Maximum effective ISO is an estimate of the highest sensitivity at which a camera can capture excellent quality photos.
Cameras with higher effective ISO will be better choices for indoor photography, night shooting, and indoor sports photography, especially if you intend to make large prints.
You can learn more at our glossary entry.
Maximum effective ISO test data courtesy of DxO Mark.K-S1 test data on DxO Mark T6s test data on DxO Mark
Highest resolution Canon APS-C camera yet; Good high ISO performance for its class; Very fast autofocus; Servo AF in Live View; Quick Control Dial & top-plate LCD screen.
Shallow buffer depth with RAW files; Below average battery life; No 60p video frame rate.