In the visual arts, particularly photography, the exposure of a composition determines the amount of detail and contrast in that composition. Traditionally, the longer the exposure the more detail and darker the overall composition.
The concept of exposure is not limited to the visual arts, a narrative composition is subject to the same rules of exposure as any medium. The longer the reader is exposed to a composition the more details are clear to them but if they are exposed to the same scene for too long it may all blend together (Over-Exposed). The same is also true if the exposure is too short. There will be too few details (Under-Exposed).
In order to achieve the Optimal Exposure the perfect balance between light and shadow, detail in the composition, it is necessary to sample the right saturation for each scene. The optimal exposure is, of course, the right exposure that achieves the desired effect. This approach may be entirely subjective however, there is a 'correct exposure' for every scene.
Controlling the exposure in a narrative can be achieved through a few specific elements, the lighting, depth of field and speed of the composition. The most important concept to consider in the process is Reciprocity. This is a simple principle that states that the longer the exposure, the reciprocally smaller aperture required. In a narrative sense this means the longer the scene the fewer details of the scene and more focus on the subject. As each change in exposure adjusts the overall composition it creates a different exposure for the reader. Through reviewing each exposure it is possible to create the optimal exposure for the scene, the perfect balance of details and focus.
A different means of bracketing the exposure in a narrative scene is to use scenes of differing exposures to bracket the selected scene. Use a slightly darker scene before the darkest scene and a slightly lighter scene leading away from that scene to achieve an exposure balance.
To prevent an over exposure in a composition it may be necessary to provide a means of compensation for the scene. If the composition is too dark it is possible to compensate for this overexposure by adding more light to the scene or just an additional lighting source. The narrative composition can find compensation in added details, lighting sources and subtle shifts in depth of field that can change the exposure.
Finding the optimal exposure of a composition can be a difficult practice but often creates the best overall compositions whether it is bracketing the composition in a single scene to find the right balance or using the surrounding scenes to bracket a single composition. It is important to recognize when the audience becomes over-exposed and under-exposed to a composition.