Exposure Latitude

In this test we look to see how tolerant of pushing exposure the D5500'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.

as the exposure is decreased, less light is collected, which leads to more overall noise visible especially in shadows and midtones.

The Canon 70D is a good camera to demonstrate the different amounts of processing latitude. Push the Canon's files by 3EV and they're already noisier than the Nikon's. Try pushing by 5EV and you start to reveal tones that have been flooded by noise on the Canon, while the Nikon's output remains much cleaner.

The stellar performance turned in by the D5500 here is due to its very capable sensor that demonstrates class-leading levels of dynamic range, as confirmed by DXO's findings. This is nothing particularly new for Nikon, as the D5500's predecessors also showed similar results, allowing these APS-C offerings from Nikon to have more dynamic range than even larger sensor, full-frame offerings from Canon. A 6 EV push of the D5500 shot still looks significantly cleaner than a smaller, 5EV push of a 6D.

Ultimately, this means that D5500 Raw files have a lot of information in them - more than what's available in the camera JPEG, where manufacturers trade off dynamic range in order to achieve more pop on your display. If you're shooting high contrast scenes like the sunset in our next section below, or if you just want a lot of processing latitude for those times you didn't nail your exposure, you'll want to shoot Raw in order to recover information in shadows you didn't even know were there.

Real world impact:

This real-world shot shows how much shadow detail you can comfortably pull out of a well-exposed image. This push is equivalent to around +3.9EV for the deeper shadow regions.

Exposure: ISO 100, F5.6, 1/10th sec
Processing: Highlights -100, Shadows +100, Whites -100, Blacks +100

When shooting the D5500, if you expose to preserve highlight tones, the camera gives you the option of recovering lots of shadow detail. This way, you can display a huge range of scene tones in your final image.

ISO Invariance

A camera with high (base ISO) dynamic range has a very low noise floor, which has an interesting implication: the low noise floor can reduce the need to amplify the sensor's signal in order to keep it above that noise floor. This can afford you benefits in situation conventionally demanding 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) or digitally correcting the brightness, later.

As you can see, there's very little difference between using ISO 3200 and shooting at ISO 100 and pushing the exposure later. The results are even more similar if you compare ISO 200, pushed by 4EV to the native ISO 3200 shot. This isn't true of all cameras: with the Canon EOS 7D II, for instance, you're better-off using the higher ISO setting.

This means that rather than using a high ISO, it's quite possible to use a lower ISO setting and push it up up to 4EV in post-processing. The advantage of this approach is that, while the shadow noise is likely to be very similar to having shot at the higher ISO in-camera, you should gain several extra stops of highlight detail, since you're using lower levels of hardware amplification and hence won't have amplified that highlight data into clipping.

The idea is that if the scene has highlights that are clipping at ISO 3200, you will be better off by keeping the same aperture value and shutter speed, but turning the camera back down to ISO 200 and brighten it later, from Raw. This way you can get essentially the same shadow noise performance but with an extra 4EV of highlight information. And this is made possible by the incredibly low noise floor of what we're calling an 'ISO-invariant' camera.