1. The switch of the fuselage focus motor is on the fuselage, m is manual and AF is automatic. Such as Nikon D90 fuselage:
2. The switch of the lens focus motor is on the lens, MF is manual and AF is automatic. For example, all autofocus lenses:
3, m stands for manual, and the manual focus of all SLR lenses can be adjusted by the focus ring of the lens.