Nikon D5100 Digital Camera Review

Noise Reduction

With the D5100, users can select from noise reduction levels of low, normal, and high, or turn the feature off altogether. There is also a long exposure noise reduction feature, but we found it ineffective and do not count it here. We found that Nikon has been able to reduce the total amount of noise produced by this particular sensor compared to the D7000, even with noise reduction turned off.

Surprisingly, we found the D5100 had even better noise performance than the D7000, which shares the same excellent Sony sensor. Nikon has managed to reduce the noise overall, while also being more aggressive with its noise reduction. We found slightly higher luma noise than color noise, but it only crossed the 2% mark at ISO 6400, and is not a distraction at lower ISOs speeds.

Even taking noise reduction out of the equation, we found that the D5100 improved the sensor’s noise performance slightly overall compared to the D7000.

With noise reduction dialed all the way up, we found the Nikon D5100 did very well in suppressing both channel and luminance noise, with both kept under 1% all the way up to ISO 6400. The effect of using this much noise reduction is a loss of some super-fine detail, but if you’re shooting in low light, it’s a nice extra to have in your camera’s back pocket. More on how we test noise.

ISO Options

Nikon has pushed this sensor just about to the brink with the D5100, with an ISO range that extends to 25600 when using the HI 2 setting. The D5100 actually pushes beyond even that speed with its night shooting mode. In that mode the D5100 will shoot a monochrome image with an ISO speed of 102400. With noise already creeping up around 2% at ISO 6400, any setting beyond that speed is mostly there just for emergencies.

Focus Performance

The D5100 does trail its big brother, the D7000, in one key area for Nikon enthusiasts: the lack of an internal focus motor. As a result, the D5100 will have to make use of AF-I or AF-S lenses if users wish to take advantage of autofocus. Nikon has continued this trend with their entry-level cameras since the D40, and it looks to continue. The lack of a motor helps reduce weight, of course, but it does limit the number of fully-functional Nikkor lenses available. When an AF-S lens is attached, however, the focus is quite snappy, with full-time autofocus during video recording a welcome addition from older models.

The D5100 allows users to select from a number of focus area settings. There are options for single-point autofocus, dynamic-area autofocus, 3D-tracking using all 11 AF points, and auto-area AF. Single point focuses on one point in the frame, while dynamic area will use information surrounding that point should the subject leave that era. 3D tracking will actually choose a new focus point should the subject move, and auto area chooses an area where the camera believes the subject is. When in live view, these options are limited to face-priority AF, wide-area AF, subject tracking, and normal-area AF.

Long Exposure

In our long exposure testing, we found that the Nikon D5100 produced slightly less accurate colors in longer exposures, though it did have a tougher time getting a correct custom white balance under the much lower lighting conditions (20 lux in this test versus 3000 lux in our bright light color test). In general, we found that the longer the shutter speed, the more accurate the colors ultimately were. More on how we test long exposure.

The D5100 produced an uncorrected color error of around 3.5 in long exposure testing, regardless of whether noise reduction was on or off. The colors were slightly more accurate in 30 second exposures compared to those of just one second, but by less than 10 percent.

Just as in our bright light testing, there was very little in the way of noise present in our long exposure color testing. We found no more than 0.76% noise, even in exposures as long as 30 seconds with an ambient temperature of 77 degrees Fahrenheit. Noise was most apparent in the red channel, but was low enough that it was hardly an issue. Long exposure noise reduction did not seem to have that great of an effect in our testing, but it might have at higher ISO values.

The D5100 was beat out only by the D7000 here, with a score of 11.66 against 11.96. The score difference is negligible, though, and both cameras beat the rest of the comparison group by a solid margin. The T3i did show a fairly large improvement here over the T2i, but not by enough to match the Nikon models.

Video: Low Light Sensitivity

We found the Nikon D5100 was able to gather a 50 IRE image with just five lux of available light. This is the least amount of light required, tying the Sony A55V. It was less than half the light required by the Nikon D7000, though the resulting image was far noisier.