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.A6500 test data on DxO Mark GX8 test data on DxO Mark
Highest resolution Micro Four Thirds camera yet; Great high ISO performance; Very fast autofocus; Fast burst mode with deep buffers; Impressive Dual I.S. system; Great 4K video.
No built-in flash; Slow buffer clearing; Below average battery life; Limited I.S. for 4K video.
Comfortable, premium body with good controls; Touch-screen for subject selection; Hybrid image stabilization system; Excellent image quality; Better high ISO JPEGs than the A6300; Extremely fast 11.1 fps burst capture; Very deep buffers for raw and JPEG alike; 4K video capture with no pixel binning
Pricey for an APS-C camera; JPEG colors aren't the most accurate; Very slow buffer clearing; Laggy touch-pad AF function; Poorly-placed movie button; No headphone jack; Mediocre battery life