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.K-1 test data on DxO Mark SL2 test data on DxO Mark
Unlocks the full potential of full-frame Pentax lenses; Excellent image quality; Great ergonomics and build; Very compact for full-frame; Decent performance; Fast autofocus with great low-light capabilities; Very wide sensitivity range; Bright, accurate viewfinder; Articulated LCD; Stabilization, Wi-Fi and GPS in-camera
No built-in flash strobe; Quite heavy compared to APS-C flagships; Somewhat soft images and blown highlights by default in JPEG mode; Warm Auto white balance indoors; Slow startup and buffer clearing; Small top-deck status display; Weak viewfinder illumination; Below-average battery life for DSLR
Higher resolution and better image quality than SL1; Much improved dynamic range; Excellent Dual Pixel CMOS AF; Compact body with improved ergonomics; Articulating touchscreen; Full HD movies up to 60p; Better battery life.
Shallow buffer depth with RAW files; Dynamic range and high ISO performance still not as good as leading competitors; No 4K video option; OVF only offers 9 AF points.