Getting Started With After Effects Expressions

After Effects December 21, 2019 4 min read

After Effects expressions are like a secret key that opens way more of After Effects’ potential. They can be used to better control animation techniques, to randomize parameters, and to create more fined tuned results for things like physics.

Also, they are super scary for the uninitiated. I mean, take a look at this expression borrowed from Greymachine.

amp = .1;
freq = 2.0;
decay = 2.0;
n = 0;
time_max = 4;
if (numKeys > 0){
n = nearestKey(time).index;
if (key(n).time > time){
if (n == 0){ t = 0;
t = time – key(n).time;
if (n > 0 && t < time_max){
v = velocityAtTime(key(n).time – thisComp.frameDuration/10);
value + v*amp*Math.sin(freq*t*2*Math.PI)/Math.exp(decay*t);

You are an artist right? You didn’t sign up for this math and coding stuff.

Well, here’s the thing…expressions aren’t that bad once you get the hang of them. If you take a little time to learn the basics of structure and variables, they can be your best friend, allowing you to work faster and smarter while taking your animations to the next level.

We’ve rounded up some great resources for getting started with After Effects expressions so you can get over your fear and learn to embrace the magic behind “t = time – key(n).time;”.

Video Copilot – After Effects Basic Training: Expressions

You know we love Video Copilot around here. Anyone who uses After Effects on a regular basis probably loves Video Copilot. Not only do they produce great plug-ins for After Effects, but they also do a lot of free training.

The After Effects Basic Training tutorial series has 10 sections, and guess what? Section 9 is on expressions. This is a great place to start with expressions as the tutorial is geared towards beginners.

In this 15 minute tutorial, Andrew Kremer shows viewers how to create a simple expression, how to change values, and how to set up controls for expressions. Not a bad way to get started.

School Of Motion – After Effects Expressions 101

School Of Motion is another great resource for After Effects education. They offer in-depth paid courses like their Animation Bootcamp which will set you back about $800.

But they also have several free tutorials that are a great source of After Effects knowledge. One example is the After Effects Expressions 101 tutorial. This tutorial features some of the same ideas as the Video Copilot example like how to create an expression and set up controls. But it can be useful to get the info from another source. And the teacher uses an example of a different kind of expression here. Double bonus!

AE Enhancers: Expressions Forum

AE Enhancers is a forum dedicated to the craft of doing “outside of the box” stuff in After Effects. In other words, it’s all about expressions, scripts, and animation presets. These are the types of things that power users look to in order to create better and more advanced animations.

Their expressions section of the forum is broken into 3 subsections, expressions discussion, expressions library, and expressions tutorials. For those getting started, we’d suggest taking a look at the expressions tutorial section.

There are currently about 20 topics in the expressions tutorials section and they aren’t all for beginners. But poking around in there, you’ll find some great things to start with like the topics “Easy Things To Do With Expressions.” As you get a little more advanced, you can check out some of the other tutorials to expand your knowledge.

Adobe – Expression Basics

While there are many great teachers out there sharing their knowledge about After Effects and expressions, it’s always smart to go to the source for some basic education. Adobe manages a great codex of learning tools for all of their products, so of course, they have a section for After Effects expressions.

The Expressions Basics page is, maybe a bit wordy, but chock full of all kinds of expression information. They cover the various expression controls, key symbols, and editing basics. But they also dig way deeper into the programming language behind expressions, and common expression errors. A must-read if you are serious about learning expressions.

Motion Script

Dan Ebbert has been working with expressions and scripting in AE since before many of you knew what AE stood for. He’s an expert on the matter, and he’s collected all of that combined knowledge into one site called Motion Script.

The site contains a wealth of information including Mastering Expressions, which gets into the nitty-gritty of the expression scripting language and the math behind it. Don’t start here, but definitely spend some time here after you understand the basics of how expressions work and you want to dig a little deeper.

Expressions aren’t really all that scary after all. Sure, they look intimidating but so do clowns, and they are cute and cuddly…right? Seriously, all you need to get a handle on expressions is a little basic knowledge and the right resources to turn to when you want to learn more. We hope these resources help get you off the ground in the world of AE expressions.