Parenting in After Effects is similar to parenting in real life, only in AE the child layers actually listen to their parents–all the time, every time. Imagine you have 32 layers that you want to move onto the screen all at one time. You could either animate all 32 layers and tell each one where to start and where to go, or, you could make one layer the parent and simply link the other 31 layers as children to the parent layer. This feature allows you to create a single animation and have each layer follow along.
Let’s see this in action. First, click on your DEMO layer and hit command+D or ctrl+D, which will duplicate your DEMO layer. Select the top layer and from your main AE program menu above click Layer > Solid Settings > and then change the name and color to something different to avoid confusion.
The next step is to use the parenting feature, which is called the Pick Whip tool. You can click on it and drag it to the layer you want to follow along. This process is what we call, parenting. It specifically defines the layer you choose as the child–all animations that happen to the parent then also happen to the child. You can also select the child layers by using the drop menu to the right for each layer and assign the parent that way.
To see how how this works, you will need to select your parent Layer. Once you have it selected, move the layer around inside your preview window and notice that your other solid layer is moving with it. This is because you have told AE that this layer is the child.
If you select the child layer and then move it on screen, the parent layer will not imitate the child.
What is a null object? A null object is an invisible layer that you can create to be a super parent. For example, you may have created multiple layers, all of which are parented to child layers, but now you want to move everything off screen at once, or better yet, spin off screen while flying towards the camera. Animating that over the keyframes you have already created will be a nightmare, so this is where null objects come in.
To create one, right click in your layer panel, then hit New > Null Object. The next step is to make the null object the parent to all of your current parent layers.
Animating A Null Object
To animate a null object, open up the transform controls the same as you would any other layer. Set your keyframes for scale, opacity, position or rotation. No matter how many or how few layers you have, you‘ll find that null objects can help tremendously in any sequence–they’re your invisible helpers making animating easier and stress-free.
After Effects has motion blur built right into the layers panels with an easy on/off toggle. If you have layers moving around, it’s best practice to make it blur. You can easily turn on motion blur by selecting the layer(s) you want to blur and select the Motion Blur switch. You can also apply motion blur to your entire comp by selecting it from you comp toolbar.
To save on preview time, keep your motion blur off until you are ready to render, as motion blur will take longer per frame to RAM Preview.