Making an Object Fade In and Out
Let’s say you want to have something fade, either in and out–maybe to get it out of your frame more subtly, maybe for an effect (like a blinking light), or maybe to create a kind of transition. Motion tweens let you do this fairly easily, even if you’re not actually moving the object.
First, create an object, convert it to a symbol, and make a motion tween. That should all be pretty basic by now.
Rather than move the symbol, we’re just going to modify its properties. So, if you want it to fade in:
Go to the keyframe that marks the start of your tween, then select the symbol. Go to the Properties menu, open up the Color Effect sub-menu, then select Alpha from the Style drop-down. Use the slider to set the alpha (opacity) to zero. The symbol should become invisible.
Move to the end keyframe and use the same directions, this time setting the alpha to 100. It’s important to always set two different alpha scores! Think of it like Premiere: if you only set one opacity score, even though you do it in a specific keyframe, the opacity/alpha for the entire section is modified.
That should be it though. The more frames your tween lasts for, the longer the symbol will take to fade in, and vice versa.