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.X100 test data on DxO Mark RX100 test data on DxO Mark
Superb image quality; Dazzling Hybrid Viewfinder; Traditional mechanical controls; Mostly excellent optical performance.
Quirky interface; Manual dials turn easily; Manual focus is too difficult to use; Dramatic lens flare, especially at night.
Excellent high-ISO performance for such a compact model; Smart controls; Small body; Bright lens; 10fps full-res burst mode; Very fast shutter response; Excellent LCD.
Lens flare at night; Poor rendering of yellows; Slow flash recycling; Soft corners wide open; Continuous AF mode slow to lock.