The D5100 has a little pop-up flash with a guide no. of 12m at ISO 100 - pretty standard for this class of camera, and the same as the entry-level D3100.

The performance is impressive enough, given its relatively modest power. Skintones are well rendered and the exposure is well-balanced.

Highlight clipping / recovery

The D5100's metering system is generally extremely reliable, but there are occasions when depending on the shooting conditions you might lose some highlight detail. As you can see from these examples, highlight detail lost from JPEG files is essentially lost forever. A small amount of tonal information can be recovered by adjusting image brightness post-capture, but the data isn't particularly useful. The simultaneously captured NEF file is much more amenable to post-capture adjustment, and as you can see, plenty of tonal information can be recovered in the highlight areas of this scene.

Crucially, color information in recovered areas is more faithful, too. We estimate that shooting in RAW mode gives you up to around 1EV of extra highlight information, which is what we've come to expect (though color accuracy is by no means guaranteed). If shooting in raw mode sounds too much like hard work, the D5100's Active D-Lighting system can do wonders when presented with scenes that contain a wide tonal range.

Camera JPEG 100% crop
Camera JPEG (-1EV exposure comp in ACR) 100% crop
RAW (-1EV exposure comp in ACR) 100% crop

Shadow Noise

The Nikon D5100 is the lucky owner of one of a new generation of sensors that show exceptionally low shadow noise at base ISO. In fact, the D5100 has the same sensor that impressed us so much in the D7000, and as such, it has a considerably lower noise floor than the entry-level D3100 and the last-generation D5000. In the example below we've taken our studio comparisons at ISO 100 and developed them in Adobe Camera Raw with 3 stops of exposure compensation to pull up the shadows. The difference between the D5100/D7000 and the D3100 and D5000 is obvious. Color noise is less pronounced, and detail is better described.

Nikon D3100 - ISO 100 raw, ACR +3.0EV Nikon D5100 - ISO 100 raw, ACR +3.0EV
100% crop 100% crop
100% crop 100% crop
Nikon 5000 - ISO 100 raw, ACR +3.0EV Nikon D7000 - ISO 100 raw, ACR +3.0EV
100% crop 100% crop
100% crop 100% crop

Overall Image Quality / Specifics

It is fair to say that the D5100's main strength is its image quality. Essentially, the D5100 combines the reliability of the D3100's metering and white balance systems with the exceptionally low-noise, high-resolution output of the D7000. As such, it is an excellent value camera, and one that you can absolutely rely on to deliver great results in virtually any environment. Right up to ISO 12,800, the D5100 gives class-leading image quality in JPEG mode, and its RAW files are malleable enough that good, printable images can be coaxed out of it even at ISO 25,600 (with a little care and attention).