Specific Image Quality Tests
The ability to successfully manage shadow noise on a per pixel level can be of interest when choosing among full frame DSLR offerings of similar resolution. In the example below we're comparing the EOS 6D against its chief rival, the Nikon D600, its higher spec'd sibling, the Canon EOS 5D Mark III, and Sony's full frame SLT-A99.
We've taken base ISO Raw shots of our studio test scene and processed them in Adobe Camera Raw 7.3 with a +3.0EV exposure adjustment. We've then taken crops in the darkest areas of our scene to compare the amount of shadow noise between the two cameras. This allows us to easily make a comparison of the amount of noise levels occurring in significantly brightened shadow areas at base ISO, which tells us something about sensor performance as it relates to read noise.
|Canon 6D ISO 100: ACR +3EV, NR off||100% crop|
|Nikon D600 ISO 100: ACR +3EV, NR off||100% crop|
|Canon 5D Mark III ISO 100: ACR +3EV, NR off||100% crop|
|Sony SLT-A99 ISO 100: ACR +3EV, NR off||100% crop|
Looking at the 100% crops above, it is clear that the 6D displays noticeably more chroma noise than both the Nikon D600 and Sony SLT-A99. Let's be clear, the 6D's performance is by no means poor, its actually very good, yet these results continue a trend in which the very impressive noise performance from Nikon and Sony place their DSLRs just that bit past what Canon has been able to accomplish in its EOS lineup. We saw this Canon EOS 5D Mark III review so it's perhaps no great surprise to see the 6D produce results very similar to its more expensive sibling.
Real world sample
While the results of our studio scene reveal interesting information about the sensor's maximum capabilities, it's important to place those results in the context of real-world photography. Below is an image shot outdoors under typical daylight conditions at ISO 100. We've taken the same raw file and converted it twice in ACR 7.3 - once at default exposure settings and again with three Basic Panel adjustments, detailed below.
|ACR 7.3: Default settings with NR off||ACR 7.3: Exposure +65, Shadows +30, Blacks +40 with NR off|
|100% crop||100% crop|
As you can see it is certainly possible to gain significant detail by opening up the shadows in ACR. And while this comes at the price of more prominent chroma noise, the results are certainly usable. It's also important to keep in mind that we're looking at 100% crops and that these noise levels will be even less objectionable in print output.
Low contrast fine detail
As we saw in our Canon EOS 5D Mark III review, the 6D's JPEG engine leaves something to be desired with fine low-contrast detail at low ISO settings. When viewed at 100%, organic textures like distant foliage and branches appear mushy. We suspect this is mainly due to the application of luminance noise reduction (even with noise reduction switched to 'Off') at base ISO. The results you can achieve from the same image files in raw conversion, as you'll see in a moment, would support this suspicion.
The images below were taken with the Canon EF 70-200mm f/2.8L IS USM lens at F8. The first sample is at default JPEG settings (NR Standard, Sharpness 3). We then re-processed the raw file in-camera with noise reduction switched off and the sharpness increased to level 5. Despite Canon saying in the manual that noise reduction is applied at all sensitivity levels the former has, at base ISO, no visible impact on the rendition of low-contrast detail or other aspects of image quality.
|JPEG - default (NR Standard / Sharpness 3)||100% crop|
|JPEG - NR Off / Sharpness 5||100% crop|
|ACR 7.3, Sharpening: Amount 65, Radius .8||100% crop|
Increasing the sharpness delivers marginally more 'crispness' in the image but no additional detail is revealed. You also get a quite unpleasant 'digital' look with visible sharpening halos in some image areas like the cluster of branches shown in the crop above. We haven't evidence that adjusting the JPEG settings gets you significantly closer to the sensor's true potential.
To do that, you'll need shoot in raw mode and process your images in a raw converter. The final image in the comparison was processed in Adobe Camera Raw with custom sharpness settings (noted above). The difference between it and the out-of-camera JPEGs is staggering. We were able to squeeze a significant amount of additional low-contrast detail out of the camera's raw files while avoiding halos and other artifacts.
As always, we remind you that evaluating 100% crops is akin to looking at a very large print from a very close distance. But if you shoot nature and landscapes and want to get the most out of your 6D's sensor, that still means working with the raw file, even at base ISO.
Lens correction settings
The 6D offers two built-in lens corrections, based on camera-stored lens profile data, which can be enabled via the shooting menu. You can use Canon's included EOS Utility to download current lens data to the camera. Note that neither of these corrections are baked into accompanying raw files. If you use Canon's own DPP raw conversion software, the corrections travel with the raw file as metadata, allowing you to adjust them to taste. Third party converters, like ACR and DxO, however, will not make use of this data, although both have their own tools for these types of corrections.
Peripheral illumination control is meant to counter corner vignetting effects. It is enabled by default. Below we've shot an evenly lit neutral area with Canon's EF 24-105mm f/4L IS USM lens at its widest aperture. As you can see, enabling the lens correction results in more even illumination, providing just over 1 stop EV of increased luminance in the farthest corners compared to the sample without the correction applied.
|Peripheral Illumination On 24mm @ F4||Peripheral Illumination Off 24mm @ F4|
The chromatic aberration (CA) setting seeks to minimize color fringing that is typically found along very high contrast edges. The scene below, with dark leaves and branches against a bright sky is a typical scenario in which you'd encounter color fringing. It was shot with the EF 24-105mm f/4L IS USM lens at 24mm. And as you can see, the in-camera software correction does an admirable job of reducing, if not completely eliminating CA.
|Chromatic aberration disabled||Chromatic aberration enabled|
Overall Image Quality
While the EOS 6D may be easily thought of as Canon's 'affordable' full frame DSLR, we're happy to say it gives up nothing in image quality to the powerhouse EOS 5D Mark III. In fact, we actually see better image quality at medium to high ISOs, and noticeably less noise at the highest settings.
Marginal lighting conditions aside, the EOS 6D produces pleasing color, saturation and contrast in a wide variety of situations. White balance and exposure are typically well-judged and detail is quite impressive straight out of the camera, although you can easily improve on these by shooting Raw images and processing them yourself.
The 6D's JPEG dynamic range performance is on par with the other full frame cameras on the market, with roughly four stops of highlight information above middle gray. Previous EOS owners may be used to instinctively reaching for HTP to gain additional highlight detail. Yet the 6D's HDR mode, borrowed from the 5D Mark III, provides in-camera multi shot processing that provides very real and impressive benefits when photographing in high contrast scenes.
If we have one complaint about image quality it centers around Canon's JPEG rendering of fine low-contrast detail at low ISO sensitivities. As we demonstrated above, shots of distant foliage and other organic textures lack not just crispness, but actual detail. Of course, it's no surprise that getting the most out of your sensor requires raw processing and we suspect the vast majority of buyers looking to spend $2000 plus on a camera body will have already established a raw file workflow. Also, these minor issues disappear if you're not intending to make large prints.