John Minihan, who worked for the Evening Standard for 30 years, is "the man who shot Beckett", so-called because of his uniquely personal, black-and-white portraits of the Irish playwright.

Of the 20 works in this quiet side-show, part of the Celtic Heart Festival, the three of Beckett are magnetic character studies among more informal portraits of Irish writers. These include Van Morrison, bursting out of a beige mac, a smiling Gerry Adams in Belfast at the height of the troubles, and Edna O'Brien relishing exposing her long, silky legs.

During Beckett's Waiting for Godot rehearsals at Riverside Studios in 1984, Minihan followed him into rehearsals - a tall, slender, aquiline figure, hands behind his back and one long thumb upturned - and produced close-up head shots revealing the elegant beauty and character in his extraordinary face; he even drew a slightly bemused smile. The unmistakable crest of badger hair frames small eyes as alert as a suspicious small mammal's, tuned to the mysteries of human existence.

After rehearsals, Minihan stopped him outside, wrapped in a cool suede coat, satchel over one shoulder, and the writer projects a resigned smile onto a photographer almost as intense as his subject. A year later, Minihan's self-portrait on a Paris street while Waiting For Beckett, reveals the anxiety of hoping for the perfect shot. Like his portraits of Beckett, the image fits his credo: "Good photography is good literature."

Until 6 July. Information: 020 8237 1111, www.riversidestudios.co.uk