What was the primary limitation on the photographs taken by niceophore niepce?
a. They take eight hours to create.
b. They could not include moving people
C. They required silver chloride which was rare
D. They would continue to darken if exposed to light
D. They would continue to darken if exposed to light
Nicéphore Niépce's early photographs, specifically his "View from the Window at Le Gras," are known for being heliographs or bitumen-based. This process involved coating a pewter plate with bitumen of Judea and then exposing it to light for an extended period, which could be several hours. After exposure, the bitumen hardened in proportion to the amount of light it received, and the unhardened bitumen was washed away with a solvent, leaving behind a light-exposed image.
However, the primary limitation, as mentioned in choice D, was that the image would continue to darken over time when exposed to light, as the bitumen could not be completely fixed to stop further reactions to light. It's also true that the process required long exposure times, which made photographing moving subjects impossible (choice B). However, the critical issue was the lack of a fixing process to make the image permanent. Silver chloride (choice C) is related to later developments in photography, not primarily to Niépce's process.