What was it used for?

The earliest cameras obscura were darkened rooms in houses. They were used for observing solar eclipses and scenery.

Some 16th-century artists used the room camera obscura as a drawing aid. They traced the images projected on the wall.

By the 1660s, portable box and tent cameras obscura were used widely by artists as drawing aids. A small box version could be carried under an artist's arm. It contained a lens in the front that focused the image onto a viewing screen of ground glass in the back. The artist traced the image projected onto the screen.

Camera obscura observatories were most popular in the 1800s. They were often situated in places with panoramic views and attracted a curious public and researchers studying nature.