On paper, Ang Lee’s “Gemini Man” is a standard-issue, shoot ’em up with Will Smith playing a deadly assassin who must battle a younger clone of himself. The explosions and gun battles aren’t what drew Lee to the project, even if they’re the reason that most people will show up at theaters when it opens on Oct. 11.

Instead, he leapt at “Gemini Man” because it gave him a chance to experiment with the high frame rates and 3D filmmaking he previously deployed to polarizing effect in 2016’s “Billy Lynn’s Long Halftime Walk.”

“I believe in it,” Lee said in an interview shortly after screening “Gemini Man” for a group of New York City journalists. “It’s a new medium. It’s full of potential. It’s a new language. If it’s not me, somebody else will figure it out.”

Lee believes that the higher frame rate of between 60 frames per second to 120 frames per second creates a more immersive experience. In the case of “Gemini Man,” it does make action sequences more visceral — guns crackle, glass shatters, motorcycles rev up in a palpable, almost tactile manner. But the hyper-realism is not for everyone.

Critics of “Billy Lynn’s Long Halftime Walk” griped that the new technology robbed the film of its cinematic touches. To them, it looked more like a telenovela than the latest work of the Oscar-winning auteur behind “Life of Pi” and “Brokeback Mountain.” Lee said he absorbed some of those complaints and experimented more with lighting in “Gemini Man,” shooting more sequences at night than he did with the previous effort. But he noted that there are challenges to shooting at a higher frame-rate. It reveals artifice. Sets, he said, can appear transparently fake, so you have to shoot on location and off of studio lots as much as possible. Actors can’t rely on heavy makeup and have to dial down their performances, so that they don’t seem too actorly. Action sequences can’t rely on quick cuts and have to include more long takes, requiring directors to find fresh ways to build suspense.

“It’s a cumulative learning,” said Lee. “It’s not like I learned from ‘Billy Lynn’ and now I know what to do. Even making this, I’m still learning.”

“Each time you have a new medium it forces you to examine things,” he added, before moving into more philosophical terrain. “Why do we exist? How do we perceive things? Why do we think something is pretty?”

It might have been a valuable learning experience, but the box office failure and lackluster reception for “Billy Lynn’s Long Halftime Walk” was painful to endure.

“It was quite brutal,” said Lee. “It wasn’t given a fair shot really.”

Part of the problem, Lee argues, is that aside from a New York Film Festival premiere during which “Billy Lynn’s Long Halftime Walk” was screened in 120 frames-per-second, it wasn’t widely available in higher frame rates. Many theaters said their projectors couldn’t screen the film at the higher speeds, but Lee also implies that Sony, the studio behind the film, didn’t fully embrace the picture.

“They didn’t know what to do with that movie,” said Lee. “They had mixed feelings.”

With “Gemini Man,” Lee says that the film’s backers Paramount and Skydance are being more supportive. He’s hopeful that the a significant percentage of the screens allocated for “Gemini Man” will offer the higher frame rates.

Lee said he was partly attracted to “Gemini Man” because the story had a compelling hook: A man fights his younger, fitter doppelganger. But that required an enormous technological investment. In order to pull it off, Smith, one of the most recognizable stars in the world and now in his fifth decade, must convincingly appear as a 20-something version of himself. To de-age Smith, Lee said the visual effects team drew on photos of the actor, as well as his work in films such “Bad Boys” and “Six Degrees of Separation.” However, there were reasons that some of Smith’s earlier performances weren’t as instructive, particularly his turn on the early ’90s sitcom “The Fresh Prince of Bel Air.”

“He wasn’t playing this kind of part,” notes Lee. “He played a swaggering, happy-go-lucky guy and here he’s kind of a melancholy fellow.”

Lee remains committed to working with higher frame rates and in 3D. He believes it’s the future and he argues that moviemakers must toss aside their old tricks and habits in pursuit of newer approaches to telling stories. It’s a change that’s been enabled by the conversion from film to digital cinema, but one that’s left moviemakers awkwardly straddling the transition between two methods of capturing drama.

“I’ll continue to chase the aesthetic of digital cinema,” said Lee. “It has an aesthetic that’s worth grasping. We’ve been imitating film and that’s not right. You can use it as a reference, but it’s a different medium.”

Digital photography, particularly when coupled with 3D and higher frame rates, also enables filmmakers to better capture the human face, he argues, and with it the roiling emotions that are just beneath its surface. In “Gemini Man’s” best moments, that startling immediacy enables viewers to experience the toll that a lifetime of killing has taken on Smith and the innate decency that all that violence has somehow failed to expunge. That’s what motivated Lee to return to the divisive world of higher frame rates.

“Curiosity overcame my fear,” said Lee. “I know it’s going to be hard. I’m going to take a lot of hits. I’m going to struggle and it could be lonely for a long time. I’m going to keep exploring because I want to see what kind of stories we can tell.”