crowsnest is the camera control module used by klipper

in the crowsnest.conf file, you can set up the camera. specifically, you can disable autofocus in the [cam] section

v4l2ctl: -c focus_automatic_continuous=0     # Add v4l2-ctl parameters to setup your camera, see Log what your cam is capable of.
                                             # not sure if the -c is required here or not          

this corresponds to the command line functions:

v4l2-ctl -l                               # will show all controls available to the camera
v4l2-ctl -c focus_automatic_continuous=0  # disable autofocus

my particular camera includes

Camera Controls

                 focus_absolute 0x009a090a (int)    : min=0 max=831 step=1 default=0 value=0
     focus_automatic_continuous 0x009a090c (bool)   : default=1 value=0