Build a camera focus rig
Control focus and DOF with 1 empty
Become a better low poly artist in 5 minutes each week.
By Samuel Sullins
THERE’S A VIDEO IN THIS ONE: scroll really fast and you’ll find it...
Imagine you’ve just finished building an awesome scene. (maybe it’s the final battle from Endgame. All done in Blender.)
Now it’s time for you to set up the camera. You spend 20 minutes looking for the default camera (it was inside your Thanos mesh.)
You position it carefully, matching your reference. Everything is looking good. Really good.
Then you remember: this is supposed to be a realistic scene. You need to turn on depth-of-field and make out-of-focus objects all blurry.
But for that to work, you have to set up a focus object—you grab the eyedropper and pick Thanos. But somehow, he’s not in focus—nothing is working!
You give up. Fine, you say. No depth of field. I’ll just have a boring scene.
And when you render it out and show it to your friends, they say stuff like “yipe I’m not an artist but even I know this needs depth-of-field” or “good render. Hope that’s just practice, ‘cause it sure doesn’t look realistic.”
I’ve had some ugly, unrealistic renders.
Then I discovered a solution that fixes this 80% of the time. Just adding depth-of-field makes a huge improvement, and it doesn’t have to be hard.
I figured out a really easy camera rig that lets you control focus AND depth-of-field with just 1 object.
The rig I’m going to show you is so simple, so easy, that it’s hopelessly boring to look at. So here’s a picture of what we’re not going to make.
If your Blender scene looks like this…you might be overcomplicating something.
And now we begin:
First, you need to understand depth of field, and why Blender’s doesn’t work properly.
Imagine a camera, pointed at a field of flowers.
The camera is focused on 1 flower. That’s the subject.
Flowers further away will be out of focus. Flowers closer to the camera will be out of focus.
Flower that are the same distance away will also be in focus, just like the subject.
The depth of field is everything that’s in focus. A shallow depth of field means that only the subject is in focus—anything closer or further away is out of focus.
A wide depth of field means that more flowers are in focus. If it’s wide enough, maybe the whole field is in focus.
Depending on what you’re taking a picture of, you want more or less of the scene in focus. A portrait photographer only wants the subject in focus. A landscape photographer wants the whole scene in focus.
A camera has a setting called the aperture that allows you to control this. The aperture is the opening at the end of the lens: a wider aperture lets more light in (which causes shallow depth of field.) A smaller opening lets in less light (which allows more objects to be in focus.)
Cameras in Blender work the same way. You choose an object to focus on, and you can adjust an aperture setting (called the Aperture F-Stop.)
(It’s backwards though! Smaller value = wider aperture = shallower depth of field = more blurry.)
There’s a problem with that.
When you pick a Focus Object, it focuses the camera on the origin of the object you choose. (just click your camera, click the Camera tab in the Properties panel, scroll down and enable Depth Of Field, and you’ll see the Focus Object option.)
That’s no good. Your Thanos’ origin point is somewhere inside his stomach, 10 meters from the camera. But the surface of the mesh is only 9 meters away from the camera.
Which means your camera is focused on the wrong spot!
Now you see the trouble. This is what you’re going to fix:
Building The Rig
“Building” is an overstatement.
Press Shift + A. Pick an Empty > Plain Axes.
Name the empty “Focus.”
Open the N sidebar panel. Find the Scale section, right-click, and select Copy As New Driver.
In the Camera settings, enable Depth Of Field.
For the Focus Object, choose Focus.
Now, in the Aperture section, right-click in the F-Stop value and choose “Paste Driver.”
This will allow the scale of the empty to control the F-Stop value. But it needs some fine-tuning.
Right-click on the F-Stop value and choose Edit Driver.
Change the driver type to Scripted Expression and in the expression box type “1/scale.”
Now the Aperture is set to the reverse of the focus object’s scale.
And the rig is complete!
How to use it:
Click the magnet at the top of the screen to turn on snapping.
Open the little arrow next to it and pick “Face Project.” Now any object you move will snap against other objects.
Select your empty and press G to move it. It will snap directly against Thanos—and he’ll be in perfect focus (do this in rendered view!)
Hit S and scale the empty to change how out-of-focus things get. Smaller = more in focus. Bigger = blurrier.
Fine. I’ll go record a video for you. But don’t expect it to be good…
Watch, if you like:
1 Low Poly Pick
Rare find this week!
This one is by Izzy Stijn.
The only color is from the lighting.
This render is one of those rare combinations of detailed and low poly that works really well.
Low poly rocks are difficult, since you have to avoid making a shapeless blob. These rocks are simple, but sharp and faceted—they’re clearly cut and broken, not natural. They’re also piled in a very realistic manner.
The wood is my favorite part. Since the entire scene is gray, how do I know it’s wood?
It’s a great example of taking a well-known real-world detail and simplifying it for use in low poly.
That’s why it’s brilliant. Just by adding a few simple cracks and dents, she’s shown us that it’s clearly wood. Nothing else in the world has that kind of cracks.
Another cool detail is the fireflies around the lamp. Adds detail without needing a detailed mesh!
Izzy even has a breakdown on the lighting and materials right here.
Can't think what to blend?
Try something wooden. A half-done building, or a dead tree.
P.S. Chapter 3 finally lives! If you’re into that kind of thing.
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