Disable/Enable Autofocus

List all devices

v4l2-ctl --list-devices

Example:

Microsoft© LifeCam Studio(TM): (usb-0000:00:14.0-2.1):
      /dev/video3
      /dev/video4

Here /dev/video3 is the webcam. To get all options:

v4l2-ctl -d /dev/video3 --list-ctrls

If the focus can be configured can be seen:

focus_abolute ... (int): min=0 max=40 step=1 dfeault=0 value=4 flags=inactive
focus_auto ... (bool)  : default=1 value=1

To deactivate autofocus and set it manually:

v4l2-ctl -d /dev/video3 --set-ctrl=focus_auto=0
v4l2-ctl -d /dev/video3 --set-ctrl=focus_absolute=12