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 D5100 test data on DxO Mark
Side-mounted tilt / swivel LCD screen; same sensor and processing as the Nikon D7000; good speed and battery life; in-camera HDR and filter effects; Full HD video capture with aperture control; audio levels control and external microphone jack.
AF-S lens mount doesn't offer autofocus with screw-drive lenses; popup flash isn't the greatest; no built-in wireless flash control; HDR function doesn't microalign source images.
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