def camstart_com(afjob=None, afrange=None, afsteps=None):
    """Start the cam scan with selected AF job and AF settings.

    Return a list with parts for the cam command.
    """
    if afjob is not None:
        afjob = 'afj', str(afjob)
    if afrange is not None:
        afrange = 'afr', str(afrange)
    if afsteps is not None:
        afsteps = 'afs', str(afsteps)
    template = [('cmd', 'startcamscan'), ('runtime', '36000'), (
        'repeattime', '36000')]
    for cmd in [afjob, afrange, afsteps]:
        if cmd:
            template.append(cmd)
    return template
