As you might know, there are different types of animation, and today I'm going to focus on the types of animation you can do in 2D. Frame-By-Frame, Rotoscoping, Cut Out Animation, And Rigged Characters with Inverse Kinematics.
This is also known as Classical Animation, Traditional Animation or Flip Animation. What you do here is pretty simple, you draw each frame. Ha! Simple, right? I know. But wait, there's a way to do it. First, you have to know your frame rate, which in the next example will be 12 fps (frames per second), and for that we will have to do 12 drawings for one second.
How to do it: You can do this by having the correct timing of the movement. First, you need a sample (if you are animating a character jumping, then you need a video of someone jumping).
Once you have the video, there are many ways to calculate time and convert it into frames. My favorite is: Stop Motion Works Stopwatch (link at the end of this article). In my example it will be a 8 frame jump.
What you do is: You draw the key frames of the skeleton of your character, and then, you continue by drawing the in-between frames. Let's make an example of a female jumping (only the action, that means, no anticipation and no aftermath, to keep this simple and friendly). You draw the starting pose (frame 1), then the character in mid-air (frame 5), and finally the landing posture (frame 9).
After you have those 3 drawings, you draw a the in-between frames. A drawing between starting pose (frame 1), mid-air pose (frame 5), and landing (frame 9). In other words, you draw frames 3 and 7. And finally, you draw the missing frames. Easy enough? After the skeleton is animated for all the frames, you add detail frame by frame, a little bit of body form, then a more detailed head on every frame, then the right arm on all the frames, and so on. You continue until you have a detailed character on every frame.
Pros: Your limit is your own imagination. Characters can do whatever you want, have any facial expression you want and any pose you can come up with.
Cons: Takes a lot of time. Animating 1 second can take a couple of hours.
Rotoscoping is another form of frame-by-frame animation. What you do is you take a piece of footage and import it into your favorite 2D animation software. Now, all you do is draw the silhouette of every frame. Then you substitute those drawings with some details that make up your character. Big nose? Long hair? Fat? Thin?
Pros: You work a bit faster, because you don't have to draw the key frames and then the in-between, you just follow each frame; and the motion is very realistic, because you just follow the footage frame by frame.
Cons: Even though it can be a bit faster than Traditional Animation, you still need a lot of time to do it, because you have to draw every frame, and also, you start to get limitations: The character will only do what the person in the footage does.
If you need it to do something else than what you have in the footage, then you will have to switch to traditional animation, drawing the key frames first, then the in-between.
3. Cutout Animation
This kind of animation takes preparation. You take each angle of your character (front, sides and back) and you "cut" the character into its parts (hence the name Cut Out Animation). For example, if you were to animate the front side, then you would have the head in one layer, the arms, forehand and hands for each side in a different layer, and so on. This takes time to prepare, but the good thing is that you don't have to draw each frame, you only prepare once and then you animate the character as if it was a puppet.
Pros: It's way faster to animate, because you don't have to draw each frame, you only draw your character and each facial expression once, and after the "puppet" is ready, you can start animating.
Cons: It can take a some time to prepare and the character is limited by the rig. That means, you can't put her in any position you can imagine, only those you can achieve with the rig. Another disadvantage is that it's not the fastest way to animate, because if you want to move his hand, then you need to rotate the shoulder, then the arm, then the forearm until you get the hand to the place you need.
4. Rigged Characters (using Inverse Kinematics)
This type of animation is the fastest to achieve. Software like Toon Boom or Animation Studio have a lot of tools that help you rig a character with inverse kinematics and automate facial expressions.
Inverse kinematics are the opposite of forward kinematics (used in Cut Out animation). In Cut Out animation, if you need the hand to be in a position, you have to rotate the shoulder, then forearm and so on. Inverse Kinematics let you click on the hand and move it to the position you want, and the positions and rotations of the shoulder, arm and forearm are automatically calculated by mathematical formulas.
Pros: You animate at top speed. With just a few clicks and drags.
Cons: It takes longer to prepare than the cut out animation, but cuts your working time exponentially. Another disadvantage is that you have limits, you can only do what the Rig allows you to. You can't move the character into any position you can imagine, but only into those allowed by the rig.
You cannot have it all. You either have unlimited movement, but huge time investment, or you get limited movement with little time investment. These are the options you have. And for the record, Disney movies use frame by frame, but the shows you see on TV, because they are under schedule, they use a combination between Rigged Characters and Frame by Frame, depending on the shot they are working on.
My advice is, learn to do Frame-by-Frame animation and Rigged Characters, you need them both. But if time is a big issue, then you should definitely master Rigged Character Animation. You can find courses online.