Manual focus is the direct control of a camera/lens's focus by the photographer. This is generally accomplished by turning a focus ring which is mechanically coupled to the lens's focus, but some cameras without focus rings allow manual control over the autofocus motor.
In my lab I have two cameras, the Canon T2i and the Canon T3i, which are without their standard lenses. Instead they are mounted on a microscope. To capture the images of my samples, I set the camera ...