Of the early photographers in Vietnam, Émile Gsell is by far the most significant. His Saigon studio was in operation from 1866, at the latest, and continued until his death in 1879. Skilled in landscape, portraiture, genre and architectural photography, his work is the benchmark by which other photographers in the region have come to be measured. Unfortunately, we know very little about his life.

Émile was born into a Protestant family in Sainte-Marie-aux-Mines in the Upper Rhine on 31 December 1838. After his younger brother Charles was born on 15 October 1840, the family moved to Paris and lived at rue du Temple. Gsell senior, also named Émile, was a printer and carried out his trade in the capital. The 1846 census listed the family as living at 80 rue Bonaparte. In around 1858 Émile enlisted in the army for seven years. In 1861 the French military offered training in the techniques of photography and it is very likely that Gsell learned the art during his military service. Searches in the military archives have so far failed to uncover any details of his military career. However, it seems likely that he served in Cochinchina with the French expeditionary forces and that when he left the army in 1865 or early 1866 he decided to stay in Saigon and open a photo studio.

Ernest Doudart de Lagrée (1823–68), who had agreed to lead the French Mekong Expedition, decided in early 1866 to take along a photographer and enlisted Gsell. We know this from the official account of the expedition written in 1873 by Francis Garnier. Included in the itinerary was a visit to the ancient ruins of Angkor Wat in Cambodia. Doudart de Lagrée had visited the ruins twice before, the last time in March 1866. At that time, he met the British photographer John Thomson, who was capturing the first ever photographs of the site. It is very likely that this meeting inspired Doudart de Lagrée to take Gsell with him on his third visit.

Gsell photographed the ruins between 24 June and 1 July 1866. The expedition members then returned to Phnom Penh where they stayed until 7 July before moving on to study the Wat Phu ruins at Bassac, Laos.