It still to this day does not make any sense to me why UE4, with all the push for physically based rendering, still defaults the motion blur amount to a value unrelated to actual framerate. Not only does it lead to issues like these, but it’s also source of the reason so many gamers hate motion blur. It’s not that motion blur is bad, but the unnatural motion blur is bad. The default MB target FPS value of 30 will give you motion blur amount adequate to frame rate of 30 FPS, even if your game runs at 120, making it look like an ugly smeary soap opera 
1 Like