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.T5i test data on DxO Mark E-420 test data on DxO Mark
Excellent image quality; 9 cross-type AF points; Stereo microphones; Built-in touchscreen; Multi-shot modes; Improved kit lens; Even more affordable.
Little-changed from the earlier T4i; Slow Live View and video autofocus; High ISO performance is unimproved; Below-average battery life; No dedicated AF illuminator.