Is Depth of Field On or Off Better? How it Affects Your FPS

Depth of Field (DoF) is basically when the game’s kinda trying to copy how our eyes’ focus on stuff at different distances. Like, you know how some things look sharp, and then other stuff in the background, it’s just all blurry.

But yeah, not everything’s perfect—DoF can totally hurt your game’s performance. It’s using up a bunch of your computer’s resources, and might even drop your FPS (frames per second) by quite a bit.

Should You Have Depth of Field On or Off?

Having depth of field on or off in games is a player-dependent choice. It can add realism but also a background blur that some people dislike. Disabling it can save GPU power and boost FPS.

Below you can see the difference that Depth of Field makes in terms of image quality.

As you can see, the effect is not very natural and you can literally make it with your eyeballs by just looking at something that’s close to you.

Now, on top of that, DoF tries to act all fancy like a camera lens. It simulates lens behavior, things like the aperture and focal length, to get that sweet, sweet blur effect in the background.

This means your machine has to render each object, like light sources, with just the right amount of blur based on how far they are from where you’re looking.

Τhis “bokeh rendering” thing is no joke regarding the work it puts on your hardware. Imagine your computer having to figure out how far every object in the game is from your “virtual eyes”.

It’s a bit like a math puzzle, and the more stuff in your game scene, the more pieces that puzzle has.

How much does Depth of Field affect your FPS?

The performance hit varies per game since every game engine handles the depth of field differently. The expected FPS loss is between 3%-15%.

Dying Light is a pretty good example of a game that gets hit hard by DoF. It can lose more than 10 FPS when you turn it on.

Technical Details of How DoF Works

Depth Calculation: So, for DoF to actually work, the game’s engine has gotta figure out the depth of every single object in the scene based on where the camera is. Basically, it needs to calculate how far each thing is from the camera, and honestly, that math can get pretty messy.

Lens Simulation: DoF is just tryna copy how camera lenses in the real world work. It messes with stuff like aperture and focal length to get that bokeh effect (you know, those blurry light spots). So yeah, it’s gotta render every little light that’s out of focus as a blurry circle, and how big or bright it is depends on how far that object is from where you’re focused.

Blur Rendering: After all the depth and lens stuff is figured out, the game’s gotta render the whole scene with the right blur for each object depending on how far away it is. This basically means the game has to re-do the scene a few times, each with different levels of blur slapped on it.