Currently the Motion Blur section of Post Process volume offers three values to tweak (Amount, Max and Per Object Size).
What “proper” motion blur values should we use to get artifact free camera and per object motion blur for a cinematic game targeting 30 FPS?
It’s really an art preference, just start playing around with it and see what works well with your project.
It’s not an art preference. The most important factor is the amount value, which defaults to 0.5, which should be equivalent of 180° shutter, which most of the movies are shot with. You should never under any circumstances use 1.0 if you don’t want your visuals looking like crappy soap opera. 360° shutter is also known as shutter crime, and makes things look just nasty and smeary. You can go lower than that though, like 0.25, which would simulate shorter shutter time, but you may end up with a motion that looks choppy and strobbing. Generally, unless you really know what you are doing, leave it at 0.5.
Max and Per Object size are error correction parameters used to limit motion blur in certain cases to alleviate visual artifacts at the expense of motion blur accuracy. Unless you are seeing some significantly distracting motion blur artifacts in your project, then there’s no real need to touch those.
There’s quite an issue of game developers in general often not understanding cinematography, and therefore motion blur, and then overkilling it with things like shutter crime, or sometimes even worse, arbitrary motion blur values without any real world camera physics basis. Such approach then most of the time leads to ugly, unbearable motion blur which is the very first thing player turns off in options the very first time they launch the game.
I would add to that the countless issues that result form post process motion blurs and the artifacts that follow, notably on transparent surfaces. I mentioned in another post that setting it to 0.25 in such circumstances minimizes these artifacts and could be a safe margin, I also noticed that values such as 0.25 act visually more like 180 degree shutter than 0.5 in these post process mblurs.
Also regarding gameplay mblur smears, i’ve noticed it has more often to do with drop of framerates pushing mblurs into such bad looking smears than the settings themselves. But could be both.
What I was talking about is that in some games, motion blur amount is not dependent on framerate, but constant, as it was implemented by developers who had no idea how it’s supposed to work. So then you would end up with same amount of motion blur regardless of if you ran at 90 or 30 FPS. You can imagine how terrible that is to look at 
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There’s actually new “Target Framerate” setting I think since 4.25, which finally makes the motion blur framerate dependent, like the real camera would, but only if you set it to 0. I have no clue why it’s not the default value. Anyway, if you want a great looking, non distracting motion blur, just use these settings:
If your game runs at anything above 30 FPS, you should see that the motion will now look a lot less smeary and natural, but motion blur won’t be completely gone. It will be just right enough so that it won’t bother people and they won’t want to turn it off.
Sometimes… ( ͡° ͜ʖ ͡°)
You rock bro…
If I’m rendering a cinematic at 24 FPS, should I set the value to 0 or 24?
0 makes it auto, so it doesnt matter. Also, if your making a game make sure to add an option to turn either one off, because 24fps+motion blur would not go over well with some players.
I’ll be sticking with 24 just in case. Appreciate the insight!