Most tripod ball heads has at least two knobs - main locking knob for the ball and pan locking knob. However, some heads has more knobs, for example Sirui G-10KX has four - pan locking, main locking, friction and plate locking.

My question is - what exactly is the difference between main locking knob and friction knob (or maybe some other friction control mechanism, not neccesarily a separate knob)? Tightening or loosing both of them affects the amount of strength required to "move" the ball. For the record the salesman told me that the friction knob affects the angle I need to turn main knob to lock the ball. This explanation seems too vague, so I tried to get an answer here.

Most tripod ball heads have at least two knobs - main locking knob for the ball and pan locking knob. However, some heads have more knobs, for example Sirui G-10KX has four - pan locking, main locking, friction and plate locking.

My question is - what exactly is the difference between main locking knob and friction knob (or maybe some other friction control mechanism, not neccesarily a separate knob)? Tightening or loosening both of them affects the amount of strength required to "move" the ball. For the record the salesman told me that the friction knob affects the angle I need to turn main knob to lock the ball. This explanation seems too vague, so I tried to get an answer here.