After Effects Key Skills Handbook

Quick start and project setup

Launch After Effects then create a project and a composition. Use 1920 by 1080, 24 or 30 frames per second, and 10 or 15 seconds to begin.
Save your project. Create a folder structure in your disk. Suggested folders are footage, audio, renders, and assets.
Import media with Cmd or Ctrl plus I. Drag items from the Project panel into the Timeline.
Reveal animated properties with U. Reset panels with Window then Workspace then Reset if you get lost.

Use 16 bit color for richer gradients. Go to the project settings and change color depth to sixteen bits per channel when banding is visible.

Clipping masks and track mattes

Use one layer to reveal or hide another. In After Effects this is done with Track Matte.

Alpha matte step by step

Place your matte layer directly above the layer you want to clip.
In the Timeline enable the Modes or TrkMat columns with the toggle at the bottom if you do not see them.
On the lower layer open the Track Matte menu and choose Alpha Matte to use the transparency of the layer above.
Choose Alpha Inverted to hide inside and show outside.

Use Luma Matte if your matte layer is grayscale. White reveals. Black hides.

Masking with the Pen tool

Select a layer then pick the Pen tool.
Click to create points around the subject. Close the path.
Press M to reveal Mask properties then animate Mask Path if needed.

Blend modes

Blend modes control how a layer interacts with the layers below. Great for collage textures and light effects.

Select a layer and open the Mode menu in the Timeline.
Try Multiply to darken, Screen to lighten, Overlay to boost contrast, and Color to borrow hue.
Place a texture layer on top and test different modes at 30 to 70 percent opacity for subtle results.

Use an Adjustment Layer with a blend mode to affect all layers underneath at once.

Import Photoshop layers and round trip

Import a layered PSD

File then Import then File. Choose the PSD.
In the Import dialog choose Composition with Retain Layer Sizes.
After Effects creates a new composition with matching layers. Open it and animate.

Edit the PSD and update in After Effects

Right click the PSD in the Project panel then choose Edit Original. This opens the file in Photoshop.
Make edits then Save in Photoshop. Return to After Effects and the project updates.

Do not rename layers in Photoshop after import if timing is already animated. Rename first then import.

Send a still from After Effects to Photoshop

Move the playhead to the desired frame.
Composition then Save Frame As then File. Choose Photoshop.
Edit in Photoshop then bring the result back if needed.

Puppet pin warp

Animate drawings as if they are jointed. Works best on a single flattened layer or a precomp.

Select the layer. Choose the Puppet Pin tool.
Click to place pins at hinges like shoulder, elbow, wrist, hip, knee, and ankle.
Move the playhead forward and drag pins to pose. Keyframes are created for each pin.
Use Starch to stiffen areas that should not bend. Use Overlap to set which parts pass in front.

If your art is a multi layer character, precompose the parts then apply Puppet to the precomp. This keeps the deformation stable.

Bring in gif and video

File then Import then File. Choose your gif or video. You can also drag into the Project panel.
For animated gif, After Effects treats it like footage. If the frame rate feels odd, right click the item then Interpret Footage then Main and set a frame rate.
Long gifs are heavy. Convert to MP4 or to a PNG sequence for smoother editing.

Image sequences are robust. Name files with a number at the end then check the sequence box on import.

Key out a background color

Remove green or blue screens or any solid color.

Keylight basic steps

Select the clip then Effect then Keying then Keylight.
In Effect Controls use the Eyedropper on the screen color.
Change the View to Screen Matte. Adjust Clip Black and Clip White until the subject is white and the background is black.
Return View to Final Result. Tweak Screen Gain and Screen Balance if needed.
Add Advanced Spill Suppressor to remove green spill on edges.

Color Key for simple backgrounds

Effect then Keying then Color Key.
Pick the color. Increase Tolerance and Edge Thin and Feather for a quick cleanup.

Roto Brush selection

Double click the clip to open it in the Layer panel. Choose the Roto Brush tool.
Paint a quick stroke inside the subject. Use Option or Alt to subtract.
Step forward a few frames. Fix edges when the selection drifts.
Refine Edge tool helps with hair and soft areas.
When the selection is correct click Freeze so the analysis locks. Return to the Comp panel to composite.

If you edit the clip timing after freezing you will need to unfreeze and propagate again.

Keyframes and animation basics

Enable keyframes by clicking the stopwatch on Position, Scale, Rotation, or Opacity.
Move in time then change a value. New keyframes appear.
Use Easy Ease with the F9 key for smooth motion.

Essential shortcuts

P Position, S Scale, R Rotation, T Opacity, A Anchor
U shows animated properties. Double press U to show modified values.
J and K jump to previous and next keyframe.
Hold Shift while dragging to snap in time.

Loop animations with keyframes and expressions

Make a manual loop

Create keyframes for a motion, for example Position from left to right.
Select those keyframes then copy and paste them later in time.
Right click then Keyframe Assistant then Time Reverse Keyframes to create a ping pong return.

Use an expression

Animate a property once.
Option or Alt click the stopwatch to add an expression.
Enter one of the following then click outside the box.

loopOut("cycle")      // repeats the last span of keys
loopOut("pingpong")  // forward then back
loopOut("offset")    // adds the delta each loop
loopOut("continue")  // continues the existing velocity

To loop a precomp with time remap: Layer then Time then Enable Time Remapping. Add an expression on Time Remap with loopOut("cycle").

Graph editor for timing and feel

Click the Graph Editor button in the Timeline.
Select a property. Switch between Value Graph and Speed Graph from the menu on the left.
Apply Easy Ease first, then drag Bezier handles to shape the curve. Steeper means faster. Flatter means slower.
Use Roving Keyframes for constant speed across many points. Right click a keyframe then enable roving.

For overshoot, pull the outgoing handle above the next value in the Value Graph, then settle back to the target.

Export tips and common fixes

Transparent background: set your comp background to transparent, then export with QuickTime ProRes 4444 or PNG sequence.
Banding: add a tiny amount of Grain or Noise at one percent or switch the project to sixteen bit color.
Missing Track Matte column: click the Toggle Switches or Modes button at the bottom of the Timeline.
Roto Brush keeps changing: freeze the result before leaving the Layer panel.

Further reading on the Adobe After Effects User Guide and our class Notion page.

Official guide: helpx.adobe.com After Effects guide
Class notes: our Notion After Effects notes