Atmospheric Dispersion Corrector (ADC) is easy to use with your planetary camera or with your eyepiece. In just few easy step you will setup ADC for observations or imaging.
1. Specify Earth horizon in your telescope. For scope where is no right-angle mirror, such as an SCT or refractor (without a star diagonal) the horizontal axis as seen through the focuser is the same orientation as the horizon relative to the observer, and so this makes the task quite straight-forward as the mid-point of the levers is also horizontal. In this case however the mid-point can be horizontally pointing left or horizontally pointing right. In one of these cases adjusting the ADC will make the atmospheric dispersion worse but in the other orientation it will make it better. You need to find which of the two possibilities is correct by experimentation. If you have a right-angled mirror in the system, such as for a Newtonian reflector, the horizontal orientation through the focuser may well not be parallel to the horizon. You'll need to first find the horizontal axis of the sky as viewed through the eyepiece.
2. Place your ADC in focuser. ADC in rest position (two red arms) must be parallel with horizon. You must update ADC rotation in focuser due telesope rotation.
3. Place your planetary camera or eyepiece on ADC.
4. Simultaneously start rotating two red arms for best view. You need to find which possibilities is best for you. You must experimentate!