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.T6i test data on DxO Mark T4i test data on DxO Mark
Excellent image quality; 9 cross-type AF points; Stereo microphones; Built-in touchscreen; Multi-shot modes.
Slow Live View and video autofocus; High ISO performance is unimproved; Below-average battery life; No dedicated AF illuminator.
Highest resolution Canon APS-C camera yet; Improved dynamic range over T5i; Good high ISO performance for its class; Very fast autofocus; Built-in Wi-Fi with NFC; Touchscreen tilt/swivel LCD.
Shallow buffer depth with RAW files; Below average battery life; No Servo AF in Live View; No 60p video frame rate.