18Speed of Materials, Sensors and Systems
Speed of Photographic Media
Two films are said to differ in speed if the exposure required to produce a negative on one differs from the exposure required to produce a negative of similar quality on the other, the material requiring the lower exposure being said to have the higher speed. The speed of a material thus varies inversely with the exposure required, and we can therefore express speed numerically by selecting a number related to exposure. The response of the photographic emulsion is complex, and speed depends on many factors, of which the following are the most important:
- Exposure
- The colour of the exposing light, e.g. whether daylight or tungsten light.
- The intensity of the exposing light. ...
Get Manual of Photography, 9th Edition now with the O’Reilly learning platform.
O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.
