Apple Motion 3 - Manual (Page 561)

Chapter 6 Keyframes and Curves 561
To set the Keyframe Thinning setting:
1 Select Off, Reduced, or Peaks Only.
2 Click OK.
Off: No thinning is applied. Keyframes are applied at every frame where the parameter
is changed.
Reduced: Motion eliminates keyframes that can easily be replaced with a simple curve.
Peaks Only: Only keyframes with dramatic value changes are recorded.
Disabling Animation While Playing
If you leave the Record button on, keyframes are added whenever you make
adjustments. If you want to restrict keyframing to when the project is not playing, you
can disable that feature individually.