MFL switch

The MFL (Manual Focus Lock) switch disengages the focus ring on the lens. After manually focusing the lens to the desired position, set the MFL switch to ‘LOCK’ in order ]to disengage the focus ring.
This prevents the focus of the lens from being moved by accident (such as when attaching a lens heater or changing the composition) and causing out of focus images. The focus ring can still be rotated but will have no effect.
* Please note that some camera bodies may continue to AF even if the MFL switch is set to ‘LOCK’, or allow AF temporarily even when the camera has been set to MF, and shift the focus when the MFL switch is set to ‘LOCK’.