AutoISO

AutoISO is a camera feature that automatically adjusts the sensor's sensitivity to light, measured as ISO, in response to scene brightness. It is designed to maintain proper exposure across a wide range of lighting conditions without manual ISO changes. AutoISO is available in many exposure modes, though its behavior and available controls vary by brand and model.

Typically, photographers set constraints such as a minimum shutter speed to protect against motion blur and a maximum ISO to limit noise. The camera meters the scene and increases or decreases ISO to reach the target exposure within those limits. In manual mode with AutoISO enabled, the aperture and shutter speed chosen by the photographer remain fixed while ISO adjusts; in other modes the camera may also adjust shutter speed or aperture.

Benefits include easier handling of changing light, maintaining shutter speeds suitable for action, and allowing use of wide apertures for depth of field without constant ISO tweaking. AutoISO is especially useful in event, street, sports, and wildlife photography where lighting can shift rapidly.

Limitations include potential jumps in exposure and increased noise when high ISO is required. Some shots may be exposed inconsistently if the scene changes quickly. To manage results, many cameras let users cap the maximum ISO and apply exposure compensation to correct brightness.

In practice, AutoISO is a standard feature on modern digital cameras and mirrorless bodies. Understanding its behavior helps photographers decide when to rely on AutoISO or maintain manual ISO control for consistency.