The temporal resolving power of the visual system is essential for the perception of the objective world. The lowest sampling rate of a sequence of images at which perception becomes fused is called the critical flicker fusion frequency. The variety of experimental data on critical frequency thresholds can be explained from a point of view of a model of the contrast sensitivity of the visual system that based on the tremor modulation signal. The model describes the dependence of critical frequency on stimulus brightness, adaptation brightness, duration, and the angular size of the stimulus. This model demonstrates that for bright stimuli with short duration and a large angular size, critical frequency values lie in the range up to 1000 Hz; the frame rate of 300-500 Hz should be considered optimal for the visual system; for small-sized angular stimuli, the critical frequency lies in the low-frequency region. Differences in the rate of flicker fusion can be explained by temporal sensitivity of magno- and parvocellular neurons.