Low light image quality

Here, we'll look at the D7100's noise suppression capabilities at a range of NR settings and in comparison with the 24MP full frame Nikon D600, which we found in our in-depth review to rank among the best high ISO performers we've seen.

Real world street scene (JPEG Noise-reduction options)

In low light outdoor scenes, a big challenge in terms of noise reduction revolves around white balance. In scenes lit by overly warm streetlights, the camera must amplify its blue channel to render a reasonably neutral color balance. And it is this blue channel which is most susceptible to displaying chroma noise. In the scene below, shot with the AF-S DX Nikkor 18-105mm f/3.5-5.6G ED VR kit lens at ISO 6400, we set a custom white balance of 3230K to offset the warm artificial light and render neutral grays in the sidewalk. We've provided crops at each of the camera's NR settings to give you a sense of their ramifications in real world use. We should note, though that at ISO 1250 and higher, you can never fully disable noise reduction. The D7100 will apply a minimal amount under those circumstances even with the NR off setting enabled.

1/20 sec, F4.8, ISO 6400: NR Normal, Custom WB
NR Off 100% crop
NR Low 100% crop
NR Normal 100% crop
NR High 100% crop

As you'd expect, chroma noise becomes less visible with each increase in noise reduction. Yet notice how much detail is retained even at the most aggressive NR setting. Nikon has taken a conservative approach to noise reduction, avoiding a heavy-handed application that smooths out noise while obliterating image detail. What's also helpful here is that the noise reduction that is applied does not have an overly detrimental effect on color saturation. The pink triangle in the crops above remains as vivid at the NR high setting as it does with NR turned off.

Real world portrait (JPEG default NR)

This indoor portrait was shot under fluorescent lighting, again with the 18-105mm kit lens at ISO 6400, in JPEG mode using the camera's Auto WB setting with the default (Normal) NR setting.

1/30 sec., F5.6, ISO 6400: NR Normal, Auto WB
100% crop 100% crop

You can see prominent chroma noise throughout the skin tones and hair of the subject, but it must be said that detail is maintained relatively well. You can easily distinguish individual strands of hair and even some eyelashes.

D7100 versus D600 (JPEG)

One of the questions we heard from readers when the D7100 was announced was, 'How does its low light performance compare to the D600'? Indeed the D600 offers some of the most impressive noise performance we've seen from any DSLR. So we were keen to see whether you give up meaningful light-gathering ability with the D7100's (smaller) APS-C sensor. On the noise performance page of this review, you can see that the D7100 falls measurably behind the D600. Below, we offer a more practical examination of this difference, comparing our forthcoming test scene with both cameras shot using the same lens and exposure settings. Both cameras were set to ISO 6400 with default sharpening and NR turned off. The scene was purposely lit from the lower right corner to produce shadow information across much of the image area. We used a very warm household bulb to simulate typical indoor lighting conditions. To maintain identical framing, the full frame D600 was shot from a closer distance.

Nikon D7100 + 50mm/1.4: 1/80 sec., F4.5, ISO 6400, JPEG NR Off
D7100 100% crop D600 100% crop
D7100 100% crop D600 100% crop

In the crops above, it's clear that the D7100 produces higher levels of chroma noise. And the downside of an increase in noise is a decrease in image detail. Look at the small test in the second crop. While you can just barely read at least some of the words in the D600 file, the entire block of text is unintelligible in the D7100. We stress, however, that the D7100 is not bad. Far from it. You get an eminently usable file that maintains good color accuracy. Yet it's important to know that if you're after the greatest degree of detail in high ISO images, there is a price to be paid with the smaller APS-C sensor.

D7100 versus D600 (RAW)

Here's exactly the same scene, showing comparative image quality in Raw mode, again at ISO 6400. The raw files were processed in ACR 7.4 with both sharpening and noise reduction disabled. We've also provided links to the original .NEF files from both cameras so that you can compare the results in a raw converter of your choice.

D7100 ACR conversion: Sharpening and NR disabled 100% crop D600 ACR conversion: Sharpening and NR disabled 100% crop
D7100 ACR conversion: Sharpening and NR disabled 100% crop D600 ACR conversion: Sharpening and NR disabled 100% crop

The raw files produce a similar story, with the D7100 displaying more noise than the D600. Of course you could easily minimize the chroma noise in ACR or any other compatible raw converter. You can see an example of that with a real-world image on the raw mode page of this review.

The D7100 is capable of good results at a high ISO, but as you'd expect does lag noticeably behind the performance of the full frame D600.