"The documentary for me started with the questions: 'Is this the end of film? Is digital going to replace it? What are we losing if that happens and what are we gaining?,'" says Keanu Reeves.
The actor serves as producer, narrator and interviewer on Side by Side, in which he sets out to examine cinema's transition from film to digital formats.
It seems a niche subject, but Reeves and director Chris Kenneally say they were conscious about making the film for a mainstream audience.
"We wanted to take something that was quite specialised and share enough information so people could understand what we'd be speaking about," Reeves says.
But does the average cinema-goer care or notice what format the film they're watching is in?
"If you're not an aficionado, probably not, as long as it was working," admits Reeves.
"If you go and expect to see a Hollywood studio movie and it looked terrible you'd go like, 'what is that?' So I think it could impact in that sense.
"But a perfect film print projected is something that is remarkable and unique."
Side By Side makes no assumptions that audiences will know the technical aspects of filmmaking, so spends some time explaining how cameras work, the photochemical process of developing film and how the introduction of digital cameras has led to the progression of editing and special effects.
And helping to explain is a cast that reads like a Who's Who of cinema.
Directors Martin Scorsese, Christopher Nolan, David Fincher, David Lynch, James Cameron, Danny Boyle, George Lucas and cinematographers Wally Pfister (Inception, The Dark Knight) and Roger Deakins (Skyfall, True Grit) are all present.
Female filmmakers are represented by the likes of legendary editor Anne Coates, who worked on movies like Lawrence of Arabia and The Elephant Man and Lena Dunham, one of Hollywood's hottest talents thanks to her TV show Girls.
Reeves conducted a large share of the interviews himself, which not only helped the filmmakers gain such unprecedented access but also made for a series of relaxed, open conversations.
"I can't say it didn't help that I've been in the industry for however many years - I was a known quantity in that sense," he says.
It took around 18 months to round up and interview all the film-makers. Luckily, a large number of contributors attended an annual cinematography festival in Poland.
However others weren't so easy to get. Directors such as Steven Spielberg and Quentin Tarantino are notably absent.
"There were people who weren't available or who didn't want to speak," he says. "We got turned down a few times which sucked."
Although mainstream Hollywood films have been shot digitally for about the last 12 years, the first digital film to win an Oscar for best cinematography was Slumdog Millionaire in 2009.
Cinematography Oscars followed for Avatar in 2010 and Hugo in 2011 - also shot digitally.
Some see this as a shift in the attitude towards digital film, which had previously been considered inferior in quality.
Filming on celluloid is an expensive and time consuming process. Reels of film that each contain about 10 minutes of footage are developed overnight, creating "dailies". Viewing them is the first chance a director will get to see the product of his previous day's work.
It is only then they discover if they have the right shots or if they have to go back and re-shoot.
The advent of video cameras showed not only that film-making could be done at a fraction of the cost, but that you could see the results immediately. It also enabled anyone to effectively become a film-maker.
The invention of low price digital cameras further democratised the film-making process.
However, advocates for celluloid include Inception director Christopher Nolan and cinematographer Wally Pfister, who maintain digital images will never have the depth or clarity of film, which they insist on using.
On the other side, the likes of George Lucas, James Cameron and David Lynch profess their love for digital and swear they'll never go back.
Another issue addressed in the documentary is digital film archiving and preservation - where the introduction of new formats every couple of years is proving to be problematic.
Indeed, Se7en director David Fincher says he has videos from the early days of his career in unplayable formats, as the hardware no longer exists.
As a result, when he finishes a film, he now stores the relevant player alongside the rushes in his archive, to ensure he is able to watch them back at a later date.
And even with modern technology, hard drives can fail, leading to the loss of digital content.
It is something Reeves admits he had not considered. "I had no idea about the situation we're in right now where there is no standardised means of archiving digital information."
"I didn't know anything about how it could all just go away - it was a bit jaw-dropping."
The irony is that celluloid is the only format that has stood the test of time over the past 100 years and will continue to do so as long as there are projectors to play them on.
Throughout Side by Side, Reeves maintains his impartiality but with filming complete, he is able to share his thoughts.
"Going into the film I was definitely biased to 'what are we losing?'. Film was being held up as the gold standard and digital was this idea of replacing [it]," he says.
"But what I've come to learn is that it's not necessarily replacing it - but that it's something else. And if it is that, then film has a better chance.
"I'm still confident that it's going to hang around."
Side By Side is out in cinemas from Friday, 15 February through Axiom Films.
Documentary Side by Side looks at the history of film-making and whether the advent of digital technology spells the end of celluloid.