The folks over at DPReview have got their hands on a 5D Mark IV. One of the tests they’ve performed with respect to video is how well it handles movement. Rolling shutter artifacts are just a fact of life with CMOS sensors. These types of sensor capture a scene line by line. They do it very quickly, although not quickly enough to prevent things from appearing to lean or just looking plain weird.
CMOS sensors have improved on the rolling shutter issues over the last few years. Canon’s new 5D Mark IV, however, doesn’t really seem to be that great at all. It’s certainly not as good as many were hoping for, especially if shooting 4K.