If you want to rotate the motor to a specified position the answer is yes, you do.
A positioning system is needed to keep track of position and turn the power off when it’s in position. Such a system is implemented on our High Resolution Twin Motor Kit.
If you’re not interested in the exact position but want to rotate, for example, a focusing lens until the camera software indicates when it’s in focus, you will not need a positioning system.
In some applications a combination of these principles can be used to decrease system response time. The positioning system can, for example, bring the focus into range, and then use microstepping to find the exact focal point.