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.5D Mark IV test data on DxO Mark D7500 test data on DxO Mark
Superb image quality from RAW files; Improved dynamic range; Excellent high ISO performance; Fast 7fps burst rate with unlimited JPEG buffer; High-quality cinema 4K video; Built-in Wi-Fi; Dual Pixel CMOS AF is very good.
JPEG files look soft at default settings; 1/200s flash sync; 4K video codec is cumbersome; 29:59 continuous video recording limit.
New carbon fiber body is light, compact and very comfortable; Same excellent image quality as the flagship D500; Quick 8.2 frames per second burst shooting with generous buffer; Very fast, accurate autofocus; Tilting touch-screen display; Very good battery life; Records ultra high-def 4K and 60fps Full HD too.
Only a single flash card slot; Doesn't support portrait / battery grip accessories; No rear infrared receiver any more; non-CPU AI lenses will be manual only; 4K video comes with a heavy crop; Movie AF is prone to hunting, Extended ISO sensitivities are a gimmick.