A camera obscura was the precursor to the modern camera, and it worked a bit like a projector. Utilizing a hole in the wall, or within a box, the camera is able to reflect light onto a surface by bouncing that light off of another surface. The photographer acts more like an artist in this case, tracing the image that he or she sees projected from the light.
This is the technique that Nicéphore Niépce utilized to create the world’s oldest existing photographic image. Niépce decided to capture his estate in France, called Le Gras, as seem from one of the building’s highest windows.
He set up his camera obscura, focusing the projected light onto a 16.2 x 20.2 cm plate of pewter. The pewter had a thin coat of Bitumen of Judea on its face, which acted as a method to translate the light in the image. The bitumen hardened in the areas of the plate where the light was focused brightes, while remaining soluble and easy to wash away in the areas where not much light had touched the plate.
This process took a very long time, so the plate had to remain exposed for several hours. This is evident in the final print, which shows sunlight and shadows on different parts of the building, suggesting a significant time change had taken place.
Interestingly, an independent researcher decided to attempt to duplicate this process. His findings seemed to suggest that this process could take several days. What is most important about this photograph is precisely that. This is the oldest surviving example of what we might call a photograph, rather than an illustration, which was the more common technique with camera obscuras.
About the Author: Samuel Phineas Upham is an investor at a family office/ hedgefund, where he focuses on special situation illiquid investing. Before this position, Phin Upham was working at Morgan Stanley in the Media and Telecom group. You may contact Phin on his Samuel Phineas Upham website or Twitter.