ISO
0x8827Also: ISOSpeedRatings, PhotographicSensitivity
How sensitive the sensor was to light.
ISO measures the camera sensor's sensitivity to light. A low ISO like 100 needs more light but gives the cleanest image; a high ISO like 6400 lets you shoot in the dark but adds visible noise (grain).
In EXIF, ISO is stored as a plain number. Doubling it (100 → 200 → 400) doubles the sensitivity, brightening the exposure by one stop.
Example value
ISO 100
Typical range
50 – 25600
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