Tacita Dean

American choreographer Mercier 'Merce' Cunningham died last year, aged 90, having changed the landscape of dance forever. The founding father of a stripped-down technique that is still the basis of contemporary dance training today, Cunningham bravely divorced dance from narrative, from melodrama and from music.

In 2003, Cunningham's company performed his ongoing series 'Events' in Tate Modern's Turbine Hall, against the backdrop of Olafur Eliasson's 'Weather Project', a staged promenade where groups of dancers performed discrete sections of movement and the audience could wander between, choosing their view. Similar 'Events' have been staged worldwide, often in unlikely dance spaces, and for three days in November 2008, the artist Tacita Dean filmed the preparations for one such performance at a former Ford factory in California, looking out on to San Francisco Bay.

It is an extraordinary space: a vast structure with windows on three sides that destroy the boundary between inside and outside. As a result, the ripples of muddy blue water, the boats and ships passing by and the seagulls swooping towards the windows are as much a part of this film as the dancers. The camera lingers on a small bird pecking its way across the floor, then focuses in on a man checking his car boot on the dock outside: it's fitting because you often get a sense while watching Cunningham's work that his dancers are part of the larger fabric of the world, a fraction of a bigger picture.

The movement is instantly recognisable to anyone who knows Cunningham's work: the stark, clean lines, the funny little jumps and hops, the killer balances. But Dean isn't interested in chronicling the dance as much as the whole experience of being there, so we see dancers warming up, stretching and waiting as much as we see them dancing. At one point we only hear the dancers moving - the slaps and squeaks of their feet on the floor - and on screen we see Cunningham in his wheelchair, head framed with cloud-like curls, beady eyes watching intently.

More than anything, 'Craneway Event' is a gorgeous study in light and line. The screen is streaked with vertical and diagonal lines - of the window frames and the metal beams of the roof. Reflections shimmer on the floor, extending those beams, and occasionally the dancers limbs unfold in pleasing parallel. As the day wears on the sun lowers and a rich golden glow shoots blurrily through the windows, sometimes almost drowning the dancers, or reducing them to shadowy silhouettes. In parts this film is jaw-droppingly beautiful; elsewhere, it really drags. It runs at just over a hundred minutes and there's lots of sitting around, practising entrances and exits, switching between shots and lingering on nothing much.

But then that's sometimes the effect of Cunningham's work itself. 'Where is this going?' you ask yourself. But to paraphrase Cunningham's partner John Cage, if something is boring, you're not looking hard enough. Ultimately, 'Craneway Event' rewards attention, especially if you can tune into its meditative pace.

There are some similarities to Frederick Wiseman's recent documentary about the Paris Opera Ballet, 'La Danse' - the lengthiness, the static frame, the unobtrusive direction. The film feels unengineered, although Dean is, of course, choosing our view. She also chooses not to edit out the moments where the cameraman is changing focus, or switching the exposure, a subtle reminder that there is a middleman between the audience and the subject.

Cunningham himself is a serene presence, his genial personality curiously quiet, just from time to time dishing out dispassionate instructions to the dancers: 'Walk a little slower', 'Face the wall'. It's an unsentimental portrait, but not without its poignant moments. In one shot, we see the piece of paper Cunningham holds as it quivers in his ageing hand - a painful reminder of the demise of the dancer's body that once held such immense strength. In another, we see the whole, enormous space of the factory floor, empty except for Cunningham's tiny form in the centre, only noticeable because of the light reflecting on his halo of curls. Here is a great figure reduced to a speck. Just one (glorious) stitch in the greater fabric of the world.

'Craneaway Event' shows at Frith Street Gallery unto June 27 2010