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 M9 test data on DxO MarkExcellent image quality, with unique film-like "Leica look"; No-nonsense controls; Solid build; Good print quality.
Difficult to focus in low light; High default contrast and saturation; Manual focus only; Lack of low-pass filter can leave moire and other artifacts.
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.
