Of course, in hand-drawn animation (and similarly in CG animation), there is the advantage of creating key poses first to create the right timing, and then filling in the in-betweens later to smooth it out. Stop-motion does not have this luxury because it is all done straight ahead, with no chance to go back and finesse the timing once it has been shot. Some contend that the terms keys and in-betweens are useless for stop-motion animators for this reason—because it is straight ahead, and every pose simply leads to the next one. Although this is true, I think it’s still useful to sometimes think in terms of keys and in-betweens when approaching stop-motion, especially if one crosses over into other mediums on occasion. At the end of the day, it’s all animation, and the basic principles still need to be relevant no matter how it’s done. Hand-drawn animation can also be executed completely straight ahead, and it is often necessary to get the right motion (such as the follow-through motions of a tail on a character).

A general rule when it comes to timing straight ahead is to decide which poses the audience really needs to see. The keys do not refer only to the main parts of an action; they can also refer to the main parts of the story being communicated to the audience. Which parts of any particular action or performance are the important parts that the audience should not miss? When you are moving straight ahead with the various poses of your puppet, and you find yourself getting to these important parts, slow down the positioning into a few tiny increments that “favor” those key poses. Those are the poses you want to hang out with for a while so the eye has a chance to see it. Better yet, you may need to cushion your positions into a hold so the pose is really noticeable. My general rule, which I picked up learning animation and often re-iterate to my students, is that at 24 frames per second, it takes six frames to feel something, eight frames to see it, and 12 frames for it to really soak into the brain. If you are shooting on twos, this principle translates into three, four, and six moves, respectively.

Animating straight ahead in stop-motion contains a deadly trap—how easily an animator can get locked into a repetitive, trance-like act of move puppet, take picture, move puppet, take picture, move puppet, and so on. True, this is basically what happens, but it becomes very easy to get sucked into this so much that the timing of the animation becomes too even, floaty, and aimless. There should be some planning and rhythm to these movements—some close together, some far apart, and, when appropriate, grinding to a halt, not moving at all, and settling into a hold. It is perfectly fine to have your puppet stop moving; I find myself reminding my students of this at times. I will admit this concept is hard to grasp because if the puppet is not moving, it’s not animated! What matters is that when it’s not moving, it still feels alive. This can be controlled by knowing how long to hold an expression or pose to make it read, and when it begins holding too long.

If a character moves into a hold, it can probably only do so for a maximum of 2 or 3 seconds before it loses its breath of life. At the very least, a hold this long or longer should be broken up by a blink or subtle secondary movement to keep it alive. For instance, if a character turns their head to look at something and holds before reacting to what they see, holding for six or eight frames would be a very quick glance, and holding for 16 to 24 frames would be a more intent look. A longer hold would indicate a slower reaction and denser character, whereas a shorter hold would indicate an immediate reaction from a character who is more alert. Breaking up a puppet’s actions with an eight-frame hold here and a 12-frame hold there, and so on, is vital to good timing and ultimately a good performance. It is more natural and lets the audience soak in the moments that are most important to the scene as a whole.