Not a Friday seems to go by without another impressive documentary receiving a theatrical release. The four on offer this week are a decidedly mixed bunch. But there's more to intrigue here than the sorry summer dross emanating from Hollywood.

Blindsight, directed by the New College graduate Lucy Walker, celebrates the courage of six sight-impaired Tibetan teenagers as they accompany Erik Weihenmayer, the first blind man to climb Mount Everest, on an expedition up its 23,000-foot neighbour, Lhakpa Ri (pictured right). The trek is compelling in itself, especially after Weihenmayer and his super-driven support team fall out with Lhasa blind school principal Sabriye Tenberken over whether trying or succeeding is the real purpose of the venture. But it's the background stories of Sonam Bhumtso, Gyenshen, Dachung, Kyila, Tenzin and Tashi Pasang that give the story the poignancy that almost renders the cultural and ethical clashes between the American, European and Asian adults an irrelevance.

Doubtless Weihenmayer would find a kindred spirit in Philippe Petit, who, on August 7, 1974, undertook an illegal tightrope walk without a safety net between the twin towers of the newly constructed World Trade Center. In Man on Wire, James Marsh recalls this reckless feat with an audiovisual panache that rarely distracts from the mesmerising narrative that charts Petit's rise from a kid who refused to accept his physical limitations to the showman who teetered between the towers of Notre Dame in Paris and the Sydney Harbour Bridge before sneaking into the WTC with his loyal crew and making his way to the top in a service elevator. With Michael Nyman's inspired score driving the action, this often feels like a 1960s heist caper. Yet while the odd reconstructed scene allows a spirit of suspenseful comedy to intrude, such tactics only emphasise the scale of Petit's unique achievement.

Lou Reed's concept album, Berlin, flopped spectacularly on its original release in 1973. Three decades later, Reed demonstrated his confidence in the material by performing it live for the first time and Julian Schnabel's film of the same name captures less the viscerality of the Brooklyn gigs than the proficiency of Reed's band and the strikingly contemporary feel of both the music and the lyrics.

In addition to such album highlight as How Do You Think It Feels? and The Bed, Reed throws in renditions of Rock Minuet and Candy Says, and has Sweet Jane playing over the closing credits. It's not quite a straight concert movie, though, as Schnabel occasionally drifts into the big-screen images he created for the stage show to bring us closer to Reed's anti-heroine, Caroline (Emmanuelle Seigner). However, the focus of Ellen Kuras's camera primarily rests on Reed and his excellent backing musicians and choral singers.

Another alumnus of the Warhol factory, photographer Bruce Weber, demonstrates that one man's deeply personal project is another's eminently resistible rattlebag in A Letter to True. Weber clearly loves his dogs. He's also fond of famous friends like Dirk Bogarde and Elizabeth Taylor and admires Vietnam War snapper Larry Burrows. He was shocked by 9/11 and laments the plight of Haitian refugees in Miami. But do such abstract musings really make a movie?

There's no question that the footage of Weber's golden retrievers looks superb, whether they're splashing in the surf or basking in his garden. But it's hard to see what he's getting at with the anecdotal philosophising in the missive he handwrites to his youngest pup, the easy listening soundtrack, the clips from The Courage of Lassie or the poems by Rilke and Spender that are read respectively by Julie Christie and Marianne Faithfull.

Married Life, Ira Sachs's homage to cinema, is more imitative than inventive. Based on John Bingham's pulp novel Five Roundabouts to Heaven and set in the autumn of 1949, it's a meticulous pastiche of the film noir style that evolved in post-war Hollywood, right down to the stylish chiaroscuro, the world-weary voiceover and the intricate plotline that sees a respectable man being lured away from the path of bourgeois propriety by overwhelming emotion.

d=3,3,1However, meek New York businessman Chris Cooper's sudden decision to murder wife Patricia Clarkson to spare her the pain of divorce rings as hollow as her furtive affair with David Wenham and caddish best friend Pierce Brosnan's sudden renunciation of his staunch bachelordom to romance Cooper's demure, widowed mistress, Rachel McAdams.

The visuals couldn't be more precise. But the flaws in character psychology are exacerbated by the stiffness of the performances and the premeditation of Sachs's direction.