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.T3i test data on DxO Mark GX-20 test data on DxO Mark
Excellent image quality; Good grip; Full HD video recording; Swiveling LCD; Very fast autofocus; HDMI output.
Slow frame rate for sports shooting; Tendency to overexpose in bright sunlight; Live View AF is slow; No microfocus adjustment.