Good portraits invite questions. And over the past 150 years photographers have used the camera not simply to record someone at a particular moment in time but to create more complex, intriguing images.  Brought up in South Africa, award- winning London-based photographer Nadav Kander has gained a reputation for his landscape work (winning the Prix Pictet in 2009) and also for turning encounters with famous figures into outstanding portraits (such as his Barack Obama). Through Kander's lens, we are offered a fresh view, whether of Erin O'Connor as Millais's Ophelia, Cheryl Cole as a curled-up bunny, or the inscrutable but honed mask of Christopher Lee. As Kander puts it: "In any session there are as many as 100 pictures made, but only a few will be portraits, in that they hold something so much more than just a likeness." With strong shadowing and no background distractions, the Lee portrait exemplifies Kander's sculptural approach, comparable perhaps to Julia Margaret Cameron's famous portrait of Thomas Carlyle, of which she noted: "Carlyle like a rough block of Michelangelo's sculpture."  Kander prefers a certain distance from his subject, not seeking like the Edwardian modernist EO Hoppé or Annie Leibovitz to do extensive research, but opting for riskier interaction on the spot. "I like to create a void between myself and the person I'm photographing, where anything can happen… I remain quite empty, so that whatever happens at first happens with the camera trained on them."  Subjects perform for a portrait, but Kander works this to advantage, whether in Lily Allen's simple turn of the head or the unexpected vulnerability in Eric Cantona's hand. Kander says: "To present people exactly how they are, or want to be, is a waste of time. Just showing positive, expected images of beauty and airbrushing away the conditions that make us human seems like deception to me." Nadav Kander: Selected Portraits, 1999-2011, is at The Lowry (thelowry.com) from 16 April to 4 September
As a major exhibition of his work opens at The Lowry, Sandy Nairne, director of the National Portrait Gallery, introduces some of Nadav Kander's most breathtaking images