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.D800E test data on DxO Mark D5500 test data on DxO Mark
Rugged build; Excellent controls; Extremely high resolution, even more than the D800; Dual cards; Surprising high ISO performance.
Moire problem with certain subjects; Very large files; Slower frame rate; Battery life lower than D700.
Amazingly small for a DSLR; Great image quality for its class, including superb low light and high ISO performance; Generous JPEG buffer depth; High resolution.
Buffer depths are shallow when shooting RAW; Lacks GPS from the predecessor; No AA filter means it's susceptible to aliasing artifacts.