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.Z6 test data on DxO Mark A7S II test data on DxO Mark
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.
Great image quality; Terrific high ISO performance; Fast AF speeds; Eye AF; Swift 12fps burst shooting; In-body image stabilization; High-quality 4K video; Robust build quality; Familiar Nikon design.
Single XQD card slot; Default high ISO NR a bit strong; No 4K 60p; 1/200s x-sync speed; Limited native lens selection (at this time).