Say "fashion film" and you instantly think of movies. You think of Michelangelo Antonioni's Blow Up, of David Hemmings as the archetypal '60s David Bailey-alike photographer. You think of Audrey Hepburn resplendent in billowing Givenchy chiffon in Funny Face. You think of The Devil Wears Prada, the glamour of high-octane, high-fashion magazine editing. But there's another meaning to the phrase: film is emerging as a new way of expressing fashion, a new type of editorial treatment. Creatives and brands are pumping time, effort and, above all, money into film, showcasing the results across websites dedicated to exactly that. One part YouTube, one part Vogue, they're voraciously consumed by young fashion fans who eat and breathe it, as well as watching it real time - you're hard-pressed to find a major label that hasn't begun live-streaming their shows via video. In short, there's a revolution going on in fashion image-making. It's been subtly creeping up on us for half a century, picking up speed over the past decade. Now it's at the gates. It's the revolution of movement, animating the familiar still image into films that are seen instantly, and by millions, across the internet.

Who better to comment on that than fashion photographer Nick Knight, who in 2000 founded SHOWstudio, a website dedicated to exploring fashion online. For Knight, that exploration lead inevitably to film: the first piece SHOWstudio launched was a film of Kate Moss singing with Bobby Gillespie of Primal Scream - and it has offered fashion creatives, Knight amongst them, the opportunity to experiment endlessly with the World Wide Web. "There's nothing wrong with photography, it's just not the most exciting medium anymore," says Knight bluntly. "It's not right to be the primary medium of expression. There are great magazines and there is great fashion photography, but this isn't the primary form of expression for society in the early 21st century. It's just not the best way of doing it."

Ten years ago that sounded like heresy - former SHOWstudio editor-in-chief Penny Martin, now editor of the Gentlewoman magazine, recalls: "When we started, it was very difficult to get people in the industry involved. Even to find someone with an email account, they didn't use computers at all. All the other communities around design and architecture and music were logged on, but fashion wasn't interested." Today, however, Knight's statement is backed up not only by the cold hard facts of companies like Prada, Louis Vuitton and Gucci sinking tens of thousands into state-of-the-art internet-only film, but a welter of creatives using motion image to experiment with their fashionable ideas.

"The internet is so far-reaching - why wouldn't the industry want to use it to communicate in a new way?" That's the question posed by Ruth Hogben, a fashion image-maker whose focus to date has been film. Hogben has collaborated with Knight on work for Lady Gaga and the late Lee Alexander McQueen, alongside labels as diverse as Gareth Pugh, Chanel and Louis Vuitton. For the latter she directed Fan Club, an all-singing, all-dancing cinematic homage to Busby Berkley musicals showcasing Vuitton's archive of shoes and handbags. The film not only ended up in the Louis Vuitton - Marc Jacobs exhibition at the Louvre, but inspired the display of said accessories in the show, high-kicking on mannequin legs like a chorus line.

Hogben's clients illustrate the fact that fashion's highest-profile labels are now fully engaged with the internet. The initial reticence experienced by Martin and Knight is long gone. Today, it's the big brands who are leading fashion's online revolution, backed by seemingly endless budgets. The reason? Precisely what Hogben outlines as the phenomenal reach of the internet. When Alexander McQueen streamed its spring/summer 2010 show, the website crashed as over 100,000 viewers logged on simultaneously. The latest film created by Dior, titled Secret Garden - Versailles, was directed by powerhouse fashion photography duo Inez van Lamsweerde and Vinoodh Matadin, and has racked up stats any Hollywood blockbuster would envy: 17.5 million YouTube views to date, and climbing. That breadth of audience is incredibly seductive to a brand, especially given the falling circulation of many a fashion magazine.

It's also new, a word the fashion industry has always adored. "For so long it has been done in a certain way - photos, shows, editorials," says Hogben. "This is a new way to communicate for everybody."

"Things have already changed massively because of the technology that's available," says Francesca Burns, fashion editor at British Vogue, which itself offers an iPad version stuffed with motion image to accompany its editorial shoots.

Photographer Liz Collins agrees. "Most editorial and commercial clients want a moving image film to accompany the stills you create - a behind-the-scenes film, or a narrative. With online participation, it's now essential to link readers to moving sites," she says. And although film is increasingly something demanded of photographers, it's a demand Collins finds inspiring. "I see film as a big part of my future... taking that forward and applying my eye to moving image, that's totally thrilling. The possibilities are endless. Film is fascinating."

Nick Knight has been fascinated by film since the late '80s - his epiphany came at the sight of Naomi Campbell modelling a coat during a shoot for one of Japanese designer Yohji Yamamoto's landmark catalogues in 1987. "From that moment on I was convinced that fashion should be really seen in a movement, not just as a still." Knight has recorded each of his shoots on film ever since, cutting the footage into video shorts that echo his editorials. "We've accepted that the way to represent clothes is by static image," says Knight. "I went over that again and again in my mind and thought, 'Well this can't be true to the designer's vision.' The designer always imagines them to be in movement; there was a desire to really get closer to the designer's original vision. That's something that's given rise to fashion film, and it's very much a feeling that it's a better way of showing fashion."

That's an assertion many designers agree with. Gareth Pugh's name is one that especially stands out among the ranks of these forward-thinking fashion creators: rather than simply live-streaming a catwalk show, Pugh has chosen to show his seasonal collections to press via fashion film on three separate occasions (autumn/winter 2009, spring/summer 2011 and a special installation at Pitti Immagine in January 2011). He's also fused fashion film with presentation, as in his spectacular spring/summer 2012 show where a giant LED video screen formed a dramatic, graphic backdrop for the collection. "I'm thinking about how I can do things differently. Because I am getting a little frustrated with showing my stuff in a fashion show," says Pugh by way of explanation. "It doesn't really make a lot of sense to me, when you really step back and think about it, to bet six months of your career on that. As a designer you have to live by those images of your fashion show." For Pugh, the move to video is about control - the ability to shoot and re-shoot to ensure his ideas are communicated accurately. "It's not the show, it's the images from it that people take. It's [the images on] Style.com that everybody sees. I forget that there are 400 people at my show and the rest just see it online."

Pugh is the designer who has made the most concerted stand for film versus live presentation of fashion. Considering the designer has quoted cinematic references like The Wizard of Oz and Predator as influences, film feels an appropriate medium to showcase his collections. But that pro-fashion film group of experimental designers has also included the likes of Hussein Chalayan, Richard Nicoll and Alexander McQueen, who have all eschewed the catwalk and shown their clothes purely via film. "Shows are becoming a little more obsolete in a way, business wise," says Lazaro Hernandez, who along with Jack McCollough form Proenza Schouler. "For us, it's the highlight of our jobs, it's our show and it's the creative part of things. But on a business level it's becoming less and less and less important for everyone, I think." Along with Alexander Wang and Jason Wu, Proenza Schouler is one of many young labels branching out into film - "campaign films", as they call them - created to accompany their advertising, with the aim of "going viral." To this end, Alexander Wang recruited rapper Azealia Banks to star in his autumn/winter 2012 T by Alexander Wang video.

Proenza Schouler, however, has taken a rawer approach, collaborating with filmmaker and friend Harmony Korine on short films Act Da Fool and Snowballs. Of the latter, a decidedly dark and almost Lynchian piece that seems to only incidentally feature Proenza Schouler's autumn/winter 2011 collection, McCollough has said, "It's not like a sales vehicle, it's a sales deterrent if anything." About as far away from a campaign film as possible, then.

The same is true of Kate and Laura Mulleavey of Rodarte - a few years ago, I asked the Mulleaveys how they would describe modern fashion. They said "cinematic", something they still feel today. "For me fashion is a way of telling stories that are visual, in the same way as cinema," explains Laura before Kate throws in, "film has become a modern way to communicate." They, too, have turned their hand to filmmaking, creating a film for Knight's showstudio.com in 2008 and, in 2011, collaborating with photographer Todd Cole to create a film for NOWNESS, the LVMH fashion website, starring their muse Elle Fanning. The common feature of all these designers? They're all young. "This is a generation of designers and stylists and people and image makers who accept the internet as a medium, so they're all automatically going to do things in a different way," says Knight.

Elle Fanning: Rodarte's Muse on Nowness.com.

For every designer, photographer and publication that sees film as the next giant leap in fashion image-making, however, there's a counterpart that sees it as the latest band-wagon in an industry built on the Next Big Thing. "I find it rather laughable when all these photographers say 'Oh I'm shooting a movie' and all you see is the model blinking," says photographer Juergen Teller. "It's dumb as hell."

Liz Collins is excited by the possibilities film offers but allows that the process "can be quite overwhelming when you're used to working in a team of three… suddenly a crew of 10 can be involved. It's important for me to separate taking the pictures and shooting the film. It requires a different mindset, another day. I'm happy holding the camera, directing, lighting, but I can't let it distract from the photography yet. My feelings are still new towards this."

The issue for many is that fashion film is presented as the death knell of the fashion magazine. "I love video and I love fashion film but I think there's a long was to go before it replaces fashion imagery," says Francesca Burns. "There's a certain charm in the still image that you're never going to get from video." The challenge for publications now is to get the balance between that "charm" of the stills and the immediacy and excitement of moving image exactly right. The best are ringing in the changes online and keeping static images for the magazine page, where they sit best. Magazines are adapting fast and offering websites and iPad apps brimming with unique features, interactivity and motion image -
all things that the internet excels in.

"I don't know what to say because I'm sort of half in that generation of adoring my Vogues and collecting them for ages. But then I have also grown up with the internet," says Ruth Hogben. "I love opening a magazine and I love photographs. I really hope magazines live forever - I mean, they are what inspired me as a child. I don't think they have to go anywhere, a staunch 'this or that.' Why can't it be just everything?"

A large poster hangs above the desk of Made in Heaven's founder Chloe Lonsdale. Stamped in faded letters are the words: "In 1969, while the world was busy putting man on the moon, here at Made in Heaven we were busy making the best jeans on Earth." It is a bold, tongue-in-cheek motto for the denim company but, under the direction of Lonsdale, it is one that is becoming a reality for the brand today. The daughter of a jeans entrepreneur and '70s model, Lonsdale reincarnated her godfather's denim company in 2005, forging it into one of the UK's most successful denim brands.

Lonsdale's godfather, Tony O'Gorman, the man responsible for the poster, founded the original company in the late '60s. O'Gorman inherited an old paint factory on London's Fulham Road but, with little understanding of the paint industry, he began using the machines to experiment with different washes for denim and launched his own line. Soon his clientele included Jane Birkin and Farrah Fawcett. At the same time, Lonsdale's father (dubbed by the British press as the "Blue Jean King") started his chain of Jean Machine stores, after he discovered that California had 582 jeans outlets yet there was not one in the UK.

"When I was born in the late '70s, I was raised in an environment where everyone around me was wearing jeans," explains Lonsdale. "My parents had created this legacy that lasted through my childhood, so denim was pretty embedded in my ID." Though the brands quietly slipped from favour as '80s power dressing arrived, denim had become part of the family.

In 2005, the Californians still dominated the jeans industry, and Lonsdale felt that the English spirit of what her family had begun was missing. So she decided to make her move and leave her position in PR at Nicole Farhi. Lonsdale's MiH revival drew inspiration from their rich archive and modernised classic denim with original cuts that have impressed today's influential style makers, including Gwyneth Paltrow, Kate Bosworth and Claudia Schiffer. She has expanded her line to include basic T-shirts, blouses, knitwear and jackets that are stocked in more than 35 countries around the world. And, alongside this, Lonsdale has brought Jean Machine back to life as a premium denim brand for men.

Though her father may have held the title of "Blue Jean King", Lonsdale has proven to be a worthy successor to the throne.

The fourth in a series of commissions by Miu Miu and opener at this year's Venice Film Festival, It's Getting Late by Iranian-American screenwriter/director Massy Tadjedin is a short film based around the process of getting ready for an evening out. The all-female cast, including Aubrey Plaza, Gemma Arterton, Patricia Clarkson and Rinko Kikuchi, are shown winding down from their disparate Los Angeles lifestyles and transforming into sirens of the night as dusk descends upon the city of angels. "It's a moment of the day that I find very romantic," Tadjedin explains to us during our Skype chat.

To a dreamy soundtrack by songstress of the moment Zola Jesus, each of the four women metamorphose from their daytime personas (a mother, an executive, a writer), into their after-dark incarnations through intimately captured personal moments, before heading separately to an underground nightclub, where the film culminates with Zola on stage singing one of her moodily sexy tracks.

The brand has enlisted a stellar roll call of female directors, including Zoe Cassavetes and Lucrecia Martel, asking each to create a short film that celebrates the Italian fashion house's femininity through their own cinematic sensibilities. Tadjedin joined their ranks and was invited to take part in the Women's Tales film series after Eva Mendes - who was cast in the filmmaker's 2010 directorial debut, Last Night - introduced her to the Miu Miu team.

It's Getting Late is a far cry from Tadjedin's usual psychological thriller repertoire and is her first script-less non-feature film. "The great thing about short films is how they are a little more open-ended -
they capture a fleeting moment. It was a great challenge," she explained. "It's about becoming ready for self-possessiveness. We all get ready very differently depending on whether it's for friends or for a lover."