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.A7S II test data on DxO Mark NX30 test data on DxO Mark
Very good image quality at low to moderately high ISOs; Blazing fast single-shot autofocus; Fast 9fps burst with RAW and JPEG files; Built-in Wi-Fi with NFC; Good build quality; Tilting EVF; Articulating touchscreen monitor; Bundled with Adobe Lightroom 5 software; Excellent value.
Dynamic range not as good as the best APS-C models; Slow buffer clearing even with fast UHS-I cards; Buffer depth with RAW files is underwhelming; Native lens selection is still fairly limited.
Comfortable and surprisingly compact camera body; Improved low light performance; Built-in image stabilization; Wide range of usable ISOs; More sophisticated autofocus performance; Excellent video capabilities.
Relatively low resolution; Mediocre continuous shooting performance; No built-in flash; No losslessly compressed RAW option.