Removing the focus ring retainer and focus ring reveals the ends of the outermost (primary) focus cams and the slots in the outer focusing barrels engaged by a leaf spring in the manual focus ring.
<a href="//commons.wikimedia.org/wiki/User:Phiarc" title="User:Phiarc">Phiarc</a>
CC BY-SA 4.0
<span class="int-own-work" lang="en">Own work</span>