Distortions involving signals in the greater than 16 msec range. Long-time distortions affect slowly varying aspects of the signal such as changes in APL which occur at intervals of a few seconds. The affected signal components range in duration from 16 msecs to tens of seconds. The peak overshoot, in IRE, which occurs as a result of an APL change is generally quoted as the amount of distortion.

Settling time is also sometimes measured. Long-time distortions are slow enough that they are often perceived as flicker in the picture. See the discussion on Linear Distortions.