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 GX7 test data on DxO Mark
Sharp retro design and solid build; High resolution, tiltable electronic viewfinder and LCD touchscreen monitor; Competitive still image quality; Very good video quality, recording Full HD at frame rates up to 60p; Fast autofocusing and all-around performance; Robust Wi-Fi and NFC capabilities, including remote shooting when paired with a smart device
Weak built-in flash; No external mic or headphone jack for video recording; Some poor results when shooting in Creative Panorama mode
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.