The focal length of a SLR camera can only be achieved by manually adjusting the zoom ring, and the focusing can be switched to manual focusing and autofocus.

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.