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.GX85 test data on DxO Mark RX100 test data on DxO Mark
Excellent high-ISO performance for such a compact model; Smart controls; Small body; Bright lens; 10fps full-res burst mode; Very fast shutter response; Excellent LCD.
Lens flare at night; Poor rendering of yellows; Slow flash recycling; Soft corners wide open; Continuous AF mode slow to lock.
Excellent build-quality; Good ergonomics for its size; Built-in 5-axis Dual IS, Built-in EVF; Tilting LCD touchscreen monitor; Competitive still image quality; Excellent 4K video quality; Fast autofocus and burst modes; Generous buffers; Tons of advanced features; Built-in Wi-Fi.
EVF could be better; Sluggish RAW and RAW+JPEG buffer clearing; No external mic and headphone jacks; Slow x-sync speed; Mediocre battery life.