ACS Distance Education UK
Managing Light for Good Exposure
When a photo is taken, light streams from each of the different parts of the subject will hit the photosensitive surface (eg. film) at the same point in time. The reaction which film has to each stream of light is broadly affected by
Exposure is proportional to illumination and duration of the exposure. Different parts of a subject can have different levels of illumination. In order to get the best exposure for any one part of a subject, the duration of the exposure must be adjusted to suit the level of illumination coming from that area of the subject.
The problem is that in order to get the best exposure for one area of a subject, it is usually necessary to move away from the best duration for another (differently illuminated) area of the subject. By choosing one or another duration for an exposure, you are generally choosing to optimise the sensitometric reaction of the film to one particular part of a subject. (Note: These variations can be corrected to some degree by using digital technology to manipulate photos after they have been taken, using advanced software such as Adobe Photoshop).
Distance Education Course
PHOTOGRAPHIC LIGHTING- BPH204
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