Exposure Latitude

In this test we look to see how tolerant of pushing exposure the G7'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 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, in real-world shooting situations you may well be limited by what shutter speed you can use, so this test gives you an idea of the amount of processing latitude different formats give.

Based on our test results, we find that the GX85's performance is virtually identical to the Panasonic G7. That means it has a similar flexibility and noise performance as the Olympus E-M5 II. That's a decent result in the Micro Four Thirds realm, although the GX8 does show a slightly better performance, especially with less drastic pushes.

The smaller sensor means it falls behind the Nikon D5500 but this is better than the Canon EOS 750D/Rebel T6i, whose sensor performs poorly by modern standards.

Using the camera's electronic shutter causes it to drop to  12-bit mode, which reduces dynamic range. Thankfully, though, the GX85's redesigned shutter shows no signs of the shutter shock that plagued the G7, so there's less need to use the electronic shutter mode.

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 situations 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 in noise performance between shooting at ISO 1600 and shooting the same exposure at ISO 200 and brightening. This means that, when in mechanical shutter mode, you are likely to be able to underexpose ISO 200 by 3EV and brighten the Raw file later, rather than shooting at ISO 1600. Why would you do this? Because using less hardware amplification means that you don't end up over-amplifying the top 3EV of highlight data: so you retain highlight data but with very little noise cost. This is essentially the same outcome as the Olympus E-M5 II.

Just like the G7, this isn't true in Electronic Shutter mode. Just as the additional noise started to creep into the exposure latitude images. A 2EV push of a file starts to exhibit more noise than natively shooting at ISO 1600 and after a 3EV push it's really obvious. Given how much of your image is likely to be made up of dark tones in the situations in which you might use high ISO settings, this difference is likely to be very obvious.