew members, including folks in the makeup, special effects, equipment, casting and editorial departments. But while "Transcendence" was shooting, Nolan remained hands-off.

"Chris never came to the set," says camera operator Scott Sakamoto, who worked on both movies. "I think Chris let Wally take the reins and go with it to see how well he would do."

Although "Transcendence" marks the start of a new phase in Pfister's career, he tackled the job with the ease of a veteran.

"He's (an) experienced filmmaker," says Depp. "But there are times when you look at a situation with a first-time director and you don't know. But never was there a stumble."

Depp's Will in the film is sharp, warm and ambitious. But he ventures into dangerous territory when his mind is uploaded into an operating system that's connected to the Internet. Soon, powerful and often-abusive capabilities verge on catastrophic results.

"You have to be wondering, 'Is this simply a soulless machine?'" says Pfister. "If you upload a mind into a computer, does it contain sentience and if so, does that affect the decision-making process of the machine? Inherently with Johnny, you want to know that he's still alive. We love Johnny. The character of Will Caster doesn't work without having a powerful, emotional person behind it. We needed somebody that you could fall for."

Depp was sold on the role after learning Pfister was directing. "We had connected and I knew the umpteen amount of hours of set time the man has had," he says, adding that Pfister was passionate and "beyond prepared" when he arrived on set.

Pfister also "created an atmosphere where everyone felt free to say, 'What about this?'" adds Depp. "That's a rare beast in today's cinema. It's all about getting it done: the product and the result."

"Johnny contributed dialogue and drove this project as if it were his baby as well," says Pfister. "That is the kind of collaboration I've always wanted and probably the reason I got into directing — to play with other players."

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