The first known photograph took at least eight hours to capture.

In the 1820s, French inventor Nicéphore Niépce was experimenting with using light to create and copy lithographs, and found success with bitumen of Judea, a kind of photosensitive asphalt. After spreading a mixture of the asphalt and lavender oil on a pewter plate and exposing it to sunlight, he found that the parts exposed to light would harden, and the parts that were in shadow would wash away easily.

Niépiece decided to expose one of his plates to a camera obscura — a device that projects real-time (but impermanent) images onto a surface. Using this method, he captured the scene outside his second-story window in 1826. Titled “View From the Window at Le Gras,” it’s now considered the first known photograph.

But because this photographic method, which he called heliography, relied on asphalt hardening, it took a really long time to capture. The exact exposure time of the first known photograph is lost to history, but experts estimate eight hours on the low end. If you ask the University of Texas Harry Ransom Center, the current stewards of the heliograph, it likely took several days. 

The first practical photograph, the daguerreotype, which was exposed onto plates of silver, came along more than a decade later in the late 1830s. It was popular in portraiture and a significant improvement on the heliograph, although it still required its subjects to sit for the better part of a minute, so people had to hold very still. 

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