The multiplane camera was a primary innovation that improved the way traditional animations were created. Disney studios is credited with inventing the multiplane, although variations on their patented version had been used beforehand. Regardless of who invented the multiplane camera, it was an important milestone for animation.
Unlike most cameras, the multiplane camera is mounted perpedicularly to the ground so that it's lense faces a number of glass racks. The purpose of these racks is to place different pieces of of the background, middleground, and foreground elements of an animation. Mounting the elements on different planes solves a number of problems that had occured with animation prior to the multiplane.
1. An animator can move a character within a scene without having to redraw or disturb and other part of the scene.
2. Similarly to moving the a character, the animator can pan a background across without disturbing the action of the elements in the foreground.
3. With the foreground, middleground, and background at differing distances from the camera, there's more atmospheric perspective, adding the the realism many animators desired to achieve within their animations.
Althougth Disney is credited with its invention, Lotte Reiniger and Bertold Brecht used their version of the multiplane to make the 1926 film The Adventures of Prince Achmed.
As shown above, there were a number of different elements within a single frame in Prince Achmed, which were lit differently. The paper cut-out character wer silouetted. The painted backgrounds were brightly lit. And for several scenes, Brecht used soup suds to create a variety of effects on the background. This beautiful film could not have been created had it not been for the multiplane.
The multiplane camera was a crucial step for animation to become more advanced, for more techniques to be experimented with, and for animation to become more realistic.