1 The Camera Obscura Turns the World Upside Down No one knows when people first noticed a strange optical illusion When light from the sun shines through a small hole and into a darkened room it creates an image The image appears on the wall opposite the hole It shows the scene outside the room The image is upside down That is because light travels in a straight line Light from the bottom of the outdoor scene shines up through the hole to the top of the wall Light from the top of the scene travels down through the hole to the bottom of the wall This image became known as camera obscura These are the Latin words for dark room By the early 1500s people were building box-size devices called camera obscuras But the images these made were not very clear A camera obscura from 1800 44
Italian scientist Daniel Barbaro placed a lens in the hole of a camera obscura The image it created was much clearer and brighter The image could be focused onto a surface such as a sheet of paper People could trace around it to make drawings or paintings In the late 1600s German scientist Johann Zahn came up with more ideas to improve the camera obscura For example adding a mirror allowed the image to be projected This type of camera obscura became popular in the 1800s Large ones were built in coastal towns They projected images of the seaside for tourists to view 55 400 BCE Year a Chinese philosopher named Mozi wrote about a camera obscura image This was the first recorded mention Camera obscura is the Latin phrase for dark room Images from a camera obscura appear upside down Camera obscuras were popular tourist attractions
2 The First Photograph Is a View Out a Window In the 1720s German scientist Johann Heinrich Schulze did an important experiment He proved that a chemical compound was photosensitive When silver nitrate was exposed to sunlight it turned dark In the late 1700s British chemist Thomas Wedgwood made one of the first tries to take a photograph He placed paper covered in silver nitrate in a camera obscura All he got was a shadowy image shined through the lighter areas of the drawing and hardened some of the bitumen Niépce washed away the rest of the bitumen A negative of the drawing was left on the plate Niépce tried a similar process with a camera obscura He aimed the camera out a window of his home in France After eight hours of exposure he took the metal plate out of the camera He washed away the bitumen In the early 1800s French inventor Joseph-Nicéphore Niépce developed a new printing method He called it heliography or sun drawing Niépce put bitumen a tar-like substance on a metal plate Then he placed a drawing over the bitumen and set it in the sun Sunlight Niépce A 19th century portrait of Joseph-Nicéphore 6
that didn’t harden What was left was a negative of the scene outside his window From this plate he printed the oldest known photograph It is called View from the Window at Le Gras THE NEGATIVE IMAGE Most early cameras produced a negative image A negative looks the opposite of what is being photographed Dark areas appear light and light areas are dark Printing or developing the negative to make a photograph reverses the dark and light areas View from the Window at Le Gras the oldest known photograph 1826 Approximate year Joseph-Nicéphore Niépce took the oldest known photograph In the 1700s scientists proved that sunlight discolors certain chemical compounds The first photographs were taken using a camera obscura They needed up to eight hours of exposure time 7
