Nikon D3100 Digital Camera Review

Noise Reduction

The D3100 just allows users two simple options when it comes to noise reduction: on or off. The camera offers an ISO range that extends from 100-3200, with "HI 1" and "HI 2" options equivalent to ISO 6400 and 12800 and shot at full resolution. We found that, with the feature activated, the camera begins applying noise reduction as soon as ISO 200, though it does not aggressively control for noise until around ISO 800 and greater.

We found that the camera offered very little image noise at ISO 100, with just under 0.5% detectable in our test. This ramped up to a little under 1% at ISO 800, though from then on we advise turning on noise reduction. Without NR, noise spiked to 1.29% and 1.58% at ISO 1600 and 3200, respectively. With NR turned on, the camera maintained noise at around 0.9% at both levels. At ISO 6400 and 12800, the shots are only really usable with noise reduction activated, keeping it to 2% and below at those levels. More on how we test noise.

ISO Options

The D3100 allows for an ISO range of 100-3200, with "Hi 1" and "Hi 2" settings that are the equivalent to ISO 6400 and 12800. The ISO speed can be set automatically by the camera, or (at least in most of the camera's modes) manually by the user. To set the ISO speed the user can go to the quick menu by pressing the "i" key and keying over to the ISO setting. This will let you set a definitive ISO setting, but doesn't offer the option to set it to auto, which is a bit frustrating. In the full menu, the D3100 gives you the option to activate automatic ISO, however, with the ability to cap it at any sensitivity above 100 or set a minimum shutter speed, which is very helpful if you're shooting hand held in low light situations.

Focus Performance

The Nikon D3100 has an 11-point phase detection autofocus sensor located in the camera that functions whenever shooting outside of live view mode. When the camera's mirror is out of the way, such as when recording video or in live view, the camera utilizes its contrast-based detection AF system, which is less accurate and slower. Nikon states that focus is sensitive within -1 to 19 EV, though we found it difficult to get the camera to necessarily attempt to autofocus in limited lighting conditions. It would eventually, sometimes it just took a few seconds to initiate.

Long Exposure

In long exposure testing the D3100 was consistent, though its color accuracy fell somewhat to a more pedestrian level. This still put it ahead of the majority of the competition, with only the Canon T3 offering better results in this test. The D3100 allows for exposures as long as 30 seconds (as well as a bulb mode in manual) and we tested the camera's capabilities from one second up to the maximum. More on how we test long exposure.

We found that the D3100's color error jumped to around 3.4 through our long exposure testing, with the worst results actually coming at the beginning of the test when exposures were just one second long. Beyond one second, color error and saturation were reined into more controlled levels, however. With noise reduction activated, the D3100 takes a "dark frame" exposure of equivalent length whenever a shutter speed longer than one second is taken. This is an attempt to map out noise that might be caused by the sensor generating heat, though it's seldom effective in any camera. We found it had no effect on the D3100's test results, with noise never rising above 0.78% and never falling below 0.67%, regardless of whether the feature was activated or not.

As stated above, the Canon T3 is the only camera that beat out the Nikon D3100 in this test, though the Pentax K-r put up a very similar result. The D3100 also showed an improvement overall compared to the D3000, while the Sony NEX-5 brought up the rear in this particular comparison group.

Video: Low Light Sensitivity

The Nikon D3100 wasn't the most sensitive camera in low light that we've ever seen, but it posted a respectable result. The camera needed just 16 lux of light to hit 50 IRE on a waveform monitor, a standard measurement that we use to determine a reasonably visible image recorded by the camera.