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.
EOS M5 test data on DxO Mark X100 test data on DxO MarkSuperb 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.
Enthusiast-oriented compact camera body; Good image quality in most situations; Built-in electronic viewfinder; Impressive Dual Pixel CMOS AF; Very good overall performance.
High ISO image quality and dynamic range aren't quite up to par with some of its competition; No 4K video recording; Native EF-M lens selection is still limited; Below average battery life.
