Much of the initial concern about the EOS 5D Mark IV’s video has been about its substantial 1.64x crop (relative to the full width of the sensor, 1.74x compared to the 3:2 region) and its use of the inefficient Motion JPEG compression system (which limits the ability to use SD cards with any dependability).
However, upon shooting with the camera we found it to have significant rolling shutter. We’ve demonstrated the effect alongside the EOS-1D X Mark II, which reads out its sensor fast enough to exhibit pretty low levels of rolling shutter, and the Sony a6300, which shows a relatively high level of rolling shutter.
Obviously we’ve panned faster than you ever sensibly would, to make the difference clearer. If you’re careful with the way you move the camera, this rolling shutter effect may not be too apparent however, for some kinds of shooting, it can be distracting.