Multiple Exposure

Image found at: https://thedarkroom.com/tips-on-creating-double-exposures/

The following information is found at: http://en.wikipedia.org/wiki/Multiple_exposure

• A multiple exposure is the superimposition of two or more exposures to create a single image. 
• The exposure values may or may not be identical to each other
• In photography and cinematography, multiple exposure is technique in which the camera shutter is opened more than once to expose the film multiple time, usually using different images.
• The resulting image contains the subsequent image/s superimposed over the original. 
• This technique is sometimes used as an artistic effect often to create ghostly images or to add a person or object to a scene that wasn't originally there. 
• It is often considered easiest to have a manual winding camera for double exposures.
• Some more advanced automatic winding cameras have a multiple exposure setting, however, the setting must be set up before each exposure. 
• Due to the fact multiple exposure exposes a frame multiple time, negative exposure composition must first be set to avoid overexposure. 
• Medium to low light is ideal for multiple exposure.
• A tripod is not always necessary if combining different scenes in one shot. However, in some conditions (such as recording an entire lunar eclipse), a stable tripod is essential to order to keep consistency. 
• More than two exposures can be combined, with care not to overexpose the film.