ISO (International Organization for Standardization)
What is ISO (International Organization for Standardization)?
Film speed rating expressed as a number indicating an image sensor's (or film's) sensitivity to light. The higher the number, the more sensitive and faster the sensor (or film) is. Although traditional cameras don't have a specific ISO rating, digital cameras do as a way to calibrate their sensitivity to light. ISO is equivalent to the older ASA.
Most digital cameras have native (basic) ISO ratings of about 100, but can be ""extended"" far beyond this base rating in order to capture sharp imagery under lower lighting conditions. When shooting at extended ISO levels, image quality begins to suffer in terms of sharpness levels, noise, contrast, and added ""graininess."" Return to Glossary