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.SX50 test data on DxO Mark SX60 test data on DxO Mark
50x optical zoom with whopping 24-1200mm-equivalent reach; Excellent image quality for its class; 2.8-inch vari-angle LCD; Ergonomic design and controls; Improved image stabilization and Zoom Framing Assist; Shoots RAW; Full 1080p HD video.
Poor low-light AF performance; Image quality deteriorates at ISO 800 and above; Sluggish cycle times; Below average battery life.