High ISO noise and detail

Compared to the Nikon D600 and Sony Alpha SLT-A99 (JPEG)

We all know that shooting in Raw mode will give you more control over image quality, but this doesn't mean that JPEGs are a non-starter. They're much more convenient, for one thing, but ultimately, JPEG image quality from modern DSLRs is extremely high, even at high ISO sensitivity settings. In this test, we're looking at the EOS 6D's image quality at ISO 6400, 12,800 and 25,600, compared to two of its closest peers, the Nikon D600 and Sony Alpha SLT-A99.

The scene below was shot under low color-temperature (Approx. 2600K) artificial light, designed to be representative of typical indoor lighting. This accentuates the appearance of noise due to the low level of blue light in the spectrum of the light source. Therefore, to achieve accurate white balance the blue channel has to be amplified strongly, and the green channel to a lesser extent - thereby increasing the visible noise. It's a stress test, basically. We've made two 100% crops per ISO sensitivity for each camera. Click on the first one (with the magnifying glass icon at lower right) for the full-sized original image.

All cameras were set to default noise reduction and color settings, in highest quality JPEG mode, and with identical exposure settings on 85mm lenses (we shot at F10 for good depth of field). Framing was matched as closely as possible and white balance was set to custom on all three cameras.
Canon EOS 6D
Nikon D600
Sony Alpha SLT-A99
ISO 6400 (100% crop) ISO 6400 (100% crop) ISO 6400 (100% crop)
ISO 12800 (100% crop) ISO 12800 (100% crop) ISO 12800 (100% crop)
ISO 25600 (100% crop) ISO 25600 (100% crop) ISO 25600 (100% crop)

In this low-light test the Canon EOS 6D compares very well to the Nikon D600 and Sony A99 - both of which use versions of the same 24MP CMOS sensor. It is clear that at default NR settings, images from the 6D are cleaner, less gritty but similarly detailed as those from the Nikon and Sony cameras. Of the three cameras in this comparison, the D600 gives the grittiest results, but in terms of detail capture, we'd be hard-pressed to say that it was any better than the smoother JPEGs from the 6D. The A99 gives similar results to the D600 but without the yellowish blotches of chroma noise which can be seen in some areas of files from the Nikon camera at ISO 12,800 and 25,600.

Multi Shot NR

The EOS 6D offers - as an additional option in the NR menu - the ability to capture four successive shots (presumably at 4.5fps) in a single burst and combine them into a single image. Because noise is a random event, the advantage of capturing multiple images and then merging them together is that you can average out the noise in the final processed image.

Multi Shot NR is a JPEG-only feature. You cannot select it in any of the 6D's raw-enabled modes. And once it is activated, switching the mode dial to any of the basic shooting modes, recording a movie, using the bulb setting, or powering off the camera will revert the NR setting back to its default, Standard setting.

The process of combining the separate images and averaging out the noise takes a bit of time. A 'busy' status is displayed for several seconds after the final exposure. While you cannot take another image during this time you can access the camera's menu system.

Using the same low light scene in which we compared the EOS 6D against two of its peers on the high ISO comparison page of this review, we compare the 6D's Multi Shot NR setting against both the default and 'high' NR settings.

ISO 25,600, 1/30 sec. @ F10 Multi Shot NR 100% crop
NR Standard (default) 100% crop NR High 100% crop

Multi Shot NR mode does a very good job of minimizing noise and image artifacts without sacrificing any of the fine-edged detail present in either of the single shot NR modes. The multiple exposure NR mode does, however, edge dangerously close to a 'plasticky' appearance, so if you have an aesthetic fondness for film grain-like structure, it may be best to use one of the other NR options.

The really good (and surprising) news here is just how effective the NR High mode is at minimizing noise while avoiding the heavy-handed smearing that we saw in our EOS 5D Mark III review. We've found that at sensitivities above ISO 6400, NR High actually now becomes a desirable option, striking, to our eyes, the most pleasing balance between noise suppression and image structure.

As you'd expect with any multi-shot mode, Canon cautions against excessive camera shake or shooting moving subjects, stating that the NR results will be 'less effective' in such situations.