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.
S1R test data on DxO Mark A7R test data on DxO MarkIncredibly small body for a fully-featured, full-frame camera; Resolution that rivals a medium-format camera; Excellent image quality even at very high sensitivities; Decent performance bearing in mind its extremely high resolution; Accepts existing Alpha-mount and E-mount lenses, and can optionally crop to APS-C image circle.
Extreme resolution makes focus and lens quality critical; Modest performance; Loud shutter; Lacks hybrid autofocus of the A7; Mediocre battery life when using electronic viewfinder; Slow X-sync; Limited selection of native Sony FE lenses.
Excellent high-resolution image quality; Good high ISO performance; Very fast single-shot autofocus; 4K 60p video; IBIS; Weather-sealing & comfortable ergonomics.
Contrast-detect AF system can struggle with fast-moving subjects; Burst shooting with C-AF is only 6fps; Sluggish buffer clearing; 4K video limited to 15min; Big & heavy; Expensive.
