Nikon D4 Digital Camera Review$5,999.95
The Nikon D4 includes three high ISO noise reduction settings, though they barely kick in before ISO 3200. The settings are the typical low, normal, and high, though you can deactivate noise reduction entirely if you wish. We did find that the "NR off" setting returned lower noise results than the "NR Normal" setting once you get beyond ISO 12800, so there's likely some level of noise reduction being applied in JPEGs by default. This only really occurs at ISO 25600 and 51200, though, so it's probably more of a software aberration in the camera than anything else. More on how we test noise.
The Nikon D4 didn't show significant detail loss at the bottom two levels of noise reduction, though we noticed it at the NR high setting. NR high is still very useful if you're looking to employ ISO levels of 102,400 or 204,800, or if your final image is going to be downscaled on the web. At the lower web resolutions, you won't notice the detail loss at that setting, but the reduction in noise levels may improve certain parts of your image.
The Nikon D4 has a native ISO range that extends from 100-12800, with options to extend that as high as 204,800 or as low as ISO 50. The high options we've discussed above. With noise reduction turned all the way to high, we'd recommend keeping it to ISO 51200. At that speed the high setting returns just 1.78% noise, which is acceptable (though that is bought at the expense of fine detail in the image). The low ISO setting is mostly a trick of the camera, as it is merely ISO 100, but with a lower tonal curve applied to the image. The low ISO will expose a given scene at the same settings as ISO 100, but the resulting image tones down highlights to retain more detail (though dynamic range is actually less than ISO 50).