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.A7R III test data on DxO Mark K-5 II test data on DxO Mark
Compact yet control-rich body packs in the features; Updated autofocus system focuses in near-darkness; Fully weather-sealed; Sharp, detailed images with very good dynamic range; In-body image stabilization; Dual-axis level with horizon correction.
Can seem intimidating at first; Fewer autofocus points than competitors; Doesn't take advantage of high-speed UHS-I flash cards; Movie feature set is very dated and file sizes huge.
Fantastic image quality; Improved dynamic range over its predecessor; Very good high ISO performance; Much improved real-world AF performance; Class-leading burst rates, even with RAW; Improved 5-axis in-body image stabilization; Better 4K video quality; 1080/120fps video; Dual card slots; Significantly better battery life.
Expensive; Menus still confusing; UHS-II support only on one card slot; No optical low-pass filter means greater risk of moire; No built-in flash; Buffer clearing still slow despite UHS-II support.