Dorothea Lange
New Jersey native Dorothea Lange began her career as a portrait photographer in San Francisco. She was good - very good - but her heart wasn't in it. For her, photography came alive when she began taking pictures of America's Depression-hit poor. Her photographic work for the California State Emergency Relief Administration and the Federal Farm Security Administration helped alert America to the plight of migrant workers living on the breadline. "Migrant Mother, Nipomo" (pictured above) is one of the most memorable images of the Depression. The image alone tells a poignant story. But Lange was in the habit of speaking to her subjects. The photograph becomes even more powerful when we learn that the woman featured had seven children, yet was only 32. The family were living off peas that had frozen on their vines.

Weegee
Think of urban mean streets and you're thinking of Weegee's world. His real name was Arthur Fellig, a Ukrainian-born immigrant who came to New York with his family in 1910. He started out as a junior for Acme Newspapers and went freelance in 1935. His gritty pictures of New York's grim underbelly - crime scenes, fires and car crashes - soon earned him celebrity status. He adopted the soubriquet Weegee (from Ouija board) in an apparent reference to his uncanny ability to arrive at the scene as a story was breaking. In fact, he monitored police radio channels.

Robert Capa
It's no surprise to learn that Robert Capa was a good friend of Ernest Hemingway. Capa was the quintessential war photographer. Born Andre Friedmann in Budapest, he made his way to Paris, where he became immersed in the avant-garde arts scene of the 1930s. His photographs of the Spanish Civil War brought him widespread recognition among the many picture-led magazines that were emerging at the time. He covered World War II for Life magazine, managing to land on the beaches of Normandy with Allied invasion forces. Unfortunately only a handful of his pictures from that assignment survived a darkroom accident. They nevertheless inspired Steven Spielberg while he was working on the D-Day scenes for Saving Private Ryan. Capa was also a founding member of the world-famous Magnum picture agency, created so that photographers would have complete control over their material. He was killed in 1954, while on assignment in French Indo-China.

Grace Robertson
Grace Robertson's sharp, witty pictures of ordinary British people at work and play delighted readers of Picture Post magazine in the years following World War II. Robertson was brought up with photography from an early age: her father was a Picture Post journalist. At 19, she submitted her first photographs to the magazine under a male pseudonym but she didn't have to wait long before getting her own byline. Her pictures are full of life. A small boy cheekily kicks the backs of an adult's legs in Petticoat Lane. A group of women in fine form make their way to a pub. The fashions and backdrops are of their time. But the people depicted are timeless.

Don McCullin
Like Robert Capa, Don McCullin's principal subject matter was war and the human misery it spawns. For 30 years he covered wars, including Cyprus, Congo, Biafra, Vietnam, Cambodia, Northern Ireland, Afghanistan and Lebanon. One of his most famous pictures shows a shell-shocked American soldier in the aftermath of prolonged action at Hue, Vietnam, in 1968. The man's eyes have seen too much. He stares blindly into the distance, oblivious to everything around him. Searing pictures like this earned McCullin such a reputation that, when the Falklands War broke out in 1982, the British government was so frightened of what his images might show that it wouldn't allow him to cover the conflict. Emotionally scarred by his experiences and disillusioned with Fleet Street, McCullin gave up war photography in the 1980s. Instead, he devoted his creative energies into producing haunting landscapes.