Frame rate
Human Vision and Perception
The human visual system processes 10 to 12 images per second individually. Modulated light is perceived as stable above 50Hz, and image recognition is possible in 13 milliseconds. The persistence of vision can make short stimuli appear longer, and multiple short stimuli can be perceived as a single stimulus.
Historical Frame Rates
Early silent films had frame rates between 16 to 24 FPS, with Thomas Edison recommending a minimum of 46 FPS for motion perception. Frame rates increased to 20-26 FPS in the mid to late 1920s, and silent films were often shown at 22 to 26 FPS in theaters. Sound film was standardized at 24 FPS to accommodate sound synchronization.
Animation Frame Rates
Drawn animation is often shot on twos, resulting in 12 drawings per second. Quick movements may require animating on ones for adequate conveyance. Saturday morning cartoons are often produced at 8 or 6 drawings per second, while anime is typically drawn on threes or twos. A blend of animating on twos and threes keeps fluidity without high cost.