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.1DX Mark II test data on DxO Mark D500 test data on DxO Mark
Superb image quality; Great high ISO performance; Rugged, comfortable camera body; Sharp articulating touchscreen display; Excellent AF point frame coverage; Fast continuous shooting speeds; 4K UHD video; Built-in Wi-Fi, NFC and Bluetooth.
Somewhat large for an APS-C camera; Expensive for a DX camera; 4K UHD video doesn't offer full DX field-of-view; No built-in flash; Still uses contrast-detect for Live View AF; Dual slots use two different card types (XQD and SD).
Excellent image quality, especially from RAWs; Fantastic high ISO performance; Fast autofocus with great tracking performance; 14fps burst rate; Amazing buffer capacity; 4K 60p video; Robust build quality.
Very heavy, bulky and expensive; Dual memory card slots use different formats; 29:59 continuous video recording limit; Touchscreen feels underutilized.