Raw Dynamic Range

Exposure Latitude

In this test we look to see how tolerant of pushing exposure the D500's Raw files are. We've done this by exposing our scene with increasingly lower exposures, then pushed them back to the correct brightness using Adobe Camera Raw. Examining what happens in the shadows allows you to assess the exposure latitude (essentially the dynamic range) of the Raw files.

Because the changes in this test noise are primarily caused by shot noise and this is mainly determined by the amount of light the camera has had access to, the results are only directly comparable between cameras of the same sensor size. However, this will also be the case in real-world shooting if you're limited by what shutter speed you can keep steady, so this test gives you an idea of the amount of processing latitude different formats give.

The results are very impressive. There's more noise in the 6EV shot but even after a 5EV push, the results look really very respectable. Compared to the Nikon D7200 the performance looks very similar - the noise level is very much alike even after the 6 stop push (the spurious purple tinge in the D7200 is likely to have as much to do with Adobe Camera Raw's calibration as the camera's output).

Bear in mind that the D7200 is one of the best-performing cameras in this respect. The very capable Sony a6300 shows more a touch more chroma noise in the shadow regions, even before we consider its Raw compression artefacts, and the D500's files will be much more malleable than those of the Canon EOS 80D, despite the improvements it's made in this area.

ISO Invariance

A camera with a very low noise floor is able to capture a large amount of dynamic range, since it add very little noise to the detail captured in the shadow regions of the image. This has an interesting implication: it minimizes the need to amplify the sensor's signal in order to keep it above that noise floor (which is what ISO amplification conventionally does). This provides an alternate way of working in situations that would traditionally demand higher ISO settings.

Here we've done something that may seem counter-intuitive: we've used the same aperture and shutter speed at different ISO settings to see how much difference there is between shooting at a particular ISO setting (and using hardware amplification) vs. digitally correcting the brightness, later. This has the advantage that all the shots should exhibit the same shot noise and any differences must have been contributed by the camera's circuitry.

As you can see from the Nikon D500's ISO Invariance testing, there's very little difference in noise between a native ISO 3200 shot and an ISO 100 image captured at the same exposure values and 'pushed' 5EV during processing. This suggests the camera itself is adding very little additional noise to its images. As well as what this tells you about the sensor performance, it also means it's possible to significantly underexpose low ISO images when working in low light, and capturing more highlight information than by using a higher ISO setting.

It's a very similar result to the one we saw from the Nikon D7200 - one of the best-performing APS-C cameras we've tested so far.