heliography

Heliography is an early photographic process developed by Nicéphore Niépce in the 1820s, named from the Greek for “sun drawing.” It produced permanent images by exposing a surface coated with bitumen of Judea (natural asphalt) to light. The technique is regarded as one of the first successful methods for capturing a real-world scene with a camera.

In the process, a metal plate, typically pewter, was coated with bitumen of Judea dissolved in a solvent such as lavender oil. The plate was then exposed to sunlight for extended periods—often hours or even days. Light hardened the bitumen in proportion to illumination, while the unexposed areas remained soluble. After exposure, the unhardened bitumen was washed away with a solvent, leaving a direct image on the plate. The resulting image was a direct positive and could not be easily reproduced, reflecting the material’s low sensitivity and the impracticality of large-scale replication at the time.

The best-known example of heliographic work is View from the Window at Le Gras, created around 1826 or 1827. This image is frequently cited as the oldest surviving photograph, and it exemplifies Niépce’s pioneering approach to fixing scenes with light.

Legacy and significance: Heliography preceded later photographic processes such as the daguerreotype and calotype and is considered a foundational step in the history of photography. Niépce’s experiments with asphalt-based coatings established key concepts of image formation by light, even as the method was eventually superseded by more sensitive and versatile techniques after Daguerre’s developments in 1839.