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.RX100 IV 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.
Vastly improved burst speeds with deep buffer; Great performance with very fast autofocus; Very high resolution gives lots of detail in good light; High ISO noise levels much better than most pocket camera rivals; High-quality 4K video with uncompressed HDMI out; Super-fast High Frame Rate video; Same great pocket-friendly design.
Pricey for a compact camera; JPEGs can look over-processed at higher ISOs; Lens doesn't offer as much telephoto reach; Battery life not as good as predecessor; 24-70mm-equivalent lens can feel limiting.