Multiple exposure

Multiple exposure is a phenomenon in photography. In chemical photography, it may happen that several shots are exposed to the same place of the emulsion, so that the individual images overlap into a single image. In digital photography, the image sensor is exposed to light multiple times before it is read out and deleted. This effect can be consciously brought about, however, is usually undesirable.

Area of ​​application

• Spatial or temporal separately recorded subjects can be compose an image. In contrast to the photo montage, however, the superimposed images on the picture are not opaque, but transparent. This effect can, if desired, be prevented by the use of masks.
• The impression of a gaze ray may be generated by a receiver with a receiver and without a cover are superposed.
• Motions can be visualized by several phases of movement are visualized on an image.

• When using a pinhole camera to multiple exposures arise inevitably due to the extremely long exposure times.
• To illustrate the process of lunar eclipses and solar eclipses.

• To increase unwanted blur caused by artistic- experimental recordings.

Technical Realization

Three methods for multiple exposure are available:

• At shutter ( position B) permanently open is achieved by triggering multiple flashlights a multiple exposure of the film. This method is feasible only in the dark, because overexposure otherwise would result. This method is particularly suitable for the analysis of extremely fast-moving, such as in ballistics.

• The shutter is reopened for each individual exposure, the film is not transported between exposures or not read the imaging chip and deleted. Cameras with automatic film transport must first be brought into an appropriate mode to suppress the fast forward the film after each individual exposure. For cameras with manual film transport which usually existing lock to prevent accidental multiple exposures must be lifted.

• At shutter speeds in the range of minutes (eg pinhole camera shots) there are always multiple exposures, as soon as the object is moving, altering the position within the image. On the other hand, a fast-moving object (such as a moving car ) is held not only on the film. In this experimental photography, both effects can be quite desirable.

Multiple exposure during scanning ( Multi-Exposure )

Scan slides, black and white film and color negative film multiple exposure can be applied to generate HDR scans. The multi-exposure method mentioned scanning the target several times with different exposure intensities. The data is then charged to a picture. This enables a much higher dynamic range, ie to capture more details of the original.