Exposure Latitude

In this test we look to see how tolerant of pushing exposure the E-M5 II'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. Here we look at images shot with matched f-number and shutter speeds. This means the images are only directly comparable when comparing cameras with the same sensor size, since there will have had access to the same amount of total light.

If you have a look at these files, pushed by an increasing number of stops, you can see that you can comfortably push by 3EV before noise starts to become too unpleasant. This is consistent with the camera's performance at ISO 1600 (which is usually accompanied by an exposure 3EV shorter than ISO 200), which is the setting at which noise starts to intrude on this camera's images. This means its Raw files are more flexible than those of the Canon EOS 70D, for instance, but less so than the Nikon D5500.

Interestingly, although the E-M5 II's shadows are noisier than the Nikon's, it's actually performing very similarly: proportionate to its sensor size. At the same shutter speed and f-number, the Olympus is receiving around 2/3EV less light than the Nikon, because its sensor is smaller. If you compare the Olympus to the Nikon when the D5500 is given 1EV less light, the Olympus is doing similarly well: suggesting that for those first few EV, the difference between the two cameras mainly comes down to sensor size.

This makes its ability to out-perform the Canon seem even more impressive.

Real-world impact:

Image Info: ISO 200, F5.6, 1/200th sec
Conversion settings: Exposure +2EV, Shadows +100, Highlights -98

The effect of this is that the E-M5 II's files have a good, though not amazing, degree of flexibility. It means you can expose to protect the highlights in high-contrast scenes, then pull the shadows up to a good degree, before the noise becomes intolerable - offering far more dynamic range than the JPEGs can.

Interestingly, the high-resolution mode offers greater dynamic range, as a result of it sampling the scene multiple times. This helps average-out the noise in the scene, meaning you get less noise when you pull up shadow detail (or can push files further before you get the same amount of noise).

ISO Invariance

It's not just high dynamic range scenes that benefit from a camera with the high (base ISO) dynamic range that comes from having a low noise floor: it can also reduce the need to amplify the sensor's signal to keep it above that noise floor at higher ISOs.

Here 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, rather than using a high ISO, it's quite possible to use a lower ISO setting and push it up up to 3EV, without too much of a cost. The advantage of this approach is that, while the shadow noise is likely to be very similar, you should gain several extra stops of highlight detail, since you're using lower levels of hardware amplification and won't have amplified that hightlight data into clipping.