Check Mr.Gunther's review, the godfather of timelapse.
The mechanism for time-lapse:
It works by adjusting the angle of rotation, not the speed of rotation, with four options: Star Tracking Mode, Move Shoot Move mode of 0.05, 0.075, 0.1, and 0.125 degrees per picture. Therefore, you control the camera's rotating based upon the angle selected, and the interval set on your timer (you need a separate timer/intervalometer, which is inexpensive). The longer the interval you set, the slower the rotation. Once you are done taking a picture (which the rotator ‘knows’ through the hot-shoe cable), the rotator will turn the defined angle, which means that the camera is not turning while the picture is being taken.