Image Quality

Our latest test scene is designed to simulate both daylight and low-light shooting. Pressing the 'lighting' buttons at the top of the widget allows you to switch between the two. The daylight scene is shot with manually set white balance aimed at achieving neutral grays, but the camera is left in its Auto setting for the low-light tests (except Raw, which is manually corrected during conversion). We also offer three different viewing sizes: 'Full', 'Print', and 'Comp', with the latter two offering 'normalized' comparisons to more fairly compare cameras of differing resolutions by using matched viewing sizes. The 'Comp' option chooses the largest-available resolution common to the cameras being compared.

Resolution

The Sony a7R II joins a growing list of ultra high-resolution consumer cameras, following formidable offerings from Pentax, Nikon, Canon, and Sony's own original a7R. Linear resolution on the a7R II has increased over the original a7R by around 8%, which does lead to finer resolved details relative to the original a7R as well as the Nikon D810, but not quite as much as the Canon 5DS R (although the increased contrast in ACR's default conversion plays a part in making the Canon appear sharper). In Raw, detail is properly resolved, and not aliased, to Nyquist / √2, which is around 3750 lines for the a7R II. The Nikon D810 and original Sony a7R begin to alias soon after 3470 lines. Unsurprisingly, the 5DS R handily beats the a7R II, properly resolving up to around 3900 lines where the a7R II (and all other cameras) show significant aliasing. This is slightly lower than the Nyquist / √2 value of 4100 lines, but this is possibly due to lens limitations.

On the subject of resolution, it's worth noting that a couple of features in the a7R II really help you get the most of the 42MP sensor. First, in-body image stabilization (IBIS) ensures you can almost always shoot at at least a stop slower (often more) than 1/focal length and still get maximal pixel sharpness. Equally as importantly, a much needed electronic first curtain solves the shutter shock issues that plagued the original a7R. These features make it easier to maximize sharpness than the careful consideration you may need to get the most out of DSLRs that demonstrate mirror or shutter-induced shake. The Nikon D800 series is particularly plagued by such issues, and although the D810 circumvents them to a large degree via electronic first curtain, this feature is implemented in a cumbersome manner. The Canon 5DS has better control over mirror and shutter-induced shake than Nikon, but it does still exhibit softening due to shock at certain shutter speeds; the only way to avoid it is to shoot in live view, making neither Canon nor Nikon implementations ideal.

JPEG Performance

We've seen JPEG performance from Sony cameras mature quite a bit over the years, and the a7R II represents the culmination of a number of improvements to the JPEG engine. The JPEG engine in the a7R II is really good, seriously challenging the big boys. For starters, sharpening is sophisticated, which is to say it's fairly modest: JPEGs (top left) shows a good amount of the detail available in Raws (top right), but aren't as overly sharpened as the Canon, while avoiding being as soft as the Nikon D810 rendering that clearly doesn't take advantage of all the information in the Raw. You'll still squeeze some more detail out of a7R II Raws, though.

Another indication of the modesty of the a7R II JPEGs is the clear lack of any sharpening halos, which can be pretty strong due to aggressive, large radius sharpening in Canon 5DS R JPEGs (pay attention to the edges of the grey square, which show a lighter strip in the transition from grey to black, in the Canon JPEG that is). What is particularly impressive is that despite Sony's more modest approach to sharpening, it still manages to squeeze out more detail in low contrast areas than either 5DS R or D810 or a7R - which is particularly mushy for an ISO 100 JPEG due to context-sensitive noise reduction, which preferentially targets low contrast detail. This is despite all cameras starting out with similar detail in Raw. The a7R II even manages to squeeze our more detail at high ISOs, producing the sharpest, most pleasing rendering of this low contrast drawing in our scene.

Finally, noise reduction has been significantly tamed with the a7R II, with context sensitive noise reduction either working really intelligently, or simply turned off altogether. Note the lack of the edge artifacts that are clearly evident at the edges of the grey box on the original a7R. Ultimately, this means remarkable, if not class-leading, preservation of detail at high ISOs.

What is particularly nice about all these facets of the JPEG engine is that good sharpening and unaggressive noise reduction means that much of the detail in the Raw makes it into the JPEG, and it's the JPEG that you preview in-camera. All that preservation of detail means you can accurately check that you captured your desired detail in the field, before you make it back home to your computer.

Low Light Performance

The a7R II introduces the world's first, backside-illuminated (BSI) CMOS sensor. BSI shifts a lot of required per-pixel electronics out of the way, making more room for the light-gathering area of the pixel. BSI tends to have diminishing returns with larger pixels, so it makes sense to use with the smaller pixels a high resolution, albeit large sensor, camera has - their pixels will be smaller relative to a lower resolution camera with equivalent sensor size. BSI has other downstream benefits: it makes more room for electronic components, leading to more advanced circuitry, like faster sensor readout. That's likely what helps enable the fully silent shooting mode, which uses both electronic first and second curtains to take a shot in silence. It's remarkable how little noise cost there is to this mode. There is some high ISO dynamic range cost, but the traditional noise cost we're used to seeing when using a fully electronic shutter is largely moot.

BSI technology in the a7R II brings significant gains to ISO performance in general, making the a7R II the best low-light stills camera we've ever tested. Compared to the a7R, the gain is nearly a full stop at the highest ISOs, and this advantage is maintained even at more modest high ISOs. At ISOs 25,600 and above, nearing the maximum ISO setting for the Nikon D810, the a7R II is at least a full stop ahead. The same cannot be said about the Nikon D810A though, which impressively shows similar performance to the a7R II, thanks to its more transmissive color filter array. A 1 EV advantage is also seen relative to the Canon 5DS R, which maxes out pretty early at ISO 12,800. Remarkably, the a7R II even outdoes the Pentax 645Z, despite the larger medium format sensor on the 645Z that ostensibly should gather more light.

Naturally, comparisons will be drawn against the 'low light king' (or brother, as it were): Sony's own a7S? It's a close one, and our SNR calculations show that the a7R II actually has a better signal to noise ratio than the a7S.* We can confirm, then, that Sony's claims that the a7R II removes the need to choose between low light (stills) performance and resolution is demonstrably true.


*The a7R II does, however, show a strong magenta cast at the bottom of the frame: something that commonly happens at a camera's maximum ISO.