A camera was an optical instrument used for taking photographs.
History
Emmett Brown had a camera in 1955, which he and Marty McFly used on November 14 to document their exacavation of the DeLorean time machine from the Delgado Mine, where his 1985 counterpart had hidden it in 1885, and also to take the photograph of the tombstone in the Boot Hill Cemetery.
Presumably, along with his notebook and reel-to-reel tape recorder, the camera was the medium Doc used to document his scientific experiments prior to the invention — and his purchase — of the JVC camcorder.
A camera of the large 19th century variety was used by the photographer at the Hill Valley Festival in 1885, who was offering those attending the opportunity to have a souvenir photograph taken with the new clock that would be installed in the tower of the Hill Valley Courthouse. When Marty mentioned that he wished he had brought his own camera, he came up with the idea of having a photograph of himself and Doc standing together in front of the clock.
Behind the scenes
- Although it is never mentioned either on-screen or in the novelization, Doc presumably developed his own photographs (being a scientist, he would know how to do this) to prevent them from falling into the wrong hands.