A camera has several features that can make your image top quality. But in order to get the best image exposure, the right settings needs to be implemented. The person behind the camera has to program the settings, and tools like light meters can help guide them.
Light can come from several sources; natural or artificial. In a professional setting, it is crucial the cinematographer or photographer be able to read what those lighting outputs are and eventually input the information into the camera to create a proper exposure.
Here is a great video from Sekonic, featuring Bobbi Lane.
Cinemills provides lighting equipment from the motion picture, television, and photography.