Though he was trained as a painter, Gustave Le Gray made his mark in the emerging medium of photography. An experimenter and technical innovator, Le Gray pioneered the use of the paper negative in France and developed a waxed-paper negative that produced sharper-focus prints. In 1851 he began to use collodion on glass negatives, which further increased the clarity of his images. He became one of the first five photographers, along with Édouard-Denis Baldus and Hippolyte Bayard, to work for the missions héliographiques, a government-sponsored commission to document the state of repair of important French monuments and buildings.
Le Gray is credited with teaching photography to many important French photographers in the 1850s. In 1851 he became a founding member of the Société Héliographique, the first photographic organization in the world, and later joined the Société Française de Photographie. In 1860 Le Gray started to tour the Mediterranean with the writer Alexandre Dumas, but they soon parted company. Le Gray went on to Lebanon and then to Egypt, where he became a professor of drawing and died in 1884.