1708, "vaulted building," from Latin camera "vaulted room" (source of Italian camera, Spanish camara, French chambre), from Greek kamara "vaulted chamber."
The word also was used early 18c. as a short form of Modern Latin camera obscura "dark chamber" (a black box with a lens that could project images of external objects), contrasted with camera lucida (Latin for "light chamber"), which uses prisms to produce on paper beneath the instrument an image, which can be traced. It became the word for "picture-taking device" when modern photography began, c.1840 (extended to television filming devices 1928). Camera-shy is attested from 1890. Old Church Slavonic komora, Lithuanian kamara, Old Irish camra all are borrowings from Latin.
Being filmed, as in When the talk-show host began, I wasn't sure if we were on camera. This usage dates from the first half of the 1900s, soon after the birth of motion-picture and television filming. The same is true of the antonym off camera, meaning “outside the view of a movie or TV camera,” as in Go ahead and scratch—we're off camera now.