Exposure Latitude

Editors' note: This page has been edited from content originally published here on August 31, 2016.

One of the most easily understandable ramifications of increased base ISO dynamic range is increased processing latitude; that is, the ability to brighten Raw exposures without drastic noise penalty (there will always be some penalty due to shot noise). This can be particularly useful in dealing with high contrast scenes, which require conventional underexposure to prevent bright tones from clipping to white, with requisite shadow brightening - or tone-mapping - to make dark tones visible on our current dim display technologies.

So in this test we look to see how tolerant of pushing exposure the 5D Mark IV's Raw files are. We've done this by exposing our scene with increasingly lower exposures, then pushing 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.**

The 5D Mark IV shows significant improvements in exposure latitude thanks to its increased dynamic range. After a 5 EV push, it's well ahead of the 5DS which, despite its old sensor design with off-chip analog-to-digital conversion, was already 2/3 EV ahead of the 5D Mark III (which we cover in-depth on the next page). That places the 5D IV well ahead of its predecessor, nearly catching up to the excellent Sony a7R II. Despite its improvements, it's not at the level of the current industry leader, the Nikon D810, nor even the best APS-C cameras. After a 6 EV push, the 5D Mark IV falls further behind the a7R II and D810, but the improvement over the 5DS is pretty dramatic.

Digging a bit deeper: the 5D IV shows improvements over the 5DS with even more moderate 3-4 EV pushes, but especially so when files are pushed 5-6 EV. This means you'll see the advantages of the on-chip ADC in the form of less noise not just with drastic exposure adjustments, but even more moderate ones. Results are about on par with, if not slightly better than, the 1D X II. And while the 5D IV falls just slightly short of the Sony a7R II, the differences are really only visible after fairly extreme pushes.

Differences against the current dynamic range market-leader, the D810, start becoming apparent after even a 3 EV push, and fairly significant after a 6 EV push. The D810 can perform so well because of even lower read noise, and increased sensor capacity for light at ISO 64 that gives its files a nearly medium format-esque quality.

On the next page, we'll look at how ISO-invariant the 5D Mark IV is, and also directly compare the Mark IV to its predecessor, the Mark III.

* Digital signals tend to be more 'protected' or immune to noise than analog signals, because they're binary. It's the same reason CDs (digital) don't exhibit the pops and crackle of records (analog).

** Differences in noise performance in our Exposure Latitude test are caused by both read noise and shot noise, the latter of which is mainly determined by the amount of light the camera has had access to. Therefore, one might argue the results are only directly comparable between cameras of the same sensor size. However, sensor size differences will also be relevant in real-world shooting if you're limited by what shutter speed you can keep steady, so this test also gives you an idea of the amount of processing latitude different formats give when light-limited.